a study on rainwater quality in selected areas of ...

A STUDY ON RAINWATER QUALITY IN SELECTED AREAS OF EASTERN AND NORTHEASTERN INDIA

A THESIS SUBMITTED TO ASSAM UNIVERSITY, SILCHAR IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN THE DEPARTMENT OF ECOLOGY AND ENVIRONMENTAL SCIENCE

By BIDISHA CHAKRABORTY Ph.D. Registration No. - Ph.D./1197/2010, dated 28.07.2010

DEPARTMENT OF ECOLOGY & ENVIRONMENTAL SCIENCE E. P. ODUM SCHOOL OF ENVIRONMENTAL SCIENCES ASSAM UNIVERSITY SILCHAR – 788011 2015

LIST OF ABBREVIATIONS ANOVA

Analysis of Variance

AP

Acidic Potential

AD

Anno Domini

BC

Before Christ

BCM

Billion Cubic Meters

B.D.L.

Below Detection Level

ºC

Centigrade

Cd

Cadmium

Co

Cobalt

Cr

Chromium

Cfu

Colony forming unit

EC

Electrical Conductivity

e.g.

For example

et al.,

et alie (and others)

EF

Enrichment Factor

Fig.

Figure

ft

Feet

GEO

Global Environment Outlook

Ha

Hectare

HCL

Hydrogen chloric acid

IMD

Indian Meteorological Department

xxxiv | P a g e

LIST OF ABBREVIATIONS In

Inch

ISM

Indian summer monsoon

Km

Kilometers

KCl

Potassium chloride

KNO3

Potassium nitrate

LP

Linear Programming

m³

Cubic Meters

MDGs

Millennium Development Goals

mg L-1

milligrams per litre

MHLG

Ministry of Housing and Local Government

mi

Miles

ml

milliliter

mS/cm

milli Siemens per centimeter

mm

Millimeters

MTA

Midterm Appraisal

NF

Neutralization Factor

Ni

Nickel

[Ni(CO)4]

Nickel carbonyl

Nm

Nanometer

NP

Neutralizing Potential

nss

Non-sea salt fraction

xxxv | P a g e

LIST OF ABBREVIATIONS NO3−

Nitrate

ND

Not detected

OCPs

Organochloride Pesticides

OFDC

Ordinance Factory Dumdum

PAHs

Polycyclic Aromatic Hydrocarbons

Pb

Lead

PCA

Principle Component Analysis

pH

Potentia hydrogenii

ppm

parts per million

RWH

Rainwater harvesting techniques

TERI

Tata Energy Research Institute

TSP

Total Suspended Particulates

UN

United Nations

UNEP

United Nations Environment Programme

UNPF

United Nations Population Fund

UV

Ultraviolet

VOCs

Volatile Organic Compounds

VWM

Volume-weighted mean

VWM

Volume Weighted Mean Average

WMS

Watershed Modeling System

WHO

World Health Organization

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LIST OF ABBREVIATIONS Zn

Zinc

µg/L

micro gram per litre

µg/m3

micro gram per cubic meter

µS cm-1

micro Siemens per centimeter

%

Percentage

xxxvii | P a g e

Acknowledgement . I thank and praise the Lord Almighty, for being with me always and for all the blessings bestowed on me during my journey as a research scholar.

I have great pleasure in placing on record my deep sense of gratitude and sincere thanks to my supervisor Prof. Abhik Gupta, Dean of the School of Environmental Sciences, Assam University, Silchar for his motivation, guidance, sincere support and constant encouragement during my research period.

I convey my thanks to the Head of the Department, all the faculty members, Prof. Ashesh Kumar Das, Dr. Aparajita Dey and the technical staffs of the Department of Ecology and Environmental Science.

I take this opportunity to sincerely acknowledge SAIF, North Eastern Hill University, Shillong and Prof. Anilava Kaviraj, Department of Zoology, University of Kalyani, West Bengal for their assistance in the Iaboratory analysis of heavy metals.

I would like to sincerely acknowledge DST INSPIRE, Department of Science & Technology, Government of India for providing financial assistance to carry out the research work.

My sincere thanks to Mr. Apurba Chakraborty of Cachar College, Silchar for providing the meteorological data.

I am deeply indebted to and owe my thankfulness to Mrs. Parvati Das, Rituparna Das, Mrs. Debonthi Roy, Archana Hazra and specially my mother Mrs. Sabitri Chakraborty, my father Mr. Sunil Kumar Chakraborty, my brother Mr. Suman Chakraborty, my maternal aunt Mrs. Manju Sen for the help rendered to me in the collection of rainwater samples from different places.

Finally my heartfelt thanks to my husband Capt. Saikat Chakraborty, my grandfather Mr. Mahendra Chandra Bhowmick, my grandmother Mrs. Bithika Bhowmick, my mother-in-law Mrs. Gouri Chakraborty, my father-in-law Mr. Dulal Chakraborty, my parents, my brother for their constant encouragement, kind co-operation and moral support given during the research period.

I sincerely all my lab mates Simi Talukdar, L. Bedabati Chanu, N. Nganbi Devi, Rinku Moni Kalita and my friends Sishirendu Das and Banasree Sinha for their kind co-operation.

CONTENTS

PAGE NO.

CERTIFICATE DECLARATION ACKNOWLEDGEMENT LIST OF FIGURES

i-xxi

LIST OF TABLES

xxii- xxxiii

LIST OF ABBREVIATIONS

xxxiv-xxxvii

CHAPTER – 1: GENERAL INTRODUCTION

1-24

1.1 Rainwater: The Indian and the Global Scenario

13-14

1.2 The Water Crisis

14-16

1.3 Water: The Indian Scenario

16-19

1.4 Overall per capita availability of water resources at present and in future 19-20 1.5 Rainfall Patterns in India

22-23

1.6 Rainfall Patterns in Assam and West Bengal

23-24

OBJECTIVES CHAPTER – 2: REVIEW OF LITERATURE

25 26-82

2.1 Rainwater Harvesting

26-30

2.2 Quality of rainwater

30-55

2.3 Quality of roof harvested rainwater 2.4 Heavy Metals Contamination of Rainwater

55-65 65

2.4.1 Direct Collection (Global Scenario)

65-72

2.4.2 Direct Collection (Indian Scenario)

73-75

2.4.3 Roof Collection/ Stored Rainwater

75-82

CHAPTER – 3: MATERIALS AND METHODS 3.1 Location and Description of the Study Sites 3.2 Collection of Rain Water samples

83-90 90

3.2.1 Direct Collection

91

3.2.2 Roof Collection

92

3.3 Chemical Analysis of Rain Water samples 3.3.1 Determination of pH of Rain water 3.3.2 Determination of Electrical Conductivity (EC) of Rain water

93-94 94

3.3.3 Nitrate Estimation of Rain water

95-96

3.3.4 Determination of Heavy Metals Concentration in Rain water

96-100

3.4 Statistical Analysis of Data 100 3.4.1 Univariate Data Analysis

100

3.4.2 Multivariate Data Analysis

101-105

a) Principal component analysis/ factor analysis

102-104

b) Cluster analysis

104-105

CHAPTER – 4: RESULTS

A. Rainfall during 2010-2013 in the study area

106

B. Rainwater Quality in Different Study Sites I. Rainwater Quality in Direct Collection Samples 1. Rainwater quality in Irongmara in 2010

110

2. Rainwater quality in different study sites in 2011

110-117

3. Rainwater quality in different study sites in 2012

151-159

4. Rainwater quality in different study sites in 2013

196-202

5. Rainwater quality in different study sites in 2011-2013

233-237

6. Comparison of pH and Nitrate

238-239

II. Rainwater Quality in Roof Collection Samples 1. Rainwater quality in different study sites in 2011

254-259

2. Rainwater quality in different study sites in 2012

275-279

3. Rainwater quality in different study sites in 2013

294-297

4. Rainwater quality in different study sites in 2011-2013

309-311

C. Statistical Analysis of Data I. Correlations among heavy metals and physicochemical variables

318-319

II. Multivariate statistical analysis of rainwater variables 1. Principal component and factor analysis

319-335

2. Cluster analysis

D. Comparison of Rainwater Quality (Direct

336

and

Roof

Standard Specifications For Drinking Water IS: 10500

Collection) with Indian 336

CHAPTER – 5: GENERAL DISCUSSION CONCLUSION

359-372 373-376

RECOMMENDATION

377

REFERENCES

378-411

APPENDICES List of Publication

412

List of Workshops/Seminars/ Conferences attended

413

CHAPTER- 1 Genaral Introduction Objectives

Chapter 1 General Introduction Water is one of the most valuable resources that is widely distributed all over the world and is available to mankind for sustenance and survival (FAO, 1997; Lamikanra, 1999). Access to safe and potable water by the populace is necessary to prevent health hazards (Lemo, 2002). The rainwater dissolve air borne particulates, water soluble gases and also incorporate air-borne microbes as it passes through the atmosphere. Trace metals in rainwater have been recognized as However,

major pollutants in forests (Matschullat et al., 1995).

precipitation

atmospheric pollutants

chemistry

and

contamination

of

rainwater

is of growing concern both on regional as well

by as

global scales (Galloway, Likens & Hawley, 1984).Its quality may further be degraded as it infiltrates the soil (Raymond, 1992; Okonkwo et al., 2008). The general assumption that rainwater is usually pure can be said to be the reason why previous studies on the quality of water resources in the tropical African environment have largely been restricted to surface water and groundwater, neglecting rainwater (Olobaniyi and Owoyemi, 2004; Olobaniyi and Owoyemi, 2006; Agbogu et al., 2006). However it has been shown that quality of rainwater can be significantly impaired especially in industrialized areas (Olobaniyil and Efe, 2007).

The issue of acid precipitation has received much attention in the international community for the last several decades because of its notable direct adverse effects on ecosystems and indirect effects on human health (Hu

1|Page

Chapter 1 General Introduction et al., 2003). The chemistry of the rainwater has been subjected to numerous investigations during the last two decades due to the increase of environmental problems caused by acid rain. Composition of rainwater varies from site to site and it is difficult to control as it is influenced by both natural and anthropogenic sources. If the source is influenced by man made activities more, it will contribute to acidic gases like NOx and SOx due to which rainwater becomes acidic and basic gases like NH3 (Possanzini et al., 1988; Kulshrestha et al., 2003).The processes controlling the composition of rain are complex and influenced by both natural

and anthropogenic sources. Several studies have

reported potential ecological deterioration caused by acid rain, such as deterioration of forests, acidification of lakes and grounds, decay of marble, and degradation of buildings and ancient monuments (Dikaiakos et al., 1990; Samara et al., 1992; Cobourn et al., 1993; Galloway, 2001; Bravo et al., 2006). According to Ihekoronye and Ngoddy, potable water can be defined as water that is free from disease producing microorganisms and chemical substances deleterious to health (Ihekoronye and Ngoddy , 1985). Clean, safe and pure water unfortunately briefly exists

in nature before it becomes polluted

by prevailing environmental factors and human activities. Rapid industrialization and urbanization throughout the world have led to the recognition and increasing

understanding

of

environment and public health.

2|Page

the

inter

relationship

between

pollution,

Chapter 1 General Introduction Water is one of man’s most important natural resources and there are many

conflicting

demands

on

it.

Therefore,

there

is

need

for

skilled

management of our natural resources for various uses such as domestic, crop irrigation, industrial supply, power generation etc. Water is sometimes known as a universal solvent and can dissolve most compounds except for a few (David et al., 2013). Rainfall is a product of climatic phenomena such as evaporation, condensation, vapour pressure and formation of cloud. It plays an important role in the assessment of climatic water balance of a region (Awasthi, 1995). Although serious atmospheric contamination of rainwater is normally limited to urban and industrial locations, studies in the north-eastern United States have revealed the presence of pesticides and herbicides in rainwater (Richards et al., 1987). Rainwater is an important means of scavenging pollutantsfrom the atmosphere, which can occur either in the gaseous or in the particulate phase. The composition of rainwater actually reflects the composition of the atmosphere through which it falls (Matos et al., 2014). Gromping et al. (1997) have reported that more than 90% of thetotal amount of pollutants present in the atmosphere iswashed outby wet deposition, beingthe predominant cleansing mechanism to remove pollutants from the air. Thus, rainwater can be a way to reduce the atmospheric loadof pollutants, as well as a source vegetation (Flues et al., 2002).

3|Page

of

contamination for soil, water and terrestrial

Chapter 1 General Introduction Rain is liquid precipitation that is the condensation of atmospheric water vapour that is pulled down by gravity into drops of water heavy enough to fall and deposited on the earth surface (Robert, 2002).Rainwater serves as a collector of many minor constituents of the atmosphere. Hence, the results of rainwater analysis helps to reveal the chemical state of the air in which the rain-bearing clouds have formed. In addition, chemical composition of rain plays a critical role in defining the level of acid deposition and the state of some important bio-geochemical cycles of the earth-atmosphere system (Naik et al., 2002). Rain acts as a powerful mechanism to remove pollutants from the atmosphere. Precipitation chemistry is the result of a series of in-cloud and below-cloud atmospheric chemical reactions and a complex interaction between microphysical processes and cloud dynamics (Mouli et al., 2005).

Wet

deposition plays a significant role as an atmospheric cleanser on one hand, while on the other hand, it has a direct impact on ecosystem and human artifacts (Goncalves et al., 2003). Studies on precipitation chemistry are useful in the evaluation of the different sources of gases and particulate matter (Khare et al., 2004). Rainwater has a lot of potential as main water resource for the future because of its high quality. Every raindrop that fall from the cloud is very soft and cleanest water sources in this world (Texas

Water Development Board,

2005). Rapid industrialization, unplanned urbanization, population and the

4|Page

Chapter 1 General Introduction vehicular growth are the major causes for the increased air pollution level in the city (Jayanthi and Krishnamoorthy, 2006). Rainwater is an important source of fresh water especially for those who live in rural areas, where water use is limited due to scarcity or where surface and underground water quality is poor. In many areas, rainwater is still considered as a safe and suitable source of potable water, and it is commonly used as such (Vikaskumaret al., 2007). Developments in science and technology have brought improved standard of living, but have also unwittingly introduced some pollution into our environment. The falling raindrop acquires slight acidity as it dissolves carbon dioxide and nitrogen (MHLG, 2008). Rainwater is a part of hydrologic cycle; the never-ending exchange of water from the atmosphere to the ocean and back again as rainwater. The precipitation like hail, rain, sleet, snow and all the consequently movement of water in nature forms are from part of this cycle. Changes in the gaseous composition of earth’s atmosphere have become a prime concern for today’s world due to human activities. Ambient air pollution in several large cities of India is amongst the highest

in the world.

India and other developing countries have experienced a progressive degradation in air quality due to industrialization, urbanization, lack of awareness, number of motor vehicles, more use of fuels with poor environmental performance, badly maintained roads and ineffective environmental regulations (CPCB, 2003;

5|Page

Chapter 1 General Introduction Joshi and Chauhan, 2008). Vehicular pollution contributes to 70% of total air pollution in Delhi, 52% in Mumbai and 30% in Calcutta (Gokhale and Patil, 2004; Raysoni and Li, 2009). Rain is a type of precipitation, a product of the condensation of atmospheric water vapor that is released on the earth’s surface. It forms when separate drops of water fall to the earth from clouds. Not all rain reaches the surface; some of it evaporates while falling through dry air. Rain is the primary source of fresh water for most areas of the world, providing suitable conditions for diverse ecosystems, as well as water for hydroelectric power plants and crop irrigation. Rain water is the most purest form of water until it is contaminated by the atmospheric pollution. It is the source to surface and ground

water

recharge.

If

ground

water

recharge

takes

place

with

uncontaminated rain water, it remains fit for drinking purposes. On the other hand rain water is an efficient pathway for removing the gases and particles from the atmosphere, which determines the composition of rain water. The composition of rain water varies from site to site and region to region due to interference of local sources of air contaminants. Agriculture of all the nations at least to some extent is dependent on rain.

Indian agriculture, for example,

(which accounts for 25% of the GDP and employs 70% of the nation’s population) is heavily dependent on the rains, especially crops like cotton, rice, oilseeds and coarse grains. A delay of a few days in the arrival of the

6|Page

Chapter 1 General Introduction monsoon can, and does, badly affect the economy, as evidenced in the numerous droughts in India in the 90s (Mishra et al., 2012). The World Health Organization (WHO) estimated that about 4.6 million people die each year from causes directly attributed to air pollution (Davis, 2002). Consequent to the realization of the potential health hazards that may result from contaminated drinking water from industrial source, thus, the contamination of

drinking water from this source is of primary importance

because of the danger and risk of water borne disease (Edema et al., 2001). Therefore, a good knowledge of the chemical qualities of rainwater through regular physico-chemical

analysis is necessary so as

to guild its suitability

(Okonkwo et al., 2008). Evaluation of rainwater quality analysis is also essential for non- potable applications and to match quality to specific uses. Rainwater quality analysis is primarily done to know the bacteriological quality of rainwater in roof

and

ground catchment systems (Gould and McPherson, 1987). Rainwater collected and stored in a tank contains a range of micro-organisms. While most of these might be harmless, the safety of rainwater will depend on excluding or minimizing the presence of pathogenic organisms introduced into the water through faecal contamination. So rainwater quality analysis is needed to know the micro-organisms present in rainwater. Rainwater used for any commercial purpose (eg.food premise) or for community based-supplies (eg. hospitals, schools, caravan parks) requires

7|Page

routine testing to ensure that the water is suitable for

Chapter 1 General Introduction drinking[http://www.earthcrafthouse.com/documents/factsheets/27_rainwater_recover y_v2pdf] The analysis of rainwater quality even in the rural / agricultural areas shows that rainwater contains trace metals and nutrients which pose serious health risks (Neal et al., 2004). Rainwater is one of the important options in areas with serious groundwater pollution with arsenic or fluoride. People are, therefore, concerned about the bacteriological quality of harvested rainwater [http://www.health.sa.gov.au/pehs/PDF-files/commercial-rainwater-qualitytesting06.pdf]. Rainwater may provide the best source of domestic water in areas affected

by

salinity,

high

fluoride

or

pollution

from

various

sources[http://docs.google.com/viwer?a=v&q=cache:mExvSIHCMIJ:www.sahra.arizo na.edu/unesco/allepo/Case-Fluoride.pdf]. Generally, water pollution is described as the presence in water of enough harmful or objectionable material to damage the water quality. Water pollution has many source and characteristics. Although, human activities have always had impact on

coastal areas, most of these impacts have led to

environmental pollution, i.e., the introduction of substance by man into the environment, which may put water resources and human health at risk (His et al., 1999). Major

heavy

metals

associated

with

water

pollution

include

the

following: Zn, Cu, Pb, Cd, Hg, Ni and Cr. The presence of metals in aquatic environment is partially due to natural processes such as volcanic activities, 8|Page

Chapter 1 General Introduction erosions and weathering, but mostly results from industrial processes particularly those concerned with mining and processing of metal ores, the finishing and plating of metals and the manufacturing of metal objects (Hernandez- Hernandez et al., 1990). Heavy metals is an exact term used to describe more than dozen elements that are metals or metalloids (elements that have both metal and non metal characteristics). They are natural components of the earth’s crust. They are high relative density minerals (relative density of about 4.5 times that of water). They are usually found in sediments, specific gravity of some metals includes; Cadmium, 8.65; Iron, 7.9; Lead, 11.34; Mercury, 13.456 (Lide, 1992). Heavy metals constitute another group of pollutants, which interact with the wet precipitation. In addition to natural sources ( such as dusty storms, volcanic eruptions, etc.), heavy metals originate mainly from metal refining, fossil fuel combustion, vehicular exhausts, and other anthropogenic activities, and stay in environment until removed by some mechanism, such as dry deposition, scavenging and rain wash out ( Hou et al., 2005). These metals remain present in the atmosphere as aerosols and, to a lesser extent, as gases. Relatively high solubility and reactivity of heavy metals emitted by combustion processes due to smaller size of their carrier particles

make them easily

soluble in rain water, especially at low pH. Trace metals in rainwater have been recognized as major pollutants in forests (Matschullat et al., 1995). However, precipitation chemistry and contamination of rainwater by atmospheric 9|Page

Chapter 1 General Introduction pollutants is of growing concern both on regional as well as global scales (Galloway et al., 1984). Atmospheric deposition is also considered to be a major source of toxic metals such as Hg, Cd, Pb and several other trace metals to our ecosystem (Barrie et al., 1987).Despite the numerous sources of atmospheric pollution, in most parts of the world, especially in rural and island locations, levels of contamination of rainfall are low. Most contamination of rainwater occurs after contact with the catchment surface (roof or ground) and during subsequent delivery and storage (Waller, 1989). Atmospheric wet deposition has been reported as one of the most important pass ways transporting terrestrial natural and anthropogenic contaminants to land and aquatic environments (Changling et al., 2005). The study of chemical composition of atmospheric aerosols is especially significant, due to the direct influence on ecosystems (Kanellopoulou, 2001, Thomidis et al., 2003). Heavy metals are present in the atmosphere in ever increasing levels as a result of anthropogenic and natural emissions (Suzuki, 2006). Frequently, anthropogenic emissions cause the levels of metal in suspended particles to be above natural background levels. The heavy metals that are emitted in the atmosphere in the form of aerosols, as by product are taken away by wet or dry deposition and cause major problems to the surface

10 | P a g e

Chapter 1 General Introduction waters and the organisms (Finlayson-Pitts and Pitts, 2000; Quiterio et al., 2004a; Quiterio et al., 2004b; Steinnea, 1990). The issue of acid precipitation has received more and more attention in the international community for the last several decades because of its notable direct adverse effects on ecosystem and indirect effects on human health. It is primarily caused by a mixture of strong acids, H2SO4 and HNO3, resulting from fossil fuel combustion so that it has been observed in many industrial regions. The natural acidity of rainwater is often taken to be pH 5.6, which is that of pure water in equilibrium with the global atmospheric concentration of CO2 (330 ppm), and this pH value of 5.6 has been used as the demarcation line for acidic precipitation. However, CO2 is not the only background trace constituent that is capable of influencing the pH of rainwater. The processes controlling the composition of rainwater are complex and influenced by both natural and anthropogenic sources. Rainwater pH values, in the absence of common basic compounds such as NH3 and CaCO3 may be expected to range from 4.5 to 5.6 due to natural sulfur compounds alone (Charlson and Rodhe, 1982; Okay et al., 2002). The pH of the precipitation is expected to be lower than 5.6 for the areas which are exposed to strong influence of SO2 and NOx gases, and free from any natural cleansing mechanism of the atmosphere. However, in regions where the atmosphere is highly loaded with one or more of the alkaline species, such as CaCO3 and NH3, acidity of the precipitation is through the aerosols containing Ca2+ and NH+4 ions (Gulsoy et al., 1999).

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Chapter 1 General Introduction The continental sources of CaCO3 have been linked to the soil type. More than 90% of the emissions are attributed to ‘open sources’, while the remaining are attributed to the industrial and miscellaneous sources. Traffic on unpaved roads (67%), wind erosion (28%), and agricultural tilling (5%) can be named as the main open sources. Emissions from the livestock waste are the dominant source of the ammonia in the precipitation. In the USA, it constitutes 62% of the total ammonia emissions, compared with 81% in Europe (Buijsman et al., 1987). Rainwater is an important source of fresh water especially for those who live in rural areas, where water use is limited due to scarcity or where surface and underground water quality is poor. The growing trend of industrialization has marked impact on the atmospheric chemistry around the globe. Such impacts are also predicted for developing countries like India. In most industrialized urban areas, the atmosphere has been polluted to such a degree that rainwater is considered unsafe to drink. Rainwater quality analysis is, therefore, carried out to understand the problems of rainwater contamination with various pollutants. Chemical composition of rainwater reflects the quantity and quality of air emissions added to the atmosphere from natural and anthropogenic sources (Obaidy and Joshi, 2006). Analysis of rainwater composition helps in evaluating the relative importance of different sources and estimating future possible acidification or buffering (Khanh et al., 2000; Choi et al., 2008). Atmospheric deposition is increasingly becoming an important source of heavy metal addition

12 | P a g e

Chapter 1 General Introduction to natural and derived ecosystems even to those situated away from the emission sources (Smirnioudi et al., 1998; Sharma et al., 2007; Bajpai et al., 2011).

1.1 Rainwater: The Indian and the Global Scenario During the last two decades, a number of studies have been carried out on the chemical composition of precipitation in India (Handa et al., 1982; Mahadevan et al., 1984; Naik et al., 1988, 1994; Mukhopadhyay et al., 1992; Rao et al., 1992, 1995; Kulshrestha et al., 1995; Saxena et al., 1991, 1996; Satsangi et al., 1998; Agarwal & Singh,2001; Pillai et al., 2001;Khare et al., 2004;Naik et al., 2002). A number of studies reported from different parts of the world reveal the prevalence of microbiological and chemical contaminants such as nitrate, sulphate, chloride, sodium, calcium and zinc in roof-collected rainwater (Yaziz et al., 1989; Thomas and Greene, 1993; Forster, 1998; 1999; Ghanayem, 2001; Simmons et al., 2001; Lye, 2002; Chang et al., 2004; Meera and Ahammed, 2006; Abbott et al., 2006; Sazakli et al., 2007; Lye, 2009). Although studies suggested that under the prevailing situation of emissions, there is no threat of acid rain in most part of the Indian subcontinent, however, there were reports of acid rain events over some parts of the country like Delhi (Ravichandran and Padmanabhamurty, 1994; Balachandran and Khilare, 2001), Bangalore (Shivashankara et al., 1999), Korba (Chandravanshi et al., 1997) and Bombay (Sequeria, 1976; Khemani et al., 1989, 1994) in the

13 | P a g e

Chapter 1 General Introduction past. The occurrence of acidic rains at these sites were attributed to the industrial

and

vehicular

emission

of

the

gaseous

pollutants.Rainwater

composition is directly related to the level of local emissions, pollutant transport, climate conditions and drop size, which influences the rain (in–cloud scavenging) and the washout (below–cloud scavenging) of pollutants (Baron and Denning, 1993). Precipitation chemistry has also been studied in many different places, including rural and urban areas around Europe (Alastuey et al., 1999; Al–Momani, 2003; Hontoria et al., 2003), Brazil (Campos et al., 1998; de Mello, 2001; Lara et al., 2001; Flues et al., 2002; Migliavacca et al., 2004) and other places in the world (Tanner, 1999; Bravo et al., 2000; Halstead et al., 2000; Seto et al., 2000). Thus, systematic observations of the chemical composition of precipitation are needed to investigate the changes and other characteristics of atmospheric pollution in a region (Xu et al., 2011).

1.2 The Water Crisis Water scarcity has led to people defending their store of the precious liquid with weapons, because thieves come in the night to steal it. Agitations over water have led to people being injured and even killed in various parts of India. Water is vital to our very existence. We still get enough water, but over the years we have done away with the traditional lakes and ponds that used to catch and store rainwater, and hence we suffer. The earth is actually a natural piggy bank for water. In many parts of the world, the amount of water being 14 | P a g e

Chapter 1 General Introduction consumed has exceeded the annual level of renewal, creating a non-sustainable situation. Here a brief description of the present water crisis and water scenario in India is given which led to an introduction to rainwater harvesting. It has been reported from various sources that at the dawn of the 21 st century, numerous countries including India, are facing a growing water crisis. About 80 countries comprising 40 percent of world’s population already suffer from serious water shortages . It is important to appreciate the fact that only 3 percent of the world’s water is fresh and roughly one-third of it is inaccessible. The rest is very unevenly distributed and the available supplies are increasingly contaminated with wastes and pollution from industry, agriculture and households. India ranks first among rain-fed agricultural countries in terms of both extent (86 Mha) and value of produce (Amarsinghe and Sharma, 2009). Over

the

years,

increasing

population,

growing

industrialization,

expanding agriculture and rising standards of living have pushed up the demand for water. Our water resources have now entered an era of scarcity. In India, this crisis is already visible, contributing to enormous social, political and environmental costs that are affecting the economy and quality of life. Nearly 44 million people in India are affected by water quality problems, either due to pollution, prevalence of fluoride, arsenic and iron deposits in groundwater, or due to ingress of sea-water into groundwater aquifers. The present scenario is that millions of people do not have enough water, particularly during summer

15 | P a g e

Chapter 1 General Introduction months, and women and girls have to walk long distances to fetch water. In search for water, people are going deeper into the ground, lowering the groundwater table and leaving the wells dry. The per capita availability of water for India in 2001 is expected to be half its 1947 level (Nigam et al., 1997).

1.3 Water: The Indian Scenario The reality of water crisis cannot be ignored. In spite of having higher average annual rainfall in India (1,170 mm) as compared to the global average (800 mm), it does not have sufficient water. By 2025, it is estimated that about two third of the world’s population i.e. about 5.5 billion people will live in areas facing moderate to high water stress (UNPF, 2002). For fast growing urban areas, water requirements are expected to double from 25 billion cubic meters (BCM) in 1990 to 52 BCM in 2025. It also has been indicated that industrial water demand would increase from 34 BCM of 1990 to 191 BCM by the year 2025. Agriculture, the largest consumer of water resources in India, would probably require 770 BCM by the year 2025 to support food demand in India. The total estimated demand of 1013 BCM by the year 2025 would be close to the current available annual utilizable water resource (1100 BCM) of India (Vasudevan and Pathak, 2000). More than 80 percent of the annual runoff of the rivers occurs in the monsoon months of June-September, often causing floods. This is a matter of concern as it is estimated that by 2025,

16 | P a g e

Chapter 1 General Introduction about two third of the world’s population - about 5.5 billion people – will live in areas facing moderate to high water tress. So in order to cope with the water scarcity rainwater quality analysis is needed in order to use rainwater as an

alternative

water

supply

for

[http://www.popularmechanics.com/home/4322898]. The

human projection

consumption of

India

becoming a water stressed country by 2025 can be proved wrong only if we are able to utilize a substantial portion of the surface runoff, which is currently lost as runoff to sea or through evaporation. It is in this context, that rainwater harvesting gain importance. India still has an enormous amount of water, theoretically as much as 173 million hectare-meters, that could be captured as rain or as runoff from small catchments in nearby villages or towns. Therefore, the theoretical potential of water harvesting for meeting the household needs is enormous. Rain captured from 1-2% of India’s land could provide India’s population if 950 million with as much as 100 litres of water per person per day (Agarwal, 1998). If rainwater is efficiently managed and stored then there is no village in India which could not meet its drinking water needs through rainwater harvesting. Rainwater harvesting (RWH) is the ancient practice of capturing rain runoff from roofs and other surfaces and storing it for a later purpose (Despins et al., 2009). Rainwater is relatively free from impurities, except those picked up by the rain from the atmosphere. Wind-blown dust contributes large 17 | P a g e

Chapter 1 General Introduction quantities of nutrients and trace metals to the atmosphere, particularly severe with certain industrial complexes. Rainwater is usually considered a safe and suitable source of potable water, and it is commonly used as such, especially in rural areas in developing countries of the world. Rainwater harvesting is a technology used for collecting and storing rainwater from rooftops, the land surfaces, steep slopes, road surfaces or rock catchments using simple techniques such as pots, tanks and cisterns as well as more complex techniques such as underground check dam (Appan, 1999; Makoto, 1999; Prinz, 1999). Rainwater harvesting is often considered to be a traditional method of water collection and storage. The practice of rainwater harvesting can be traced back to many centuries, especially in country like India where rainwater harvesting is mentioned in ancient inscriptions as far back as 5th century Before Christ (BC). However, types and methods of rainwater harvesting have changed over time and many different systems are now available all over the world. Ground water resource gets naturally recharged through percolation. But due to indiscriminate development and rapid urbanization exposed surface for soil has reduced drastically with resultant reduction in percolation of rainwater, thereby depleting ground water resource. Rainwater harvesting is the process of augmenting the natural filtration of rainwater into the underground formation by some artificial methods. “Conscious collection and storage of rainwater to cater

18 | P a g e

Chapter 1 General Introduction to demands of water for drinking, domestic purpose and irrigation is termed as Rainwater Harvesting” [http://www.mppcb.nic.in/rwh.htm]. The application of an appropriate rainwater harvesting technology can make possible the utilization of rainwater as a valuable and, in many cases, essential water resource. Rainwater harvesting has been practiced for more than 4,000 years, and in most developing countries, is becoming essential owing to the temporal and spatial variability of necessary in

areas having significant

rainfall. Rainwater harvesting is rainfall

but

lacking any kind

of

conventional, centralized government supply system, and also in areas where good

quality

fresh

surface

water

or

ground

water

is

lacking

[http://www.oas.org/osde/publication/unit/oea59e/ch10.htm].

1.4 Overall per capita availability of water resources at present and in future The increasing demand on fresh water resources by our burgeoning population and diminishing quality of existing water resources because of pollution and the additional requirements of serving our spiraling industrial and agricultural growth have led to a situation where the consumption of water is rapidly increasing and the supply of fresh water remains more or less constant. It may be mentioned that the water available to us is the same as it was before but the population and the consequent demand for water has increased manifold. The consequences of scarcity is more in arid and semi-arid regions. 19 | P a g e

Chapter 1 General Introduction India is a seriously water - stressed nation, with per capita availability of water falling sharply from 5,177 cubic metres in 1951 to 1,545 cubic metres in 2011. According to the midterm appraisal (MTA) of the 10th Plan, per capita availability of water is likely to fall down to 1,340 cubic metres in 2025 and 1,140 cubic metres in 2050. Figure 1 shows the probable trends in per capita water availability for hundred years from 1947 to 2047. The per capita water availability in the country is reducing progressively due to increase in population. As can be seen in Table 1, the per capita water availability in 1951 was 5177 m3 per year when the total population was only 361 million. In 2001, as the population increased to 1027 million, the per capita water availability reduced drastically to 1820 m3 per year. By 2025, the per capita water availability will further drop down to 1341 m3 and to 1140 m3 in 2050. As the water available within the country varies widely as a result of rainfall, ground water reserve and proximity to river basins, most of the Indian States will reach the water stress condition by 2020 and water scarcity condition by 2025. This would further hamper the food security, as the scarcity of water will directly suppress agricultural production. The average annual per capita availability of water

in the country,

taking into consideration the population of the country as per the 2001 census, 2011 census and the population projections for the year 2025 and 2050 is shown in Table 1 as under :-

20 | P a g e

Chapter 1 General Introduction Table 1 Per Capita Water Availability in India Year

Population (Million)

Per capita water availability (m3/year)

1947

350

6042

1951

361

5177

1955

395

4732

1991

846

2209

2001

1027 (2001 Census)

1820

2010

1186

1588

2011

1210 (2011 Census)

1545

2025

1394 (Projected)

1340

2050

1640 (Projected)

1140

Source: Govt. of India, Ministry of Water Resources (2009)

Fig: 1` India: Declining availability of water 21 | P a g e

Chapter 1 General Introduction Food self - sufficiency is difficult at a runoff level of less than 1700m³ per person and India will reach this stage by 2025 AD. Per capita availability of water at less than 1700m³ /annum leads to water stress and when it goes down to 1000m³/annum, it gives rise to water scarcity. In certain areas of Tamil Nadu, it has already reached a level of 400m³/person (Sharma, 2000). India is at the threshold of a water scarcity situation. India’s six major basins are already classified as those with less than 1000 m³ of water available per head per year. It has been reported that about one-third of the country’s area, comprising the states of Rajasthan, Gujarat, Andhra Pradesh, Madhya Pradesh, Maharashtra, Tamil Nadu and Karnataka

is drought-prone. The area needing

immediate attention for drought proofing is about 12% of the total area (Chaddha and Kapoor, 2000).

1.5 Rainfall Patterns in India India is blessed with a very good rainfall averaging around 1,160 mmwell distributed over 5-6 months in the year though it fluctuates widely over the country. India receives annual precipitation (including snowfall) of about 4000 km³. The long-term average annual rainfall in the country is 1,160 mm (world average 1,110 mm), which is the highest in the world for a country of comparable size. Regions can be broadly classified according to rainfall figures: Desert (0-100 mm), Semi-desert (100-250), Arid (250-500), Semi-arid (500-750 22 | P a g e

Chapter 1 General Introduction mm) and medium-high rainfall areas (1000-3000 mm or more). The coastal areas of the country receives high rainfall, decreasing over the interiors. The entire west coast covering the coastal areas of Maharashtra, Karnataka and Kerala receives annual rainfall of the order of 2500 mm. The rainfall increases all along the western Ghats to 4000 mm. Owing to physiographic factors, rainfall in India is highly variable. The monsoon season in India typically begins in late May/early June. It advances gradually and covers the Indian land mass

by

June-end/July.

After

mid-August

the

Indian

summer

monsoon

undergoes a gradual decaying phase and withdrawal of monsoon begins. By September, the monsoon season in India ends. Indian Meteorological Department (IMD) defines a four month period from June to September as Indian summer monsoon (ISM) period. About 75% of the annual rainfall is received during a short span of these four months (Attri and Tyagi, 2010).

1.6 Rainfall Patterns in Assam and West Bengal Assam and West Bengal are extremely wet and humid. The southeastern part of the state of Meghalaya Mawsynram has the world’s highest average annual rainfall of about 11,872 millimeters during monsoon seasons from MaySeptember. The major rainfall season for

Assam and West Bengal is the south

west monsoon period from June to September. The normal date of onset of south west monsoon is 2nd week of June. Kolkata has an average annual rainfall of 1,582 mm. The highest rainfall occurs during the monsoon in

23 | P a g e

Chapter 1 General Introduction August. The average annual precipitation of Bongaigaon district is 1,717.7 mm. Cachar receives an average annual rainfall of more than 3,000 mm. The growth of population and expansion in urbanization, industrialization and irrigated agricultural land is imposing growing demand and pressure on water resource. The existing water resources nowadays were facing the pollution because of this phenomenon. A new development of water resource like rainwater is very important to make sure that there is no water shortage in future. Regular networks to observe atmospheric deposition of

anthropogenic

substances have been established in Europe, North America and parts of Asia in response to a concern about ecological and other effects. During the last decade, a number of studies on the chemical composition of precipitation have been carried out in parts of North India. Precipitation studies to investigate into the atmospheric deposition have not been reported from Assam. The present study attempts to find the chemical composition as well as quality of rainwater at various locations rural, urban, industrial and sub-urban areas in eastern and north eastern India.

24 | P a g e

Objectives In view of the above, the present investigation has the following objectives:

1. To analyze the physico-chemical properties of rainwater (direct and roof collection) from urban and rural sites in Barak Valley, Assam, in different time of the year, and different stages of rainfall events.

2. To analyze the trace metal content of the direct collection rainwater from different sites, time, and stages of rainfall events.

3. To analyze the trace metal content of the roof collected rainwater from different sites, time, and stages of rainfall events.

25| P a g e

Chapter 2 Review of Literature

Chapter 2 Review Of Literature Water is an important element for all human beings in the world. Our body consists mostly of water. We need water for drinking, cooking, washing, agriculture and to run our industries. While water is a renewable resource, it is at the same time a finite resource. The total quantity of water on the globe is the same as it was two thousand years ago. We usually take it for granted because of its availability but when in scarcity it becomes our most precious resource (Che-Ani et al., 2009). The importance of water is obvious to everyone. Existence of life in the form of flora and fauna cannot be imagined without water. At present, space scientists are vigorously engaged in searching for water on other planets. It is because no life can exist without water and existence of life on other planets is not conceivable for the human mind, unless there is evidence of water on other planets. Water is a fundamental basic need for sustaining human economic activities. This chapter deals with the relevant literature regarding the concept of rainwater harvesting- an

overview, the quality of rainwater, roof

harvested rainwater etc. and it also throws light into the relevant literature concerning heavy metals contamination of rainwater. 2.1 Rainwater Harvesting Water quality analysis of harvested rainwater was done in Tanzania for the purpose of domestic use. The bacteriological, chemical and physical analyses of water samples from rainwater cistern systems at the University of 26 | P a g e

Chapter 2 Review Of Literature Dar es Salaam in Tanzania were carried out between October 1988 and December 1989. Faecal coliforms, total coliforms and faecal streptococci were enumerated. The results showed that 86% of the samples were free from faecal coliforms. However, faecal streptococci were obtained in 53% of the samples and 45% of the samples tested for total coliforms were positive (Mayo and Mashauri, 1991). Water harvesting has been of particular importance in the arid and semiarid regions and remote isolated habitations and in difficult terrains, where it may often provide the only feasible solution for an improved water supply. Hence in India, traditionally water harvesting technique had sustained in certain areas . For example, the type of water harvesting systems in different kinds of terrain’s have been documented by Agarwal (Agarwal and Narain, 1997). Water harvesting is the deliberate collection and storage of rain water that runs off a natural or man-made catchment surface. Catchments include roof tops,

compound

rocky

surfaces

or

hill slopes

or

artificially

prepared

impervious/semi-impervious land surfaces. Rainwater can be captured by using the rainwater harvesting system. Generally, rainwater harvesting system is the direct collection of rainwater from roofs and other purpose built catchments, the collection of sheet runoff from man-made ground or natural surface catchments and rock catchments for domestic, industry, agriculture and environment use. The systems can be categorized as small, medium and 1999). 27 | P a g e

large scale (Gould,

Chapter 2 Review Of Literature Rainwater harvesting is a traditional practice that dates back hundreds of years. Archeological evidence attests to the capture of rainwater as far as 4,000 years ago and the concept of rainwater harvesting in China may date back 6,000 years (Texas Water Development Board, 2005). A study showed that the microbiological and chemical quality of tankstored rainwater was impacted directly by roof catchment and subsequent run-off contamination, via direct depositions by birds and small mammals, decay of accumulated organic debris, and atmospheric deposition of airborne microorganisms and chemical pollutants.. This study involved analyses of direct roof run-off at an urban housing development in Newcastle, on the east coast of Australia.

Results

indicated

that

airborne

micro-organisms

represented

a

significant contribution to the bacterial load of roof water at this site, and that the overall contaminant load was influenced by wind velocities, while the profile (composition) of the load varied with wind direction (Coombes et al., 2005). The water supply situation today is very different than it was 100, 50, or even 25 years ago. Populations continue to increase throughout the years, while water supplies remain constant. The amount of water available today is the same amount of water that was available 100 years ago. Since water is a finite resource, current and future plans must strive to maintain or improve available water quality while utilizing the available water resources as efficiently as possible. Since only 2.5% of the world’s water is freshwater, 28 | P a g e

Chapter 2 Review Of Literature ensuring that this small amount of available water is utilized efficiently and quality is maintained is a daunting task. This is becoming even more important as populations increase worldwide. A recent report by Credit Suisse stated that by 2025 18 countries will experience water demand beyond supply capabilities. Worldwide water consumption is rising at double the rate of population growth (Garthwaite et al., 2007). Rainwater has been the main source of water supply for potable and non-potable uses in the old days because the water supply systems were not developing yet. The method of rainwater harvesting at that time was very simple. Usage of the collected water volume from rainwater harvesting was direct and without any treatment. Usually, the rainwater was mostly collected from roofs and some was directly collected. Normally, the size of rainwater harvesting was based on the size of catchment area (Thamer et al., 2007). An investigation was carried out to study the present status and future prospects of rainwater harvesting in Northern Iraq. Scarcity of water resources in the Middle East represented an extremely important factor in the stability of the region and an integral element in its economic development and prosperity. Water crisis in Iraq is expected to be more severe in the future where the Tigris and Euphrates are expected to

dry up by 2040. Rain Water harvesting

techniques (RWH) will definitely help to overcome or minimize the effect of this problem but all indicators suggested that rainfall is decreasing with time.

29 | P a g e

Chapter 2 Review Of Literature To test this, two areas of northern Iraq were selected

to evaluate the

feasibility of RWH using small dams not more than 6m height. Watershed modeling system (WMS) and linear programming (LP) optimization techniques were applied first on rainfall daily data for the period 1990–2009. Generated rainfall data were used in two emission scenarios of climatic change (A2 and B2) for the period 2020-2099 to test the future validity of RWH. These data were used in the WMS model. The results showed that RWH technique can supply good quantities of water using the historical and generated data (Ansari et al., 2015).

2.2 Quality of rainwater Precipitation is the main process by which trace gases and aerosols are scavenged from the atmosphere in temperate climates. Atmospheric aerosol particles and gases play a major role in the chemistry of rain water by in cloud and below cloud scavenging processes. As a result, the following chemical species are typically found in rain water: ammonium, sodium, potassium, calcium, magnesium, hydrogen, sulphate, chloride, nitrate, carbonate and

bicarbonate

ions.

Among

these

chemical

species,

hydrogen

ion

concentration (or pH) is very important for acid rain assessment. Absolutely neutral precipitation would have a pH of 7. However presumed that pure water is in equilibrium with global atmospheric CO2 and 30 | P a g e

Chapter 2 Review Of Literature yield the natural acidity to the rain water with pH 5.6. This pH value 5.6 has been taken as the demarcation line for acidic precipitation. However in the absence of common basic

components, such as NH3 and CaCO3, rain water

pH would be expected to be about 5 due to natural sulphur compounds (Charlson and Rodhe, 1982). Daily measurements of pH and conductivity of rainwater at Coimbra, Portugal in the period between autumn 1978 to autumn 1980 were reported. The average conductivity was 26 µΩ-1 cm-1 and the average pH was 4.75. Neutral salt

contribution to conductivity was significant and was highest in

autum/winter. Correlations between neutral salt conductivity and wind direction were found. pH values have a large dispersion and more than 30% of the samples had a pH NH4+ > NO3- >Na+ >K+ >H+. The alkaline components

((Ca2+, Na+, K+)

contributed

52%,

NH4+

8%,

whereas,

the

contribution from the acidic components was relatively small (40%). The low concentrations of H+ found in rainwater samples from Mugla suggested that an important portion of H2SO4 and HNO3 have been neutralized by alkaline particles in the atmosphere. The dust-rich local and surrounding limestone environment might have caused the high concentration of Ca2+ in Mugla area. The relatively high concentration of NH4+ observed at Mugla was suspected to be due to surrounding agricultural areas (Demirak et al., 2006).

44 | P a g e

Chapter 2 Review Of Literature A study was carried out to investigate the chemical composition of wet atmospheric precipitation over Dhanbad, coal city of India. The precipitation samples were collected on event basis for three years (July 2003 to October 2005) at Central Mining Research Institute.

The pH value varied from 4.01 to

6.92 (avg. 5.37) indicating acidic to alkaline nature of rainwater. The pH of the rainwater was found well above the reference pH (5.6), showing alkalinity during the non-monsoon and early phase of monsoon, but during the late phase of monsoon, pH tendency was towards acidity (10%). The principal component analysis (PCA) identified the possible sources of ionic species and heavy metals in the wet precipitation samples (Singh et al., 2007). Rain water samples, covering 44 rain events of 2008 and 52 rain events of 2009, were collected at urban and suburban locations of Varanasi and analyzed for pH, conductivity and for metal and nutrient ions. The pH of rainwater varied between 6.3

and 7.9, with over 70% of samples having

alkaline range. Among the heavy metals, Cr (12.60 to 44.60 µg l -1), Zn (4.25 to 34.55 µg l-1) and Mn (10.62 to 28.40 µg l-1) were found to be the dominant component of rain water. The varimax rotation of PCA results extracted four major factors namely urban-industrial emission, crustal aerosols, wind transport and biomass burning accounting for 80% of the total variance. The study has relevance in establishing cause-effect relationships for terrestrial as well as for aquatic ecosystems (Pandey and Singh, 2012). 74 | P a g e

Chapter 2 Review Of Literature A study was conducted to highlight the lead levels in rain water and study the seasonal and spatial variations in the concentration of

lead. The rain

water samples were collected on the event basis at three sites (representative of urban, industrial and remote): Raipur, Korba, and Ambikapur (Madhya Pradesh). The maximum concentration of lead was found at sampling site Raipur in month of April-May which may be due to dirty atmosphere. In rainy season (June-Sept.) the concentration of lead was found in decreasing order may be due to continuously washing of atmosphere by rain. The mean concentration of Pb in three sites Raipur, Korba and Ambikapur were 547, 545, 405 ppb respectively (Tripathi and Jha, 2014).

2.4.3 Roof Collection/ Stored Rainwater Potentially, the adverse health implications of the long term consumption of rainwater containing elevated levels of heavy metals such as lead pose a serious health threat. Lead is a cumulative poison which can cause serious damage to the central nervous system and infants and foetuses are particularly vulnerable (NHMRC 1996). For roof catchment systems several potential sources of lead contamination exist. These include the use of lead flushing, lead headed nails, lead based paints/primers for roof construction and the deposition of lead particles on the catchment surface in regions subject to

75 | P a g e

Chapter 2 Review Of Literature heavy industrial or traffic pollution (especially in countries still using leaded petrol). Water quality analysis was done to analyze the impact of storage tanks on drinking water quality in Al-Karak Province, Jordan. One hundred water samples

were analyzed for major anions, major cations and heavy metals (Pb,

Fe, Cu. Zn, Mn and Ni) in order to evaluate the impact of the residential storage tanks on the drinking water quality in comparison to its water source. The water quality of storage tanks showed higher ionic concentration in comparison to its source. Despite the fact that the contact period between the water and the residential water storage tank is short, elevated levels of heavy metals were found in the drinking water indicating dissolution of these metals from the storage tanks to the water (Ziadat, 2005). A study was conducted to investigate the quality of harvested rainwater which is used for domestic and drinking purposes in the northern area of Kefalonia Island in SW Greece and the factors affecting it were assessed through 3-year surveillance. In 12 seasonal samplings, 156 rainwater and 144 ground- or mixed water samples were collected from ferroconcrete storage tanks , which are adjacent to cement-paved catchment areas (600–3000 m2).

All of

the rainwater samples were within the guidelines for chemical parameters established by EU. As far as microbiological quality is concerned, total coliforms, Escherichia coli and enterococci were detected in 80.3%, 40.9% and

76 | P a g e

Chapter 2 Review Of Literature 28.8% of the rainwater samples, respectively, although they were found in low concentrations (Sazakli et al., 2007). An investigation was carried out to study the effect of age of roof on water quality. Rain water was collected from corrugated iron sheets from different locations and was analyzed in order to determine the influence of aging roof on the quality of water harvested from various roofs.

Iron was

found to be highly implicated with concentration in the aged roof > new roof > direct collection.

There was no significant difference in the concentration of Pb

and Cu over the three sample locations. However for Fe and Zn, there was significant difference in the concentrations from the aged roofing sheet and the new roofing sheet and the sample collected directly from the source.

The

concentration of Fe for both the new roofing sheet and aged roof was far above the 0.30 ppm allowed by WHO for drinking water (Eletta and Oyeyipo, 2008). A comprehensive survey was carried out to cover governorates in northern region of Jordan, where rainwater collection for domestic use is practiced on regular basis.

indicated that water quality in these tanks and

cisterns varies depending on location, on catchment area, and on the availability of public sanitary systems. It was concluded that collected rainwater is unsuitable for drinking purpose while it could be used for irrigation within houses (Radaideh et al., 2009).

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Chapter 2 Review Of Literature In an investigation carried out at Akwa Ibom State, Nigeria, rainwater samples were harvested from different rooftops within Uyo metropolis in the months of March and April being onset of the rainy season in the study area. Rainwater samples were also obtained directly from the atmosphere in the vicinity of each roof type and used as Control. These samples and Control were analyzed using atomic absorption spectrophotometer for their iron (Fe); zinc (Zn); cadmium (Cd); aluminium (Al); copper (Cu) and lead (Pb) contents. Results obtained indicated that the rainwater samples harvested from aluminium coated roof recorded levels of Zn and Al higher than their recommended limits for drinking water in Nigeria while the concentrations of other metals were within the acceptable limits. Samples obtained from asbestos roof recorded concentrations of Cd and Pb above the Nigerian standards for drinking water whereas the

rest were within the acceptable limits. Concentrations of zinc

recorded in rainwater samples harvested from zinc galvanized iron roof and zinc roofs were two and three times respectively higher than the Nigerian standard for Zn in drinking water. Copper roof samples recorded concentrations of Al and Cu above their recommended limits for drinking. Rainwater harvested from ceramic tiles roof recorded concentrations of these metals within the acceptable limits in drinking water by Nigerian standards. Results obtained in this study indicated that roofing materials may contribute substantial amounts of toxic metals to rainwater harvested from them and their concentrations could be influenced by where they are located. The results also indicated that drinking 78 | P a g e

Chapter 2 Review Of Literature of rainwater harvested from metallic roofs might pose serious health risks to human (Ebong et al., 2012). Rain water samples were collected from four tanks presented in four areas

of

Misurata,

Libya.

All

the

samples

were

analyzed

for

four

physicochemical parameters such as temperature, conductivity, total dissolved solids (TDS) and pH, and four heavy metals, viz., Fe, Cu, Pb and Cd using standard procedures. The data showed

that the investigated parameters and

concentration of heavy metals in the rain water samples from Misurata were within the permissible limits of the World Health Organization drinking water quality guidelines (Mayouf, 2012). A study was conducted for the development of affordable technologies for capturing and retaining rainwater runoff including that from roof tops; and using this as a valuable source of water to supplement the water needs of households in drought area.

A project conducted at Madgyal, Maharashtra, India,

verified the extent to which adoption of the adapted technologies could help greatly in conserving water resources in the semi-arid regions in developing countries and at the same time helping to alleviate poverty by improving the quality of life of women and children in these regions. It was envisaged that the systems would enable poor households in the community to supplement their water supply needs as well as engage in small scale backyard gardening; extend their cropping seasons through improved security of water resources,

79 | P a g e

Chapter 2 Review Of Literature ultimately enhancing food security and contributing to poverty reduction (Jankar and Bhanuse, 2013). A study was conducted to assess concentration of micro-pollutants (heavy metals- Cd, Cu, Fe, Mn, Pb, and Zn; organic compound – PAHs, pathogenic microorganisms) in ambient and harvested rainwater under urban residential rooftops. Samples were analysed using standard analytical procedures. Rainwater harvested from the rooftops were alkaline (8.5-9.6) compared to pH of 5.94 for the ambient rainwater. Conductivity ranged from 95.2 - 150.4 μS/cm due to the dissolution of deposited aerosols and leaching of roofing materials. Turbidity, Cu, and microbial counts (HPC, E. coli, TC and FC) exceeded the allowable limits for drinking water with inputs from the rooftops. Concentration of Cu and Pb in harvested rainwater was higher than the WHO standards. Relative abundance of metals is as follows: Fe > Zn > Cu > Mn > Pb > Cd. Water quality from asbestos was the worst among the rooftops examined. Total PAHs was low ranging from 0.04 found in ambient rainwater to 0.18 in rusted galvanized iron sheet. All samples contained high amount of microbiological contaminants with the asbestos roofing sheet having TC and E. coli of 14000 and 12000 cfu/mL respectively. These can result in illnesses such as diarrhoea, urinary tract infections, respiratory illness and pneumonia. The study had shown that rooftops contributed significantly to contamination of harvested rainwater

80 | P a g e

Chapter 2 Review Of Literature due to composition of roofing materials and age of the roof (Adedeji et al., 2014). Rainwater samples harvested for drinking from the west part of Hebron (south of West Bank in Palestine), the largest city in the West Bank, were analyzed for the content of different trace heavy metals (Cr, Mn, Co, Ni, Cu, Zn, Mo, Ag, Cd, Bi, and Pb) by inductively coupled plasma mass spectrometry (ICP-MS). This study was conducted to determine the water quality of harvested rainwater used for drinking in south West Bank (Hebron area). A total of 44 water samples were collected in November 2012 from 44 house cisterns used to collect rainwater from the roofs of houses. The samples were analyzed for their pH, temperature, electrical conductivity, total dissolved solids, and different heavy metal contents. The pH of all water samples was within the US Environmental Protection Agency limits (6.5-8.5), while some water samples were found to exceed the allowed WHO limit for total dissolved solids (TDSs) in drinking water. Results showed that concentrations of the heavy metals vary significantly

between

the

44

samples.

Results

also

showed

that

the

concentration of five heavy metals (Cr, Mn, Ni, Ag, and Pb) was higher than the WHO limits for these heavy metals in drinking water. Overall, their findings revealed that harvested rainwater used for drinking of Hebron area is contaminated with heavy metals that might affect human health (Malassa et al., 2014).

81 | P a g e

Chapter 2 Review Of Literature An investigation was carried out to study rainwater and sediment/sludge samples

harvested from various storage tanks including concrete, metallic and

plastic tanks whose house roofs are galvanized iron sheets. The samples were collected in four geographical locations in Kampala City, Uganda. Both rainwater and sediment/sludge samples collected were analysed for temperature, pH, EC, TDS, DO, hardness (Ca and Mg), nutrients (TN and TP) and some trace metals including Zn, Cu, Pb and Cd. The quality of rainwater varied slightly with different storage tanks. In terms of dissolved trace metals, Zn was the most predominant trace metal in rainwater samples with mean concentration values 0.389±0.186 mg/l, 0.920±0.629 mg/l and 1.119±1.039 mg/l for concrete, metallic and plastic t anks respectively. On the other hand, Cu was not detected in rainwater but had mean concentration values 0.498±0.193 mg/kg in the sediment/sludge samples. However, Pb exceeded WHO permissible limits for drinking water in all sampled tanks. The high levels of these trace metals, nutrients and other physico-chemical parameters obtained in this study may likely result in consumer complaints. This is because some of the parameters are not only liable to impacting bad taste in rainwater but are also carcinogenic (Ntale et al., 2015).

82 | P a g e

Chapter 3 Materials and Methods

Figure 2. Map showing the location of the study sites in Assam.

Figure 3. Map showing the location of the study sites in West Bengal.

Chapter 3

Materials and Methods

Water is a precious natural resource essential to human sustainability and most of the water is received in the form of rainfall. It is evident from the available literature that high population growth and increased energy consumption during last few decades have resulted in elevated atmospheric pollutants load in India. As most public health problems are

related to

contaminated water, access to good quality water is one of the most important factors to improve people’s health (May and Prado, 2006; Singh et al., 2007). After having a critical review of the available literature it is found that rainwater

can be used as an alternative source of water in future if it is

managed efficiently and skillfully.

Thus it is needed to study the quality of

rainwater at individual locations in order to ascertain the health risks, if any involved. The sampling and analytical methods adopted for carrying out the desired work are described in this chapter.

3.1 Location and Description of the Study Sites India is geographically located at 28º36.8ʹ N and 77º12.5ʹ E in the northern hemisphere of the globe. For the proposed study, total seven sampling sites were selected which were classified with regard to how they may be influenced by the surroundings. Among the selected sites, five were from different parts of Assam and two from West Bengal. The classification is based on reported information, and supplemented with our knowledge of the locations. The selected study sites were representatives of urban, suburban and industrial 83 | P a g e

Chapter 3

Materials and Methods

areas. The sampling sites within the city limits are termed urban and those located in the outskirts of a city are termed as suburban. These sampling sites are thought to be affected both by local emissions, including the extra dust, which is stirred up in this environment and those emissions constituting the regional levels. A brief description of the location (Figure 1 & 2) and nature of the seven (7) sites from where the rainwater samples were collected are given below.

3.1.1 Irongmara Irongmara is a village panchayat located in the Cachar district of Assam, India. The latitude 24°41ʹ22ʺ N and the longitude 92°44ʹ34ʺ E are the geocoordinates of Irongmara. It is located at the south of Silchar at a distance of 22 kms from Silchar. Irongmara does not have any industrial units, although a few nearby tea gardens operate their factories in this area. This site is located in the outskirts of the city which represents a typical suburban area. It receives an average annual rainfall of more than 3000 mm. The maximum rainfall occurs during monsoon period between May to August. It experiences a sub-tropical 0

0

and humid climate. The temperature varies from 12 C in winter to 35 C in summer. The humidity varies from 32% to maximum of 98% during July and October.

84 | P a g e

Chapter 3

Materials and Methods

3.1.2 Badarpur Badarpur is a town and a town area committee in Karimganj district in the state of Assam. It located at 24°54ʹ00ʺ N and 92°36ʹ00ʺ E. It has an average elevation of 16 metres. It receives an average annual rainfall of more than 2515 mm. As of 2011 census, Badarpur had a population of 11,291. Males constitute 52% of the population and females 48%. Badarpur has an average literacy rate of 84%, higher than the national average of 79.5%. 10% of the population is under 6 years of age. It receives an average annual rainfall of more than 2515 mm. Some

of the important industries in the vicinity of

Badarpur are Cachar Paper Mill (CPM) and Barak Valley Cements

Limited

(BVCL). Cachar Paper Mill is situated at Panchgram by the side of the Barak river in the Hailakandi district of Assam on the National Highway No. 57 between Silchar and Guwahati. The mill is located at a distance of 25 km from Silchar. The mill have the capacity to produce 1 lakh MT of finest paper (Writing and Printing Paper and Newsprint) from the virgin of bamboo. The manufacturing unit of Barak Valley Cements

Limited (BVCL) is located at

Jhoom Basti, Devendranagar, Badarpurghat, District Karimganj, Assam and all the operations of the company are concentrated in the North Eastern region. Presently the Company is engaged in the business of manufacturing of cement of different grades and is marketing its product under the brand name "Valley Strong Cement".

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3.1.3 Bongaigaon Bongaigaon (26°29ʹ00ʺ N and 90°34ʹ00ʺ E) is the largest city in Lower Assam and one of the most important cities in Assam having a total area of 4,710 km2. It is one of the biggest commercial and industrial hubs of NorthEast India and also of Assam. It is also the 4th largest city of Assam by municipal area and population. It has an average elevation of 54 metres. The city is situated 180 kilometers north west of Guwahati. Many industries have been set up near the city which include Bongaigaon Refinery situated at Dhaligaon and Aluminium factory situated at Chapaguri road, Bongaigaon. It has two parts - Old Bongaigaon and New Bongaigaon. It has an average annual rainfall of 1,717.7 millimeters.

3.1.4 Dolaigaon Dolaigaon (26°28ʹ41ʺ N and 90°33ʹ40ʺ E) has an area of about 874 km 2. It is situated at a distance of 5 kms from Bongaigaon and 180 kms north west of Guwahati. It is located at an average elevation of 36 metres. It has a population of 1,74,810 including Bongaigaon. It has a Carbon Factory. It has an average annual rainfall of 1,717.7 millimeters. The New Bongaigaon railway station near Dolaigaon is a major junction connecting Assam with rest of India. It also has an average annual rainfall of 1,717.7 millimeters.

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3.1.5 BGR Township BGR Township (26°30ʹ20ʺ N and 90°31ʹ12ʺ E) is an quarter campus of the employees of IOCL BGR having a total area of 3 km2. The town is located at Dhaligaon near Bongaigaon Refinery in Chirang district of Assam, 200 km west of Guwahati. It has a major petrochemical industry, the Indian Oil Corporation Limited (IOCL BGR). It is situated at a distance of 5 kms from Bongaigaon. The Bongaigaon Refinery is the eighth largest refinery of Indian Oil formed upon the amalgamation of Bongaigaon Refinery and Petrochemicals Limited (BRPL) and Indian Oil on March 25, 2009. It has two Crude Distillation Units (CDU), two Delayed Coker Units (DCU) and a Coke Calcination Unit (CCU) with a processing capacity of 2.35 MMTPA of crude oil. The refinery produces a wide range of petroleum products, namely LPG, Naphtha, MS, SKO, HSD, LDO, LSHS, LVFO, RPC, CPC, Needle coke and solvents (Petrosol and Bonmex-II) are produced by processing Assam Crude and Ravva Crude (from the Ravva oil fields of Krishna Godavari Basin). Refineries emit a wide variety of pollutants Sulfur dioxide (SO2), Oxides of Nitrogen (NOX), Carbon Monoxide (CO), Particulate Matter (PM), Volatile Organic

Compounds

(VOCs),

Hazardous

Air

Pollutants

(HAP)

such

as

Polycyclic aromatic hydrocarbons (PAH), Greenhouse Gases (GHG), Hydrogen Sulfide (H2S) etc.

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3.1.6 Kolkata Kolkata is located on the east bank of the Hooghly river. The city proper has 4.5 million residents. It is the third- most populous metropolitan area in India and the 13th – most populous urban area in the world. The site selected is Dum Dum (22°34ʹ11ʺ N and 88°22ʹ11ʺ E), a populated municipality area in north Kolkata, which represents a typical urban area. It has an average elevation of 11 metres. It is one of the main entry points to the city of Kolkata from the northwest and it is very close to the Netaji Subhas Chandra Bose International Airport, formerly known as Dum Dum Airport. Dum Dum has developed into a modern commercial centre and also hosts the Ordinance Factory

Dumdum

(OFDC)

of

the

Ordinance

Factories

Board,

which

manufactures armaments and other equipment for the Indian Armed Forces. Dum Dum also houses a large number of small scale industrial units such as those engaged in

lead battery manufacture and repair, iron welding shops,

cardboard manufacturing units, and others. Besides, Kolkata along with its twin city Howrah is an urban-industrial centre that also has small, medium and large scale

industries

manufacturing

ships,

rail

locomotive,

industrial

furnace,

engineering and chemical based articles etc. A number of industries like engineering, casting, steel fabrication, ship building, consumer goods industries, construction pressure die casting, forging, electric installations, manufacturing of industrial electrical goods etc. had a large concentration in the district. Metal

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Casting Foundry, Shuttle cock Manufacturing, Metal Spare Parts, Re-Rolling Mill Cluster, Embroidery & Garments Mfg. cluster are the major clusters available in Howrah district. Rains brought by the Bay of Bengal branch of the south-west summer monsoon lash Kolkata between June and September, supplying with most of its average annual rainfall of 1,582 mm. The highest average monthly annual rainfall total, 306 mm, occurs in August.

3.1.7 Kharagpur Kharagpur (20°19ʹ49ʺ N and 87°19ʹ25ʺ E) is the fourth largest city of West Bengal in area, covering an area of about 127 km² located in the southwest part of Midnapore. It is located at a distance of 116 km from Kolkata. It has an average elevation of 29 metres. Total annual rainfall is around 1400 mm, out of this the monsoon season accounts for about 1140 mm of rain. Kharagpur is an industrial city. Many large industrial setups are located in and around Kharagpur due to its proximity to Kolkata. Some of important

establishments

include

Tata

Metaliks,

Tata

Bearings,

the more Siemens,

Kharagpur Metal, Telcon, Century Extrusions, Humboldt, Rashmi Metaliks and BRG Group. These industries manufacture the following products: In 2012-13, Tata Metaliks introduced its premium product Tata eFee®, the first branded pig iron that reduces energy consumption in foundries by 5-15%. Tata Metaliks also manufactures Ductile Iron Pipes through its 100% subsidiary company, Tata Metaliks DI Pipes Ltd. (TMDIPL). Tata Bearings manufacture ball bearings. 89 | P a g e

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Ball bearing 6204ELDLRS for wheel application of Nano Car.

One Ball

Bearing 60132RS was launched for propeller shaft application of Tata range of commercial vehicle.

Tata Bearings

also

developed a new ball bearing

6302C3ELB for engine application of Piaggio range of three wheelers. BRG Group is a steel manufacturer which manufactures wide range of kitchen essentials such as cookware, cutlery, pressure cookers, flasks etc. Telcon is the largest manufacturer of construction equipment in India. The Kharagpur plant manufactures backhoe loaders, midi excavators, off-highway dump trucks, wheel loaders and large mining shovels. 3.2 Collection of Rain Water samples Samples of rainwater were collected from seven different locations which include Irongmara (Cachar district) and Badarpur (Karimganj district) in Barak Valley region of Assam, Bongaigaon, Dolaigaon and BGR Township in the Bongaigaon district of western Assam, and Kolkata (Kolkata district) and Kharagpur (West Midnapore district in West Bengal). These locations are industrialized and partially industrialized. The sampling sites were selected in such a way as to cover areas representing the semi-urban at the outskirts of the town, highly populated in the old congested city and industrial zones. Both direct and roof collection of rainwater were done. Direct rainwater collection in 2010 was only done in Irongmara and continued till 2013; in all the other sites except Badarpur, direct collection was done during 2011-2013; and

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collection in Badarpur was done during 2012-2013. In case of roof collection, rainwater samples were collected from Irongmara, Bongaigaon and Dolaigaon during 2011-2013.

3.2.1 Direct Collection A total of 213, 60, 206, 138, 141, 103 and 82 rainwater samples were directly

collected

at

Irongmara,

Badarpur,

Bongaigaon,

Dolaigaon,

BGR

Township, Kolkata and Kharagpur respectively during the sampling period 2010-2013. First monsoon precipitation water samples (single event in a day or as multiple events in a day) were collected from all the sites. Care was taken to ensure that samples were representative of water to be examined and that no accidental contamination occurs during sampling. Rainwater samples were collected in clean polycarbonate plastic containers by placing the container on a raised platform in an open environment in order to ensure that the water has no contact with any object before getting into the container. The rain samplers were mounted on a raised platform to avoid rain splash as recommended in standard literature (Naik et al., 2002; Olobaniyi and Efe, 2007; Singh et al., 2007; Lara et al., 2010). The samples were collected using a

polypropylene

funnel fitted to a 5 litre polycarbonate containers and then transferred to litre plastic bottles.

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3.2.2

Materials and Methods

Roof Collection

A total of 98, 93 and 82 rainwater samples were collected at Irongmara, Bongaigaon and Dolaigaon respectively during the sampling period 2011-2013. Rainwater samples were collected via roof tops made of corrugated iron sheets with the help of gutters made up of plastic pipes. Sample collection equipment used were washed with 10% HCL and then they were thoroughly rinsed with distilled water and dried prior to the collection of samples (Al-Khashman, 2005). To avoid dry deposition, the sampling funnels were uncovered only during precipitation events and were washed with distilled water in the morning and evening. The sample collectors were

deployed

just

before

the

onset

of

rainfall

and

were

withdrawn

immediately after they were filled up or when the rain ceased. Immediately after collection the samples were filtered using Whatman filter No. 41 (Singh et al., 2001) and divided into two portions: to a 200 ml aliquot 0.2 ml HCL was added and this part was kept for determination of heavy metals. The other portion was used for pH, electrical conductivity (EC) and other chemical analysis. Same procedure was applied in case of both direct collection and roof collection. The filtered samples were stored at low temperature (4ºC) in a refrigerator until analyzed for all the parameters. The rainwater samples were then transported to the laboratory for examination. Subsequent to the collection of samples their pH and electrical conductivity were measured as immediately as possible. 92 | P a g e

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3.3 Chemical Analysis of Rain Water samples 3.3.1 Determination of pH of Rain water One of the important characteristics of rainfall is its hydrogen ion concentration or pH. By definition, pH is the negative log of the hydrogten ion concentration. pH (the negative log 10 of hydrogen ion concentration in a solution) is a useful parameter to indicate the presence of acidic or alkaline substances in water. The pH of water without contaminants is around 7 (neutral). If acids are present pH goes below 7 and with alkali it rises above 7. The pH of the rain water samples were determined using a digital pH meter (pH Meter ESICO Model 1013. To find out pH of rain water samples the following procedure is subsequently adopted. 1) Switch on the instrument and allow it to warm up for some time. 2) Prepare the buffer solution of known pH by dissolving the buffer tablets in specific volume of distilled water. These are necessary for calibrating the instrument. 3) Adjust the temperature Knob according to the temperature of solution under study . 4) Insert the electrode assembly into the buffer solution and carefully adjust the system knob until the meter reading coincides with the known pH of the selected buffer solution. 5) Withdraw the electrode assembly and wash it by distilled water and then insert in a beaker containing the second buffer solution, adjust the slope control to achieve the same. Now withdraw the electrode assembly and wash it with

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distilled water and then dip it in beaker and introduce into a test solution taken in another small beaker. Take reading of the pH of the unknown solution from the pH Meter. Remove the electrode assembly. Rinse in a distilled water and place it in the beaker containing another rain water sample of unknown pH and record the pH of rain water. The pH meter was calibrated before every measurement using standard buffer solutions of pH 4.00 and 7.00 (SCFI, 2000a).

3.3.2 Determination of Electrical Conductivity (EC) of Rain water Electrical

conductivity is

commonly used

for indicating the

total

concentration of ionic (salt) soluble constituents. It is closely related to the sum of the cations or anions as determined chemically and usually correlates closely with

the

total

dissolved

solids.

It

is

a

rapid

and

reasonably precise

determination that does not alter or consume any of the sample. The apparatus for measuring electrical conductivity consists of an electrical resistance bridge and conductivity cell having electrodes coated with platinum black. The conductivity of the rain water samples were determined using a digital conductivity

meter

(Conductivity/ TDS Meter

conductivity

measurements

(25ºC),

a

ESICO

conductivity

Model

meter

was

1601).

For

used

after

calibration with KCl standard solutions (SCFI, 2000b). The measurement of EC (expressed in µS cm-1) is adjusted for a known temperature (usually 25ºC) of the solution by setting up the knob provided for this purpose. The higher the 94 | P a g e

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salt concentration, the higher is the EC. Calibration is not required frequently once it is done before every batch of measurements.

3.3.3 Nitrate Estimation of Rain water Nitrates from decomposition of organic residues may reach ground water. Rain may normally be free of nitrate unless there is a high level of oxides of nitrogen in the atmosphere and rainwater dissolves it. The spectrophotometric method for the measurement of NO3− is discussed below. The nitrate estimation was done with the help of UV/VIS Spectrophotometer Model 1371. Principle:

Measurement

of

UV

absorption

at

220

nm

enables

rapid

determination of NO3− . The NO3− calibration curve follows Beer’s law up to 11 mg/ml. This technique is used only for screening samples that have low organic matter content. Reagents: a. Nitrate free water b. Stock Nitrate Solution: Potassium nitrate (KNO3) is dried in an oven at 105ºC for 24 hours. Dissolve 0.3609 g in water and dilute to 500 ml. Preserve with 2 ml CHCl3/L. This solution is stable for atleast 6 months. c. Intermediate Nitrate Solution: Dilute 50 ml stock nitrate solution to 500 ml with water. Preserve with 2 ml CHCl3/L. This solution is stable for atleast 6 months. d. Hydrochloric acid solution, HCl (1N).

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Procedure: a. Treatment of sample: To 50 ml clear sample, filtered if necessary, add 1 ml of HCl solution and mix thoroughly. b. Preparation of Standard Curve: Prepare NO3− calibration standards in the range of 0-7 mg by diluting the standard solution. c. Spectrophometric

Measurement:

Read

absorbance

or

transmittance

against

distilled water set at zero absorbance or 100% transmittance. A wavelength of 220 nm is used to obtain NO3− reading and a wavelength of 275 nm is used to determine interference due to dissolved organic matter.

3.3.4 Determination of Heavy Metals Concentration in Rain water Sample Preparation: For heavy metal analysis, 200 ml of the rainwater samples were subjected to slow evaporation at 70°c- 80°c to bring down the volume of water samples from 200 ml to 20 ml. The determination of heavy metals was done using an Atomic Absorption Spectrometer (Perkin Elmer PE 3110 and ANALYTIKJENA AG VARIO 6) by the flame method and graphite furnace method respectively at the Sophisticated Analytical Instrument Facility at North Eastern

Hill

University,

Shillong

(SAIF-NEHU),

Meghalaya

and

Atomic

Absorption Spectrometer (Varian AA 240) by the flame method at the Department of Zoology, University of Kalyani, West Bengal. For the proposed

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study, six heavy metals (Pb, Cd, Cr, Co, Ni and Zn) were analyzed in the rainwater samples. The detection limits of the elements are as follows: Perkin Elmer PE 3110 - Pb (0.08 mg/L); Cd (0.007 mg/L); Ni (0.001 mg/L); Zn (0.0008 mg/L); Cr (0.002 mg/L); Co (0.006 mg/L), ANALYTIKJENA AG VARIO 6 - Pb (0.08 µg/L); Cd (0.007 µg/L); Zn (0.002 µg/L); Cr (0.1 µg/L) and Varian AA 240 - Pb (0.001 mg/L); Cd (0.002 mg/L). (a) Lead (Pb): Lead (Pb) is the fifth element in Group IV A in the periodic table; it has an atomic number of 82, atomic weight of 207.19, and valences of 2 and 4. The average abundance of Pb in the earth’s crust is 13 ppm; in soils it ranges from 2.6 to 25 ppm; in streams it is 3 µg/L, and in ground waters it is generally BGR Township (BGR) > Kharagpur (KGP) > Bongaigaon (BNG) >Irongmara (IM) > Dolaigaon (DLG).

ii) Monthly fluctuations inpH The mean monthly pH values at the different sites in 2011 are shown in Figures 611. In Irongmara,the pH ranged between 4.997 in May and 6.16 in September 110

Chapter 4 Results (Fig. 6). In Bongaigaon, the pH ranged between 5.41 in September and 6.15 in July (Fig. 7). In Dolaigaon, the pH ranged between 5.12 in June and 6.11 in July (Fig. 8).In BGR Township, the pH ranged between 5.61 in September and 6.65 in July (Fig. 9). In Kolkata, the pH ranged between 6.71 in May and 6.96 in July (Fig. 10).In Kharagpur, the pH ranged between 5.95 in July and 6.21 in August (Fig. 11).

b) Electrical Conductivity (EC) i) Mean ECat the different study sites The conductivity of rainwater (direct collection) at the different sites in 2011 is shown in Table 8. It can be observed from the Table that the highest mean conductivity of rainwater (direct collection)

is

recordedat Kolkata,

while the lowest is at Kharagpur. The highest individual conductivity was recorded

at

Dolaigaon on 25-04-2011,

whereas

the lowest

individual

conductivity is detected at Irongmara on 31-05-2011. The mean conductivity values in 2011 at the different sites are found to be in the following descending

order: Kolkata (KOL) > Dolaigaon (DLG)> Bongaigaon (BNG)

>BGR Township (BGR) > Irongmara (IM) >Kharagpur (KGP).

ii) Monthly fluctuations inconductivity (EC)

The mean monthly conductivity values at the different sites in 2011 are shown in Figures 12-17. In Irongmara, the conductivity ranged between 11.45µS cm-1in May and 26.8 µS cm-1in September (Fig. 12). In Bongaigaon, the conductivity ranged between 5.02 µS cm-1in June and 40.3 µS cm-1 in

111

Chapter 4 Results August (Fig. 13). In Dolaigaon, the conductivity ranged between 12.15 µS cm1

in July and 47.76 µS cm-1in April (Fig. 14). In BGR Township, the

conductivity ranged between 8.34 µS cm-1

in July and 30.63 µS cm-1 in

September (Fig. 15).In Kolkata, the conductivity ranged between 43.8 µS cm1

in June and 52.2 µS cm-1in May (Fig. 16).In Kharagpur, the conductivity

ranged between 7.005 µS cm-1 in June and 10.12µS cm-1in August (Fig. 17).

c) Heavy Metals i) Mean Heavy Metals at the different study sites The heavy metals of rainwater (direct collection) at the different sites in 2011 is shown in Table 9. It can be observed from the Table that the highest mean Lead (Pb)in rainwater (direct collection)

is

recordedat

Kolkata, while the lowest is at Dolaigaon. The highest individual Pb was also recorded at Kolkata on 18-06-2011. The mean Pb values in 2011 at the different sites are found to be in the following descending order: Kolkata (KOL) >Bongaigaon (BNG) > Irongmara (IM) >BGR Township (BGR) > Kharagpur (KGP) > Dolaigaon (DLG). rainwater (direct collection)

Highest

mean

Cadmium

(Cd) in

is recorded at Kharagpur, while the lowest is

at Kolkata. The highest individual Cd was also recorded at Kharagpur on 18-06-2011. The mean Cd values in 2011 at the different sites are found to be in the following descending order:Kharagpur (KGP) > Dolaigaon (DLG) > Bongaigaon (BNG) ~ BGR Township (BGR) > Irongmara (IM)> Kolkata (KOL).Highest meanNickel (Ni)in rainwater (direct collection)

is recorded at

Irongmara, while the lowest is at Bongaigaon and Kharagpur. The highest individual Ni was also recorded at Irongmara on 04-05-2011. The mean Ni 112

Chapter 4 Results values in 2011 at the different sites are found to be in the following descending order: Irongmara (IM) > Kolkata (KOL) > Dolaigaon (DLG) > BGR Township (BGR) > Bongaigaon (BNG) ~ Kharagpur (KGP). Highest mean Zinc (Zn)in rainwater (direct collection)

is

recordedat Irongmara, while the

lowest is at Kharagpur. The highest individual Zn was recorded at Dolaigaon on 18-07-2011, while the lowest is at Bongaigaon on 27-05-2011. The mean Zn values in 2011 at the different sites are found to be in the following

descending

order: Irongmara (IM) > BGR Township (BGR)>

Dolaigaon (DLG) >Kolkata (KOL) >Bongaigaon (BNG) >Kharagpur (KGP). It is observed from the Table that the highest mean Chromium (Cr)in rainwater (direct collection)

is recordedat Irongmara, while the lowest is at Kolkata.

The highest individual Cr was also recorded at Irongmara on 30-06-2011. The mean Cr values in 2011 at the different sites are found to be in the following

descending

order: Irongmara (IM) >BGR Township (BGR) >

Kharagpur (KGP) > Dolaigaon (DLG) ~ Bongaigaon (BNG) >Kolkata (KOL). Highest mean Cobalt (Co)in rainwater (direct collection)

is

recorded at

Irongmara and lowest at BGR Township, while at Kolkata it is Below Detection Level (B.D.L.). The highest individual Co was also recorded at Irongmara on 05-08-2011. The mean Co values in 2011 at the different sites are

found

to

be

in

the

following

descending

order: Irongmara (IM)

>Kharagpur (KGP) >Bongaigaon (BNG) > Dolaigaon (DLG) >BGR Township (BGR).

113

Chapter 4 Results ii) Monthly fluctuations inHeavy Metals The mean monthly heavy metals values at the different sites in 2011 are shown in Figures 18-52. Irongmara: The Lead (Pb) concentration ranged between 0.001 mg L-1in June and 0.0206mg L-1 in May (Fig. 18). Cadmium (Cd) concentration ranged between 0.00013 mg L-1 in May and 0.002 mg L-1 in June while the concentration in April is Below Detection Level (Fig. 19). Nickel (Ni) concentration ranged between 0.0018 mg L-1 in August and 0.0051 mg L-1 in June (Fig. 20). Zinc (Zn )concentration ranged between 0.0052 mg L-1 in June and 0.1286 mg L-1 in May (Fig. 21).Chromium (Cr) concentration ranged between 0.0003 mg L-1 in April and 0.0127 mg L-1 in July (Fig. 22). Cobalt (Co) concentration ranged between 0.0015 mg L-1 in July and 0.0087 mg L-1 in April (Fig. 23). Bongaigaon: The Lead (Pb) concentration ranged between 0.0012 mg L-1 in June and 0.0192 mg L-1 in May (Fig. 24).Cadmium (Cd) concentration ranged between 0.0021 mg L-1 in May and 0.0044 mg L-1 in August (Fig. 25). Nickel (Ni) concentration ranged between 0.0005 mg L-1 in June and September and 0.0017 mg L-1 in August (Fig. 26). Zinc (Zn) concentration ranged between 0.011 mg L-1 in May and 0.0211 mg L-1 in September (Fig. 27). Chromium (Cr) concentration ranged between 0.0006 mg L-1 in July and 0.00353 mg L-1 in April (Fig. 28). Cobalt (Co) concentration ranged between 0.0003 mg L-1 in July and 0.004 mg L-1in August (Fig. 29). Dolaigaon: The Lead (Pb) concentration ranged between 0.0006 mg L-1 in April and 0.0017 mg L-1 in June (Fig. 30). Cadmium (Cd) concentration ranged between 0.0004 mg L-1 in July and 0.0058 mg L-1 in June (Fig. 31). 114

Chapter 4 Results Nickel (Ni) concentration ranged between 0.0006 mg L-1 in September and 0.0057 mg L-1 in August (Fig. 32). Zinc (Zn) concentration ranged between 0.0105 mg L-1 in May and 0.159 mg L-1 in July (Fig. 33).Chromium (Cr) concentration ranged between 0.0003 mg L-1 in July and 0.0049 mg L-1 in June (Fig. 34). Cobalt (Co) concentration ranged between 0.0005 mg L-1 in September and 0.0031 mg L-1 in May (Fig. 35). BGR Township: The Lead (Pb) concentration ranged between 0.0013 mg L-1 in April and August and 0.0033 mg L-1 in June (Fig. 36). Cadmium (Cd) concentration ranged between 0.0009 mg L-1 in June and 0.0039 mg L-1 in September (Fig. 37). Nickel (Ni) concentration ranged between 0.0009 mg L-1 in September and 0.0046 mg L-1 in May (Fig. 38). Zinc (Zn) concentration ranged between 0.039 mg L-1 in August and 0.073 mg L-1 in June (Fig. 39). Chromium (Cr) concentration ranged between 0.0014 mg L-1in June and 0.0064 mg L-1 in May (Fig. 40). Cobalt (Co) concentration ranged between 0.0002 mg L-1 in May and September and 0.0004 mg L-1 in July (Fig. 41). Kolkata: The Lead (Pb) concentration ranged between 0.00175 mg L-1 in July and 0.086 mg L-1 in June (Fig. 42). Cadmium (Cd) concentration ranged between 0.001 mg L-1 in August and 0.00195 mg L-1 in May (Fig. 43). Nickel (Ni) concentration ranged between 0.00285 mg L-1 in July and 0.0034 mg L-1 in August (Fig. 44). Zinc (Zn) concentration ranged between 0.0107 mg L-1 in May and 0.03245 mg L-1 in August (Fig. 45). Chromium (Cr) concentration ranged between 0.0001 mg L-1 in June and 0.0005 mg L-1 in July (Fig. 46). Kharagpur: The Lead (Pb) concentration ranged between 0.0007 mg L-1 in July and 0.0021 mg L-1 in August (Fig. 47). Cadmium (Cd) concentration ranged between 0.0003mg L-1 in July and 0.0076mg L-1 in June (Fig. 48). 115

Chapter 4 Results Nickel (Ni) concentration ranged between 0.00065 mg L-1 in August and 0.0009mg L-1 in July (Fig. 49). Zinc (Zn) concentration ranged between 0.0035 mg L-1 in July and 0.0072 mg L-1 in May (Fig. 50). Chromium (Cr) concentration ranged between 0.0011mg L-1 in July and 0.0048mg L-1 in May(Fig. 51). Cobalt (Co) concentration ranged between 0.0007 mg L-1 in August and 0.0029 mg L-1 in May (Fig. 52).

d) Monthly fluctuations in Nitrate The mean monthly nitrate values at the different sites in 2011 are shown in Figures 53-58. In Irongmara, the nitrate concentration ranged between 0.655 mg L-1 in April and 1.765 mg L-1 in May(Fig. 53). In Bongaigaon,the nitrate concentration ranged between 0.079 mg L-1 in June and 1.75 mg L-1 in August (Fig. 54). In Dolaigaon,the nitrate concentration ranged between 1.005 mg L-1 in June and 1.715 mg L-1 in August (Fig. 55). In BGR Township, the nitrate concentration ranged between 0.605 mg L-1 in September and 2.28 mg L-1 in August (Fig. 56). In Kolkata,the nitrate concentration ranged between 0.84 mg L-1 in June and 1.345 mg L-1in May (Fig. 57). In Kharagpur,the nitrate concentration ranged between 0.845 mg L-1 in June and July and2.43 mg L-1 in August (Fig. 58).

e) Statistical Analysisof Data i) Comparisons of pH and EC amongstudy sites in 2011 Table 10 summarizes the results of one-way analysis-of-variance (ANOVA) in pH among the different study sites in 2011. The differences are significant at p < 0.001. Multiple comparisons using Tukey test reveal that pH of 116

Chapter 4 Results Kolkata rainwater was significantly more alkaline than those in the other study sites;pH in Kharagpur was significantly higher than that in Dolaigaon; and that in BGR Township was significantly morealkaline than those in Irongmara, Dolaigaon and Bongaigaon. Table 11 summarizes the results of one-way analysis-ofvariance (ANOVA) in EC among the different study sites in 2011. The differences are significant at p < 0.001. Multiple comparisons using Tukey test reveal that EC of Kolkata rainwater was significantly more alkaline than those in the other study sites; EC in Bongaigaon was significantly higher than that in Kharagpur; and that in Dolaigaon was significantly more alkaline than those in Irongmara, Kharagpur and BGR Township.

ii) Comparisons ofheavy metals among study sites in 2011 Table

12-15

summarizes

the

results

of

one-way

analysis-of-variance

(ANOVA) in Lead (Pb), Cadmium (Cd), Nickel (Ni) and Cobalt (Co) among the different study sites in 2011. The differences are significant at p < 0.001. In Table 12 multiple comparisons using Tukey test reveal that Pb concentration in Kolkata rainwater was significantly higher than that in Dolaigaon and BGR Township. In Table 13 multiple comparisons using Tukey test reveal that Cd concentration in Kharagpur rainwater was significantly higher than that in Irongmara. In Table 14 multiple comparisons using Tukey test reveal that Ni concentration in Irongmara rainwater was found to be significantly higher than that in Bongaigaon. In Table 15 multiple comparisons using Tukey test reveal that Co concentration in Irongmara rainwater was found to be significantly higher than those in Kolkata, Dolaigaon, Bongaigaon and BGR Township. 117

Chapter 4 Results Direct Collection Figures 2010

Irongmara 7.0 6.5

pH

6.0

5.89

5.71

5.5

5.66 5.303

5.09

5.0

5.17 5.12

4.5 4.0 March

April

May

June

July

August

September

2010

Fig. 4. pH in rainwater (direct collection) in 2010, at Irongmara, Cachar, Assam.

EC (µS cm -1)

Irongmara 90 80 70 60 50 40 30 20 10 0

54.3

59 45.5 36.6

24.9

36.8 12.4 March

April

May

June

July

August

September

2010

Fig. 5. Electrical Conductivityin rainwater (direct collection) Irongmara, Cachar, Assam.

118

in

2010, at

Chapter 4 Results 2011

Irongmara 7 6.09

6.5

6.162

pH

6

5.55

5.43

5.5

5.43

5

4.997

4.5 4 April

May

June

July

August

September

2011

Fig. 6. pH in rainwater (direct collection) during in 2011, at Irongmara, Cachar, Assam.

Bongaigaon 7 6.5 6.15

pH

6 5.702

5.5 5

5.5

5.93

5.41

5.72

4.5 4 April

May

June

July

August

September

2011

Fig.7. pH in rainwater (direct collection) in 2011, at Bongaigaon, Assam.

119

Chapter 4 Results

Dolaigaon 7 6.5 6.11

pH

6 5.45

5.5

5.45

5.14

5.33

5.12

5 4.5 4 April

May

June

July

August

September

2011

Fig. 8. pH in rainwater (direct collection) in 2011, at Dolaigaon, Assam.

BGR Township 7

6.36

6.65

6.5 pH

6

5.74

6.41

6.224

5.61

5.5 5 4.5 4 April

May

June

July

August

September

2011

Fig. 9. pH in rainwater (direct collection) in 2011, at BGR Township, Assam.

120

Chapter 4 Results

Kolkata 7

6.88

6.5

6.71

6 pH

6.96

6.83

5.5 5 4.5 4 May

June

July

August

2011

Fig. 10. pH in rainwater (direct collection) in 2011, at Kolkata, West Bengal.

Kharagpur 7 6.5

6.02

5.95

6.06

pH

6

6.21

5.5 5 4.5 4 May

June

July

August

2011

Fig. 11. pH in rainwater (direct collection) in 2011, at Kharagpur, West Midnapore, West Bengal.

121

Chapter 4 Results

EC (µS cm -1)

Irongmara 44 39 34 29 24 19 14 9 4

21.8

20.9 20.802

26.8 18.9

11.45

April

May

June

July

August

September

2011

Fig. 12. Electrical Conductivity in rainwater (direct collection) in 2011, at Irongmara, Cachar, Assam.

Bongaigaon EC (µS cm -1)

60 50 40

40.3

36.13

30

25.7

20

19.51 5.02

10

6.21

0 April

May

June

July

August

September

2011

Fig. 13. Electrical Conductivity in rainwater (direct collection) in 2011, at Bongaigaon, Assam.

122

Chapter 4 Results

EC (µS cm -1)

Dolaigaon 80 70 60 50 40 30 20 10 0

47.76

37.68 37.96

33.4

23.13 12.15 April

May

June

July

August

September

2011

Fig. 14. Electrical Conductivity in rainwater (direct collection) in 2011, at Dolaigaon, Assam.

EC (µS cm -1)

BGR Township 45 40 35 30 25 20 15 10 5 0

30.63 26.14

25.8 20.25

19.72

8.34

April

May

June

July

August

September

2011

Fig. 15. Electrical Conductivity in rainwater (direct collection) in 2011, at BGR Township, Assam.

123

Chapter 4 Results

EC (µS cm -1)

Kolkata 80 70 60 50 40 30 20 10 0

51.2

52.2

43.9

43.8

May

June

July

August

2011

Fig. 16.ElectricalConductivity in rainwater (direct collection) in 2011, at Kolkata, West Bengal.

EC (µS cm -1)

Kharagpur 16 14 12 10 8 6 4 2 0

9.17

10.12 7.81

7.005

May

June

July

August

2011

Fig. 17. Electrical Conductivity in rainwater (direct collection) in 2011, at Kharagpur, West Midnapore, West Bengal.

124

Chapter 4 Results

Lead (mg L-1)

Irongmara 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0

0.0206 0.001

0.0013

0.005

0.0019 0.0011

April

May

June

July

August

September

2011

Fig. 18. Concentration of Lead (Pb) in rainwater (direct collection) in 2011, at Irongmara, Cachar, Assam.

Cadmium (mg L-1)

Irongmara 0.004 0.0035 0.003 0.0025 0.002 0.0015 0.001 0.0005 0

0.0023

0.002 0.0014 ND 0.0002

0.00013 April

May

June

July

August

September

2011

Fig. 19. Concentration of Cadmium (Cd) in rainwater (direct collection) in 2011, at Irongmara, Cachar, Assam.

125

Chapter 4 Results

Irongmara Nickel (mg L-1)

0.012 0.01 0.008 0.0051

0.006 0.003

0.004

0.0041

0.0018

0.003

0.002

0.0022

0 April

May

June

July

August

September

2011

Fig. 20. Concentration of Nickel (Ni) in rainwater (direct collection) in 2011, at Irongmara, Cachar, Assam.

Irongmara Zinc (mg L-1)

0.25 0.2 0.1213

0.15

0.1286 0.1 0.05

0.0082

0.0052

0.0059 0.008

0 April

May

June

July

August

September

2011

Fig. 21. Concentration of Zinc (Zn) in rainwater (direct collection) in 2011, at Irongmara, Cachar, Assam.

126

Chapter 4 Results

Irongmara Chromium (mg L-1)

0.035 0.03 0.025 0.02 0.015

0.0127

0.0006

0.01

0.0092

0.0003

0.005

0.0038

0.0025

0 April

May

June

July

August

September

2011

Fig. 22. Concentration of Chromium (Cr) in rainwater (direct collection) in 2011, at Irongmara, Cachar, Assam.

Irongmara Cobalt (mg L-1)

0.025 0.02 0.015 0.01

0.0087

0.0036

0.005

0.007

0.0028

0.0024

0.0015

0 April

May

June

July

August

September

2011

Fig. 23. Concentration of Cobalt (Co) in rainwater (direct collection) in 2011, at Irongmara, Cachar, Assam.

127

Chapter 4 Results

Bongaigaon 0.06 Lead (mg L-1)

0.05 0.04 0.03 0.02

0.0192 0.0012

0.01 0

0.0023

0.0014

0.00345 April

0.00123 May

June

July

August

September

2011

Fig. 24. Concentration of Lead (Pb) in rainwater (direct collection) in 2011, at Bongaigaon, Assam.

Cadmium (mg L-1)

Bongaigaon 0.009 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.0026

0.0044

0.0025

0.0035

0.0021

ND April

May

June

July

August

September

2011

Fig. 25. Concentration of Cadmium (Cd) in rainwater (direct collection) in 2011, at Bongaigaon, Assam.

128

Chapter 4 Results

Nickel (mg L-1)

Bongaigaon 0.0045 0.004 0.0035 0.003 0.0025 0.002 0.0015 0.001 0.0005 0

0.0006

0.0005

0.0008

0.0014

0.0017 0.0005

April

May

June

July

August

September

2011

Fig. 26. Concentration of Nickel (Ni) in rainwater (direct collection) in 2011, at Bongaigaon, Assam.

Zinc (mg L-1)

Bongaigaon 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0

0.018

0.0211

0.0204

0.013 0.0134

0.011

April

May

June

July

August

September

2011

Fig. 27. Concentration of Zinc (Zn) in rainwater (direct collection) in 2011, at Bongaigaon, Assam.

129

Chapter 4 Results

Chromium (mg L-1)

Bongaigaon 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.00348

0.00353

0.003 0.0035 0.0018 0.0006

April

May

June

July

August

September

2011

Fig. 28. Concentration of Chromium (Cr) in rainwater (direct collection) in 2011, at Bongaigaon, Assam.

Cobalt (mg L-1)

Bongaigaon 0.009 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.004

0.002

0.003 0.0013

0.0009

0.0003 April

May

June

July

August

September

2011

Fig. 29. Concentration of Cobalt (Co) in rainwater (direct collection) in 2011, at Bongaigaon, Assam.

130

Chapter 4 Results

Dolaigaon 0.0035

Lead (mg L-1)

0.003 0.0025

0.0017

0.002

0.0013

0.0015

0.0013

0.0012

0.001

0.0007

0.0006

0.0005 0

April

May

June

July

August

September

2011

Fig. 30. Concentration of Lead (Pb) in rainwater (direct collection) in 2011, at Dolaigaon, Assam.

Dolaigaon Cadmium (mg L-1)

0.012 0.01 0.008

0.0058

0.006 0.0043

0.004 0.002

0.0028

0.0019

0.0011

0.0004

0 April

May

June

July

August

September

2011

Fig. 31. Concentration of Cadmium (Cd) in rainwater (direct collection) in 2011, at Dolaigaon, Assam.

131

Chapter 4 Results

Nickel (mg L-1)

Dolaigaon 0.009 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.0057 0.003

0.004

0.0009 0.0029

0.0006 April

May

June

July

August

September

2011

Fig. 32. Concentration of Nickel (Ni) in rainwater (direct collection) in 2011, at Dolaigaon, Assam.

Dolaigaon 0.6 Zinc (mg L-1)

0.5 0.4 0.3 0.2 0.1

0.033

0.0105

0.195

0.0171

0.026 0.0241

0 April

May

June

July

August

September

2011

Fig. 33. Concentration of Zinc (Zn) in rainwater (direct collection) in 2011, at Dolaigaon, Assam.

132

Chapter 4 Results

Dolaigaon Chromium (mg L-1)

0.014 0.012 0.01 0.008

0.0049

0.006 0.0043

0.004

0.0029

0.002

0.0019 0.0012

0.0003

0 April

May

June

July

August

September

2011

Fig. 34. Concentration of Chromium (Cr) in rainwater (direct collection) in 2011, at Dolaigaon, Assam.

Cobalt (mg L-1)

Dolaigaon 0.004 0.0035 0.003 0.0025 0.002 0.0015 0.001 0.0005 0

0.0031 0.0013 0.0012

0.0014 0.0012 0.0005

April

May

June

July

August

September

2011

Fig. 35. Concentration of Cobalt (Co) in rainwater (direct collection) in 2011, at Dolaigaon, Assam.

133

Chapter 4 Results

BGR Township 0.006 Lead (mg L-1)

0.005 0.0033

0.004 0.003

0.0013

0.0022

0.002 0.0015

0.001

0.0019 0.0013

0 April

May

June

July

August

September

2011

Fig. 36. Concentration of Lead (Pb) in rainwater (direct collection) in 2011, at BGR Township, Assam.

BGR Township Cadmium (mg L-1)

0.012 0.01 0.008 0.006 0.004

0.0039 0.0017

0.002

0.0009

0.0015

0.0035

0.0016

0 April

May

June

July

August

September

2011

Fig. 37. Concentration of Cadmium (Cd) in rainwater (direct collection) in 2011, at BGR Township, Assam.

134

Chapter 4 Results

BGR Township 0.007 Nickel (mg L-1)

0.006 0.005

0.0046

0.004 0.003

0.003 0.0019

0.0025

0.002

0.0017

0.001

0.0009

0 April

May

June

July

August

September

2011

Fig. 38. Concentration of Nickel (Ni) in rainwater (direct collection) in 2011, at BGR Township, Assam.

BGR Township 0.14 Zinc (mg L-1)

0.12 0.1

0.073 0.068

0.08

0.0533

0.06

0.039

0.044

0.04

0.046

0.02 0 April

May

June

July

August

September

2011

Fig. 39. Concentration of Zinc (Zn) in rainwater (direct collection) in 2011, at BGR Township, Assam.

135

Chapter 4 Results

BGR Township Chromium (mg L-1)

0.012 0.01 0.008 0.0064

0.006 0.004

0.0044

0.0028

0.0014

0.0027

0.002

0.0015

0 April

May

June

July

August

September

2011

Fig. 40. Concentration of Chromium (Cr) in rainwater (direct collection) in 2011, at BGR Township, Assam.

BGR Township Cobalt (mg L-1)

0.001 0.0008 0.0006 0.0003

0.0004

0.0004

0.0003

0.0003

0.0002

0.0002

0.0002

0 April

May

June

July

August

September

2011

Fig. 41. Concentration of Cobalt (Co) in rainwater (direct collection) in 2011, at BGR Township, Assam.

136

Chapter 4 Results

Kolkata Lead (mg L-1)

0.25 0.2 0.15 0.1

0.086

0.05

0.00175 0.018

0 May

0.003 June

July

August

2011

Fig. 42. Concentration of Lead (Pb) in rainwater (direct collection) in 2011, at Kolkata, West Bengal.

Cadmium (mg L-1)

Kolkata 0.004 0.0035 0.003 0.0025 0.002 0.0015 0.001 0.0005 0

0.00195

0.0014

0.0015

0.001

May

June

July

August

2011

Fig. 43. Concentration of Cadmium (Cd) in rainwater (direct collection) in 2011, at Kolkata, West Bengal.

137

Chapter 4 Results

Nickel (mg L-1)

Kolkata 0.009 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.0032

0.00305

May

0.00285 0.0034

June

July

August

2011

Fig. 44. Concentration of Nickel (Ni) in rainwater (direct collection) in 2011, at Kolkata, West Bengal.

Zinc (mg L-1)

Kolkata 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0

0.02105

0.03245

0.0107 0.0111

May

June

July

August

2011

Fig. 45. Concentration of Zinc (Zn) in rainwater (direct collection) in 2011, at Kolkata, West Bengal.

138

Chapter 4 Results

Kolkata Chromium (mg L-1)

0.0012 0.001 0.0008 0.0005

0.0006 0.0004

0.0004

0.00035

0.0002 0.0001

0 May

June

July

August

2011

Fig. 46. Concentration of Chromium (Cr) in rainwater (direct collection) in 2011, at Kolkata, West Bengal.

Kharagpur 0.006 Lead (mg L-1)

0.005 0.004 0.003 0.002 0.001

0.0007

0.0011

0.00105

0.0021

0 May

June

July

August

2011

Fig. 47. Concentration of Lead (Pb) in rainwater (direct collection) in 2011, at Kharagpur, West Midnapore, West Bengal.

139

Chapter 4 Results

Cadmium (mg L-1)

Kharagpur 0.018 0.016 0.014 0.012 0.01 0.008 0.006 0.004 0.002 0

0.0071

0.0076 0.0003

May

June

July

0.0069

August

2011

Fig. 48. Concentration of Cadmium (Cd) in rainwater (direct collection) in 2011, at Kharagpur, West Midnapore, West Bengal.

Kharagpur Nickel (mg L-1)

0.0025 0.002 0.0015

0.0009

0.001

0.00085

0.0007

0.00065

0.0005 0 May

June

July

August

2011

Fig. 49. Concentration of Nickel (Ni) in rainwater (direct collection) in 2011, at Kharagpur, West Midnapore, West Bengal.

140

Chapter 4 Results

Zinc (mg L-1)

Kharagpur 0.016 0.014 0.012 0.01 0.008 0.006 0.004 0.002 0

0.0072

0.007

0.0035 0.0036

May

June

July

August

2011

Fig. 50. Concentration of Zinc (Zn) in rainwater (direct collection) in 2011, at Kharagpur, West Midnapore, West Bengal.

Kharagpur Chromium (mg L-1)

0.01 0.008 0.006 0.0048

0.004

0.0011

0.0012

0.002

0.0022

0 May

June

July

August

2011

Fig. 51. Concentration of Chromium (Cr) in rainwater (direct collection) in 2011, at Kharagpur, West Midnapore, West Bengal.

141

Chapter 4 Results

Kharagpur Cobalt (mg L-1)

0.005 0.004 0.003

0.0029

0.0021

0.002 0.00105

0.001

0.0007

0 May

June

July

August

2011

Fig. 52. Concentration of Cobalt (Co) in rainwater (direct collection) in 2011, at Kharagpur, West Midnapore, West Bengal.

Irongmara Nitrate (mg L-1)

3 2.5 2

1.765

1.74

1.5

1.45 1.045

1 0.5

1.01

0.655

0 April

May

June

July

August

September

2011

Fig. 53. Concentration of Nitrate (NO3-) in rainwater (direct collection) in 2011, at Irongmara, Cachar, Assam.

142

Chapter 4 Results

Bongaigaon Nitrate (mg L-1)

3 2.5 2 1.75

1.5

1.12 1.06

1

1.041 0.5445

0.5 0.079

0 April

May

June

July

August

September

2011

Fig. 54. Concentration of Nitrate (NO3-) in rainwater (direct collection) in 2011, at Bongaigaon, Assam.

Nitrate (mg L-1)

Dolaigaon 4 3.5 3 2.5 2 1.5 1 0.5 0

1.57

1.715

1.445

1.28

1.205 1.005

April

May

June

July

August

September

2011

Fig. 55. Concentration of Nitrate (NO3-) in rainwater (direct collection) in 2011, at Dolaigaon, Assam.

143

Chapter 4 Results

Nitrate (mg L-1)

BGR Township 4 3.5 3 2.5 2 1.5 1 0.5 0

2.28 1.33

1.58

1.14 0.865 April

May

0.605 June

July

August

September

2011

Fig. 56. Concentration of Nitrate (NO3-) in rainwater (direct collection) in 2011, at BGR Township, Assam.

Kolkata Nitrate (mg L-1)

3 2.5 2 1.5

1.04

1.345

1.34

1 0.5

0.84

0 May

June

July

August

2011

Fig. 57. Concentration of Nitrate (NO3-) in rainwater (direct collection) in 2011, at Kolkata, West Bengal.

144

Chapter 4 Results

Nitrate (mg L-1)

Kharagpur 4 3.5 3 2.5 2 1.5 1 0.5 0

2.43 1.65

0.845 0.845

May

June

July

August

2011

Fig. 58. Concentration of Nitrate (NO3-) in rainwater (direct collection) in 2011, at Kharagpur, West Midnapore, West Bengal.

145

Chapter 4 Results 2011 Table 7Descriptive statistics for pH (Direct Collection) in Rainwater at different geographical locations during 2011

Site

Mean

Median

S.D.

Min

Max

Irongmara

5.53

5.62

0.79

2.004

6.93

Bongaigaon

5.71

5.81

0.413

4.76

6.379

Dolaigaon

5.46

5.315

0.49

4.76

6.502

BGR

6.18

6.28

0.44

5.21

6.771

Kolkata Township

6.93

6.866

0.26

6.61

7.5

Kharagpur

6.067

6.04

0.17

5.89

6.502

Table

8

Descriptive

statistics

for

ElectricalConductivity

(Direct

Collection) in Rainwater at different geographical locations during 2011

Site

Mean

Median

S.D.

Min

Max

19.24 (µS cm-1) 23.97

16.91

9.82

2.41

52.7

28.1

15.41

3.38

52.7

Dolaigaon

33.06

33

17.31

3.46

88.1

BGR

21.72

21.7

9.93

6.43

42.1

Township Kolkata

50.3

53.75

13.2

31.2

69.2

Kharagpur

9.04

9.25

2.61

4.41

12.6

Irongmara Bongaigaon

146

Chapter 4 Results Table9 Descriptive statistics for Heavy Metal Concentrations in Rainwater (Direct Collection) at different geographical locations during 2011 Heavy Metals Pb

Site

Mean

Median

S.D.

Min

Max

Irongmara

0.0044

0.002

0.008

ND

0.0389

(mg L-1)

Bongaigaon

0.0048

0.002

0.014

ND

0.07

Dolaigaon

0.001

0.0009

0.0011

ND

0.0031

BGR Township

0.0018

0.0018

0.0014

ND

0.0055

Kolkata

0.022

0.0017

0.054

ND

0.172

Kharagpur

0.0013

0.0007

0.0015

ND

0.0041

Irongmara

0.00124

ND

0.003

ND

0.005

Bongaigaon

0.0024

0.00255

0.0024

ND

0.0084

Dolaigaon

0.003

0.0021

0.0031

ND

0.0107

BGR Township

0.0024

0.0018

0.003

ND

0.0117

Kolkata

0.0012

0.0007

0.0011

ND

0.0032

Kharagpur

0.005

0.00255

0.005

ND

0.0131

Irongmara

Cd

Ni

Zn

Cr

Co

0.0043

0.003

0.0053

ND

Bongaigaon

0.0009

0.0006

0.0012

ND

0.024 0.005

Dolaigaon

0.0028

0.0017

0.0028

ND

0.009

BGR Township

0.00234

0.00255

0.0023

ND

0.0063

Kolkata

0.0032

0.0034

0.003

ND

0.007

Kharagpur

0.0009

0.00125

0.0008

ND

0.0018

Irongmara

0.0136

0.063

0.0018

0.215

Bongaigaon

0.0534 0.018

0.0157

0.01513

0.0015

0.059

Dolaigaon

0.0461

0.02

0.115

0.0056

0.5289

BGR Township

0.0521

0.04795

0.0279

0.017

0.128

Kolkata

0.0187

0.0188

0.0104

0.0018

0.0337

Kharagpur

0.0053

0.00415

0.0032

0.0016

0.0128

Irongmara

0.0057 0.0025

0.0014

0.0112

ND

Bongaigaon

0.0019

0.0026

ND

0.045 0.0072

Dolaigaon

0.0025

0.0005

0.0039

ND

0.0143

BGR Township

0.0031

0.0031

0.0033

ND

0.0107

Kolkata

0.00027

0.00025

0.0003

ND

0.0008

Kharagpur

0.003

0.00165

0.0022

0.001

0.008

Irongmara

0.0032

0.0049

ND

Bongaigaon

0.0046 0.0018

0.0008

0.0024

ND

0.021 0.008

Dolaigaon

0.0017

0.0017

0.0016

ND

0.006

0.00025

0.0001

0.0003

ND

0.0009

ND

ND

0

ND

0

0.002

0.00155

0.00145

ND

0.0041

BGR Township Kolkata Kharagpur

ND not detected

147

Chapter 4 Results

Table 10 Results of one way analysis of variance (ANOVA) for pH of rainwater along with multiple comparisons using Tukey test among the sites during 2011 F

Significance

16.418

P Irongmara, Kharagpur, Dolaigaon, Kharagpur>Dolaigaon Bongaigaon, BGR Township BGR Township>Irongmara, Dolaigaon,

P=0.000 - 0.006 P= 0.030 P= 0.000 - 0.008

Bongaigaon

Table 11 Results of one way analysis of variance (ANOVA) for Electrical Conductivity (EC) of rainwater along with multiple comparisons using Tukey test among the sites during 2011 F

Significance

14.446

P Irongmara, Kharagpur,

P= 0.000 - 0.006

Dolaigaon, Bongaigaon, BGR Township Dolaigaon > Irongmara, Kharagpur,BGR

P= 0.000 - 0.019

Township Bongaigaon> Kharagpur

148

P= 0.021

Chapter 4 Results Table 12 Results of one way analysis of variance (ANOVA) for Lead (Pb) of rainwater along with multiple comparisons using Tukey test among the sites during 2011 F

Significance

2.253

P= 0.055

Summary of Multiple Comparisons using Tukey test Kolkata > Dolaigaon, BGR Township

Range of Significance

P= 0.032 - 0.046

Table 13 Results of one way analysis of variance (ANOVA) for Cadmium (Cd) of rainwater along with multiple comparisons using Tukey test among the sites during 2011 F

Significance

2.671

P= 0.026

Summary of Multiple Comparisons using Tukey test Kharagpur > Irongmara

149

Range of Significance

P= 0.015

Chapter 4 Results Table 14 Results of one way analysis of variance (ANOVA) for Nickel (Ni) of rainwater along with multiple comparisons using Tukey test among the sites during 2011 F

Significance

3.618

P= 0.005

Summary of Multiple Comparisons using Tukey test Irongmara > Bongaigaon

Range of Significance

P= 0.003

Table 15 Results of one way analysis of variance (ANOVA) for Cobalt (Co) of rainwater along with multiple comparisons using Tukey test among the sites during 2011 F

Significance

7.180

P Kolkata, Dolaigaon, Bongaigaon, BGR Township

150

Range of Significance

P= 0.000 - 0.009

Chapter 4 Results 3. Rainwater quality in different study sites in 2012 a) pH i) Mean pH at the different study sites The pH of rainwater (direct collection) at the different sites in 2012 is shown in Table 16. It can be observed from the Table that the highest mean pH of rainwater (direct collection)

is recordedat Kolkata, while the

lowest is at Dolaigaon. The highest individual

pH was also recorded at

Kolkata on 28-07-2012, whereas the lowest individual pH is detected at Irongmara on 06-07-2012. The mean pH values in 2012 at the different sites are found to be in the following descending order: Kolkata (KOL) >Kharagpur (KGP) > Badarpur (BPB) > BGR Township (BGR) >Bongaigaon (BNG) > Irongmara (IM) > Dolaigaon (DLG).

ii) Monthly fluctuations inpH The mean monthly pH values at the different sites in 2012 are shown in Figures 5965. In Irongmara, the pH ranged between 5.49 in June and 6.36 in January (Fig. 59). In Badarpur, the pH ranged between 5.92 in July and 6.15 in August (Fig. 60).In Bongaigaon, the pH ranged between 5.37 in April and 5.85 in June (Fig. 61). In Dolaigaon, the pH ranged between 4.97 in April and 5.63 in May (Fig. 62).In BGR Township, the pH ranged between 5.35 in April and 6.11 in July (Fig. 63). In Kolkata, the pH ranged between 5.96 in June and 6.95 in August (Fig. 64).In Kharagpur, the pH ranged between 5.93 in June and 6.36 in May(Fig. 65).

151

Chapter 4 Results b) Electrical Conductivity (EC) i) Mean EC at the different study sites The conductivity of rainwater (direct collection) at the different sites in 2012 is shown in Table 17. It can be observed from the Table that the highest mean conductivity of rainwater (direct collection)

is

recordedat Kolkata,

while the lowest is at BGR Township. The highest individual conductivity was recorded at Irongmara on 20-01-2012, whereas the lowest individual conductivity is detected at Bongaigaon and BGR Township on 13-08-2012 and 09-07-2012 respectively. The mean conductivity values in 2012 at the different sites are found to be in the following descending order: Kolkata (KOL) >Badarpur (BPB) > Irongmara (IM) >Dolaigaon (DLG)> Bongaigaon (BNG) >Kharagpur (KGP) >BGR Township (BGR).

ii) Monthly fluctuations inconductivity (EC)

The mean monthly conductivity values at the different sites in 2012 are shown in Figures 66-72. In Irongmara, the conductivity ranged between 11.73µS cm-1 in May and 73.9µS cm-1 in January (Fig. 66). In Badarpur, the conductivity ranged between 21.55 µS cm-1 in April and 39.1 µS cm-1 in September (Fig. 67). In Bongaigaon, the conductivity ranged between 24.3 µS cm-1 in September and 29.04 µS cm-1in June (Fig. 68).In Dolaigaon, the conductivity ranged between 20.15 µS cm-1in June and 33.63µS cm-1 in September (Fig. 69). In BGR Township, the conductivity ranged between 16.8µS cm-1in July and 32.05µS cm-1in April (Fig. 70).In Kolkata, the conductivity ranged between 26.6 µS cm-1in August and 59.6 µS cm-1in

152

Chapter 4 Results September (Fig. 71).In Kharagpur, the conductivity ranged between 10.32 µS cm-1in May and 87.1 µS cm-1in April (Fig. 72). c) Heavy Metals i) Mean Heavy Metals at the different study sites The heavy metals of rainwater (direct collection) at the different sites in 2012 is shown in Table 18. It can be observed from the Table that the highest mean Lead (Pb)in rainwater (direct collection) is recordedat Kolkata, while the lowest is at Dolaigaon. The highest individual Pb was recorded at Bongaigaon on 20-04-2012. The mean Pb values in 2012 at the different sites are found to be in the following descending order: Kolkata (KOL) > Bongaigaon (BNG) >Badarpur (BPB) >Irongmara (IM) >BGR Township (BGR) > Kharagpur (KGP) > Dolaigaon (DLG). rainwater (direct collection)

Highest

mean

Cadmium

(Cd)in

is recordedat Kharagpur, while the lowest is at

Irongmara. The highest individual Cd was recorded at BGR Township on 2706-2012. The mean Cd values in 2012 at the different sites are found to be in the following descending order: Kharagpur (KGP) >BGR Township (BGR) > Kolkata (KOL) >Dolaigaon (DLG) > Bongaigaon (BNG) > Irongmara (IM). Highest

mean

Nickel

(Ni)in

rainwater

(direct

collection)is

recordedat

Irongmara, while the lowest is at Bongaigaon. The highest individual Ni was also recorded at Irongmara on 01-08-2012. The mean Ni values in 2012 at the different sites are found to be in the following descending order: Irongmara (IM) > Kolkata (KOL) ~BGR Township (BGR)>Kharagpur (KGP) >Dolaigaon (DLG) > Bongaigaon (BNG). Highest mean Zinc (Zn)in rainwater (direct collection)

is recordedat Irongmara, while the lowest is at Kolkata.

The highest individual Zn was also recorded at Irongmara as well as BGR 153

Chapter 4 Results Township on 23-09-2012 and 16-04-2012 respectively, while the lowest individual Zn is recorded at Kharagpur on 22-06-2012. The mean Zn values in 2012 at the different sites are found to be in the following descending order: Irongmara (IM) > Kharagpur (KGP) > BGR Township (BGR) >Badarpur (BPB) >Dolaigaon (DLG) >Bongaigaon (BNG) >Kolkata (KOL). It is observed from the Table that the highest mean Chromium (Cr)in rainwater (direct collection) is recorded at Kharagpur, while the lowest is at Badarpur. The highest individual Cr was also recorded at Kharagpur on 26-04-2012. The mean Cr values in 2012 at the different sites are found to be in the following descending order: Kharagpur (KGP) >Irongmara (IM) >Kolkata (KOL) > Bongaigaon (BNG) > Dolaigaon (DLG) >BGR Township (BGR) > Badarpur (BPB).

Highest

mean

Cobalt

(Co)in

rainwater

(direct

collection)

is

recordedat Irongmara and lowest at BGR Township, while at Kolkata it is Below Detection Level (B.D.L.). The highest individual Co was also recorded at Irongmara on 01-08-2012. The mean Co values in 2012 at the different sites are found to be in the following descending order: Irongmara (IM) >Bongaigaon (BNG) > Dolaigaon (DLG) >Kharagpur (KGP) > BGR Township (BGR).

ii) Monthly fluctuations inHeavy Metals The mean monthly heavy metals values at the different sites in 2012 are shown in Figures 73-110. Irongmara:The Lead (Pb) concentration ranged between 0.001 mg L-1 in June and 0.0062 mg L-1 in August (Fig. 73). Cadmium (Cd) concentration ranged between 0.0016 mg L-1 in August and 0.0035 mg L-1 in April (Fig. 154

Chapter 4 Results 74). Nickel (Ni) concentration ranged between 0.0023 mg L-1 in April and 0.006 mg L-1 in August (Fig. 75). Zinc (Zn) concentration ranged between 0.02 mg L-1 in August and 0.513 mg L-1 in April (Fig. 76).Chromium (Cr) concentration ranged between 0.0022 mg L-1 in July and 0.0083 mg L-1 in August (Fig. 77). Cobalt (Co) concentration ranged between 0.0014mg L-1 in September and 0.0064 mg L-1 in July (Fig. 78). Badarpur:The Lead (Pb) concentration ranged between 0.0014 mg L-1 in June and 0.0032 mg L-1 in August (Fig. 79). Zinc (Zn) concentration ranged between 0.0131 mg L-1 in July and 0.042 mg L-1 in September (Fig. 80). Chromium (Cr) concentration ranged between 0.0006 mg L-1 in August and 0.0021 mg L-1 in September (Fig. 81). Bongaigaon:The Lead (Pb) concentration ranged between 0.0014 mg L-1 in May and 0.0152 mg L-1 in April (Fig. 82). Cadmium (Cd) concentration ranged between 0.0008 mg L-1 in May and 0.0043 mg L-1 in August (Fig. 83). Nickel (Ni) concentration ranged between 0.0003 mg L-1 in July and 0.001 mg L-1 in May (Fig. 84). Zinc (Zn) concentration ranged between 0.01 mg L-1 in August and 0.04 mg L-1 in April (Fig. 85). Chromium (Cr) concentration ranged between 0.0019 mg L-1 in May and 0.009 mg L-1 in April (Fig. 86). Cobalt (Co) concentration ranged between 0.0006 mg L-1 in July and 0.0034 mg L-1 in September (Fig. 87). Dolaigaon: The Lead (Pb) concentration ranged between 0.0003mg L-1 in April and 0.0025mg L-1 in September (Fig. 88). Cadmium (Cd) concentration ranged between 0.0003 mg L-1 in May and 0.0043mg L-1 in June (Fig. 89). Nickel

(Ni)

concentration

ranged

between

0.0003mg L-1

in

July and

0.0015mg L-1 in June (Fig. 90). Zinc (Zn) concentration ranged between 155

Chapter 4 Results 0.012mg L-1 in June and 0.054mg L-1 in April (Fig. 91).Chromium (Cr) concentration ranged between 0.0024mg L-1 in July and 0.005mg L-1 in August (Fig. 92). Cobalt (Co) concentration ranged between 0.0009mg L-1 in July and 0.003 mg L-1 in September (Fig. 93). BGR Township: The Lead (Pb) concentration ranged between 0.0007 mg L-1 in April and 0.0027mg L-1 in August (Fig. 94). Cadmium (Cd) concentration ranged between 0.0011mg L-1 in August and 0.013mg L-1 in June (Fig. 95). Nickel (Ni) concentration ranged between 0.0012mg L-1 in

April and

0.0043mg L-1 in September (Fig. 96). Zinc (Zn) concentration ranged between 0.0124mg L-1 in August and 0.063 mg L-1in June (Fig. 97). Chromium (Cr) concentration ranged between 0.0025mg L-1in April and 0.0042mg L-1 in May (Fig. 98). Cobalt (Co) concentration ranged between 0.00013mg L-1 in April and 0.0004 mg L-1 in July while the concentration in September is Below Detection Level (Fig. 99). Kolkata:The Lead (Pb) concentration ranged between 0.0029 mg L-1in May and 0.0095 mg L-1 in August (Fig. 100). Cadmium (Cd) concentration ranged between 0.0009 mg L-1 in August and 0.0019 mg L-1 in September (Fig. 101). Nickel (Ni) concentration ranged between 0.002 mg L-1 in May and June and 0.0038 mg L-1 in September (Fig. 102). Zinc (Zn) concentration ranged between 0.0123 mg L-1 in July and 0.02 mg L-1 in September (Fig. 103).Chromium (Cr) concentration ranged between 0.0008 mg L-1 in July and 0.0072 mg L-1 in May (Fig. 104). Kharagpur: The Lead (Pb) concentration ranged between 0.0003 mg L-1 in April and 0.0025 mg L-1 in July (Fig. 105). Cadmium (Cd) concentration ranged between 0.0022 mg L-1 in August and 0.0067 mg L-1 in July (Fig. 156

Chapter 4 Results 106). Nickel (Ni) concentration ranged between 0.0006 mg L-1 in August and 0.0026 mg L-1 in June while the concentration in April is Below Detection Level (Fig. 107). Zinc (Zn) concentration ranged between 0.0073 mg L-1 in June and 0.058 mg L-1 in July (Fig. 108).Chromium (Cr) concentration ranged between 0.0009 mg L-1in July and 0.0132 mg L-1in April (Fig. 109). Cobalt (Co) concentration ranged between 0.0006 mg L-1 in September and 0.0026 mg L-1 in May while the concentration in April is Below Detection Level (Fig. 110).

d) Monthly fluctuations in Nitrate The mean monthly nitrate values at the different sites in 2012 are shown in Figures 111-117. In Irongmara, the nitrate concentration ranged between 1.25 mg L-1 in July and 1.92mg L-1 in September (Fig. 111). In Badarpur, the nitrate concentration ranged between 0.88 mg L-1 in July and 2.09 mg L-1 in September (Fig. 112). In Bongaigaon, the nitrate concentration ranged between 0.69 mg L-1 in September and 2.62 mg L-1 in April (Fig. 113). In Dolaigaon, the nitrate concentration ranged between 0.82 mg L-1 in August and

2.61

mg L-1

in

May

(Fig. 114).In

BGR Township,

the

nitrate

concentration ranged between 0.89 mg L-1 in June and 1.75 mg L-1 in May (Fig. 115). In Kolkata, the nitrate concentration ranged between 0.77mg L-1 in September and 1.23mg L-1 in May and July (Fig. 116).In Kharagpur, the nitrate concentration ranged between 0.82mg L-1 in June and 1.83mg L-1 in September (Fig. 117).

157

Chapter 4 Results e) Statistical Analysisof Data i) Comparisons of pH and EC amongstudy sites in 2012 Table 19 summarizes the results of one-way analysis-of-variance (ANOVA) in pH among the different study sites in 2012. The differences are significant at p < 0.001. Multiple comparisons using Tukey test reveal that pH of Kolkata rainwater was significantly more alkaline than those in the other study sites; pH in Kharagpur was significantly higher than that in Irongmara ,

Dolaigaon

and

Bongaigaon;

and

that

in

Dolaigaon

was

significantly less alkaline than those in the other study sites. Table 20 summarizes the results of one-way analysis-of-variance (ANOVA) in EC among the different study sites in 2012. The differences are significant at p < 0.001. Multiple comparisons using Tukey test reveal that EC of Kolkata rainwater was significantly higher than that in Irongmara, Kharagpur, Dolaigaon, Bongaigaon and BGR Township.

ii) Comparisons ofheavy metals among study sites in 2012 Table

21-23

summarizes

the

results

of

one-way

analysis-of-variance

(ANOVA) in Nickel (Ni), Zinc (Zn) and Cobalt (Co) among the different study sites in 2012. The differences are significant at p < 0.001. In Table 21 multiple comparisons using Tukey test reveal that Ni concentration in Irongmara rainwater was significantly higher than that in

Kharagpur,

Dolaigaon and Bongaigaon; Ni in BGR Township was significantly higher than that in Bongaigaon. In Table 22 multiple comparisons using Tukey test reveal that Zn concentration in Irongmara rainwater was significantly higher than that in Kolkata. In Table 23 multiple comparisons using Tukey test 158

Chapter 4 Results reveal that Co concentration in Irongmara rainwater was found to be significantly higher than those in the other study sites.

159

Chapter 4 Results 2012

Irongmara 7 6.5

6.36

pH

6

5.59

5.865 5.88

5.5

5.49 5.52

5.87

5.54

5 4.5 4

2012

Fig. 59. pH in rainwater (direct collection) in 2012, at Irongmara, Cachar, Assam.

pH

Badarpur 7 6.5 6 5.5 5 4.5 4

6.14

5.95

6.03

5.926.15

6.04

5.98

2012 Fig. 60. pH in rainwater (direct collection) in 2012, at Badarpur, Karimganj, Assam.

160

Chapter 4 Results

Bongaigaon 7 6.5 5.85

pH

6

5.73 5.683

5.5

5.37

5.68

5.65

5 4.5 4 April

May

June

July

August

September

2012

Fig. 61. pH in rainwater (direct collection) in 2012, at Bongaigaon, Assam.

Dolaigaon 7 6.5 pH

6

5.63

5.45 5.27

5.5 5

5.28

4.97

4.95

4.5 4 April

May

June

July

August

September

2012

Fig. 62. pH in rainwater (direct collection) in 2012, at Dolaigaon, Assam.

161

Chapter 4 Results

BGR Township 7 6.5

6.1 6.11

pH

6

5.52

6.02

5.5

5.532

5.35

5 4.5 4 April

May

June

July

August

September

2012

Fig. 63. pH in rainwater (direct collection) in 2012, at BGR Township, Assam.

Kolkata 7

6.95

6.84

6.5 6 pH

6.47

6.41 5.96

5.5 5 4.5 4 May

June

July

August

September

2012

Fig. 64. pH in rainwater (direct collection) in 2012, at Kolkata, West Bengal.

162

Chapter 4 Results

Kharagpur 7 6.5 pH

6

6.07

6.36

6.113

6.023

5.5

5.93

5.97

5 4.5 4 April

May

June

July

August

September

2012

Fig. 65. pH in rainwater (direct collection) in 2012, at Kharagpur, West Midnapore,

EC (µS cm -1)

West Bengal.

160 140 120 100 80 60 40 20 0

Irongmara

73.9

53.75

57.9 53.7

46.9 27.5 11.73

14.43

2012

Fig. 66. Electrical Conductivity in rainwater (direct collection) in 2012, at Irongmara, Cachar, Assam.

163

Chapter 4 Results

Badarpur 70 EC (µS cm -1)

60 50 40

32.35

30.1

25.8

39.1

30

27.1

37.65

20 21.55

10 0 March

April

May

June

July

August

September

2012

Fig. 67. Electrical Conductivity in rainwater (direct collection) in 2012, at Badarpur, Cachar, Assam.

EC (µS cm -1)

Bongaigaon 45 40 35 30 25 20 15 10 5 0

26.5

28.72

May

24.3

29.04

26.72

April

24.51

June

July

August

September

2012

Fig. 68. Electrical Conductivity in rainwater (direct collection) in 2012, at Bongaigaon, Assam.

164

Chapter 4 Results

Dolaigaon EC (µS cm -1)

50 40 28.1

33.63

30

28.34

20.15

29.4

23.6

20 10 0 April

May

June

July

August

September

2012

Fig. 69. Electrical Conductivity in rainwater (direct collection) in 2012, at Dolaigaon, Assam.

.

BGR Township 70 EC (µS cm -1)

60 50 40 32.05

30

21.03

21.3

20.6

16.8

20

19.32

10 0 April

May

June

July

August

September

2012

Fig. 70. Electrical Conductivity in rainwater (direct collection) in 2012, at BGR Township, Assam.

165

Chapter 4 Results

EC (µS cm -1)

Kolkata 80 70 60 50 40 30 20 10 0

52.7

51.08

59.6 44.2 26.6

May

June

July

August

September

2012

Fig. 71. Electrical Conductivity in rainwater (direct collection) in 2012, at Kolkata, West Bengal.

EC (µS cm -1)

Kharagpur 160 140 120 100 80 60 40 20 0

87.1

April

10.32

11.47

16.37

14.35

13.82

May

June

July

August

September

2012

Fig. 72. Electrical Conductivity in rainwater (direct collection) in 2012, at Kharagpur, West Midnapore, West Bengal.

166

Chapter 4 Results

Irongmara 0.014 Lead (mg L-1)

0.012 0.01 0.008 0.0062

0.006 0.0012

0.004

0.0043

0.001 0.0022

0.002

0.0013

0 April

May

June

July

August

September

2012

Fig. 73. Concentration of Lead (Pb) in rainwater (direct collection) in 2012, at Irongmara, Cachar, Assam.

Cadmium (mg L-1)

Irongmara 0.009 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.0035 0.0017

0.0031

0.0025 0.0016

April

May

June

July

August

0.0023

September

2012

Fig. 74. Concentration of Cadmium (Cd) in rainwater (direct collection) in 2012, at Irongmara, Cachar, Assam.

167

Chapter 4 Results

Irongmara 0.014 Nickel (mg L-1)

0.012 0.01 0.008 0.006 0.004

0.0023

0.006

0.0032

0.00234

0.0044

0.004

0.002 0 April

May

June

July

August

September

2012

Fig. 75. Concentration of Nickel (Ni) in rainwater (direct collection) in 2012, at Irongmara, Cachar, Assam.

Irongmara 0.14 Zinc (mg L-1)

0.12 0.1 0.08 0.06 0.04

0.0513

0.0312

0.0353

0.051

0.0413

0.02

0.02

0 April

May

June

July

August

September

2012

Fig. 76. Concentration of Zinc (Zn) in rainwater (direct collection) in 2012, at Irongmara, Cachar, Assam.

168

Chapter 4 Results

Irongmara Chromium (mg L-1)

0.025 0.02 0.015 0.0083

0.01

0.006

0.0037

0.005

0.0036

0.0062 0.0022

0 April

May

June

July

August

September

2012

Fig. 77. Concentration of Chromium (Cr) in rainwater (direct collection) in 2012, at Irongmara, Cachar, Assam.

Cobalt (mg L-1)

Irongmara 0.016 0.014 0.012 0.01 0.008 0.006 0.004 0.002 0

0.005

0.0064

0.00496 0.0041

0.0059 0.0014

April

May

June

July

August

September

2012

Fig. 78. Concentration of Cobalt (Co) in rainwater (direct collection) in 2012, at Irongmara, Cachar, Assam.

169

Chapter 4 Results

Lead (mg L-1)

Badarpur 0.0045 0.004 0.0035 0.003 0.0025 0.002 0.0015 0.001 0.0005 0

0.0032

0.003 0.0014

0.00245

0.0022

April

May

June

July

0.0021

August

September

2012

Fig. 79. Concentration of Lead (Pb) in rainwater (direct collection) in 2012, at Badarpur, Cachar, Assam.

Badarpur Zinc (mg L-1)

0.1 0.08 0.06

0.0413

0.04 0.02

0.04

0.042

0.02

0.022 0.0131

0 April

May

June

July

August

September

2012

Fig. 80. Concentration of Zinc (Zn) in rainwater (direct collection) in 2012, at Badarpur, Cachar, Assam.

170

Chapter 4 Results

Badarpur Chromium (mg L-1)

0.003 0.0025 0.0021

0.002

0.0012

0.0015 0.0007

0.0011

0.001

0.0007 0.0006

0.0005 0 April

May

June

July

August

September

2012

Fig. 81. Concentration of Chromium (Cr) in rainwater (direct collection) in 2012, at Badarpur, Cachar, Assam.

Bongaigaon Lead (mg L-1)

0.05 0.04 0.03 0.02 0.0152 0.01

0.0014

0.0025

0.0023

0.0015 0.00146

0 April

May

June

July

August

September

2012

Fig. 82. Concentration of Lead (Pb) in rainwater (direct collection) in 2012, at Bongaigaon, Assam.

171

Chapter 4 Results

Cadmium (mg L-1)

Bongaigaon 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.0033

0.0043 0.0028

0.0009

0.0015 0.0008

April

May

June

July

August

September

2012

Fig. 83. Concentration of Cadmium (Cd) in rainwater (direct collection) in 2012, at Bongaigaon, Assam.

Bongaigaon Nickel (mg L-1)

0.0025 0.002 0.0015 0.001

0.0007

0.001

0.0006

0.0006

0.0005

0.0005

0.0003

0 April

May

June

July

August

September

2012

Fig. 84. Concentration of Nickel (Ni) in rainwater (direct collection) in 2012, at Bongaigaon, Assam.

172

Chapter 4 Results

Zinc (mg L-1)

Bongaigaon 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0

0.04

0.03

0.015

0.02

0.014 0.01

April

May

June

July

August

September

2012

Fig. 85. Concentration of Zinc (Zn) in rainwater (direct collection) in 2012, at Bongaigaon, Assam.

Bongaigaon Chromium (mg L-1)

0.03 0.025 0.02 0.015 0.01

0.009

0.0019

0.0033

0.0034

0.005

0.002 0.0026

0 April

May

June

July

August

September

2012

Fig. 86. Concentration of Chromium (Cr) in rainwater (direct collection) in 2012, at Bongaigaon, Assam.

173

Chapter 4 Results

Bongaigaon Cobalt (mg L-1)

0.006 0.005 0.004

0.0028

0.0034

0.003 0.002

0.0018

0.0013

0.001

0.0014 0.0006

0 April

May

June

July

August

September

2012

Fig. 87. Concentration of Cobalt (Co) in rainwater (direct collection) in 2012, at Bongaigaon, Assam.

Dolaigaon 0.0035 Lead (mg L-1)

0.003 0.0025

0.0025

0.002 0.0015 0.001

0.0005

0.0003

0.0007

0.0011 0.0006

0.0005 0 April

May

June

July

August

September

2012

Fig. 88. Concentration of Lead (Pb) in rainwater (direct collection) in 2012, at Dolaigaon, Assam.

174

Chapter 4 Results

Cadmiun (mg L-1)

Dolaigaon 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.0043 0.004

0.0022

0.0026

0.0021 0.0003

April

May

June

July

August

September

2012

Fig. 89. Concentration of Cadmium (Cd) in rainwater (direct collection) in 2012, at Dolaigaon, Assam.

Dolaigaon 0.0035 Nickel (mg L-1)

0.003 0.0025 0.0015

0.002 0.0015

0.0012 0.0011

0.001

0.0008

0.0005

0.0005

0.0003

0 April

May

June

July

August

September

2012

Fig. 90. Concentration of Nickel (Ni) in rainwater (direct collection) in 2012, at Dolaigaon, Assam.

175

Chapter 4 Results

Zinc (mg L-1)

Dolaigaon 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0

0.054 0.036

0.03

0.0125

0.012

0.0184

April

May

June

July

August

September

2012

Fig. 91. Concentration of Zinc (Zn) in rainwater (direct collection) in 2012, at Dolaigaon, Assam.

Dolaigaon Chromium (mg L-1)

0.012 0.01 0.008 0.006 0.0034

0.00338

0.004

0.0037

0.005 0.0031

0.0024

0.002 0 April

May

June

July

August

September

2012

Fig. 92. Concentration of Chromium (Cr) in rainwater (direct collection) in 2012, at Dolaigaon, Assam.

176

Chapter 4 Results

Cobalt (mg L-1)

Dolaigaon 0.0045 0.004 0.0035 0.003 0.0025 0.002 0.0015 0.001 0.0005 0

0.003 0.002

0.002

0.002 0.00092

April

0.0009

May

June

July

August

September

2012

Fig. 93. Concentration of Cobalt (Co) in rainwater (direct collection) in 2012, at Dolaigaon, Assam.

BGR Township Lead (mg L-1)

0.005 0.004 0.0027 0.0022

0.002 0.001

0.0026

0.0025

0.003

0.0022

0.0007

0 April

May

June

July

August

September

2012

Fig. 94. Concentration of Lead (Pb) in rainwater (direct collection) in 2012, at BGR Township, Assam.

177

Chapter 4 Results

Cadmium (mg L-1)

BGR Township 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0

0.013 0.0027

0.004

0.0011

0.0043 April

May

0.003 June

July

August

September

2012

Fig. 95. Concentration of Cadmium (Cd) in rainwater (direct collection) in 2012, at BGR Township, Assam.

BGR Township Nickel (mg L-1)

0.03 0.025 0.02 0.015 0.01

0.0031

0.0025

0.005 0

0.0027 0.0043 0.0016

0.0012 April

May

June

July

August

September

2012

Fig. 96. Concentration of Nickel (Ni) in rainwater (direct collection) in 2012, at BGR Township, Assam.

178

Chapter 4 Results

BGR Township 0.12 Zinc (mg L-1)

0.1 0.063

0.08 0.06 0.0462

0.04

0.0174 0.021

0.02

0.0124 0.017

0 April

May

June

July

August

September

2012

Fig. 97. Concentration of Zinc (Zn) in rainwater (direct collection) in 2012, at BGR Township, Assam.

Chromium (mg L-1)

BGR Township 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.0042

0.0037

0.0033

0.0031 0.0032

0.0025

April

May

June

July

August

September

2012

Fig. 98. Concentration of Chromium (Cr) in rainwater (direct collection) in 2012, at BGR Township, Assam.

179

Chapter 4 Results

Cobalt (mg L-1)

BGR Township 0.0008 0.0007 0.0006 0.0005 0.0004 0.0003 0.0002 0.0001 0

0.0004

0.0002 0.0002

0.0003

0.00013 April

May

June

July

August

ND September

2012

Fig. 99. Concentration of Cobalt (Co) in rainwater (direct collection) in 2012, at BGR Township, Assam.

Kolkata Lead (mg L-1)

0.02 0.015 0.01

0.0024 0.0029

0.005

0.0095 0.0061

0.003

0 May

June

July

August

September

2012

Fig. 100. Concentration of Lead (Pb) in rainwater (direct collection) in 2012, at Kolkata, West Bengal.

180

Chapter 4 Results

Cadmium (mg L-1)

Kolkata 0.018 0.016 0.014 0.012 0.01 0.008 0.006 0.004 0.002 0

0.001

May

0.0016

0.0014

June

0.0009 0.0019

July

August

September

2012

Fig. 101. Concentration of Cadmium (Cd) in rainwater (direct collection) in 2012, at Kolkata, West Bengal.

Kolkata Nickel (mg L-1)

0.006 0.005

0.0036

0.0035

0.004

0.0038

0.003

0.002

0.002

0.002

0.001 0 May

June

July

August

September

2012

Fig. 102. Concentration of Nickel (Ni) in rainwater (direct collection) in 2012, at Kolkata, West Bengal.

181

Chapter 4 Results

Kolkata 0.03 Zinc (mg L-1)

0.025 0.02 0.015

0.02

0.014

0.013

0.0123

0.016

0.01 0.005 0 May

June

July

August

September

2012

Fig. 103. Concentration of Zinc (Zn) in rainwater (direct collection) in 2012, at Kolkata, West Bengal.

Kolkata Chromium (mg L-1)

0.025 0.02 0.015 0.01

0.0072 0.0057

0.005

0.0008

0.0017 0.0034

0 May

June

July

August

September

2012

Fig. 104. Concentration of Chromium (Cr) in rainwater (direct collection) in 2012, at Kolkata, West Bengal.

182

Chapter 4 Results

Lead (mg L-1)

Kharagpur 0.004 0.0035 0.003 0.0025 0.002 0.0015 0.001 0.0005 0

0.0016

0.0025

0.0018

0.0012 0.001 0.0003 April

May

June

July

August

September

2012

Fig. 105. Concentration of Lead (Pb) in rainwater (direct collection) in 2012, at Kharagpur, West Midnapore, West Bengal.

Kharagpur Cadmium (mg L-1)

0.014 0.012 0.01

0.0063

0.008 0.0067

0.006

0.0064

0.0053

0.004 0.002

0.0026

0.0022

0 April

May

June

July

August

September

2012

Fig. 106. Concentration of Cadmium (Cd) in rainwater (direct collection) in 2012, at Kharagpur, West Midnapore, West Bengal.

183

Chapter 4 Results

Nickel (mg L-1)

Kharagpur 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.0026

April

0.0024

0.001

ND

0.001 May

0.0006 June

July

August

September

2012

Fig. 107. Concentration of Nickel (Ni) in rainwater (direct collection) in 2012, at Kharagpur, West Midnapore, West Bengal.

Kharagpur 0.12 Zinc (mg L-1)

0.1 0.08 0.06

0.058

0.054

0.0073

0.04

0.042

0.034

0.02

0.017

0 April

May

June

July

August

September

2012

Fig. 108. Concentration of Zinc (Zn) in rainwater (direct collection) in 2012, at Kharagpur, West Midnapore, West Bengal.

184

Chapter 4 Results

Kharagpur Chromium (mg L-1)

0.035 0.03 0.025 0.02 0.015

0.009

0.0132

0.01

0.0029

0.0009

0.005 0.002

0 April

May

0.002 June

July

August

September

2012

Fig. 109. Concentration of Chromium (Cr) in rainwater (direct collection) in 2012, at Kharagpur, West Midnapore, West Bengal.

Cobalt (mg L-1)

Kharagpur 0.0045 0.004 0.0035 0.003 0.0025 0.002 0.0015 0.001 0.0005 0

0.0026 0.0011

0.0016 0.0015 0.0006

ND April

May

June

July

August

September

2012

Fig. 110. Concentration of Cobalt (Co) in rainwater (direct collection) in 2012, at Kharagpur, West Midnapore, West Bengal.

185

Chapter 4 Results

Irongmara Nitrate (mg L-1)

3 2.5 1.765

1.73

2 1.5

1.92

1.25

1.67

1.55

1 0.5 0 April

May

June

July

August

September

2012

Fig. 111. Concentration of Nitrate (NO3-) in rainwater (direct collection) in 2012, at Irongmara, Cachar, Assam.

Nitrate (mg L-1)

Bongaigaon 4 3.5 3 2.5 2 1.5 1 0.5 0

2.62 2.07 1.68 1.29 0.77

April

May

June

July

0.69 August

September

2012

Fig. 112. Concentration of Nitrate (NO3-) in rainwater (direct collection) in 2012, at Bongaigaon, Assam.

186

Chapter 4 Results

Nitrate (mg L-1)

Dolaigaon 4 3.5 3 2.5 2 1.5 1 0.5 0

2.61 1.82

1.76 1.38

1.09 0.82 April

May

June

July

August

September

2012

Fig. 113. Concentration of Nitrate (NO3-) in rainwater (direct collection) in 2012, at Dolaigaon, Assam.

BGR Township Nitrate (mg L-1)

3 2.5 1.55

2

1.75

1.5

1.29 1.09

1 0.5

0.92

0.89

0 April

May

June

July

August

September

2012

Fig. 114. Concentration of Nitrate (NO3-) in rainwater (direct collection) in 2012, at BGR Township, Assam.

187

Chapter 4 Results

Badarpur Nitrate (mg L-1)

3 2.5 2.09

2 1.5

1.24

1.42

1

1.26

0.94

0.88

0.5 0 April

May

June

July

August

September

2012

Fig. 115. Concentration of Nitrate (NO3-) in rainwater (direct collection) in 2012, at Badarpur, Cachar, Assam.

Kolkata Nitrate (mg L-1)

3 2.5 2 1.23

1.5

1.23 1.19

1

0.77

1.13

0.5 0 May

June

July

August

September

2012

Fig. 116. Concentration of Nitrate (NO3-) in rainwater (direct collection) in 2012, at Kolkata, West Bengal.

188

Chapter 4 Results

Nitrate (mg L-1)

Kharagpur 4 3.5 3 2.5 2 1.5 1 0.5 0

1.72 1.2

1.83

1.21 1.56

0.82

April

May

June

July

August

September

2012

Fig. 117. Concentration of Nitrate (NO3-) in rainwater (direct collection) in 2012, at Kharagpur, West Midnapore, West Bengal.

189

Chapter 4 Results 2012 Table 16 Descriptive statistics for pH (Direct Collection) in Rainwater at different geographical locations during 2012

Site

Mean

Median

S.D.

Min

Max

5.63

5.64

0.43

4.31

7.22

5.94

5.91

0.25

5.51

6.35

Bongaigaon

5.66

5.755

0.38

4.74

6.45

Dolaigaon

5.25

5.27

0.64

4.32

6.52

5.84

5.71

0.59

4.57

6.71

6.57

6.595

0.51

5.21

7.5

6.07

6.05

0.23

5.7

6.88

Irongmara

Badarpur

BGR Township

Kolkata

Kharagpur

190

Chapter 4 Results Table 17Descriptive statistics for ElectricalConductivity (Direct Collection) in Rainwater at different geographical locations during 2012

Site

Mean

Median

S.D.

Min

Max

(µS cm-1) Irongmara

28.63

22.05

20.9

5.69

120.4

Badarpur

33.62

31.5

10.72

17.5

57.8

Bongaigaon

26.21

25.3

11.08

4.49

57.8

Dolaigaon

26.48

25.45

10.3

5.27

47.6

BGR

22.06

20.1

13.2

4.49

99.8

Kolkata

45.33

42.5

14.03

21.7

74.2

Kharagpur

23.59

12.1

32.61

5.71

155.3

Township

191

Chapter 4 Results Table 18Descriptive statistics for Heavy Metal Concentration in Rainwater (Direct Collection) at different geographical locations during 2012 Heavy Metals Pb (mg L-1)

Cd

Ni

Zn

Cr

Co

ND not detected

192

Site Irongmara Badarpur Bongaigaon Dolaigaon BGR Township Kolkata Kharagpur Irongmara Bongaigaon Dolaigaon BGR Township Kolkata Kharagpur Irongmara Bongaigaon Dolaigaon BGR Township Kolkata Kharagpur Irongmara Badarpur Bongaigaon Dolaigaon BGR Township Kolkata Kharagpur Irongmara Badarpur Bongaigaon Dolaigaon BGR Township Kolkata Kharagpur Irongmara Bongaigaon Dolaigaon BGR Township Kolkata Kharagpur

Mean 0.0023 0.0024 0.0045 0.0008 0.0021 0.0049 0.0013 0.0022 0.0023 0.0029 0.0047 0.0038 0.0048 0.0032 0.00064 0.0009 0.0025 0.0025 0.0011 0.0437 0.0287 0.0209 0.0281 0.0321 0.0157 0.0353 0.0044 0.0022 0.0038 0.0036 0.0034 0.004 0.0052 0.0043 0.0019 0.0017 0.0002 ND 0.0012

Median 0.00115 0.0027 0.002 0.00015 0.0024 0.00255 0.0014 0.00195 0.0024 0.003 0.0032 0.00235 0.0031 0.00225 0.0002 0.0007 0.0033 0.00275 ND 0.0213 0.0198 0.0158 0.01565 0.0207 0.0148 0.0133 0.0029 0.0013 0.002 0.00305 0.0035 0.00125 0.0015 0.00305 0.0012 0.0016 0.0001 ND 0.0012

S.D. 0.0034 0.001 0.0137 0.001 0.0015 0.0064 0.0013 0.0027 0.0022 0.0027 0.0097 0.0067 0.005 0.0036 0.0007 0.001 0.0021 0.0018 0.0021 0.0406 0.0228 0.0166 0.028 0.0322 0.0065 0.036 0.0057 0.0043 0.0074 0.004 0.0027 0.0061 0.0105 0.0052 0.0022 0.0015 0.0003 0 0.0013

Min ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND 0.006 5 0.008 1 0.006 9 0.005 6 0.007 2 0.005 7 0.003 2 ND ND ND ND ND ND ND ND ND ND ND ND ND

Max 0.015 0.0037 0.07 0.0031 0.0052 0.021 0.0039 0.0121 0.0071 0.0078 0.054 0.031 0.0131 0.012 0.0027 0.0032 0.0057 0.0057 0.008 0.128 0.075 0.089 0.1131 0.128 0.0256 0.109 0.024 0.017 0.0372 0.0143 0.0104 0.021 0.042 0.018 0.007 0.005 0.0008 0 0.0041

Chapter 4 Results Table 19 Results of one way analysis of variance (ANOVA) for pH of rainwater along with multiple comparisons using Tukey test among the sites during 2012 F

Significance

26.426

P< 0.001

Summary of Multiple Comparisons using Tukey test

Range of Significance

Kolkata > Irongmara, Kharagpur, Dolaigaon, Bongaigaon, BGR Township, Badarpur

P=0.000 - 0.002

Kharagpur> Irongmara, Dolaigaon, Bongaigaon

P=0.000 - 0.002

Dolaigaon Irongmara, Kharagpur, Dolaigaon, Bongaigaon, BGR Township

P=0.000

Table 21 Results of one way analysis of variance (ANOVA) for Nickel (Ni) of rainwater along with multiple comparisons using Tukey test among the sites during 2012 193

Chapter 4 Results F

Significance

5.788

P< 0.001

Summary of Multiple Comparisons

Range of Significance

using Tukey test Irongmara >Kharagpur, Dolaigaon, Bongaigaon BGR Township> Bongaigaon

P= 0.001 - 0.021

P= 0.023

Table 22 Results of one way analysis of variance (ANOVA) for Zinc (Zn) of rainwater along with multiple comparisons using Tukey test among the sites during 2012 F

Significance

2.392

P= 0.031

Summary of Multiple Comparisons

Range of Significance

using Tukey test Irongmara >Kolkata

194

P= 0.022

Chapter 4 Results Table 23 Results of one way analysis of variance (ANOVA) for Cobalt (Co) of rainwater along with multiple comparisons using Tukey test among the sites during 2012

F

Significance

9.518

P< 0.001

Summary of Multiple Comparisons using Tukey test

Range of Significance

Irongmara > Kolkata, Kharagpur, Dolaigaon, Bongaigaon, BGR Township

195

P= 0.000 - 0.018

Chapter 4 Results 4. Rainwater quality in different study sites in 2013 a) pH i) Mean pH at the different study sites The pH of rainwater (direct collection) at the different sites in 2013 is shown in Table 24. It can be observed from the Table that the highest mean pH of rainwater (direct collection)

is recordedat Kolkata, while the

lowest is at Dolaigaon. Both the highest and the lowestindividual pH was recorded at Irongmara on 02-07-2013 and 25-03-2013 respectively. The mean pH values in 2013 at the different sites are found to be in the following descending order: Kolkata (KOL) > Kharagpur (KGP) >BGR Township (BGR) >Badarpur (BPB) >Irongmara (IM) >Bongaigaon (BNG) > Dolaigaon (DLG).

ii) Monthly fluctuations inpH The mean monthly pH values at the different sites in 2013 are shown in Figures 118-124. In Irongmara, the pH ranged between 4.51 in April and 6.13 in June (Fig. 118). In Badarpur, the pH ranged between 5.59 in August and 6.02 in April (Fig. 119). In Bongaigaon, the pH ranged between 5.164 in April and 5.79 in August and October

(Fig. 120). In Dolaigaon, the pH

ranged between 5.18 in June and 5.58 in October (Fig. 121).In BGR Township, the pH ranged between 5.84 in October and 6.18 in June (Fig. 122). In Kolkata, the pH ranged between 6.16 in June and 6.83 in September (Fig. 123).In Kharagpur, the pH ranged between 6.02 in August and 6.09 in April and July respectively (Fig. 124).

196

Chapter 4 Results b) Electrical Conductivity (EC) i) Mean ECat the different study sites The conductivity of rainwater (direct collection) at the different sites in 2013 is shown in Table 25. It can be observed from the Table that the highest mean conductivity of rainwater (direct collection)

is

recordedat Kolkata,

while the lowest is at Kharagpur. The highest individual conductivity was also recorded at Kolkata on 12-05-2013, whereas the lowest individual conductivity is detected at Irongmara on 24-07-2013. The mean conductivity values in 2013 at the different sites are found to be in the following descending

order: Kolkata (KOL) >Dolaigaon (DLG)>Badarpur (BPB) >

Irongmara (IM) > Bongaigaon (BNG) >BGR Township (BGR) >Kharagpur (KGP).

ii) Monthly fluctuations inconductivity (EC)

The mean monthly conductivity values at the different sites in 2013 are shown in Figures 125-131. In Irongmara, the conductivity ranged between 16.52µS cm-1in July and 41.5µS cm-1in October (Fig. 125). In Badarpur, the conductivity ranged between 15.03 µS cm-1in September and 34.7 µS cm-1in July (Fig. 126). In Bongaigaon, the conductivity ranged between 20.5 µS cm1

in June and 32.31 µS cm-1in September (Fig. 127). In Dolaigaon, the

conductivity ranged between 25.67µS cm-1in October and 32.56µS cm-1in April (Fig. 128).In BGR Township, the conductivity ranged between 17.42µS cm-1in

June

and

29.8µS cm-1in

October

(Fig. 129).

In

Kolkata,

the

conductivity ranged between 44.9 µS cm-1 in October and 70.7 µS cm-1in 197

Chapter 4 Results May (Fig. 130). In Kharagpur, the conductivity ranged between 16.13 µS cm1

in July and 47.5 µS cm-1in August (Fig. 131).

c) Heavy Metals i) Mean Heavy Metals at the different study sites The heavy metals of rainwater (direct collection) at the different sites in 2013 is shown in Table 26. It can be observed from the Table that the highest

mean

Lead

(Pb)in

rainwater

(direct

Irongmara, while the lowest is at Kharagpur

collection)

is

recordedat

and Dolaigaon. The highest

individual Pb was also recorded at Irongmara on 20-04-2013. The mean Pb values in 2013 at the different sites are found to be in the following descending

order: Irongmara (IM) > Kolkata (KOL) ~ Badarpur (BPB) >

Bongaigaon (BNG) > BGR Township (BGR) > Kharagpur (KGP) ~ Dolaigaon (DLG). Highest mean Cadmium (Cd)in rainwater (direct collection)

is

recordedat Kolkata and Dolaigaon, while the lowest is at BGR Township. The highest individual Cd was recorded at Kolkata on 06-09-2013. The mean Cd values in 2013 at the different sites are found to be in the following descending order: Kolkata (KOL) ~ Dolaigaon (DLG) >Kharagpur (KGP) >Irongmara (IM) > Bongaigaon (BNG) >BGR Township (BGR). Highest mean Zinc (Zn)in rainwater (direct collection) isrecordedat Irongmara, while the lowest is at Kharagpur. The highest individual Zn was recorded at Badarpur on 05-07-2013, while the lowest individual Zn is also recorded at Badarpur on 02-05-2013 whereas the concentration in Kharagpur is Below Detection Level. The mean Zn values in 2013 at the different sites are found to be in the following descending order: Irongmara (IM) > Badarpur 198

Chapter 4 Results (BPB) > Kolkata (KOL) >BGR Township (BGR) > Bongaigaon (BNG) > Dolaigaon (DLG) > Kharagpur (KGP). It is observed from the Table that the highest mean Chromium (Cr)in rainwater (direct collection) is recordedat Kharagpur, while the lowest is at Kolkata. The highest individual Cr was also recorded at Kharagpur on 22-10-2013. The mean Cr values in 2013 at the different sites are found to be in the following descending order: Kharagpur (KGP) > Dolaigaon (DLG) > Bongaigaon (BNG) > BGR Township (BGR) > Badarpur (BPB) > Irongmara (IM) > Kolkata (KOL).

ii) Monthly fluctuations inHeavy Metals The mean monthly heavy metals values at the different sites in 2013 are shown in Figures 132-158. Irongmara:The Lead (Pb) concentration ranged between 0.0026mg L-1 in July and 0.0104mg L-1 in April (Fig. 132). Cadmium (Cd) concentration ranged between 0.0021mg L-1 in July and 0.0059mg L-1 in September (Fig. 133). Zinc (Zn) concentration ranged between 0.027mg L-1 in September and 0.164mg L1 in May (Fig. 134). Chromium (Cr) concentration ranged between 0.002 mg L-1in July and 0.0061mg L-1 in October (Fig. 135). Badarpur: The Lead (Pb) concentration ranged between 0.0011 mg L-1 in June and 0.0038 mg L-1 in July (Fig. 136). Zinc (Zn) concentration ranged between 0.002 mg L-1 in May and 0.09 mg L-1 in July (Fig. 137). Chromium (Cr) concentration ranged between 0.0013 mg L-1 in June and 0.0065 mg L1

in September (Fig. 138).

Bongaigaon:The Lead (Pb) concentration ranged between 0.0021 mg L-1 in August and 0.0037 mg L-1 in April, while the concentration in September is 199

Chapter 4 Results Below Detection Level (Fig. 139). Cadmium (Cd) concentration ranged between 0.0009 mg L-1 in July and 0.0055 mg L-1 in May (Fig. 140). Zinc (Zn) concentration ranged between 0.0112 mg L-1in June and 0.0304 mg L-1 in April (Fig. 141). Chromium (Cr) concentration ranged between 0.003 mg L1

in April and 0.0142 mg L-1in October (Fig. 142).

Dolaigaon: The Lead (Pb) concentration ranged between 0.0005 mg L-1 in July and 0.0046 mg L-1 in May (Fig. 143).

Cadmium (Cd) concentration

ranged between 0.001 mg L-1 in October and 0.0051 mg L-1 in June (Fig. 144). Zinc (Zn) concentration ranged between 0.0114 mg L-1in September and 0.023 mg L-1 in April (Fig. 145). Chromium (Cr) concentration ranged between 0.0015 mg L-1 in July and 0.02 mg L-1 in May (Fig. 146). BGR Township: The Lead (Pb) concentration ranged between 0.00195 mg L-1 in April and 0.00395 mg L-1 in September (Fig. 147). Cadmium (Cd) concentration ranged between 0.0008 mg L-1 in May and 0.005 mg L-1 in July while the concentration in September is Below Detection Level (Fig. 148). Zinc (Zn) concentration ranged between 0.0145 mg L-1 in August and 0.028 mg L-1 in September (Fig. 149). Chromium (Cr) concentration ranged between 0.0026 mg L-1 in August and 0.012 mg L-1 in June (Fig. 150). Kolkata:The Lead (Pb) concentration ranged between 0.0007mg L-1in June and 0.0046mg L-1 in August (Fig. 151). Cadmium (Cd) concentration ranged between 0.0012mg L-1 in May and 0.016mg L-1 in September (Fig. 152). Zinc (Zn) concentration ranged between 0.0076mg L-1 in July and 0.019mg L-1 in June (Fig. 153). Chromium (Cr) concentration ranged between 0.0004mg L-1 in July and 0.004mg L-1 in May, while the concentration in September is Below Detection Level (Fig. 154). 200

Chapter 4 Results Kharagpur:The Lead (Pb) concentration ranged between 0.0013 mg L-1 in May and July and 0.0028mg L-1 in September (Fig. 155). Cadmium (Cd) concentration ranged between 0.0017mg L-1 in April and 0.0058mg L-1 in July (Fig. 156). Zinc (Zn) concentration ranged between 0.0004mg L-1 in April and 0.0157mg L-1 in August (Fig. 157). Chromium (Cr) concentration ranged between 0.0032mg L-1 in September and 0.0554mg L-1 in October (Fig. 158). d) Monthly fluctuations in Nitrate The mean monthly nitrate values at the different sites in 2013 are shown in Figures 159-165. In Irongmara, the nitrate concentration ranged between 0.82mg L-1 in May and 1.82 mg L-1 in June (Fig. 159). In Badarpur, the nitrate concentration ranged between 1.115 mg L-1 in May and 1.555 mg L-1 in July (Fig. 160). In Bongaigaon, the nitrate concentration ranged between 0.05 mg L-1in August and 2.32 mg L-1in July (Fig. 161). In Dolaigaon, the nitrate concentration ranged between 0.685 mg L-1 in September and 2.335 mg L-1 in October (Fig. 162). In BGR Township, the nitrate concentration ranged between 0.735 mg L-1 in June and 1.77 mg L-1 in October (Fig. 163). In Kolkata, the nitrate concentration ranged between 0.94 mg L-1 in May and 1.475 mg L-1 in June (Fig. 164).In Kharagpur, the nitrate concentration ranged between 0.765 mg L-1 in October and 2.275 mg L-1 in August (Fig. 165).

e) Statistical Analysisof Data i) Comparisons of pH and EC amongstudy sites in 2013 Table 27 summarizes the results of one-way analysis-of-variance (ANOVA) in pH among the different study sites in 2013. The differences are 201

Chapter 4 Results significant at p < 0.001. Multiple comparisons using Tukey test reveal that pH of Kolkata rainwater was significantly more alkaline than those in the other study sites; pH in Kharagpur and BGR Township was significantly higher than that in Irongmara , Dolaigaon and Bongaigaon; and that in Badarpur was significantly higher than those in Dolaigaon and Bongaigaon. Table 28 summarizes the results of one-way analysis-of-variance (ANOVA) in EC among the different study sites in 2013. The differences are significant at p < 0.001. Multiple comparisons using Tukey test reveal that EC of Kolkata rainwater was significantly more than those in the other study sites.

ii) Comparisons ofheavy metals among study sites in 2013 Table

29-32

summarizes

the

results

of

one-way

analysis-of-variance

(ANOVA) in Lead (Pb), Cadmium (Cd), Zinc (Zn) and Chromium (Cr) among the different study sites in 2013. The differences are significant at p < 0.001. In Table 29 multiple comparisons using Tukey test reveal that Pb concentration in Irongmara rainwater was significantly higher than that in Kharagpur, Dolaigaon and BGR Township; Cdconcentration in Badarpur was significantlylower than that in Kolkata,Kharagpur and Dolaigaon. In Table 31 multiple comparisons using Tukey test reveal that Zn concentration in Irongmara rainwater was significantly higher than those in the other study sites. In Table 32 multiple comparisons using Tukey test reveal that Cr concentration in Kharagpur rainwater was found to be significantly higher than those of Irongmara, Kolkata and Badarpur.

202

Chapter 4 Results 2013

Irongmara 7 6.5

6.13

5.88

pH

6

5.66

5.58

5.5

5.65

5 4.5

5.74

4.51

4 April

May

June

July

August

September

October

2013

Fig. 118. pH in rainwater (direct collection) in 2013, at Irongmara, Cachar, Assam.

Badarpur 7 6.5

5.913

6.02

6.012

pH

6

5.88 5.59

5.5 5.71

5 4.5 4 April

May

June

July

August

September

2013

Fig. 119. pH in rainwater (direct collection) in 2013, at Badarpur, Cachar, Assam.

203

Chapter 4 Results

Bongaigaon 7 6.5

5.79

pH

6

5.59

5.49

5.79

5.5 5

5.164

5.72

5.481

4.5 4 April

May

June

July

August

September

October

2013

Fig. 120. pH in rainwater (direct collection) in 2013, at Bongaigaon, Assam.

Dolaigaon 7 6.5 pH

6

5.31

5.27

5.5

5.352

5

5.27

5.58 5.45

5.18

4.5 4 April

May

June

July

August

September

October

2013

Fig. 121. pH in rainwater (direct collection) in 2013, at Dolaigaon, Assam.

204

Chapter 4 Results

BGR Township 7 6.5

6.18

6.14

5.92

6.045

pH

6 5.96

5.5

5.84

5.94

5 4.5 4 April

May

June

July

August

September

October

2013

Fig. 122. pH in rainwater (direct collection) in 2013, at BGR Township, Assam.

Kolkata 7.5 6.35

7

6.69

6.5 pH

6.83

6.32

6.79 6.43

6 6.16

5.5 5 4.5 4 April

May

June

July

August

September

October

2013

Fig. 123. pH in rainwater (direct collection) in 2013, at Kolkata, West Bengal.

205

Chapter 4 Results

Kharagpur 7 6.09

6.5

6.02

6.09

6.04

pH

6 6.06

5.5

6.088

6.05

5 4.5 4 April

May

June

July

August

September

October

2013

Fig. 124. pH in rainwater (direct collection) in 2013, at Kharagpur, West Midnapore, West Bengal.

Irongmara 70 EC (µS cm -1)

60 50 40

33.21

41.5

23.6

30

24.71

20

30.14 16.52

25.5

10 0 April

May

June

July

August

September

October

2013

Fig. 125. Electrical Conductivity in rainwater (direct collection) in 2013, at Irongmara, Cachar, Assam.

206

Chapter 4 Results

Badarpur 70 EC (µS cm -1)

60 50 40 30

34.7

27.34

25.3

27.3

26.73

20

15.03

10 0 April

May

June

July

August

September

2013

Fig. 126. Electrical Conductivity in rainwater (direct collection) in 2013, at Badarpur, Cachar, Assam.

Bongaigaon EC (µS cm -1)

50 40

32.31 31.5

24.3

30

27.24

26.9 20.5

20

26.2

10 0 April

May

June

July

August

September

October

2013

Fig. 127. Electrical Conductivity in rainwater (direct collection) in 2013, at Bongaigaon, Assam.

207

Chapter 4 Results

Dolaigaon EC (µS cm -1)

50 40

32.56

31.78

29.75

30 29.27

20

30.82 25.67

27.6

10 0 April

May

June

July

August

September

October

2013

Fig. 128. Electrical Conductivity in rainwater (direct collection) in 2013, at Dolaigaon, Assam.

EC (µS cm -1)

BGR Township 45 40 35 30 25 20 15 10 5 0

27.8

25.037 26.82

29.8 24.9

21.8 17.42

April

May

June

July

August

September

October

2013

Fig. 129. Electrical Conductivity in rainwater (direct collection) in 2013, at BGR Township, Assam.

208

Chapter 4 Results

Kolkata 140 EC (µS cm -1)

120 100 80 40

53.7

70.7

60

59.6 46.3

45.9

44.9

50.7

20 0 April

May

June

July

August

September October

2013

Fig. 130. Electrical Conductivity in rainwater (direct collection) in 2013, at Kolkata, West Bengal.

Kharagpur 120 EC (µS cm -1)

100 80 60 47.5

40 20

16.75

33.33 19.93

18.26 20.24

16.13

0 April

May

June

July

August

September October

2013

Fig. 131. Electrical Conductivity in rainwater (direct collection) in 2013, at Kharagpur, West Midnapore, West Bengal.

209

Chapter 4 Results

Irongmara Lead (mg L-1)

0.025 0.02 0.015 0.01

0.0081

0.0104

0.009

0.005

0.0037

0.003 0.0041

0.0026

0 April

May

June

July

August

September October

2013

Fig. 132. Concentration of Lead (Pb) in rainwater (direct collection) in 2013, at Irongmara, Cachar, Assam.

Irongmara Cadmium (mg L-1)

0.012 0.01 0.008 0.006 0.004

0.0059 0.0041

0.0027

0.0022

0.0045

0.0046

0.0021

0.002 0 April

May

June

July

August

September October

2013

Fig. 133. Concentration of Cadmium (Cd) in rainwater (direct collection) in 2013, at Irongmara, Cachar, Assam.

210

Chapter 4 Results

Irongmara Zinc (mg L-1)

0.25 0.2 0.164

0.15

0.061

0.1 0.05

0.095

0.07

0.0614

0.042

0.027

0 April

May

June

July

August

September October

2013

Fig. 134. Concentration of Zinc (Zn) in rainwater (direct collection) in 2013, at Irongmara, Cachar, Assam.

Irongmara Chromium (mg L-1)

0.012 0.01 0.008 0.006

0.0038

0.0061

0.0035

0.0036

0.0039

0.004 0.002

0.0041

0.002

0 April

May

June

July

August

September October

2013

Fig. 135. Concentration of Chromium (Cr) in rainwater (direct collection) in 2013, at Irongmara, Cachar, Assam.

211

Chapter 4 Results

Lead (mg L-1)

Badarpur 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.0023

April

0.0023

May

0.0038

0.0011

0.0035 0.0031

June

July

August

September

2013

Fig. 136. Concentration of Lead (Pb) in rainwater (direct collection) in 2013, at Badarpur, Cachar, Assam.

Badarpur Zinc (mg L-1)

0.25 0.2 0.15 0.1 0.05

0.09

0.009

0.022

0.043 0.032

0.002 0 April

May

June

July

August

September

2013

Fig. 137. Concentration of Zinc (Zn) in rainwater (direct collection) in 2013, at Badarpur, Cachar, Assam.

212

Chapter 4 Results

Chromium (mg L-1)

Badarpur 0.018 0.016 0.014 0.012 0.01 0.008 0.006 0.004 0.002 0 April

0.0052

0.0013

0.0021

0.0065 0.0045

0.0018

May

June

July

August

September

2013

Fig. 138. Concentration of Chromium (Cr) in rainwater (direct collection) in 2013, at Badarpur, Cachar, Assam.

Bongaigaon Lead (mg L-1)

0.005 0.004

0.0037 0.0031

0.003

0.003

0.0021

0.0027 0.0021

0.002 0.001 0 April

May

June

July

August

ND September October

2013

Fig. 139. Concentration of Lead (Pb) in rainwater (direct collection) in 2013, at Bongaigaon, Assam.

213

Chapter 4 Results

Cadmium (mg L-1)

Bongaigaon 0.009 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.0055 0.0038

0.0028 0.0033 0.0009 April

May

June

July

0.0039

0.0014

August

September October

2013

Fig. 140. Concentration of Cadmium (Cd) in rainwater (direct collection) in 2013, at Bongaigaon, Assam.

Zinc (mg L-1)

Bongaigaon 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0

0.0304 0.0196

0.0112

0.0192

0.0162

April

May

June

July

August

0.0162

0.0175

September October

2013

Fig. 141. Concentration of Zinc (Zn) in rainwater (direct collection) in 2013, at Bongaigaon, Assam.

214

Chapter 4 Results

Bongaigaon Chromium (mg L-1)

0.035 0.03 0.025 0.02 0.015

0.0142

0.0049

0.01

0.003

0.005

0.0063

0.0036

0.0049

0.0031

0 April

May

June

July

August

September October

2013

Fig. 142. Concentration of Chromium (Cr) in rainwater (direct collection) in 2013, at Bongaigaon, Assam.

Dolaigaon 0.012 Lead (mg L-1)

0.01 0.008 0.006 0.0046

0.004 0.002

0.0017

0.0021

0.0019 0.0005

0 April

May

June

July

August

0.0011

0.0017

September October

2013

Fig. 143. Concentration of Lead (Pb) in rainwater (direct collection) in 2013, at Dolaigaon, Assam.

215

Chapter 4 Results

Cadmium (mg L-1)

Dolaigaon 0.009 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.0051 0.005

0.0045

0.004

0.0036

0.0014 April

May

June

July

August

0.001

September October

2013

Fig. 144. Concentration of Cadmium (Cd) in rainwater (direct collection) in 2013, at Dolaigaon, Assam.

Zinc (mg L-1)

Dolaigaon 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0

0.023 0.0129

0.0223

0.0195 0.0191

0.018 0.0114

April

May

June

July

August

September October

2013

Fig. 145. Concentration of Zinc (Zn) in rainwater (direct collection) in 2013, at Dolaigaon, Assam.

216

Chapter 4 Results

Chromium (mg L-1)

Dolaigaon 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0

0.02 0.0131

0.0044

0.009

0.0045 0.002

0.0015 April

May

June

July

August

September October

2013

Fig. 146. Concentration of Chromium (Cr) in rainwater (direct collection) in 2013, at Dolaigaon, Assam.

BGR Township Lead (mg L-1)

0.005 0.004

0.00395 0.0027

0.003

0.0025

0.00195 0.002

0.0021

0.002

0.0023

0.001 0 April

May

June

July

August

September October

2013

Fig. 147. Concentration of Lead (Pb) in rainwater (direct collection) in 2013, at BGR Township, Assam.

217

Chapter 4 Results

Cadmium (mg L-1)

BGR Township 0.009 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.005

0.0026 0.0034

0.00265

0.0023

0.0008 April

May

June

July

August

ND September October

2013

Fig. 148. Concentration of Cadmium (Cd) in rainwater (direct collection) in 2013, at BGR Township, Assam.

BGR Township Zinc (mg L-1)

0.05 0.04 0.03 0.02

0.023

0.025

0.028

0.0278

0.022

0.019 0.0145

0.01 0 April

May

June

July

August

September October

2013

Fig. 149. Concentration of Zinc (Zn) in rainwater (direct collection) in 2013, at BGR Township, Assam.

218

Chapter 4 Results

BGR Township Chromium (mg L-1)

0.025 0.02 0.012

0.015 0.01 0.0078 0.005

0.0041

0.0039

0.004 0.0042

0.0026

0 April

May

June

July

August

September October

2013

Fig. 150. Concentration of Chromium (Cr) in rainwater (direct collection) in 2013, at BGR Township, Assam.

Kolkata Lead (mg L-1)

0.01 0.008 0.006 0.004

0.0046 0.00455

0.0043 0.0025

0.002

0.0007

0.0016

0 April

May

June

July

August

September

2013

Fig. 151. Concentration of Lead (Pb) in rainwater (direct collection) in 2013, at Kolkata, West Bengal.

219

Chapter 4 Results

Cadmium (mg L-1)

Kolkata 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0

0.016 0.0021

0.0012

0.0045

0.0014 0.0025

April

May

June

July

August

September

2013

Fig. 152. Concentration of Cadmium (Cd) in rainwater (direct collection) in 2013, at Kolkata, West Bengal.

Kolkata 0.03 Zinc (mg L-1)

0.025

0.019

0.02 0.015 0.01

0.0162

0.014 0.011

0.0092

0.0076

0.005 0 April

May

June

July

August

September

2013

Fig. 153. Concentration of Zinc (Zn) in rainwater (direct collection) in 2013, at Kolkata, West Bengal.

220

Chapter 4 Results

Kolkata Chromium (mg L-1)

0.012 0.01 0.008 0.006 0.004 0.002

0.004

0.002 0.0027

0.0016 0.0004

0 April

May

June

July

August

ND September

2013

Fig. 154. Concentration of Chromium (Cr) in rainwater (direct collection) in 2013, at Kolkata, West Bengal.

Lead (mg L-1)

Kharagpur 0.0045 0.004 0.0035 0.003 0.0025 0.002 0.0015 0.001 0.0005 0

0.0028

0.0018

0.0024

0.0023 0.0018

0.0013

April

May

June

0.0013

July

August September October

2013

Fig. 155. Concentration of Lead (Pb) in rainwater (direct collection) in 2013, at Kharagpur, West Midnapore, West Bengal.

221

Chapter 4 Results

Kharagpur Cadmium (mg L-1)

0.014 0.012 0.01 0.008 0.006 0.002

0.0058

0.0021

0.0045

0.004

0.0037

0.0041 0.0032

0.0017

0 April

May

June

July

August

September October

2013

Fig. 156. Concentration of Cadmium (Cd) in rainwater (direct collection) in 2013, at Kharagpur, West Midnapore, West Bengal.

Kharagpur 0.035 Zinc (mg L-1)

0.03 0.025 0.02 0.015

0.0085

0.01

0.0073

0.0157 0.012 0.0064

0.005 0

0.0078

0.0004 April

May

June

July

August

September October

2013

Fig. 157. Concentration of Zinc (Zn) in rainwater (direct collection) in 2013, at Kharagpur, West Midnapore, West Bengal.

222

Chapter 4 Results

Kharagpur Chromium (mg L-1)

0.14 0.12 0.1 0.08 0.06

0.0554

0.04

0.0192

0.017

0.02

0.0061

0.0079

0.0062 0.0032

0 April

May

June

July

August

September October

2013

Fig. 158. Concentration of Chromium (Cr) in rainwater (direct collection) in 2013, at Kharagpur, West Midnapore, West Bengal.

Irongmara Nitrate (mg L-1)

3 2.5 2 1.5

1.82 1.095

1.41

1.39

1

0.82

0.925

1.135

0.5 0 April

May

June

July

August

September

October

2013

Fig. 159. Concentration of Nitrate (NO3-) in rainwater (direct collection) in 2013, at Irongmara, Cachar, Assam.

223

Chapter 4 Results

Badarpur Nitrate (mg L-1)

3 2.5 2

1.555

1.5

1.125

1.055

1 1.115

0.5

1.135

1.065

0

April

May

June

July

August September

2013 Fig. 160. Concentration of Nitrate (NO3-) in rainwater (direct collection) in 2013, at Badarpur, Cachar, Assam.

Nitrate (mg L-1)

Bongaigaon 4 3.5 3 2.5 2 1.5 1 0.5 0

2.32

1.825 1.68

1.215 0.865

0.82 0.05 April

May

June

July

August

September

October

2013

Fig. 161. Concentration of Nitrate (NO3-) in rainwater (direct collection) in 2013, at Bongaigaon, Assam.

224

Chapter 4 Results

Nitrate (mg L-1)

Dolaigaon 4 3.5 3 2.5 2 1.5 1 0.5 0

2.08

2.335 1.915

1.61 0.885

April

May

June

1.325

July

0.685

August

September

October

2013

Fig. 162. Concentration of Nitrate (NO3-) in rainwater (direct collection) in 2013, at Dolaigaon, Assam.

BGR Township Nitrate (mg L-1)

3 2.5 2

1.77

1.66

1.325

1.5

1.04

1

1.455 0.735

0.5

0.935

0 April

May

June

July

August

September

October

2013

Fig. 163. Concentration of Nitrate (NO3-) in rainwater (direct collection) in 2013, at BGR Township, Assam.

225

Chapter 4 Results

Kolkata Nitrate (mg L-1)

3 2.5 2 1.215

1.475

1.5

0.96

1

1.105

0.94

0.5

1.025

0 April

May

June

July

August

September

2013

Fig. 164. Concentration of Nitrate (NO3-) in rainwater (direct collection) in 2013, at Kolkata, West Bengal.

Nitrate (mg L-1)

Kharagpur 4 3.5 3 2.5 2 1.5 1 0.5 0

2.055 2.275

2.035

0.955 1.765

0.885

April

May

June

July

0.765

August

September

October

2013

Fig. 165. Concentration of Nitrate (NO3-) in rainwater (direct collection) in 2013, at Kharagpur, West Midnapore, West Bengal.

226

Chapter 4 Results 2013 Table 24 Descriptive statistics for pH (Direct Collection) in Rainwater at different geographical locations during 2013

Site

Mean

Median

S.D.

Min

Max

Irongmara

5.57

5.63

0.803

3.76

7.9

Badarpur

5.85

5.82

0.31

5.21

6.33

Bongaigaon

5.52

5.72

0.57

3.76

6.45

Dolaigaon

5.33

5.27

0.56

4.32

6.52

BGR

6.03

6.05

0.513

4.71

6.71

Kolkata

6.425

6.46

0.413

5.72

7.42

Kharagpur

6.05

6.04

0.27

5.34

6.88

Township

227

Chapter 4 Results Table

25

Descriptive

statistics

for

ElectricalConductivity

(Direct

Collection) in Rainwater at different geographical locations during 2013

Site

Mean

Median

S.D.

Min

Max

(µS cm-1) Irongmara

27.76

24.7

17.5

3.02

75.5

Badarpur

28.75

22.5

18.2

5.2

83.9

Bongaigaon

26.02

25.3

11.6

4.49

57.8

Dolaigaon

29.43

27.7

10.8

6.38

52.7

BGR

24.32

23.1

9.21

4.68

55.3

Kolkata

46.25

42.7

18.8

21.7

137.2

Kharagpur

21.24

16.8

17.2

6.75

107.3

Township

228

Chapter 4 Results Table

26Descriptive

statistics

for

Heavy

Metal

Concentration

in

Rainwater (Direct Collection) at different geographical locations during 2013

Heavy

Site

Mean

Median

S.D.

Min

Max

Metals Pb

Irongmara

0.0049

0.0027

0.005

0.0011

0.018

Badarpur

0.0026

0.0028

0.0017

ND

0.007

Bongaigaon

0.0025

0.0028

0.0015

ND

0.0048

BGR

0.0023

0.0024

0.001

ND

0.0042

Township Dolaigaon

0.0019

0.0017

0.0022

ND

0.01

Kolkata

0.0026

0.0021

0.0023

ND

0.008

Kharagpur

0.0019

0.0018

0.0014

ND

0.0042

Irongmara

0.0032

0.0029

0.0021

ND

0.009

Bongaigaon

0.003

0.0029

0.0023

ND

0.0084

Dolaigaon

0.0036

0.0041

0.0026

ND

0.0071

BGR

0.0023

0.0022

0.0019

ND

0.007

Township Kolkata

0.0036

0.0021

0.0069

ND

0.032

Kharagpur

0.0034

0.003

0.0035

ND

0.0132

Irongmara

0.0593

0.0354

0.0504

0.0065

0.215

Badarpur

0.0331

0.0197

0.0505

0.0045

0.235

Bongaigaon

0.0187

0.0155

0.0096

0.0064

0.038

Dolaigaon

0.018

0.0164

0.0079

0.0081

0.0364

BGR

0.0205

0.0208

0.0093

0.006

0.041

Township Kolkata

0.0236

0.0125

0.0291

0.0057

0.109

Kharagpur

0.0092

0.0057

0.0091

ND

0.031

Irongmara

0.0031

0.003

0.0023

ND

0.0081

Badarpur

0.0033

0.0016

0.0051

ND

0.018

Bongaigaon

0.0058

0.0047

0.0072

ND

0.035

Dolaigaon

0.0095

0.0068

0.0108

ND

0.037

BGR

0.0049

0.0039

0.0047

ND

0.017

Township Kolkata

0.0016

0.0009

0.0019

ND

0.008

Kharagpur

0.0137

0.0054

0.0246

ND

0.109

(mg L1

)

Cd

Zn

Cr

ND not detected

229

Chapter 4 Results Table 27 Results of one way analysis of variance (ANOVA) for pH of rainwater along with multiple comparisons using Tukey test among the sites during 2013 F

Significance

32.363

P< 0.001

Summary of Multiple Comparisons using Tukey test

Range of Significance

Kolkata > Irongmara, Kharagpur,

P=0.000 - 0.010

Dolaigaon, Bongaigaon, BGR Township, Badarpur Kharagpur ~ BGR Township

P=0.000 - 0.010

Badarpur >Dolaigaon, Bongaigaon

P=0.000 - 0.031

Table 28 Results of one way analysis of variance (ANOVA) for Electrical Conductivity (EC) of rainwater along with multiple comparisons using Tukey test among the sites during 2013 F

Significance

19.138

P< 0.001

Summary of Multiple Comparisons using Tukey test

Range of Significance

Kolkata > Irongmara, Kharagpur, Dolaigaon, Bongaigaon, BGR Township, Badarpur

230

P=0.000

Chapter 4 Results Table 29 Results of one way analysis of variance (ANOVA) for Lead (Pb) of rainwater along with multiple comparisons using Tukey test among the sites during 2013 F

Significance

3.217

P=0.006

Summary of Multiple Comparisons using Tukey test

Range of Significance

Irongmara > Kharagpur, Dolaigaon, BGR

P=0.005 - 0.032

Township

Table 30 Results of one way analysis of variance (ANOVA) for Cadmium (Cd) of rainwater along with multiple comparisons using Tukey test among the sites during 2013 F

Significance

2.881

P=0.011

Summary of Multiple Comparisons using Tukey test

Range of Significance

Badarpur< Kolkata, Kharagpur, Dolaigaon

231

P=0.015 - 0.026

Chapter 4 Results Table 31 Results of one way analysis of variance (ANOVA) for Zinc (Zn) of rainwater along with multiple comparisons using Tukey test among the sites during 2013 F

Significance

5.938

P< 0.001

Summary of Multiple Comparisons using Tukey test

Range of Significance

Irongmara > Kolkata, Kharagpur,

P=0.000 - 0.005

Dolaigaon, Bongaigaon, BGR Township

Table 32 Results of one way analysis of variance (ANOVA) for Chromium (Cr) of rainwater along with multiple comparisons using Tukey test among the sites during 2013 F

Significance

2.997

P=0.009

Summary of Multiple Comparisons using Tukey test

Range of Significance

Kharagpur > Irongmara, Kolkata, Badarpur

232

P=0.012 - 0.049

Chapter 4 Results 5. Rainwater quality in different study sites in 2011-2013 a) pH i) Mean pH at the different study sites The pH of rainwater (direct collection) at the different sites in 2011-2013 is shown in Figure 166. It can be observed from the Figure that the highest mean pH of rainwater (direct collection)

was recordedat Kolkata, while the

lowest is at Dolaigaon. The pH ranged between 5.35 in Dolaigaon and 6.64 in Kolkata. The mean pH values in 2011-2013 at the different sites are found to be in the following descending order: Kolkata (KOL) >Kharagpur (KGP) >BGR Township (BGR) >Badarpur (BPB) >Bongaigaon (BNG) > Irongmara (IM) > Dolaigaon (DLG).

b) Electrical Conductivity (EC) i) Mean ECat the different study sites The conductivity of rainwater (direct collection) at the different sites in 2011-2013 is shown in Figure 167. It can be observed from the Figure that the highest mean conductivity of rainwater (direct collection) wasrecordedat Kolkata, while the lowest is at Kharagpur. The conductivity ranged between 17.9 µS cm-1

in Kharagpur and 47.3µS cm-1 in Kolkata. The mean

conductivity values in 2011-2013 at the different sites are found to be in the following descending order: Kolkata (KOL) >Badarpur (BPB) > Dolaigaon (DLG) > Irongmara (IM) > Bongaigaon (BNG) > BGR Township (BGR) >Kharagpur (KGP).

233

Chapter 4 Results c) Heavy Metals i) Mean Heavy Metals at the different study sites The heavy metals of rainwater (direct collection) at the different sites in 2011-2013 is shown in Figures 168-173. The highest mean Lead (Pb)in rainwater (direct collection)

wasrecordedat Kolkata, while the lowest is at

Dolaigaon. The Lead (Pb) concentration ranged between 0.0012 mg L-1 in Dolaigaon and 0.0098 mg L-1in Kolkata (Fig. 168). The highest mean Cadmium (Cd)in rainwater (direct collection) wasrecordedat Kharagpur and the lowest is at Irongmara, while the concentration in Badarpur is Below Detection Level. The Cadmium (Cd) concentration ranged between 0.0022 mg L-1 in Irongmara and 0.0044 mg L-1 in Kharagpur (Fig. 169). The highest mean Nickel (Ni)in rainwater (direct collection) was recordedat Irongmara and the lowest is at Bongaigaon, while the concentration in Badarpur is Below Detection Level. The Nickel (Ni) concentration ranged between 0.00077 mg L-1 in Bongaigaon and 0.0038 mg L-1in Irongmara (Fig. 170). The highest mean Zinc (Zn)in rainwater (direct collection)wasrecordedat Irongmara, while the lowest is at Kharagpur. The Zinc (Zn) concentration ranged between 0.0166mg L-1in Kharagpur and 0.0521mg L-1 in Irongmara (Fig. 171). The highest mean Chromium (Cr)in rainwater (direct collection)

was recordedat

Irongmara, while the lowest is at Kolkata. The Chromium (Cr) concentration ranged between 0.002 mg L-1 in Kolkata and 0.0217mg L-1 in Irongmara (Fig. 172). The highest mean Cobalt (Co)in rainwater (direct collection) was recordedat Irongmara and the lowest is at BGR Township, while the concentration in Kolkata and Badarpur is Below Detection Level. The Cobalt

234

Chapter 4 Results (Co) concentration ranged between 0.00023mg L-1 in BGR Township and 0.0045mg L-1in Irongmara (Fig. 173).

d) Statistical Analysisof Data i) Comparisons of pH and EC amongthe years 2011-2013 Table

33-34

summarizes

the

results

of

one-way

analysis-of-variance

(ANOVA) in pH among the years2011-2013. The differences are significant at p < 0.001. Multiple comparisons using Tukey test reveal that pH of Kolkata rainwater in 2011 was significantly more alkaline than that of 2013; pH of Dolaigaon rainwater in 2011 was significantly higher than that in 2012. Table 35 summarizes the results of one-way analysis-of-variance (ANOVA) in EC among the years 2010-2013. The differences are significant at p < 0.001. Multiple comparisons using Tukey test reveal that EC of Irongmara rainwater in 2010 was significantly higher than those in the other consecutive years 2011-2013.

ii) Comparisons ofheavy metals among the years 2011-2013 Table

36-40

summarizes

the

results

of

one-way

analysis-of-variance

(ANOVA) in Lead (Pb), Cadmium (Cd), Zinc (Zn) and Chromium (Cr) among the years 2010-2013. The differences are significant at p < 0.001. In Table 36 multiple comparisons using Tukey test reveal that Pb concentration in Dolaigaon rainwater in 2013 was significantly higher than that in 2012. In Table 37 multiple comparisons using Tukey test reveal that

Cd

concentration in Irongmara rainwater in 2013 was significantly higher than that in 2011. In Table 38 multiple comparisons using Tukey test reveal that 235

Chapter 4 Results Zn concentration in Kharagpur rainwater in 2012 was found to be significantly higher than those of 2011 and

2013. In Table 39 multiple

comparisons using Tukey test reveal that Zn concentration in Dolaigaon rainwater in 2011 was found to be significantly higher than those of 2012 and 2013. In Table 40 multiple comparisons using Tukey test reveal that Cr concentration in Dolaigaon rainwater in 2013 was found to be significantly higher than those of 2011 and 2012.

iii) Comparisons of pH and EC amongstudy sites in 2011-2013 Table 41 summarizes the results of one-way analysis-of-variance (ANOVA) in pH among the different study sites in 2011-2013. The differences are significant at p < 0.001. Multiple comparisons using Tukey test reveal that pH of Kolkata rainwater was significantly more alkaline than those in the other study sites; pH in Kharagpur and BGR Township were found to be significantly equivalent, pH in Dolaigaon was significantly lower than Irongmara and Bongaigaon; and that in Badarpur was significantly higher than those in Irongmara, Dolaigaon and Bongaigaon. Table 42 summarizes the results of one-way analysis-of-variance (ANOVA) in EC among the different study sites in 2011-2013. The differences are significant at p < 0.001. Multiple comparisons using Tukey test reveal that EC of Kolkata rainwater was significantly more than those in the other study sites; EC in Irongmara was significantly higher than Kharagpur and BGR Township, EC in Kharagpur and BGR Township and that of Dolaigaon and Badarpur were found to be significantly equivalent.

236

Chapter 4 Results iv) Comparisons ofheavy metals among study sites in 2011-2013 Table

43-48

summarizes

the

results

of

one-way

analysis-of-variance

(ANOVA) in Lead (Pb), Cadmium (Cd), Nickel (Ni), Zinc (Zn), Chromium (Cr) and Cobalt (Co) among the different study sites in 2011-2013. The differences are significant at p < 0.001. In Table 43 multiple comparisons using Tukey test reveal that Pb concentration in Kolkata rainwater was significantly higher than that in Dolaigaon. In Table 44multiple comparisons using Tukey test reveal that Cd concentration in Kharagpur rainwater was significantly higher than those in Irongmara and Bongaigaon. In Table 45 multiple comparisons using Tukey test reveal that Ni concentration in Irongmara rainwater was found to be significantly higher than those of Kharagpur, Dolaigaon and Bongaigaon;and that of Ni concentration in Kolkata and BGR Township were found to be significantly equivalent. In Table 46 multiple comparisons using Tukey test reveal that Zn concentration in Irongmara rainwater was significantly higher than those in the other study sites.In Table 47 multiple comparisons using Tukey test reveal that Cr concentration in Kharagpur rainwater was significantly higher than that in Kolkata. In Table 48 multiple comparisons using Tukey test reveal that Co concentration in Irongmara rainwater was significantly higher than those in the other study sites; and that in Bongaigaon was significantly higher than BGR Township.

6. Comparison of pH and Nitrate Table 49-50 summarizes the results of Comparison of pH and nitrate with some other selected sites of India. It is observed from the Table 49 that the

237

Chapter 4 Results pH of some of the study sites are alkaline in nature and comparable with the pH of some of the metropolitan cities such as Delhi, Mumbai, Hyderabad and Asansol.

238

Chapter 4 Results 2011-2013

pH

2011-2013 7 6 5 4 3 2 1 0

6.64 5.52

Irongmara

6.06 5.35

Kolkata

6.02

5.89

BGR Township

Badarpur

5.63

Kharagpur Dolaigaon Bongaigaon STUDY SITES

Fig. 166. pH in rainwater (direct collection) during 2011-2013.

EC (µS cm -1)

2011-2013 60 50 40 30 20 10 0

29.35

47.3

31.2 17.9

29.7

25.4

22.7

STUDY SITES

Fig. 167. Electrical Conductivity in rainwater (direct collection) during 2011-2013.

239

Chapter 4 Results

Lead (Pb) Concentration (mg L-1)

0.025 0.02 0.015 0.0098 0.01 0.0039

0.0039

0.005

0.0015

0.0012

0.0021

0.0025

0

STUDY SITES

Fig. 168. Concentration of Lead (Pb) in rainwater (direct collection) during 20112013.

Cadmium (Cd) Concentration (mg L-1)

0.006 0.0044

0.005 0.004

0.0029

0.0032

0.0022

0.0026

0.0031

0.003 0.002 0.001 ND 0

STUDY SITES

Fig. 169. Concentration of Cadmium (Cd) in rainwater (direct collection) during 2011-2013.

240

Chapter 4 Results

Nickel (Ni) Concentration (mg L-1)

0.006 0.005

0.0038 0.0029

0.004

0.0019

0.003 0.001

0.002

0.00242

0.00077

0.001

ND

6E-18 -0.001

STUDY SITES

Fig. 170. Concentration of Nickel (Ni) in rainwater (direct collection) during 20112013.

Zinc (Zn) Concentration (mg L-1)

0.07 0.06

0.0521 0.0349

0.05

0.0309

0.0307

0.04 0.03

0.0193

0.0166 0.0192

0.02 0.01 0 Irongmara

Kolkata

Kharagpur Dolaigaon Bongaigaon

BGR Township

Badarpur

STUDY SITES

Fig. 171. Concentration of Zinc (Zn) in rainwater (direct collection) during 20112013.

241

Chapter 4 Results

Chromium (Cr)

Concentration (mg L-1)

0.014 0.012 0.01 0.008

0.0073 0.0052

0.0044

0.006

0.004

0.0038 0.00275

0.002

0.004 0.002 0

STUDY SITES

Fig. 172. Concentration of Chromium (Cr) in rainwater (direct collection) during 2011-2013.

Cobalt (Co) Concentration (mg L-1)

0.006 0.005

0.0045

0.004 0.003

0.0016

0.0017

0.00185

0.002 0.001

0.00023

ND

ND

6E-18 -0.001

STUDY SITES Fig. 173. Concentration of Cobalt (Co) in rainwater (direct collection) during 20112013.

242

Chapter 4 Results 2011-2013

Table 33 Results of one way analysis of variance (ANOVA) for pH of rainwater of Kolkata along with multiple comparisons using Tukey test among the years 2011 – 2013 F

Significance

6.216

P=0.003

Summary of Multiple Comparisons using Tukey test

Range of Significance

2011 > 2013

P=0.003

Table34 Results of one way analysis of variance (ANOVA) for pH of rainwater of Dolaigaon along with multiple comparisons using Tukey test

among the years 2011 – 2013 F

Significance

3.972

P=0.021

Summary of Multiple Comparisons using Tukey test

Range of Significance

2011 > 2012

P=0.019

243

Chapter 4 Results Table 35 Results of one way analysis of variance (ANOVA) for Electrical Conductivity (EC) of rainwater of Irongmara along with multiple comparisons using Tukey test among the years 2010 – 2013 F

Significance

7.091

P 2011, 2012, 2013

P=0.000 - 0.015

Table 36 Results of one way analysis of variance (ANOVA) for Lead (Pb) of rainwater of Dolaigaon along with multiple comparisons using Tukey test

among the years 2011 – 2013 F

Significance

3.365

P=0.041

Summary of Multiple Comparisons using Tukey test

Range of Significance

2013 > 2012

P=0.042

Table 37 Results of one way analysis of variance (ANOVA) for Cadmium

(Cd))

of

rainwater

of

Irongmara

along

with

multiple

comparisons using Tukey test among the years 2010 – 2013 F

Significance

4.095

P=0.021

Summary of Multiple Comparisons using Tukey test

Range of Significance

2013 > 2011

P=0.016

244

Chapter 4 Results

Table 38 Results of one way analysis of variance (ANOVA) for Zinc (Zn) of rainwater of Kharagpur along with multiple comparisons using Tukey test

among the years 2011 – 2013 F

Significance

8.374

P=0.001

Summary of Multiple Comparisons using Tukey test

Range of Significance

2012 > 2011, 2013

P=0.002 - 0.005

Table 39 Results of one way analysis of variance (ANOVA) for Zinc (Zn) of rainwater of Dolaigaon along with multiple comparisons using Tukey test

among the years 2011 – 2013 F

Significance

6.890

P=0.002

Summary of Multiple Comparisons using Tukey test

Range of Significance

2011 > 2012, 2013

P=0.002 - 0.032

Table 40 Results of one way analysis of variance (ANOVA) for Chromium

(Cr)

of

rainwater

comparisons using Tukey test

of

Dolaigaon

along

with

multiple

among the years 2011 – 2013

F

Significance

6.394

P=0.003

Summary of Multiple Comparisons using Tukey test

Range of Significance

2013 > 2011, 2012

P=0.005 - 0.013

245

Chapter 4 Results Table 41 Results of one way analysis of variance (ANOVA) for pH of rainwater along with multiple comparisons using Tukey test among the sites during 2011– 2013 F

Significance

68.120

P Irongmara, Kharagpur, Dolaigaon, Bongaigaon, BGR Township, Badarpur

P=0.000

Kharagpur ~ BGR Township

P=0.000

Dolaigaon Irongmara, Dolaigaon, Bongaigaon

P=0.000 - 0.003

Table 42 Results of one way analysis of variance (ANOVA) for Electrical

Conductivity

(EC)

of

rainwater

along

with

multiple

comparisons using Tukey test among the sites during 2011– 2013 F

Significance

29.749

P Kharagpur, BGR Township

P=0.003 - 0.044

Kolkata > Irongmara, Kharagpur, Dolaigaon, Bongaigaon, BGR Township, Badarpur

P=0.000

Kharagpur ~ BGR Township

P=0.001 - 0.024

Dolaigaon ~ Badarpur

P=0.001 - 0.024

246

Chapter 4 Results Table 43 Results of one way analysis of variance (ANOVA) for Lead (Pb) of rainwater along with multiple comparisons using Tukey test among the sites during 2011– 2013 F

Significance

2.302

P=0.034

Summary of Multiple Comparisons using Tukey test

Range of Significance

Kolkata > Dolaigaon

P=0.025

Table 44 Results of one way analysis of variance (ANOVA) for Cadmium (Cd) of rainwater along with multiple comparisons using Tukey test among the sites during 2011– 2013 F

Significance

1.679

P=0.139

Summary of Multiple Comparisons using Tukey test

Range of Significance

Kharagpur> Irongmara, Bongaigaon

P=0.009 - 0.036

Table 45 Results of one way analysis of variance (ANOVA) for Nickel (Ni) of rainwater along with multiple comparisons using Tukey test among the sites during 2011– 2013 F

Significance

8.028

P Kharagpur, Dolaigaon, Bongaigaon

P=0.000 - 0.006

Kolkata ~ BGR Township

P=0.016 - 0.021

247

Chapter 4 Results Table 46 Results of one way analysis of variance (ANOVA) for Zinc (Zn) of rainwater along with multiple comparisons using Tukey test among the sites during 2011– 2013 F

Significance

5.681

P Kolkata, Kharagpur, Dolaigaon, Bongaigaon

P=0.000 - 0.045

Table 47 Results of one way analysis of variance (ANOVA) for Chromium (Cr) of rainwater along with multiple comparisons using Tukey test among the sites during 2011– 2013 F

Significance

2.679

P=0.015

Summary of Multiple Comparisons using Tukey test

Range of Significance

Kharagpur > Kolkata

P=0.008

Table 48 Results of one way analysis of variance (ANOVA) for Cobalt (Co) of rainwater along with multiple comparisons using Tukey test among the sites during 2011– 2013 F

Significance

15.639

P Kharagpur, Dolaigaon, Bongaigaon, BGR Township

P=0.000

Bongaigaon>BGR Township

P=0.028

248

Chapter 4 Results Table 49 Comparison of pH with some other selected sites of India

Site

pH

Reference

Irongmara

5.52

Present study

Badarpur

5.89

Present study

Bongaigaon

5.63

Present study

Dolaigaon

5.35

Present study

BGR Township

6.02

Present study

Kolkata

6.64

Present study

Kharagpur

6.06

Present study

Delhi

5.7

Ravichandran and Padmanamurty (1994)

249

Ahmedabad

6.7

Rastogi and Sarin (2005)

Dyalbagh (Agra)

7.01

Kumar et al. (2002)

Gopalpura (Agra)

6.5

Satsangi et al. (1998)

Chapter 4 Results

250

Lucknow

6.5

Khare et al. (2004)

Korba

4.8

Chandravanshi et al. (1997)

Pune

6.1

Pillai et al. (2001)

Hyderabad

6.1

Kulshrestha et al. (2003)

Hyderabad

6.34

Srinivas et al. (2001)

Bangalore

4.82

Shivashankara et al. (1999)

Bhubaneswar

6.2

Das et al. (2005)

Goa

6.3

Parashar et al. (2001)

Kalyan

5.7

Khemani et al. (1989)

Kalyan

5.28

Naik et al. (2002)

Colaba

6.4

Naik et al. (2002)

Alibag

6.74

Naik et al. (2002)

Chembur

4.8

Khemani et al. (1989)

Chapter 4 Results

Dhanbad

5.3

Singh et al. (2006)

Asansol

6.08

Banerjee (2008)

Tirupati

6.78

Mouli et al. (2005)

Table 50 Comparison of Nitrate with some other selected sites of India

Site

Mean Concentration in mg L-1 (range)

Reference

Irongmara

1.46

Present study

(1.28-1.68) Badarpur

1.24

Present study

(1.22-1.26) Bongaigaon

0.99

Present study

(0.085-1.58) Dolaigaon

1.48

Present study

(1.29-1.59) BGR Township

1.21

Present study

(1.18-1.26) Kolkata

1.12

Present study

(1.014-1.19) Kharagpur

1.41 (1.368-1.48)

251

Present study

Chapter 4 Results

252

Delhi

66.8

Ravichandran and Padmanamurty (1994)

Ahmedabad

13

Rastogi and Sarin (2005)

Dyalbagh (Agra)

22.8

Kumar et al. (2002)

Gopalpura (Agra)

43

Satsangi et al. (1998)

Lucknow

7.7

Khare et al. (2004)

Korba

25.1

Chandravanshi et al. (1997)

Pune

18

Pillai et al. 2001

Hyderabad

10.3

Kulshrestha et al. (2003)

Bangalore

26.5

Shivashankara et al. (1999)

Bhubaneswar

10.0

Das et al. (2005)

Goa

5.5

Parashar et al. ( 2001)

Kalyan

31

Khemani et al. (1989)

Kalyan

66

Naik et al. (2002)

Colaba

34

Naik et al. (2002)

Chapter 4 Results Alibag

9

Naik et al. (2002)

Nilgiris (South India)

21

Rao et al. (1995)

Dhanbad

10.2

Singh et al. (2006)

Asansol

16

Banerjee (2008)

253

Chapter 4 Results II. Rainwater Quality in Roof Collection Samples 1. Rainwater quality in different study sites in 2011 a) pH i) Mean pH at the different study sites The pH of rainwater (roof collection) at the different sites in 2011 is shown in Table 51. It can be observed from the Table that the highest mean pH of rainwater (roof collection)

is recordedat Bongaigaon, while the lowest is

at Dolaigaon. The highest individual pH was also recorded at Bongaigaon on 21-07-2011, whereas the lowest individual pH is detected at Irongmara on 11-05-2011. The mean pH values in 2011 at the different sites are found to be in the following descending order: Bongaigaon (BNG) > Irongmara (IM) > Dolaigaon (DLG).

ii) Monthly fluctuations inpH The mean monthly pH values at the different sites in 2011 are shown in Figures 174-176. In Irongmara, the pH ranged between 6.13 in June and 6.803 in April(Fig. 174). In Bongaigaon, the pH ranged between 6.39 in May and 6.93 in July (Fig. 175). In Dolaigaon, the pH ranged between 5.85 in June and 6.66 in July (Fig. 176).

b) Electrical Conductivity (EC) i) Mean EC at the different study sites The conductivity of rainwater (roof collection) at the different sites in 2011 is shown in Table 52. It can be observed from the Table that the highest mean conductivity of rainwater (roof collection) wasrecordedat Bongaigaon, 254

Chapter 4 Results while the lowest is at Irongmara. The highest individual conductivity was also recorded at Bongaigaon on 15-06-2011, whereas the lowest individual conductivity is detected at Irongmara on 06-07-2011. The mean conductivity values in 2011 at the different sites are found to be in the following descending order: Bongaigaon (BNG) >Dolaigaon (DLG) >Irongmara (IM).

ii) Monthly fluctuations in conductivity (EC)

The mean monthly conductivity values at the different sites in 2011 are shown in Figures 177-179. In Irongmara, the conductivity ranged between 8.305µS cm-1 in July and 35.05µS cm-1 in March (Fig. 177). In Bongaigaon, the conductivity ranged between 21.6 µS cm-1 in July and 64.4 µS cm-1 in June (Fig. 178). In Dolaigaon, the conductivity ranged between 19.22µS cm-1 in July and 51.5µS cm-1 in June (Fig. 179).

c) Heavy Metals i) Mean Heavy Metals at the different study sites The heavy metals of rainwater (roof collection) at the different sites in 2011 is shown in Table 53. It can be observed from the Table that the highest mean Lead (Pb)in rainwater (roof collection) is recordedat Irongmara, while the lowest is at Dolaigaon. The highest individual Pb was recorded at both Irongmaraand Bongaigaon on 24-07-2011 and 12-08-2011 respectively. The mean Pb values in 2011 at the different sites are found to be in the following descending order: Irongmara (IM) > Bongaigaon (BNG) > Dolaigaon (DLG). Highest mean Cadmium (Cd)in rainwater (roof collection)

was

recordedat Dolaigaon, while the lowest is at Irongmara. The highestindividual 255

Chapter 4 Results Cd was recorded at Bongaigaon on 19-07-2011. The mean Cd values in 2011 at the different sites are found to be in the following descending order: Dolaigaon (DLG) > Bongaigaon > Irongmara (IM). Highest mean Nickel (Ni)in rainwater (roof collection) was recordedat Irongmara, while the lowest is at Dolaigaon. The highest individual Ni was also recorded at Irongmara on 11-05-2011. The mean Ni values in 2011 at the different sites are found to be in the following descending order: Irongmara (IM) >Bongaigaon (BNG) >Dolaigaon (DLG). Highest mean Zinc (Zn)in rainwater (roof collection) was recordedat Irongmara, while the lowest is at Dolaigaon. The highest individual Zn was also recorded at Irongmara on 11-05-2011, while the lowest is at Bongaigaon on 19-07-2011. The mean Zn values in 2011 at the different sites are found to be in the following descending order: Irongmara (IM) >Bongaigaon (BNG) > Dolaigaon (DLG). It is observed from the Table that

the

highest

mean

Chromium

(Cr)in

rainwater

(roof

collection)

wasrecordedat Dolaigaon, while the lowest is at Irongmara. The highest individual Cr was also recorded at Dolaigaon on 24-08-2011. The mean Cr values in 2011 at the different sites are found to be in the following descending

order: Dolaigaon (DLG) > Bongaigaon (BNG) >Irongmara (IM).

Highest mean Cobalt (Co)in rainwater (roof collection)

was recordedat

Irongmara and lowest at Bongaigaon. The highest individual Co was also recorded at Irongmara on 01-08-2011. The mean Co values in 2011 at the different sites are found to be in the following descending order: Irongmara (IM) >Bongaigaon (BNG) > Dolaigaon (DLG).

256

Chapter 4 Results ii) Monthly fluctuations inHeavy Metals The mean monthly heavy metals values at the different sites in 2011 are shown in Figures 180-197. Irongmara: The Lead (Pb) concentration ranged between 0.001 mg L-1 in June and 0.0205 mg L-1 in July (Fig. 180). Cadmium (Cd) concentration ranged between 0.0005 mg L-1in August and 0.0045 mg L-1in September, while the concentration in July is Below Detection Level (Fig. 181). (Ni) concentration ranged between 0.0006mg L-1 in April and 0.0215 mg L-1 in June (Fig. 182). Zinc (Zn) concentration ranged between 0.251 mg L-1 in August and 0.373mg L-1 in May (Fig. 183). Chromium (Cr) concentration ranged between 0.0015 mg L-1 in May and 0.006 mg L-1 in July, while the concentration in August is Below Detection Level (Fig. 184). Cobalt (Co) concentration ranged between 0.0014 mg L-1 in September and 0.012 mg L-1 in June, while the concentration in July is Below Detection Level (Fig. 185). Bongaigaon: The Lead (Pb) concentration ranged between 0.0015 mg L-1 in August

and

0.012

mg L-1

in

September

(Fig. 186).

Cadmium

(Cd)

concentration ranged between 0.003 mg L-1 in May and 0.0091 mg L-1in July,

while the concentration in September is Below Detection Level (Fig.

187). Nickel (Ni) concentration ranged between 0.0024 mg L-1 in May and September and 0.011 mg L-1 in July (Fig. 188). Zinc (Zn) concentration ranged between 0.142 mg L-1 in July and 0.422 mg L-1 in April (Fig. 189). Chromium (Cr) concentration ranged between 0.0044 mg L-1 in August and 0.014 mg L-1 in May (Fig. 190). Cobalt (Co) concentration ranged between 0.0015 mg L-1 in June and 0.0059 mg L-1 in April (Fig. 191).

257

Chapter 4 Results Dolaigaon: The Lead (Pb) concentration ranged between 0.0016 mg L-1 in June and 0.0051 mg L-1 in September (Fig. 192). Cadmium (Cd) concentration ranged between 0.002 mg L-1 in May and 0.0069 mg L-1 in July (Fig. 193). Nickel

(Ni)

concentration

ranged

between

0.0015mg L-1

in

July and

0.0066mg L-1in April, while the concentration in August is Below Detection Level (Fig. 194). Zinc (Zn) concentration ranged between 0.0524 mg L-1 in July and 0.286 mg L-1 in June (Fig. 195).Chromium (Cr) concentration ranged between 0.0038 mg L-1 in July and 0.0186 mg L-1 in August (Fig. 196). Cobalt (Co) concentration ranged between 0.0019 mg L-1 in September and 0.0061 mg L-1 in July (Fig. 197). d) Statistical Analysisof Data i) Comparisons of pH and EC amongstudy sites in 2011 Table 54 summarizes the results of one-way analysis-of-variance (ANOVA) in pH among the different study sites in 2011. The differences are significant at p < 0.001. Multiple comparisons using Tukey test reveal that pH of Bongaigaon rainwater was significantly more alkaline than that of Dolaigaon. Table 55 summarizes the results of one-way analysis-of-variance (ANOVA) in EC among the different study sites in 2011. The differences are significant at p < 0.001. Multiple comparisons using Tukey test reveal that EC of Irongmara rainwater was significantly lower than those of Dolaigaon and Bongaigaon.

ii) Comparisons ofheavy metals among study sites in 2011 Table

56-57

summarizes

the

results

of

one-way

analysis-of-variance

(ANOVA) in Cadmium (Cd) and Zinc (Zn) among the different study sites 258

Chapter 4 Results in 2011. The differences are significant at p < 0.001. In Table 56 multiple comparisons using Tukey test reveal that Cd concentration in Dolaigaon rainwater was significantly higher than that in Irongmara. In Table 57 multiple comparisons using Tukey test reveal that Zn concentration in Irongmara rainwater was significantly higher than those of the other two study sites Dolaigaon and Bongaigaon; and that Zn concentration in Bongaigaon rainwater was significantly more than that of Dolaigaon.

259

Chapter 4 Results Roof Collection 2011

pH

Irongmara 7.5 7 6.5 6 5.5 5 4.5 4

6.803 6.78

6.58

6.414

6.164

6.795

6.13

March

April

May

June

July

August

September

2011

Fig. 174. pH in rainwater (roof collection) in 2011, at Irongmara, Cachar, Assam.

Bongaigaon 7.5 6.55

7

pH

6.93

6.67

6.5

6.67 6.36

6

6.39

5.5 5 4.5 4 April

May

June

July

August

September

2011

Fig. 175. pH in rainwater (roof collection) in 2011, at Bongaigaon, Assam.

260

Chapter 4 Results

Dolaigaon 7.5 6.64

7

pH

6.66

6.652

6.5 6

6.103

5.85

6.323

5.5 5 4.5 4 April

May

June

July

August

September

2011

Fig. 176. pH in rainwater (roof collection) in 2011, at Dolaigaon, Assam.

EC (µS cm -1)

Irongmara 50 45 40 35 30 25 20 15 10 5 0

35.05

29.9 29.9 23.65

28.3 23.4 8.305 March

April

May

June

July

August

September

2011

Fig. 177. Electrical Conductivity in rainwater (roof collection) in 2011, at Irongmara, Cachar, Assam.

261

Chapter 4 Results

Bongaigaon 100 EC (µS cm -1)

80 64.4

60

39.33

30.08

40

31.88

29.9

21.6

20 0 April

May

June

July

August

September

2011

Fig. 178. Electrical Conductivity in rainwater (roof collection) in 2011, at Bongaigaon, Assam.

Dolaigaon 70 EC (µS cm -1)

60 42.55

51.5

50 40 30.25

30

40.25

35.95

20

19.22

10 0 April

May

June

July

August

September

2011

Fig. 179. Electrical Conductivity in rainwater (roof collection) in 2011, at Dolaigaon, Assam.

262

Chapter 4 Results

Irongmara 0.035 Lead (mg L-1)

0.03 0.025

0.0205

0.02 0.015

0.0095

0.01

0.0015

0.005

0.0025

0.001

0.004

0 April

May

June

July

August

September

2011

Fig. 180. Concentration of Lead (Pb) in rainwater (roof collection) in 2011, at Irongmara, Cachar, Assam.

Cadmium (mg L-1)

Irongmara 0.009 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.0034

0.0045

0.0021 ND

0.0016

0.0005 April

May

June

July

August

September

2011

Fig. 181. Concentration of Cadmium (Cd) in rainwater (roof collection) in 2011, at Irongmara, Cachar, Assam.

263

Chapter 4 Results

Nickel (mg L-1)

Irongmara 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0

0.0215 0.016 0.0075

0.0056 0.001

0.0006 April

May

June

July

August

September

2011

Fig. 182. Concentration of Nickel (Ni) in rainwater (roof collection) in 2011, at Irongmara, Cachar, Assam.

Irongmara 0.6 Zinc (mg L-1)

0.5

0.304

0.3725

0.373

0.4

0.296

0.292

0.3 0.2 0.251

0.1 0 April

May

June

July

August

September

2011

Fig. 183. Concentration of Zinc (Zn) in rainwater (roof collection) in 2011, at Irongmara, Cachar, Assam.

264

Chapter 4 Results

Irongmara Chromium (mg L-1)

0.01 0.008 0.006

0.0038

0.006

0.005 0.004

0.004

0.002

0.0015

0 April

May

June

ND August September

July 2011

Fig. 184. Concentration of Chromium (Cr) in rainwater (roof collection) in 2011, at Irongmara, Cachar, Assam.

Irongmara Cobalt (mg L-1)

0.03 0.025 0.02 0.012

0.015

0.011

0.01 0.003

0.005

0.003

0

0.0014

ND April

May

June

July

August

September

2011

Fig. 185. Concentration of Cobalt (Co) in rainwater (roof collection) in 2011, at Irongmara, Cachar, Assam.

265

Chapter 4 Results

Bongaigaon Lead (mg L-1)

0.02 0.015 0.012 0.01

0.0055

0.0095

0.005

0.0016

0.0032

0.0015

0 April

May

June

July

August

September

2011

Fig. 186. Concentration of Lead (Pb) in rainwater (roof collection) in 2011, at Bongaigaon, Assam.

Bongaigaon Cadmium (mg L-1)

0.014 0.012 0.01

0.0091

0.008 0.006 0.004

0.005 0.003

0.002

0.0042

0.0037

0 April

May

June

July

August

ND September

2011

Fig. 187. Concentration of Cadmium (Cd) in rainwater (roof collection) in 2011, at Bongaigaon, Assam.

266

Chapter 4 Results

Nickel (mg L-1)

Bongaigaon 0.018 0.016 0.014 0.012 0.01 0.008 0.006 0.004 0.002 0

0.011 0.0024

0.0029

0.0045 0.0033

April

May

June

0.0036

July

August

September

2011

Fig. 188. Concentration of Nickel (Ni) in rainwater (roof collection) in 2011, at Bongaigaon, Assam.

Bongaigaon 0.6 Zinc (mg L-1)

0.5 0.4

0.422

0.302

0.3

0.219 0.205

0.2

0.19

0.142

0.1 0 April

May

June

July

August

September

2011

Fig. 189. Concentration of Zinc (Zn) in rainwater (roof collection) in 2011, at Bongaigaon, Assam.

267

Chapter 4 Results

Bongaigaon Chromium (mg L-1)

0.035 0.03 0.025 0.02 0.015 0.01

0.014

0.007

0.005

0.0091

0.0044 0.0063

0.005 0 April

May

June

July

August

September

2011

Fig. 190. Concentration of Chromium (Cr) in rainwater (roof collection) in 2011, at Bongaigaon, Assam.

Cobalt (mg L-1)

Bongaigaon 0.009 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.0059

0.0058 0.0048 0.0031

April

May

0.0015

June

July

0.0029

August

September

2011

Fig. 191. Concentration of Cobalt (Co) in rainwater (roof collection) in 2011, at Bongaigaon, Assam.

268

Chapter 4 Results

Dolaigaon Lead (mg L-1)

0.01 0.008 0.006

0.0051

0.0031

0.004

0.0029

0.0016

0.0022 0.0023

0.002 0 April

May

June

July

August

September

2011

Fig. 192. Concentration of Lead (Pb) in rainwater (roof collection) in 2011, at Dolaigaon, Assam.

Cadmium (mg L-1)

Dolaigaon 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.0058 0.0069 0.0062 0.0053 0.0037 0.002

April

May

June

July

August

September

2011

Fig. 193. Concentration of Cadmium (Cd) in rainwater (roof collection) in 2011, at Dolaigaon, Assam.

269

Chapter 4 Results

Dolaigaon 0.012 Nickel (mg L-1)

0.01 0.008 0.0066

0.006

0.0037

0.0056

0.0044

0.004 0.002

0.0015

0 April

May

June

ND August September

July 2011

Fig. 194. Concentration of Nickel (Ni) in rainwater (roof collection) in 2011, at Dolaigaon, Assam.

Zinc (mg L-1)

Dolaigaon 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0

0.286

0.167 0.152

0.0524

0.119 0.075

April

May

June

July

August

September

2011

Fig. 195. Concentration of Zinc (Zn) in rainwater (roof collection) in 2011, at Dolaigaon, Assam.

270

Chapter 4 Results

Chromium (mg L-1)

Dolaigaon 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0

0.0136

0.0186

0.01

0.0096 0.0058 April

0.0038 May

June

July

August

September

2011

Fig. 196. Concentration of Chromium (Cr) in rainwater (roof collection) in 2011, at Dolaigaon, Assam.

Cobalt (mg L-1)

Dolaigaon 0.009 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.0057 0.0061 0.0049 0.0023

0.0031

0.0019

April

May

June

July

August

September

2011

Fig. 197. Concentration of Cobalt (Co) in rainwater (roof collection) in 2011, at Dolaigaon, Assam.

271

Chapter 4 Results Roof Collection 2011 Table 51 Descriptive statistics for pH (Roof Collection) in Rainwater at different geographical locations during 2011

Site

Mean

Median

S.D.

Min

Max

Irongmara

6.38

6.42

0.374

5.764

6.972

Bongaigaon

6.577

6.62

0.26

5.998

6.998

Dolaigoon

6.345

6.381

0.35

5.808

6.971

Table

52

Descriptive

statistics

for

Electrical

Conductivity

(Roof

Collection) in Rainwater at different geographical locations during 2011 Site

Mean

Median

S.D.

Min

Max

Irongmara

25.65

9.45

6.28

55.2

Bongaigaon

27.02 (µS cm-1) 38.3

35.6

17.5

13.49

88.2

Dolaigoon

36.76

34.9

12.4

11.56

61.5

Table 53Descriptive statistics for Heavy Metal Concentration in Rainwater (Roof Collection) at different geographical locations during 2011 Heavy

Site

Mean

Median

S.D.

Min

Max

Pb Metals

Irongmara

0.007

0.0088

ND

Bongaigaon

0.0085 0.0067

0.004

0.0073

ND

0.027 0.027

(mg L

Dolaigaon

0.003

0.0027

0.0023

ND

0.0077

1

Irongmara

0.0018

0.001

0.0024

ND

0.007

Bongaigaon

0.0043

0.0048

0.0035

ND

0.012

Dolaigaon

0.0048

0.0046

0.00263

ND

0.0087

Irongmara

0.0095

0.007

0.0104

ND

0.032

Bongaigaon

0.0043

0.0036

0.0041

ND

0.015

Dolaigaon

0.0036

0.0032

0.0027

ND

0.009

Irongmara

0.3441

0.318

0.0947

0.227

0.507

Bongaigaon

0.2465

0.247

0.1048

0.0372

0.476

-

) Cd

Ni

Zn

272

Chapter 4 Results

Cr

Co

Dolaigaon

0.1463

0.128

0.0904

0.0428

0.357

Irongmara

0.0031

0.002

0.00304

ND

0.008

Bongaigaon

0.0067

0.0054

0.0074

ND

0.0271

Dolaigaon

0.0087

0.0076

0.0086

ND

0.031

Irongmara

0.0064

0.004

0.0068

ND

0.021

Bongaigaon

0.0036

0.0036

0.0024

ND

0.0074

Dolaigaon

0.004

0.0042

0.00244

ND

0.0072

ND not detected

Table 54 Results of one way analysis of variance (ANOVA) for pH of rainwater along with multiple comparisons using Tukey test among the sites during 2011 F

Significance

3.521

P= 0.034

Summary of Multiple Comparisons using Tukey test

Range of Significance

Bongaigaon> Dolaigaon

P= 0.043

Table 55 Results of one way analysis of variance (ANOVA) for Electrical

Conductivity

(EC)

of

rainwater

along

with

multiple

comparisons using Tukey test among the sites during 2011 F

Significance

6.578

P= 0.002

Summary of Multiple Comparisons using Tukey test

Range of Significance

Irongmara < Dolaigaon, Bongaigaon

P= 0.005 - 0.017

273

Chapter 4 Results Table 56 Results of one way analysis of variance (ANOVA) for Cadmium (Cd) of

rainwater along with multiple comparisons using

Tukey test among the sites during 2011 F

Significance

4.550

P= 0.016

Summary of Multiple Comparisons using Tukey test

Range of Significance

Dolaigaon > Irongmara

P= 0.021

Table 57 Results of one way analysis of variance (ANOVA) for Zinc (Zn) of

rainwater along with multiple comparisons using Tukey test

among the sites during 2011 F

Significance

15.649

P Dolaigaon, Bongaigaon

P= 0.000 - 0.023

Bongaigaon> Dolaigaon

P= 0.019

274

Chapter 4 Results 2. Rainwater quality in different study sites in 2012 a) pH i) Mean pH at the different study sites The pH of rainwater (roof collection) at the different sites in 2012 is shown in Table 58. It can be observed from the Table that the highest mean pH of rainwater (roof collection) was recordedat Dolaigaon, while the lowest is at Bongaigaon. The highest individual pH was also recorded at Bongaigaon on 17-05-2012, whereas the lowest individual pH is also detected at Bongaigaon on 10-04-2012. The mean pH values in 2012 at the different sites are found to be in the following descending order: Dolaigaon (DLG) > Irongmara (IM) >Bongaigaon (BNG).

ii) Monthly fluctuations inpH The mean monthly pH values at the different sites in 2012 are shown in Figures 198-200. In Irongmara, the pH ranged between 5.737 in April and 6.583 in January (Fig. 198). In Bongaigaon, the pH ranged between 6.024 in July and 6.304 in September (Fig. 199). In Dolaigaon, the pH ranged between 6.12 in April and 6.45 in July (Fig. 200).

b) Electrical Conductivity (EC) i) Mean ECat the different study sites The conductivity of rainwater (roof collection) at the different sites in 2012 is shown in Table 59. It can be observed from the Table that the highest mean conductivity of rainwater (roof collection) was recorded at Dolaigaon, while the lowest is at Bongaigaon. The highest individual conductivity was 275

Chapter 4 Results also recorded at Dolaigaon on 22-06-2012, whereas the lowest individual conductivity is also detected at Bongaigaon on 11-09-2012. The mean conductivity values in 2012 at the different sites are found to be in the following descending order: Dolaigaon (DLG) > Irongmara (IM)> Bongaigaon (BNG).

ii) Monthly fluctuations inconductivity (EC)

The mean monthly conductivity values at the different sites in 2012 are shown in Figures 201-203. In Irongmara, the conductivity ranged between 20.91µS cm-1 in July and 40.7µS cm-1 in September (Fig. 201). In Dolaigaon, the conductivity ranged between 24.2µS cm-1 in April and 46.7µS cm-1 in June (Fig. 202). In Bongaigaon, the conductivity ranged between 24.3µS cm-1 in August and 37.2 µS cm-1 in April (Fig. 203).

c) Heavy Metals i) Mean Heavy Metals at the different study sites The heavy metals of rainwater (roof collection) at the different sites in 2012 is shown in Table 60. It can be observed from the Table that the highest mean Lead (Pb) in rainwater (roof collection) was recorded at Irongmara, while the lowest is at Dolaigaon. The highest individual Pb was also recorded at Irongmara on 27-06-2012. The mean Pb values in 2012 at the different sites are found to be in the following descending order: Irongmara (IM) > Bongaigaon (BNG) > Dolaigaon (DLG). Highest mean Cadmium (Cd) in rainwater (roof collection) was recordedat Irongmara, while the lowest is at Dolaigaon. The highest individual Cd was also recorded at Irongmara on 22276

Chapter 4 Results 03-2012. The mean Cd values in 2012 at the different sites are found to be in the following descending order: Irongmara (IM) > Bongaigaon > Dolaigaon (DLG). Highest mean Nickel (Ni)in rainwater (roof collection) was recordedat Irongmara, while the lowest is at Dolaigaon. The highest individual Ni was also recorded at Irongmara on 21-03-2012. The mean Ni values in 2012 at the different sites are found to be in the following descending order: Irongmara (IM) > Bongaigaon (BNG) > Dolaigaon (DLG). Highest mean Zinc (Zn)in rainwater (roof collection) was recordedat Bongaigaon, while the lowest is at Irongmara. On the other hand, both the highest and the lowest individual Zn was recorded at Irongmara on 29-05-2012 and 20-04-2012 respectively. The mean Zn values in 2012 at the different sites are found to be in the following descending order: Bongaigaon (BNG) > Dolaigaon (DLG)> Irongmara (IM). It is observed from the Table that the highest mean Chromium (Cr) in rainwater (roof collection) was recordedat Dolaigaon, while the lowest is at Bongaigaon. The highest individual Cr was also recorded at Dolaigaon on 22-06-2012. The mean Cr values in 2012 at the different sites are found to be in the following descending order: Dolaigaon (DLG) > Irongmara (IM) > Bongaigaon (BNG). Highest mean Cobalt (Co)in rainwater (roof collection) was recordedat Irongmara and lowest at Bongaigaon. The highest individual Co was also recorded at Irongmara on 22-03-2012. The mean Co values in 2012 at the different sites are found to be in the following descending order: Irongmara (IM) > Dolaigaon (DLG) > Bongaigaon (BNG).

277

Chapter 4 Results ii) Monthly fluctuations inHeavy Metals The mean monthly heavy metals values at the different sites in 2012 are shown in Figures 204-221. Irongmara: The Lead (Pb) concentration ranged between 0.0021 mg L-1 in May and 0.02 mg L-1in June (Fig. 204). Cadmium (Cd) concentration ranged between 0.0015 mg L-1 in June and 0.009mg L-1 in March, while the concentration in April is Below Detection Level (Fig. 205). Nickel (Ni) concentration ranged between 0.0017mg L-1 in May and 0.0134mg L-1 in March (Fig. 206). Zinc (Zn) concentration ranged between 0.161 mg L-1 in June and 0.376 mg L-1in May (Fig. 207).Chromium (Cr) concentration ranged between 0.0014mg L-1 in June and 0.03mg L-1 in May (Fig. 208). Cobalt (Co) concentration ranged between 0.0015mg L-1 in April and 0.012 mg L-1 in March (Fig. 209). Bongaigaon: The Lead (Pb) concentration ranged between 0.0019 mg L-1 in July and 0.011 mg L-1 in April (Fig. 210). Cadmium (Cd) concentration ranged between 0.0017 mg L-1 in June and 0.0046 mg L-1 in May and August (Fig. 211). Nickel (Ni) concentration ranged between 0.0035 mg L-1in May and 0.005 mg L-1 in August, while the concentration in July is Below Detection Level (Fig. 212). Zinc (Zn) concentration ranged between 0.117 mg L-1 in July and 0.344 mg L-1 in April (Fig. 213). Chromium (Cr) concentration ranged between 0.001 mg L-1 in September and 0.0077 mg L-1 in April (Fig. 214). Cobalt (Co) concentration ranged between 0.0014 mg L-1 in May and 0.0056 mg L-1 in April (Fig. 215). Dolaigaon:The

Lead (Pb)

concentration

ranged

between

0.0033mg L-1in

September and 0.008mg L-1 in August, while the concentration in June is 278

Chapter 4 Results Below

Detection

Level(Fig. 216).

Cadmium

(Cd)

concentration

ranged

between 0.0019mg L-1 in August and 0.0056mg L-1 in May (Fig. 217). Nickel (Ni) concentration ranged between 0.00045 mg L-1in May and 0.0049mg L-1 in September, while the concentration in July is Below Detection Level (Fig. 218). Zinc (Zn) concentration ranged between 0.194 mg L-1 in July and 0.291 mg L-1 in April (Fig. 219).Chromium (Cr) concentration ranged between 0.0018 mg L-1

in

September

and

0.055 mg L-1

in

June,

while

the

concentration in July is Below Detection Level (Fig. 220). Cobalt (Co) concentration ranged between 0.0017 mg L-1 in September and 0.0064 mg L1

in May (Fig. 221).

d) Statistical Analysisof Data i) Comparisons of EC amongstudy sites in 2012 Table 61 summarizes the results of one-way analysis-of-variance (ANOVA) in EC among the different study sites in 2012. The differences are significant at p < 0.001. Multiple comparisons using Tukey test reveal that EC of Dolaigaon rainwater was significantly higher than those of Irongmara and Bongaigaon.

279

Chapter 4 Results

2012

pH

Irongmara 7.5 7 6.5 6 5.5 5 4.5 4

6.491

6.198

6.583

6.33

6.077 5.737 6.337

6.189

2012

Fig. 198. pH in rainwater (roof collection) in 2012, at Irongmara, Cachar, Assam.

Bongaigaon 7 6.5

6.214

6.291

6.211

6.304

pH

6 6.067

5.5

6.024

5 4.5 4 April

May

June

July

August

September

2012

Fig. 199. pH in rainwater (roof collection) in 2012, at Bongaigaon, Assam.

280

Chapter 4 Results

Dolaigaon 7.5 7

pH

6.5

6.44

6.39

6.12

6.424

6

6.45

6.39

5.5 5 4.5 4 April

May

June

July

August

September

2012

Fig. 200. pH in rainwater (roof collection) in 2012, at Dolaigaon, Assam.

Irongmara EC (µS cm -1)

60 50 40

40.7

27.3 33.45

30 20

31.25

31.05

28.75 21.4

20.91

10 0

2012

Fig. 201. Electrical Conductivity in rainwater (roof collection) in 2012, at Irongmara, Cachar, Assam.

281

Chapter 4 Results

Bongaigaon 60 EC (µS cm -1)

50 37.2

40

27.5

27.3

30

26.5

20

28.9

24.3

10 0 April

May

June

July

August

September

2012

Fig. 202. Electrical Conductivity in rainwater (roof collection) in 2012, at Bongaigaon, Assam.

Dolaigaon 70 EC (µS cm -1)

60

46.7

50

39.9

40

36.9

33.8

30

39.2

24.2

20 10 0 April

May

June

July

August

September

2012

Fig. 203. Electrical Conductivity in rainwater (roof collection) in 2012, at Dolaigaon, Assam.

282

Chapter 4 Results

Lead (mg L-1)

Irongmara 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0

0.02 0.0104

0.0035

0.0065

0.0021

0.0053 0.0043

March

April

May

June

July

August

September

2012

Fig. 204. Concentration of Lead (Pb) in rainwater (roof collection) in 2012, at Irongmara, Cachar, Assam.

Cadmium (mg L-1)

Irongmara 0.018 0.016 0.014 0.012 0.01 0.008 0.006 0.004 0.002 0

0.0064

0.009

0.003

April

May

0.0028

0.0015

ND March

0.0035

June

July

August

September

2012

Fig. 205. Concentration of Cadmium (Cd) in rainwater (roof collection) in 2012, at Irongmara, Cachar, Assam.

283

Chapter 4 Results

Irongmara Nickel (mg L-1)

0.03 0.025 0.02 0.015

0.0134

0.01 0.002

0.005

0.0081

0.0031

0.0017

0.003

0.0027

0 March

April

May

June

July

August

September

2012

Fig. 206. Concentration of Nickel (Ni) in rainwater (roof collection) in 2012, at Irongmara, Cachar, Assam.

Irongmara 0.5 Zinc (mg L-1)

0.376 0.4 0.3 0.2

0.224

0.257

0.22 0.164

0.1645

0.161

0.1 0 March

April

May

June

July

August

September

2012

Fig. 207. Concentration of Zinc (Zn) in rainwater (roof collection) in 2012, at Irongmara, Cachar, Assam.

284

Chapter 4 Results

Irongmara Chromium (mg L-1)

0.06 0.05 0.04

0.03

0.03 0.02 0.01

0.004

0.0014

0.005

0.008

0.0039

0.0015

0 March

April

May

June

July

August

September

2012

Fig. 208. Concentration of Chromium (Cr) in rainwater (roof collection) in 2012, at Irongmara, Cachar, Assam.

Irongmara Cobalt (mg L-1)

0.02 0.015 0.012 0.01

0.0095 0.0029

0.007 0.0038

0.005

0.0026

0.0015

0 March

April

May

June

July

August

September

2012

Fig. 209. Concentration of Cobalt (Co) in rainwater (roof collection) in 2012, at Irongmara, Cachar, Assam.

285

Chapter 4 Results

Bongaigaon Lead (mg L-1)

0.025 0.02 0.015 0.01

0.011 0.0028

0.005

0.0024

0.0057 0.0029

0.0019

0 April

May

June

July

August

September

2012

Fig. 210. Concentration of Lead (Pb) in rainwater (roof collection) in 2012, at Bongaigaon, Assam.

Bongaigaon Cadmium (mg L-1)

0.01 0.008 0.006 0.004

0.0043 0.0046

0.0046

0.0017

0.0036

0.0034

0.002 0 April

May

June

July

August

September

2012

Fig. 211. Concentration of Cadmium (Cd) in rainwater (roof collection) in 2012, at Bongaigaon, Assam.

286

Chapter 4 Results

Bongaigaon Nickel (mg L-1)

0.01 0.008 0.0045

0.006

0.005

0.0036

0.004

0.0042

0.0035

0.002 0

ND April

May

June

July

August

September

2012

Fig. 212. Concentration of Nickel (Ni) in rainwater (roof collection) in 2012, at Bongaigaon, Assam.

Bongaigaon Zinc (mg L-1)

0.5 0.4 0.344

0.269

0.3

0.295

0.24

0.287

0.2 0.117

0.1 0 April

May

June

July

August

September

2012

Fig. 213. Concentration of Zinc (Zn) in rainwater (roof collection) in 2012, at Bongaigaon, Assam.

287

Chapter 4 Results

Bongaigaon Chromium (mg L-1)

0.012 0.01 0.008

0.0077

0.006

0.0037 0.0032

0.004

0.004

0.002

0.0014

0.001

0 April

May

June

July

August

September

2012

Fig. 214. Concentration of Chromium (Cr) in rainwater (roof collection) in 2012, at Bongaigaon, Assam.

Cobalt (mg L-1)

Bongaigaon 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.0046

0.0056

0.0041 0.0032 0.0025 0.0014 April

May

June

July

August

September

2012

Fig. 215. Concentration of Cobalt (Co) in rainwater (roof collection) in 2012, at Bongaigaon, Assam.

288

Chapter 4 Results

Lead (mg L-1)

Dolaigaon 0.009 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.008

0.0044

0.0054 0.0038

0.0033 ND

April

May

June

July

August

September

2012

Fig. 216. Concentration of Lead (Pb) in rainwater (roof collection) in 2012, at Dolaigaon, Assam.

Cadmium (mg L-1)

Dolaigaon 0.009 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.0056

0.003

0.0049

0.0034

0.0019 0.0022

April

May

June

July

August

September

2012

Fig. 217. Concentration of Cadmium (Cd) in rainwater (roof collection) in 2012, at Dolaigaon, Assam.

289

Chapter 4 Results

Dolaigaon Nickel (mg L-1)

0.01 0.008 0.006

0.00455

0.0049

0.004 0.0029

0.0029

0.002 0.00045

0 April

May

ND June

July

August

September

2012

Fig. 218. Concentration of Nickel (Ni) in rainwater (roof collection) in 2012, at Dolaigaon, Assam.

Zinc (mg L-1)

Dolaigaon 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0

0.259 0.291

0.241

0.247

0.262 0.194

April

May

June

July

August

September

2012

Fig. 219. Concentration of Zinc (Zn) in rainwater (roof collection) in 2012, at Dolaigaon, Assam.

290

Chapter 4 Results

Dolaigaon Chromium (mg L-1)

0.14 0.12 0.1 0.08

0.055

0.06 0.04 0.0054

0.02

ND

0.005

0 April

May

June

July

0.0068 August

0.0018

September

2012

Fig. 220. Concentration of Chromium (Cr) in rainwater (roof collection) in 2012, at Dolaigaon, Assam.

Dolaigaon Cobalt (mg L-1)

0.007 0.0064

0.006 0.005 0.0041

0.004

0.004

0.0044

0.0018

0.003 0.002

0.0017

0.001 0 April

May

June

July

August

September

2012

Fig. 221. Concentration of Cobalt (Co) in rainwater (roof collection) in 2012, at Dolaigaon, Assam.

291

Chapter 4 Results 2012 Table 58 Descriptive statistics for pH (Roof Collection) in Rainwater at different geographical locations during 2012

Site

Mean

Median

S.D.

Min

Max

Irongmara

6.228

6.184

0.38

5.681

6.882

Bongaigaon

6.183

6.135

0.39

5.582

6.937

Dolaigoon

6.362

6.436

0.37

5.681

6.913

Table

59

Descriptive

statistics

for Electrical

Conductivity

(Roof

Collection) in Rainwater at different geographical locations during 2012 Site

Mean

Median

S.D.

Min

Max

Irongmara

30.7

8.5

14.42

57.8

Bongaigaon

29.79 (µS cm-1) 28.63

25.7

10.52

13.68

52.7

Dolaigoon

36.64

33.2

13.31

20.9

69.5

Table

60Descriptive

statistics

for

Heavy

Metal

Concentration

in

Rainwater (Roof Collection) at different geographical locations during 2012

Heavy

Site

Mean

Median

S.D.

Min

Max

Metals Pb

Irongmara

0.00704

0.0041

0.009

ND

0.035

Bongaigaon

0.00466

0.0037

0.0051

ND

0.021

Dolaigaon

0.0043

0.0044

0.0025

ND

0.008

Irongmara

0.0043

0.0031

0.0043

ND

0.014

Bongaigaon

0.0036

0.0036

0.0027

ND

0.0072

Dolaigaon

0.0032

0.0037

0.00217

ND

0.0071

Irongmara

0.0047

0.003

0.0052

ND

0.024

Bongaigaon

0.0035

0.003

0.00265

ND

0.008

Dolaigaon

0.00282

0.0026

0.00252

ND

0.008

Irongmara

0.2226

0.217

0.099

0.086

0.425

Bongaigaon

0.2636

0.276

0.101

0.108

0.415

(mg L1

) Cd

Ni

Zn

292

Chapter 4 Results

Cr

Co

Dolaigaon

0.2433

0.256

0.0645

0.156

0.362

Irongmara

0.00742

0.0036

0.0112

ND

0.045

Bongaigaon

0.0038

0.0034

0.0028

ND

0.0091

Dolaigaon

0.0115

0.0041

0.0269

ND

0.108

Irongmara

0.0052

0.0045

0.0046

ND

0.016

Bongaigaon

0.00362

0.004

0.0022

ND

0.0072

Dolaigaon

0.0038

0.0037

0.00254

ND

0.0081

ND not detected

Table 61 Results of one way analysis of variance (ANOVA) for Electrical

Conductivity

(EC)

of

rainwater

along

with

multiple

comparisons using Tukey test among the sites during 2012 F

Significance

4.682

P=0.012

Summary of Multiple Comparisons using Tukey test

Range of Significance

Dolaigaon > Irongmara, Bongaigaon

P=0.014 - 0.038

293

Chapter 4 Results 3. Rainwater quality in different study sites in 2013 a) pH i) Mean pH at the different study sites The pH of rainwater (roof collection) at the different sites in 2013 is shown in Table 62. It can be observed from the Table that the highest mean pH of rainwater (roof collection) was recordedat Bongaigaon, while the lowest is at Irongmara. The highest individual pH was also recorded at Bongaigaon on 15-04-2013, whereas the lowest individual pH is detected at Dolaigaon on 10-09-2013. The mean pH values in 2013 at the different sites are found to be in the following descending order: Bongaigaon (BNG) >Dolaigaon (DLG) > Irongmara (IM).

ii) Monthly fluctuations inpH The mean monthly pH values at the different sites in 2013 are shown in Figures 222-224. In Irongmara, the pH ranged between 5.94 in July and 6.19 in April (Fig. 222). In Bongaigaon, the pH ranged between 6.03 in June and 6.45 in April (Fig. 223).In Dolaigaon, the pH ranged between 5.96 in June and 6.25 in October (Fig. 224).

b) Electrical Conductivity (EC) i) Mean ECat the different study sites The conductivity of rainwater (roof collection) at the different sites in 2013 is shown in Table 63. It can be observed from the Table that the highest mean conductivity of rainwater (roof collection) was recorded at Irongmara, while the lowest is at Dolaigaon. On the other hand, both the highest and 294

Chapter 4 Results the lowest individual conductivity was recorded at Irongmara on 12-04-2013 and 25-07-2013 respectively. The mean conductivity values in 2013 at the different sites are found to be in the following descending order: Irongmara (IM) > Bongaigaon (BNG)> Dolaigaon (DLG).

ii) Monthly fluctuations inconductivity (EC)

The mean monthly conductivity values at the different sites in 2013 are shown in Figures 225-227. In Irongmara, the conductivity ranged between 19.62 µS cm-1 in July and 41.38 µS cm-1 in June (Fig. 225). In Bongaigaon, the conductivity ranged between 24.73 µS cm-1 in October and 34.64 µS cm1

in June (Fig. 226). In Dolaigaon, the conductivity ranged between 23.83 µS

cm-1 in October and 33.15 µS cm-1 in May (Fig. 227).

c) Heavy Metals i) Mean Heavy Metals at the different study sites The heavy metals of rainwater (roof collection) at the different sites in 2013 is shown in Table 64. It can be observed from the Table that the highest mean Lead (Pb) in rainwater (roof collection) wasrecordedat Irongmara, while the lowest is at Dolaigaon. The highest individual Pb was also recorded at Irongmara on 12-04-2013. The mean Pb values in 2013 at the different sites are found to be in the following descending order: Irongmara (IM) > Bongaigaon (BNG) > Dolaigaon (DLG).

Highest

mean

Cadmium

(Cd)in

rainwater (roof collection) was recorded at Bongaigaon, while the lowest is at Dolaigaon. The highest individual Cd was also recorded at Bongaigaonon 295

Chapter 4 Results 18-10-2013. The mean Cd values in 2013 at the different sites are found to be

in

the

following

descending

order:

Bongaigaon >Irongmara (IM)

>Dolaigaon (DLG). Highest mean Zinc (Zn)in rainwater (roof collection) was recordedat Bongaigaon, while the lowest is at Irongmara. On the other hand, both the highest and the lowest individual Zn was also recorded at Bongaigaon and Irongmara on 21-10-2013 and 17-09-2013 respectively. The mean Zn values in 2013 at the different sites are found to be in the following

descending

order:

Bongaigaon (BNG)

> Dolaigaon (DLG) >

Irongmara (IM). Highest mean Chromium (Cr) in rainwater (roof collection) was recordedat Irongmara, while the lowest is at Bongaigaon. The highest individual Cr was also recorded at Irongmara on 22-08-2013. The mean Cr values in 2013 at the different sites are found to be in the following descending order: Irongmara (IM) >Dolaigaon (DLG) > Bongaigaon (BNG).

ii) Monthly fluctuations inHeavy Metals The mean monthly heavy metals values at the different sites in 2013 are shown in Figures 228-239. Irongmara: The Lead (Pb) concentration ranged between 0.0005 mg L-1 in May and 0.066 mg L-1 in April (Fig. 228). Cadmium (Cd) concentration ranged between 0.0014 mg L-1 in August and 0.0069 mg L-1 in April, while the concentration in May is Below Detection Level (Fig. 229). Zinc (Zn) concentration ranged between 0.167 mg L-1 in September and 0.292 mg L-1 in June (Fig. 230). Chromium (Cr) concentration ranged between 0.0021 mg L-1 in May and 0.0285 mg L-1 in August (Fig. 231).

296

Chapter 4 Results Bongaigaon: The Lead (Pb) concentration ranged between 0.0024 mg L-1 in July and 0.028 mg L-1 in April (Fig. 232). Cadmium (Cd) concentration ranged between 0.0012 mg L-1 in September and 0.0179 mg L-1 in October (Fig. 233). Zinc (Zn) concentration ranged between 0.193 mg L-1 in July and 0.382 mg L-1 in October (Fig. 234). Chromium (Cr) concentration ranged between 0.0014 mg L-1 in August and 0.0046 mg L-1 in April (Fig. 235). Dolaigaon: The Lead (Pb) concentration ranged between 0.0013 mg L-1 in October and 0.0052 mg L-1 in April (Fig. 236). Cadmium (Cd) concentration ranged between 0.0011 mg L-1 in July and 0.0046 mg L-1 in August (Fig. 237). Zinc (Zn) concentration ranged between 0.164 mg L-1 in May and 0.395 mg L-1 in September (Fig. 238). Chromium (Cr) concentration ranged between 0.0011mg L-1 in June and 0.0058mg L-1 in May, while the concentration in August is Below Detection Level (Fig. 239).

297

Chapter 4 Results 2013

Irongmara 7 6.19

6.5

6.09

6.114

6.045

pH

6 6.014

5.5

5.94

5.943

5 4.5 4 April

May

June

July

August

September

October

2013

Fig. 222. pH in rainwater (roof collection) in 2013, at Irongmara, Cachar, Assam.

Bongaigaon 7 6.45

6.5

6.28

6.03

6.19

pH

6

6.26

5.5

6.15

6.09

5 4.5 4 April

May

June

July

August

September

October

2013

Fig. 223. pH in rainwater (roof collection) in 2013, at Bongaigaon, Assam.

298

Chapter 4 Results

Dolaigaon 7 6.14

6.5

6.168

5.96

6.25

pH

6

5.98 6.153

6.02

5.5 5 4.5 4 April

May

June

July

August

September

October

2013

Fig. 224. pH in rainwater (roof collection) in 2013, at Dolaigaon, Assam.

Irongmara 60 EC (µS cm -1)

50 36.56

40

41.38 34.93

30

34.36

20

19.62

24.61

31.76

10 0 April

May

June

July

August

September

October

2013

Fig. 225. Electrical Conductivity in rainwater (roof collection) in 2013, at Irongmara, Cachar, Assam.

299

Chapter 4 Results

Bongaigaon 60 EC (µS cm -1)

50 34.64

33.18

40

33.96

30

32.96

31.74

20

24.73

32.16

10 0 April

May

June

July

August

September

October

2013

Fig. 226. Electrical Conductivity in rainwater (roof collection) in 2013, at Bongaigaon, Assam.

EC (µS cm -1)

Dolaigaon 50 45 40 35 30 25 20 15 10 5 0

32.3

30.68

30.56 33.15

April

May

June

30.18

July

August

24.84

September

23.83

October

2013

Fig. 227. Electrical Conductivity in rainwater (roof collection) in 2013, at Dolaigaon, Assam.

300

Chapter 4 Results

Irongmara 0.14 Lead (mg L-1)

0.12 0.1 0.08 0.06

0.066

0.04 0.0037

0.02

0.0005

0.0015

0 April

May

June

July

0.0035

August

0.0042

0.0047

September October

2013

Fig. 228. Concentration of Lead (Pb) in rainwater (roof collection) in 2013, at Irongmara, Cachar, Assam.

Irongmara Cadmium (mg L-1)

0.01 0.008 0.0069

0.0048

0.006

0.0055

0.004 0.0027

0.002

0.0023 0.0014

0

ND April

May

June

July

August

September October

2013

Fig. 229. Concentration of Cadmium (Cd) in rainwater (roof collection) in 2013, at Irongmara, Cachar, Assam.

301

Chapter 4 Results

Zinc (mg L-1)

Irongmara 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0

0.292 0.279 0.237

0.229

0.196

0.167 0.179

April

May

June

July

August

September October

2013

Fig. 230. Concentration of Zinc (Zn) in rainwater (roof collection) in 2013, at Irongmara, Cachar, Assam.

Irongmara Chromium (mg L-1)

0.03

0.0285

0.025 0.02 0.015 0.01

0.0109 0.0021

0.0042

0.0033

0.005

0.0056 0.0029

0 April

May

June

July

August

September October

2013

Fig. 231. Concentration of Chromium (Cr) in rainwater (roof collection) in 2013, at Irongmara, Cachar, Assam.

302

Chapter 4 Results

Lead (mg L-1)

Bongaigaon 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0

0.028 0.0032

0.0029

0.0045

0.0024

0.0048 0.0039

April

May

June

July

August

September October

2013

Fig. 232. Concentration of Lead (Pb) in rainwater (roof collection) in 2013, at Bongaigaon, Assam.

Cadmium (mg L-1)

Bongaigaon 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0

0.0012 0.0062

April

May

0.0023

June

0.0028

0.0018

July

0.0179

0.0045

August

September October

2013

Fig. 233. Concentration of Cadmium (Cd) in rainwater (roof collection) in 2013, at Bongaigaon, Assam.

303

Chapter 4 Results

Bongaigaon Zinc (mg L-1)

0.5 0.4

0.382 0.284

0.3

0.206

0.267

0.251

0.2

0.249

0.193

0.1 0 April

May

June

July

August

September

October

2013

Fig. 234. Concentration of Zinc (Zn) in rainwater (roof collection) in 2013, at Bongaigaon, Assam.

Bongaigaon Chromium (mg L-1)

0.006 0.005

0.0042 0.0046

0.004 0.003 0.002

0.0017

0.0019

0.0025

0.0014 0.0016

0.001 0 April

May

June

July

August

September October

2013

Fig. 235. Concentration of Chromium (Cr) in rainwater (roof collection) in 2013, at Bongaigaon, Assam.

304

Chapter 4 Results

Lead (mg L-1)

Dolaigaon 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.0052 0.0031

0.00495 0.0028

0.0037 0.00135

April

May

June

July

August

0.0013

September October

2013

Fig. 236. Concentration of Lead (Pb) in rainwater (roof collection) in 2013, at Dolaigaon, Assam.

Dolaigaon Cadmium (mg L-1)

0.012 0.01 0.008 0.006

0.0043

0.0046

0.0031

0.004 0.002

0.0016

0.004

0.0045

0.0011

0 April

May

June

July

August

September October

2013

Fig. 237. Concentration of Cadmium (Cd) in rainwater (roof collection) in 2013, at Dolaigaon, Assam.

305

Chapter 4 Results

Dolaigaon Zinc (mg L-1)

0.5 0.4

0.395

0.32 0.304 0.217

0.3

0.23

0.22

0.2

0.164

0.1 0 April

May

June

July

August

September

October

2013

Fig. 238. Concentration of Zinc (Zn) in rainwater (roof collection) in 2013, at Dolaigaon, Assam.

Chromium (mg L-1)

Dolaigaon 0.009 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0

0.0058

0.0041

0.0047 0.0039

0.0011

April

May

June

July

0.0042

ND August September October

2013

Fig. 239. Concentration of Chromium (Cr) in rainwater (roof collection) in 2013, at Dolaigaon, Assam.

306

Chapter 4 Results 2013 Table 62 Descriptive statistics for pH (Roof Collection) in Rainwater at different geographical locations during 2013

Site

Mean

Median

S.D.

Min

Max

Irongmara

6.025

6.06

0.24

5.64

6.63

Bongaigaon

6.21

6.238

0.35

5.658

6.725

Dolaigaon

6.07

6.03

0.26

5.61

6.63

Table

63

Descriptive

statistics

for Electrical

Conductivity

(Roof

Collection) in Rainwater at different geographical locations during 2013 Site

Mean

Median

S.D.

Min

Max

(µS cm-1) Irongmara

32.72

31.8

14.4

4.91

69.2

Bongaigaon

32.67

30.6

8.78

20.7

55.4

Dolaigaon

29.8

27.7

8.09

17.48

43.7

307

Chapter 4 Results Table

64Descriptive

statistics

for

Heavy

Metal

Concentration

in

Rainwater (Roof Collection) at different geographical locations during 2013

Heavy

Site

Mean

Median

S.D.

Min

Max

Irongmara

0.0157

0.0042

0.0333

ND

0.114

Bongaigaon

0.00852

0.0047

0.0188

ND

0.076

Dolaigaon

0.0029

0.003

0.0022

ND

0.0062

Irongmara

0.00362

0.003

0.0027

ND

0.008

Bongaigaon

0.0053

0.0036

0.0075

ND

0.031

Dolaigaon

0.0031

0.0032

0.0026

ND

0.008

Irongmara

0.229

0.224

0.0764

0.109

0.386

Bongaigaon

0.263

0.256

0.0725

0.158

0.436

Dolaigaon

0.2544

0.271

0.096

0.112

0.428

Irongmara

0.0084

0.0042

0.0142

ND

0.057

Bongaigaon

0.0027

0.0031

0.0019

ND

0.0054

Dolaigaon

0.0034

0.0036

0.0022

ND

0.0073

Metals Pb (mg L1

)

Cd

Zn

Cr

ND not detected

308

Chapter 4 Results 4. Rainwater quality in different study sites in 2011-2013 a) pH i) Mean pH at the different study sites The pH of rainwater (roof collection) at the different sites in 2011-2013 is shown in Figure 240. It can be observed from the Figure that the highest mean pH of rainwater (roof collection)

was recorded at Bongaigaon, while

the lowest is at Irongmara. The pH ranged between 6.21 in Irongmara and 6.32 in Bongaigaon. The mean pH values in 2011-2013 at the different sites are found to be in the following descending order: Bongaigaon (BNG) > Dolaigaon (DLG) > Irongmara (IM).

b) Electrical Conductivity (EC) i) Mean ECat the different study sites The conductivity of rainwater (roof collection) at the different sites in 20112013 is shown in Figure 241. It can be observed from the Figure that the highest mean conductivity of rainwater (roof collection) was recorded at Dolaigaon, while the lowest is at Irongmara. The conductivity ranged between 29.84 µS cm-1 in Irongmara and 34.4 µS cm-1 in Dolaigaon. The mean conductivity values in 2011-2013 at the different sites are found to be in the following descending order: Dolaigaon (DLG) > Bongaigaon (BNG) > Irongmara (IM).

309

Chapter 4 Results c) Heavy Metals i) Mean Heavy Metals at the different study sites The heavy metals of rainwater (roof collection) at the different sites in 20112013 is shown in Figures 242-245. The highest mean Lead (Pb)in rainwater (roof collection)

was recorded at Irongmara, while the lowest is at

Dolaigaon. The Lead (Pb) concentration ranged between 0.0034mg L-1 in Dolaigaon and 0.0104mg L-1 in Irongmara (Fig. 242). The highest mean Cadmium (Cd) in rainwater (roof collection) wasrecordedat Bongaigaon and the lowest is at Irongmara. The Cadmium (Cd) concentration ranged between 0.00324 mg L-1 in Irongmara and 0.0044 mg L-1 in Bongaigaon (Fig. 243). The highest mean Zinc (Zn)in rainwater (roof collection) was recordedat Irongmara, while the lowest is at Dolaigaon. The Zinc (Zn) concentration ranged between 0.2146 mg L-1 in Dolaigaon and 0.2652mg L-1in Irongmara (Fig. 244). The highest mean Chromium (Cr) in rainwater (roof collection) was recordedat Dolaigaon, while the lowest is at Bongaigaon. The Chromium (Cr) concentration ranged between 0.0044 mg L-1 in Bongaigaon and 0.0079 mg L-1 in Dolaigaon (Fig. 245).

e) Statistical Analysisof Data i) Comparisons of pH and EC among the years 2011-2013 Table

65-67

summarizes

the

results

of

one-way

analysis-of-variance

(ANOVA) in pH among the years 2011-2013. The differences are significant at p < 0.001. Multiple comparisons using Tukey test reveal that pH of Irongmara rainwater in 2011 was significantly more alkaline than that of 2013; pH of Dolaigaon rainwater in 2011 was significantly equivalent tothat 310

Chapter 4 Results in 2012; pH of Bongaigaon rainwater in 2011 was significantly more alkaline than those of 2012 and 2013. Table 68 summarizes the results of one-way analysis-of-variance (ANOVA) in EC among the years 2010-2013. The differences are significant at p < 0.001. Multiple comparisons using Tukey test reveal that EC of Bongaigaon rainwater in 2011 was significantly higher than that of 2012.

ii) Comparisons ofheavy metals among the years 2011-2013 Table

69-70

summarizes

(ANOVA) Zinc (Zn)

the

results

of

one-way

analysis-of-variance

among the years 2010-2013. The differences are

significant at p < 0.001. Multiple comparisons using Tukey test reveal that Zn concentration in Irongmara rainwater in 2011 was significantly higher than that in 2012 and 2013; Zn concentration in Dolaigaon rainwater in 2011 was significantly lower than that in 2012 and 2013.

311

Chapter 4 Results 2011-2013

7 6.21

6.32

6.26

6.5

pH

6 5.5 5 4.5 4 Irongmara

Bongaigaon

Dolaigaon

STUDY SITES

Fig. 240. pH in rainwater (roof collection) during 2011-2013.

45 40

29.84

33.2

34.4

EC (µS cm -1)

35 30 25 20 15 10 5 0 Irongmara

Bongaigaon

Dolaigaon

STUDY SITES

Fig. 241. Electrical Conductivity in rainwater (roof collection) during 2011-2013.

312

Chapter 4 Results

Concentration (mg L-1)

Lead (Pb) 0.016 0.014 0.012 0.01 0.008 0.006 0.004 0.002 0

0.0104 0.0066 0.0034

Irongmara

Dolaigaon

Bongaigaon

STUDY SITES

Fig. 242. Concentration of Lead (Pb) in rainwater (roof collection) during 20112013.

Cadmium (Cd) Concentration (mg L-1)

0.006 0.0044

0.005

0.0037 0.00324

0.004 0.003 0.002 0.001 0 Irongmara

Dolaigaon

Bongaigaon

STUDY SITES

Fig. 243. Concentration of Cadmium (Cd) in rainwater (roof collection) during 2011-2013.

313

Chapter 4 Results

Concentration (mg L-1)

Zinc (Zn) 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0

0.2652

Irongmara

0.2146

Dolaigaon

0.2577

Bongaigaon

STUDY SITES

Fig. 244. Concentration of Zinc (Zn) in rainwater (roof collection) during 20112013.

Concentration (mg L-1)

Chromium (Cr) 0.014 0.012 0.01

0.0079 0.0063

0.008

0.0044

0.006 0.004 0.002 0 Irongmara

Dolaigaon

Bongaigaon

STUDY SITES

Fig. 245. Concentration of Chromium (Cr) in rainwater (roof collection) during 2011-2013.

314

Chapter 4 Results 2011-2013 Table 65 Results of one way analysis of variance (ANOVA) for pH of rainwater of Irongmara along with multiple comparisons using Tukey test

among the years 2011 – 2013 F

Significance

7.185

P=0.001

Summary of Multiple Comparisons using Tukey test 2011 > 2013

Range of Significance P=0.001

Table 66 Results of one way analysis of variance (ANOVA) for pH of rainwater of Dolaigaon along with multiple comparisons using Tukey test

among the years 2011 – 2013 F

Significance

6.661

P=0.002

Summary of Multiple Comparisons using Tukey test

Range of Significance

2011 ~ 2012

P=0.005 - 0.011

315

Chapter 4 Results Table 67 Results of one way analysis of variance (ANOVA) for pH of rainwater of Bongaigaon along with multiple comparisons using Tukey test

among the years 2011 – 2013 F

Significance

11.258

P 2012, 2013

P=0.000

Table 68 Results of one way analysis of variance (ANOVA) for Electrical Conductivity (EC) of rainwater of Bongaigaon along with multiple comparisons using Tukey test

among the years 2011 – 2013

F

Significance

4.396

P=0.015

Summary of Multiple Comparisons using Tukey test

Range of Significance

2011 > 2012

P=0.011

316

Chapter 4 Results Table 69 Results of one way analysis of variance (ANOVA) for Zinc (Zn) of rainwater of Irongmara along with multiple comparisons using Tukey test

among the years 2011 – 2013 F

Significance

8.549

P=0.001

Summary of Multiple Comparisons using Tukey test

Range of Significance

2011 > 2012, 2013

P=0.002 - 0.003

Table 70 Results of one way analysis of variance (ANOVA) for Zinc (Zn) of rainwater of Dolaigaon along with multiple comparisons using Tukey test

among the years 2011 – 2013 F

Significance

7.370

P=0.002

Summary of Multiple Comparisons using Tukey test

Range of Significance

2011 < 2012, 2013

P=0.003 - 0.009

317

Chapter 4 Results C. Statistical Analysis of Data I. Correlations among heavy metals and physicochemical variables The Pearson correlation coefficient (r) values among the different heavy metals and other physicochemical variables in

rainwater

(direct

collection) of the

different study sites during 2011-2013 are presented inTable 71-77. Irongmara: Table 71 reveals that significant positivecorrelations included that between Zn and Pb; and between Co and Ni; negative correlations comprised that of Zn with Cd and Cr; and between pH and Pb. Badarpur: Table 72 reveals that significant positivecorrelations included that between Pb and Cr; negative correlations included that between pH and Cr. Bongaigaon: Table 73 reveals that significant positive correlations included that between Pb and Zn; NO3-and Cd. Dolaigaon: Table 74 reveals that significant positive correlations comprised that of Niwith pH andNO3-. BGR Township: Table 75 reveals

that

significant

positive correlations

comprised that of Niwith Pb, Cr and Co; between Co and Pb; and that of Cd with NO3- and Zn; negative correlations included that between pH and Cr. Kolkata: Table 76 reveals that significant negative correlations included that between Ni and Cr. Kharagpur:Table 77 reveals that significant positive correlations included that between Pb and NO3-; and Zn and EC.

The Pearson correlation coefficient (r) values among the different heavy metals and other physicochemical variables in rainwater (roof collection) of the different study sites during 2011-2013 at Irongmara is presented in Table 78. 318

Chapter 4 Results Irongmara: Table

78

reveals

that

at

Irongmara

significant

positive

correlations included that between pH and EC; Cd and Cr; and that of Ni with Zn. Bongaigaon:At

Bongaigaon

significant

positive correlations included that

between pH and Ni. Dolaigaon:At

Dolaigaon

significant

positive correlations comprised that of

Crwith EC.

II. Multivariate statistical analysis of rainwater variables 1. Principal component and factor analysis a) Direct Collection Irongmara: Four principal components (PCs) having eigenvalue greater than unity (>1) andanother four with eigenvalues ranging from 0.5-1.0 were selected. These eight PCs together accounted for 75.371 per cent of the total variance. The PCAloadings are summarized in Table 79. The highlightsare given below:

Principal Component 1 (PC1): This PC has an Eigenvalue of 1.927 and explains 21.408 per cent of the observed variance. It has major positive contributions from Pb and Zn with Cd, Cr and pH exerting strong negative influence.

Principal Component 2 (PC2): This PC has an Eigenvalue of 1.406 and explains 15.623 per cent of the observed variance. It has major positive contributions from Ni and pH, and negative influences from Pb.

Principal Component 3 (PC3): This PC has an Eigenvalue of 1.143 and explains 12.700 per cent of the observed variance. It has major positive contribution from EC. 319

Chapter 4 Results

Principal Component 4 (PC4): This PC has an Eigenvalue of 1.100 and explains 12.217 per cent of the observed variance. It has major positive contributions from Cd and Co.

Principal Component 5 (PC5): This PC hasan Eigenvalue of 0.973 and explains 10.806 per cent of the observed variance. It has major positive contribution from NO3-. Principal Component 6 (PC6): This PC has an Eigenvalue of 0.797 and explains 8.859 per cent of the observed variance. It has major negative loading of Ni.

Principal Component 7 (PC7): This PC has anEigenvalueof 0.679 and explains 7.542 per cent of the observed variance.It has major positive contributions from Cr and Co.

Principal Component 8 (PC8): This PC has an Eigenvalue of 0.586 and explains 6.509 per cent of the observed variance. It has positive contribution from Zn.

The PCA-extracted datawere subjected to varimax rotation. The varimax-rotated distributions of the variable in the different PCs which are now called Varifactors (VFs) are shown in Table80.

Varifactor 1 (VF1): The major positive contribution to this VF is from pH, with a strong negative influence of Pb. Varifactor 2 (VF2):The major positive contribution to this VF is from EC. Varifactor 3 (VF3): Cd is the major positive contributor to this VF. Varifactor 4 (VF4): The majorpositive contribution to this VF is from Co. Varifactor 5 (VF5): The major positive contribution to this VFis from Zn. 320

Chapter 4 Results

Varifactor 6 (VF6): Cr is the major contributors to this VF. Varifactor 7 (VF7): The major positive contribution to this VF is from Ni. Varifactor 8 (VF8): Nitrate has major positive loading in this VF.

Badarpur: Three principal components (PCs) having eigenvalue greater than unity (>1) andanother onewith eigenvalue ranging from 0.5 were selected. These four PCs together accounted for 69.021 per cent of the total variance. The PCAloadings are summarized in Table 81. The highlightsare given below: Principal Component 1 (PC1): This PC has an Eigenvalue of 1.870 and explains 31.166 per cent of the observed variance. It has major positive contributions from Pb and Cr and pH exerting strong negative influence.

Principal Component 2 (PC2): This PC has an Eigenvalue of1.342 and explains 22.361 per cent of the observed variance. It hasmajor positive contributions from EC and NO3-. Principal Component 3 (PC3): This PC has an Eigenvalue of 1.182 and explains 19.706 per cent of the observed variance. It has major positive contribution from Zn with EC exerting negative influence.

Principal Component 4 (PC4): This PC has an Eigenvalue of 0.753 and explains 12.543 per cent of the observed variance. It has major positive contribution from pH and EC.

The PCA-extracted data were subjected to varimax rotation. The varimax-rotated distributions of the variable in the different PCs which are now called Varifactors (VFs) are shown in Table82. 321

Chapter 4 Results

Varifactor 1 (VF1): The major positive contribution to this VF is from Pb and Cr. Varifactor 2 (VF2): The major positive contribution to this VF is fromNO3- with a strong negative influence of pH. Varifactor 3 (VF3): The major positive contribution to this VF is from EC. Varifactor 4 (VF4): The major positive contribution to this VF is fromZn.

Bongaigaon: Four principal components (PCs) having eigenvalue greater than unity (>1) andanother four with eigenvalues ranging from 0.5-1.0 were selected. These eight PCs together accounted for 75.232 per cent of the total variance. The PCAloadings are summarized in Table 83. The highlightsare given below: Principal Component 1 (PC1): This PC has an Eigenvalue of 1.790 and explains 19.888 per cent of the observed variance. It has major positive contributions from Cd, Ni and CowithPb, Zn and EC exerting strong negative influence.

Principal Component 2 (PC2): This PC has an Eigenvalue of 1.394 and explains 15.490 per cent of the observed variance. It has major positive contributions from Pb, Cd and NO3-. Principal Component 3 (PC3): This PC has an Eigenvalue of 1.186 and explains13.174 per cent of the observed variance. It has major positive contribution from Cd and EC with Cr exerting negative influence.

Principal Component 4 (PC4): This PC has an Eigenvalue of 1.014 and explains 11.265 per cent of the observed variance. It has major negative contributions from pH.

322

Chapter 4 Results

Principal Component 5 (PC5): This PC has an Eigenvalue of 0.948 and explains 10.535 per cent of the observed variance. It has major positive contribution from Pb and Ni.

Principal Component 6 (PC6): This PC has an Eigenvalue of 0.863 and explains 9.585 per cent of the observed variance. It has major positive contribution from Ni with Co exerting negative influence.

Principal Component 7 (PC7): This PC has an Eigenvalue of 0.769 and explains 8.550 per cent of the observed variance.It has major negative contributions from EC and Cd.

Principal Component 8 (PC8): This PC has an Eigenvalue of 0.609 and explains 6.769 per cent of theobserved variance.It has major positive contribution from Co and negative contributions from Cr.

The PCA-extracted data were subjectedto varimax rotation. The varimax-rotated distributions of the variable in the different PCs which are now called Varifactors (VFs) are shown in Table84.

Varifactor 1 (VF1): The major positive contribution to this VF is from Cd and Zn. Varifactor 2 (VF2): The major positive contribution to this VF is from EC. Varifactor 3 (VF3): The major positive contribution to this VF is from NO3- and Zn. Varifactor 4 (VF4): The major positive contribution to this VF is from Pb. Varifactor 5 (VF5): The major positive contribution to this VF is from Co. 323

Chapter 4 Results Varifactor 6 (VF6): pH is the major contributor to this VF. Varifactor 7 (VF7): The major positive contribution to this VF is from Cr. Varifactor 8 (VF8): Ni has major positive loading in this VF.

Dolaigaon: Four principal components (PCs) having eigenvalue greater than unity (>1) and another four with eigenvalues ranging from 0.5-1.0 were selected. These eight PCs together accounted for 73.426 per cent of the total variance. The PCA loadings are summarized in Table 85. The highlights are given below: Principal Component 1 (PC1): This PC has an Eigenvalue of 1.790 and explains 19.888 per cent of the observed variance. It has major positive contributions from Ni, pH and NO3- with Zn exerting negative influence. Principal Component 2 (PC2): This PC has an Eigenvalue of 1.420 and explains 15.779 per cent of the observed variance. It has major positive contributions from Cr and Co.

Principal Component 3 (PC3): This PC has an Eigenvalue of 1.156 and explains 12.846 per cent of the observed variance. It has major positive contribution from Zn withEC exerting strong negative influence.

Principal Component 4 (PC4): This PC has an Eigenvalue of 1.064 and explains 11.825 per cent of the observed variance. It has major positive contributions from Zn and negative influence from Cr.

Principal Component 5 (PC5): This PC has an Eigenvalue of 0.988 and explains 10.979 per cent of the observed variance. It has major positive contribution from Ni and negative influence from Pb.

324

Chapter 4 Results Principal Component 6 (PC6): This PC has an Eigenvalue of 0.793 and explains 8.815 per cent of the observed variance. It has major positive contribution from Pb.

Principal Component 7 (PC7): This PC has an Eigenvalueof 0.702 and explains 7.802 per cent of the observed variance.It has major negative contributions from pH.

Principal Component 8 (PC8): This PC has an Eigenvalue of 0.615 and explains 6.836 per cent of the observed variance. It has major positive contribution from Cd and negative contributions from Co.

The PCA-extracted data were subjected to varimax rotation. The varimax-rotated distributions of the variable in the different PCs which are now called Varifactors (VFs) are shown in Table 86.

Varifactor 1 (VF1): The major positive contribution to this VF is from Ni and NO3-. Varifactor 2 (VF2): The major positive contribution to this VF is from Co. Varifactor 3 (VF3): The major positive contribution to this VF is from Cr. Varifactor 4 (VF4): The major positive contribution to this VF is from pH. Varifactor 5 (VF5): The major positive contribution to this VF is from Pb. Varifactor 6 (VF6): Zn is the major contributors to this VF. Varifactor 7 (VF7): The major positive contribution to this VF is from Cd. Varifactor 8 (VF8): EC has major positive loading in this VF.

325

Chapter 4 Results BGR Township: Three principal components (PCs) having eigenvalue greater than unity (>1) and another four with eigenvalues ranging from 0.5-1.0 were selected. These seven PCs together accounted for 70.04 per cent of the total variance. The PCA loadings are summarized in Table 87. The highlightsare given below: Principal Component 1 (PC1): This PC has an Eigenvalue of 1.964 and explains 21.826 per cent of the observed variance. It has major positive contributions from Pb, Ni, Cr and Co with Zn exerting negative influence.

Principal Component 2 (PC2): This PC has an Eigenvalue of 1.645 and explains 18.274 per cent of the observed variance. It has major positive contributions from Cd, Zn, pH and NO3-. Principal Component 3 (PC3): This PC has an Eigenvalue of 1.261 and explains 14.010 per cent of the observed variance. It has major positive contribution from Cd, Cr and EC with pH exerting negative influence.

Principal Component 4 (PC4): This PC has an Eigenvalue of 0.976 and explains 10.846 per cent of the observed variance. It has major positive contribution from Pb. Principal Component 5 (PC5): This PC has an Eigenvalue of 0.960 and explains 10.670 per cent of the observed variance. It has major positive contribution from EC and major negative contributions from Cr.

Principal Component 6 (PC6): This PC has an Eigenvalue of 0.729 and explains 8.101 per cent of the observed variance. It has major positive contribution from Cd withNO3- exerting negative influence. 326

Chapter 4 Results

Principal Component 7 (PC7): This PC has an Eigenvalue of 0.660 and explains 7.332 per cent of the observed variance. It has major positivecontributions from Zn with Cd and NO3-and Zn exerting negative influence.

The PCA-extracted data were subjected to varimax rotation. The varimax-rotated distributions of the variable in the different PCs which are now called Varifactors (VFs) are shown in Table88.

Varifactor 1 (VF1): The major positive contribution to this VF is from Co and Ni. Varifactor 2 (VF2): The major positive contribution to this VF is from Cr with a strong negative influence of pH. Varifactor 3 (VF3): The major positive contribution to this VF is from NO3- and Ni. Varifactor 4 (VF4): The major positive contribution to this VF is from Pb. Varifactor 5 (VF5): The major positive contribution to this VFis fromCd. Varifactor 6 (VF6): EC is the major contributors to this VF. Varifactor 7 (VF7): The major positive contribution to this VF is from Zn.

Kolkata: Three principal components (PCs) having eigenvalue greater than unity (>1) andanother four with eigenvalues ranging from 0.5-1.0 were selected. These seven PCs together accounted for 71.945 per cent of the total variance. The PCA loadings are summarized in Table 89. The highlights are given below:

Principal Component 1 (PC1): This PC has an Eigenvalue of 1.662 and explains 20.777 per cent of the observed variance. It has major positive contributions from Pb and Ni with Cr exerting strong negative influence. 327

Chapter 4 Results

Principal Component 2 (PC2): This PC has an Eigenvalue of 1.355 and explains 16.942 per cent of the observed variance. It has major positive contributions from Zn, pH and NO3-, and negative influences from Cd. Principal Component 3 (PC3): This PC has an Eigenvalue of 1.219 and explains 15.233 per cent of the observed variance. It has major positive contribution from EC with Cd exerting strong negative influence.

Principal Component 4 (PC4): This PC has an Eigenvalue of 0.951 and explains 11.890 per cent of the observed variance. It has major positive contributions from Pb and Cr with EC exerting strong negative influence.

Principal Component 5 (PC5): This PC has an Eigenvalue of 0.851and explains 10.641 per cent of the observed variance. It has major positive contribution from Zn, Cd and EC.

Principal Component 6 (PC6): This PC has an Eigenvalue of 0.821 and explains 10.266 per cent of the observed variance. It has major positive contribution from NO3- and has major negative loading of pH. Principal Component 7 (PC7): This PC has an Eigenvalue of 0.736 and explains 9.202 per cent of the observed variance. It has major positive contributions from Cd and pH.

The PCA-extracted data were subjected to varimax rotation. The varimax-rotated distributions of the variable in the different PCs which are now called Varifactors (VFs) are shown in Table90. 328

Chapter 4 Results

Varifactor 1 (VF1): The major positive contribution to this VF is from Cr, with a strong negative influence of Ni. Varifactor 2 (VF2): The major positive contribution to this VF is fromPb. Varifactor 3 (VF3): Znis the major positive contributor to this VF. Varifactor 4 (VF4): The major positive contribution to this VF is fromNO3-. Varifactor 5 (VF5): The major positive contribution to this VF is fromCd. Varifactor 6 (VF6): EC is the major contributors to this VF. Varifactor 7 (VF7): The major positive contribution to this VF is from pH.

Kharagpur: Four principal components (PCs) having eigenvalue greater than unity (>1) and another four with eigenvalues ranging from 0.5-1.0 were selected. These eight PCs together accounted for 75.762 per cent of the total variance. The PCA loadings are summarized in Table 91. The highlightsare given below: Principal Component 1 (PC1): This PC has an Eigenvalue of 1.821 and explains 20.233 per cent of the observed variance. It has major positive contributions from Pb, Ni and NO3- with EC and Znexerting strong negative influence. Principal Component 2 (PC2): This PC has an Eigenvalue of 1.630 and explains 18.112 per cent of the observed variance. It has major positive contributions from pH, EC and NO3-, and strong negative influence from Co. Principal Component 3 (PC3): This PC has an Eigenvalue of 1.359 and explains15.102 per cent of the observed variance. It has major positive contribution from pH with Ni and Cr exerting strong negative influence.

329

Chapter 4 Results Principal Component 4 (PC4): This PC has an Eigenvalue of 1.030 and explains 11.439 per cent of the observed variance. It has major positive contributions from Cd.

Principal Component 5 (PC5): This PC has an Eigenvalue of 0.898 and explains 9.981 per cent of the observed variance. It has major positive contribution from Zn.

Principal Component 6 (PC6): This PC has an Eigenvalue of 0.733 and explains 8.144 per cent of the observed variance. It has major positive contribution from Cr and Co.

Principal Component 7 (PC7): This PC has an Eigenvalue of 0.577 and explains 6.416 per cent of the observed variance. It has major positive contributions from Pb and negative influence from NO3-. Principal Component 8 (PC8): This PC has an Eigenvalue of 0.562 and explains 6.247 per cent of the observed variance.It has major negative contributions from pH.

The PCA-extracted data were subjected to varimax rotation. The varimax-rotated distributions of the variable in the different PCs which are now called Varifactors (VFs) are shown in Table 92.

Varifactor 1 (VF1): The majorpositive contribution to this VF is from Cr. Varifactor 2 (VF2): The major positive contribution to this VF is fromZn. Varifactor 3 (VF3): The major positive contribution to this VF is from Ni, with a strong negative influence of EC. Varifactor 4 (VF4): The major positive contribution to this VF is from Co. 330

Chapter 4 Results Varifactor 5 (VF5): The major positive contribution to this VF is from pH. Varifactor 6 (VF6): NO3- is the major contributors to this VF. Varifactor 7 (VF7): The major positive contribution to this VF is from Cd. Varifactor 8 (VF8): Pb has major positive loading in this VF.

b)Roof Collection Irongmara: Four principal components (PCs) having eigenvalue greater than unity (>1) and another two with eigenvalues ranging from 0.5-1.0 were selected. These six PCs together accounted for 64.394 per cent of the total variance. The PCAloadings are summarized in Table 93. The highlights are given below:

Principal Component 1 (PC1): This PC has an Eigenvalue of 1.921 and explains 24.013 per cent of the observed variance. It has major positive contributions from Ni, Zn, Coand EC.

Principal Component 2 (PC2): This PC has an Eigenvalue of 1.459 and explains 18.238 per cent of the observed variance. It has major positive contributions from Pb, Cd and pH.

Principal Component 3 (PC3): This PC has an Eigenvalue of 1.257 and explains 15.715 per cent of the observed variance. It has major positive contribution from Cr.

Principal Component 4 (PC4): This PC has an Eigenvalue of 1.016 and explains 12.696 per cent of the observed variance. It has major positive contributions from Co with pH exerting negative influence.

331

Chapter 4 Results Principal Component 5 (PC5): This PC has an Eigenvalue of 0.859 and explains 10.738 per cent of the observed variance. It has major positive contribution from Cd with Pb exertingnegative influence.

Principal Component 6 (PC6): This PC has an Eigenvalue of 0.705 and explains 8.815 per cent of the observed variance. It has major positive loading of Zn.

The PCA-extracted data were subjected to varimax rotation. The varimax-rotated distributions of the variable in the different PCs which are now called Varifactors (VFs) are shown in Table94.

Varifactor 1 (VF1): The major positive contribution to this VF is from EC and Ni. Varifactor 2 (VF2): The major positive contribution to this VF is from Cr with a strong negative influence of pH. Varifactor 3 (VF3): Pbis the major positive contributor to this VF. Varifactor 4 (VF4): The major positive contribution to this VF is from Co. Varifactor 5 (VF5): The major positive contribution to this VF is from Cd. Varifactor 6 (VF6): Zn is the major contributors to this VF.

Bongaigaon: Three principal components (PCs) having eigenvalue greater than unity (>1) andanother four with eigenvalues ranging from 0.5-1.0 were selected. These seven PCs together accounted for 72.219 per cent of the total variance. The PCAloadings are summarized in Table 95. The highlightsare given below: Principal Component 1 (PC1): This PC has an Eigenvalue of 1.736 and explains 21.706 per cent of the observed variance. It has major positive contributions from Pb, Cr, Co and pH with Cd exerting negative influence.

332

Chapter 4 Results Principal Component 2 (PC2): This PC has an Eigenvalue of 1.500 and explains 18.753 per cent of the observed variance. It has major positive contributions from Ni and with Zn exerting negative influence.

Principal Component 3 (PC3): This PC has an Eigenvalue of 1.347 and explains 16.832 per cent of the observed variance. It has major positive contributions from Ni, Co, Cd with pH exerting negative influence.

Principal Component 4 (PC4): This PC hasan Eigenvalue of 0.917and explains11.457 per cent of the observed variance. It has major positive contributions from Pb and Cd.

Principal Component 5 (PC5): This PC hasan Eigenvalue of 0.882 and explains 11.023 per cent of the observed variance. It has major positive contribution from Cr and Cd.

Principal Component 6 (PC6): This PC has an Eigenvalue of 0.685 and explains 8.560 per cent of the observed variance. It has major positive contribution from EC.

Principal Component 7 (PC7): This PC has an Eigenvalue of 0.605 and explains 7.566 per cent of the observed variance. It has major positive contribution from pH.

The PCA-extracted data were subjected to varimax rotation. The varimax-rotated distributions of the variable in the different PCs which are now called Varifactors (VFs) are shown in Table 96. 333

Chapter 4 Results

Varifactor 1 (VF1): The major positive contribution to this VF is from Ni and Co. Varifactor 2 (VF2): The major positive contribution to this VF is from EC. Varifactor 3 (VF3): The major positive contribution to this VF is from Pb. Varifactor 4 (VF4): The major positive contribution to this VF is from Cr. Varifactor 5 (VF5): The major positive contribution to this VF is from Zn. Varifactor 6 (VF6): pH is the major contributor to this VF. Varifactor 7 (VF7): The major positive contribution to this VF is from Cd.

Dolaigaon: Four principal components (PCs) having eigenvalue greater than unity (>1) and another three with eigenvalues ranging from 0.5-1.0 were selected. These seven PCs together accounted for 70.041 per cent of the total variance. The PCA loadings are summarized in Table 97. The highlightsare given below: Principal Component 1 (PC1): This PC has an Eigenvalue of 1.699 and explains 21.238 per cent of the observed variance. It has major positive contributions from Ni, Zn and Cr with Cd exerting negative influence.

Principal Component 2 (PC2): This PC has an Eigenvalue of 1.396 and explains17.445 per cent of the observed variance. It has major positive contributions from Pb and EC with pH exerting strong negative influence.

Principal Component 3 (PC3): This PC has an Eigenvalue of 1.230 and explains 15.373 per cent of the observed variance. It has major positive contributions from pH and Co.

334

Chapter 4 Results Principal Component 4 (PC4): This PC has an Eigenvalue of 1.121and explains 14.014 per cent of the observed variance. It has major negative contributions from Zn and Pb.

Principal Component 5 (PC5): This PC hasan Eigenvalue of 0.748 and explains 9.352 per cent of the observed variance. It has major positive contributions from Ni and Cd.

Principal Component 6 (PC6): This PC has an Eigenvalue of 0.720 and explains 9.003 per cent of the observed variance. It has major positive contribution from Zn and negative contribution from Ni.

Principal Component 7 (PC7): This PC has an Eigenvalue of 0.563 and explains 7.041 per cent of the observed variance.It has major positive contribution from Cr.

The PCA-extracted data were subjected to varimax rotation. The varimax-rotated distributions of the variable in the different PCs which are now called Varifactors (VFs) are shown in Table98.

Varifactor 1 (VF1): The major positive contribution to this VF is from ECwith a strong negative influence of pH. Varifactor 2 (VF2): The major positive contribution to this VF is from Pb. Varifactor 3 (VF3): The major positive contribution to this VF is from Zn. Varifactor 4 (VF4): The major positive contribution to this VF is from Co. Varifactor 5 (VF5): The major positive contribution to this VF is fromNi. Varifactor 6 (VF6): Cr is the major contributors to this VF. Varifactor 7 (VF7): The major positive contribution to this VF is from Cd

335

Chapter 4 Results 2. Cluster analysis Table 99 reveals that the agglomeration schedule of cluster analysis divided the sites into three major clusters. Cluster I contains three suburban areas Irongmara, Dolaigaon, Badarpur; cluster II contains one urban area Kolkata; and cluster III contains three industrialized areas Kharagpur, Bongaigaon, BGR Township. D. Comparison of Rainwater Quality (Direct

and Roof Collection) with

Indian Standard Specifications For Drinking Water IS: 10500

Table

100-101

shows

the

comparison

of

rainwater

(direct

and

roof

collection) with Indian drinking water quality values which indicates a few departures for parameters like pH

and Cd. It is observed that the mean

concentration of all the heavy metals studied in case of direct collection are generally within the acceptable limits for drinking water by Indian Standard Specifications for drinking water IS: 10500 with only exception in case of pH and Cd which are below and above their permissible limits. Galvanized iron roof sample recorded concentrations of EC, Pb, Ni, Zn, Cr and Co within

the

acceptable

limits

for

drinking

water

by

Indian

Standard

Specifications for drinking water IS: 10500 while the levels of pH and Cd were below and above their permissible limits.

336

Chapter 4 Results Statistical Analysis of Data Direct Collection Table 71 Pearson correlation coefficient (r) for heavy metal and physicochemical variables in direct collection rainwater samples of Irongmara during 2011-2013 -

NO3 -

NO3

Pb

Cd

Ni

Cr

Co

pH

EC

-0.075

1

1

Pb

-0.140

1

Cd

0.053

-0.027

1

Ni

0.003

0.022

-0.079

Zn

Zn

0.012

0.232* -0.281* -0.105

1 0.132

1

0.227

-0.140

-0.242*

Cr

0.104

Co

-0.064

0.125

-0.010

0.275*

0.173

-0.189

pH

0.168

-0.491** 0.146

-0.009

-0.069

0.029

0.036

EC

0.107

-0.085

-0.152

-0.099

-0.106

0.045

0.100

1 1 1

* Correlation is significant at the 0.05 level (2-tailed), ** Correlation is significant at the 0.01 level (2-tailed)

Table 72 Pearson correlation coefficient (r) for heavy metal and physicochemical variables in direct collection rainwater samples of Badarpur during 2011-2013 -

NO3 -

NO3

Pb

Zn

Cr

pH

EC

1

Pb

-0.059

1

Zn

0.171

0.145

Cr

-0.043

0.483**

pH

-0.270

-0.316

-0.124

-0.442**

1

EC

0.299

-0.018

-0.090

0.151

-0.031

1 -0.151

1

** Correlation is significant at the 0.01 level (2-tailed)

337

1

Chapter 4 Results Table 73 Pearson correlation coefficient (r) for heavy metal and physicochemical variables in direct collection rainwater samples of Bongaigaon during 2011-2013 -

NO3 -

NO3

Pb

Cd

Ni

Zn

Cr

pH

EC

Co

1

Pb

0.015

1

Cd

0.344*

-0.032

1

Ni

-0.071

-0.102

0.093

Zn

0.124

0.313** -0.200

-0.149

Cr

0.070

-0.084

-0.028

0.174

-0.124

pH

0.034

-0.118

-0.121

0.006

-0.168

EC

-0.156

0.033

-0.089

-0.051

0.054

-0.059

-0.083

Co

0.183

0.027

0.183

0.131

-0.262

0.185

0.053

0.050

1 1 1 1 1 0.127

1

* Correlation is significant at the 0.05 level (2-tailed), ** Correlation is significant at the 0.01 level (2-tailed)

Table 74 Pearson correlation coefficient (r) for heavy metal and physicochemical variables in direct collection rainwater samples of Dolaigaon during 2011-2013 -

NO3 -

Pb

NO3

1

Pb

0.178

1

Cd

0.124

0.147

Ni

0.389** 0.091

Cd

Ni

Zn

Cr

pH

Co

1 0.106

1

Zn

-0.131

-0.121

-0.109

-0.054

1

Cr

-0.212

0.034

0.052

0.028

-0.089

pH

0.211

-0.072

0.299*

-0.101

-0.037

EC

0.029

-0.106

-0.047

-0.005

-0.147

-0.125

-0.083

Co

-0.085

0.077

0.222

0.167

0.065

0.151

-0.038

0.140

EC

1 1 1 -0.059

1

* Correlation is significant at the 0.05 level (2-tailed), ** Correlation is significant at the 0.01 level (2-tailed)

338

Chapter 4 Results Table 75 Pearson correlation coefficient (r) for heavy metal and physicochemical variables in direct collection rainwater samples of BGR Township during 2011-2013 -

NO3 -

Pb

Cd

Ni

Zn

Cr

Co

NO3

1

Pb

0.011

1

Cd

0.338*

0.079

1

Ni

0.200

0.330*

-0.049

1

Zn

0.129

-0.081

0.272*

-0.194

Cr

0.125

0.014

0.171

0.295*

-0.102

1

Co

0.098

0.284*

0.052

0.409**

-0.199

0.190

pH

0.217

-0.136

0.144

-0.099

0.076

-0.251*

0.133

EC

-0.143

-0.105

0.063

0.072

-0.042

-0.039

-0.168

pH

EC

-0.146

1

1

1 1

* Correlation is significant at the 0.05 level (2-tailed), ** Correlation is significant at the 0.01 level (2-tailed)

Table 76 Pearson correlation coefficient (r) for heavy metal and physicochemical variables in direct collection rainwater samples of Kolkata during 2011-2013 -

NO3 -

NO3 Pb

Pb

Cd

Ni

Zn

Cr

pH

EC

1 -0.131

1

Cd

-0.105

-0.056

1

Ni

-0.132

0.309

-0.046

1

Zn

0.160

-0.029

0.000

0.215

1

Cr

0.019

-0.070

-0.062

-0.459*

-0.008

1

0.082

-0.015

0.102

1

-0.161

0.144

0.127

pH

0.079

0.112

-0.228

EC

-0.057

0.124

0.205

0.015

* Correlation is significant at the 0.05 level (2-tailed)

339

1

Chapter 4 Results Table 77 Pearson correlation coefficient (r) for heavy metal and physicochemical variables in direct collection rainwater samples of Kharagpur during 2011-2013 -

NO3 -

NO3 Pb

Pb

Cd

Ni

Zn

Cr

pH

EC

Co

1 0.368*

Cd

1

0.162

0.008

1

Ni

0.152

0.240

-0.039

1

Zn

-0.044

-0.101

-0.015

-0.069

Cr

0.139

0.059

-0.055

0.259

pH

0.268

0.011

-0.197

EC

-0.107

-0.182

-0.104

-0.201 0.325*

Co

-0.075

0.103

0.007

0.269

1

0.014

-0.045

1

0.137

0.006

1

0.268

0.050

-0.191

-0.076

-0.092

1 -0.334

1

* Correlation is significant at the 0.05 level (2-tailed)

Roof Collection Table 78 Pearson correlation coefficient (r) for heavy metal and physicochemical

variables

in

roof

collection

rainwater

samples

of

Irongmara during 2011-2013

Pb

Cd

Ni

Zn

Cr

Co

Pb

1

Cd

-.193

Ni

0.076

0.034 1

Zn

-0.022

-0.014

0.427*

1

Cr

-0.155

0.400*

-0.005

0.129

1

Co

0.123

0.079

0.265

0.206

-0.170

1

pH

-0.020

-0.074

-0.263

-0.137

0.060

-0.073

EC

0.107

-0.146

0.171

0.085

-0.120

pH

EC

1

-0.108

1 .418*

1

* Correlation is significant at the 0.05 level (2-tailed), ** Correlation is significant at the 0.01 level (2-tailed)

340

Chapter 4 Results Multivariate Statistical Analysis of Rainwater Variables Direct Collection Table 79 Loadings of variables on eight significant PCs for 189 rainwater samples of Irongmara, Assam, India Variables

PC 1

PC 2

PC 3

PC 4

PC 5

PC 6

PC 7

PC 8

Pb

.613

-.522

.008

.215

.285

.187

-.145

-.158

Cd

-.480

-.144

.148

.646

.121

.317

-.361

.189

Ni

.373

.487

-.194

.405

.136

-.542

-.171

.260

Zn

.615

.235

-.044

-.301

.283

.427

.062

.444

Cr

-.522

-.304

-.391

.200

.335

-.043

.522

.212

Co

.414

.421

.254

.533

.006

.175

.428

-.277

pH

-.493

.679

-.104

-.035

-.146

.346

-.051

-.012

EC

-.151

-.089

.903

-.053

-.024

-.156

.151

.271

NO3-

-.305

.286

.193

-.232

.802

-.098

-.113

-.254

Eigen value

1.927

1.406

1.143

1.100

.973

.797

.679

.586

%Variance

21.408

15.623

12.700

12.217

10.806

8.859

7.542

6.509

%Cumulati ve Variance

21.408

37.031

49.731

61.948

72.754

81.613

89.155

95.664

341

Chapter 4 Results Table 80 Loadings of varimax rotated variables on eight significant PCs for 189 rainwater samples of Irongmara, Assam, India Variables

VF 1

VF 2

VF 3

VF 4

VF 5

VF 6

VF 7

VF 8

Pb

-.852

-.181

.135

.148

.192

-.122

-.080

-.014

Cd

.047

.068

.964

-.004

-.142

.119

-.019

.015

Ni

-.005

-.092

-.019

.144

.059

-.071

.975

.013

Zn

-.092

-.041

-.145

.075

.968

-.106

.062

.015

Cr

.032

-.074

.119

-.080

-.106

.971

-.072

.057

Co

-.020

.039

-.004

.976

.074

-.078

.144

-.036

pH

.862

-.178

.202

.112

.059

-.073

-.086

.122

EC

-.003

.972

.066

.039

-.039

-.072

-.091

.064

NO3-

.100

.063

.015

-.035

.014

.055

.012

.989

Eigen value

1.491

1.035

1.029

1.022

1.020

1.008

1.003

1.002

%Variance

16.562

11.501

11.434

11.357

11.332

11.204

11.139

11.135

%Cumulati ve Variance

16.562

28.063

39.497

50.854

62.185

73.390

84.529

95.664

342

Chapter 4 Results Table 81 Loadings of variables on four significant PCs for 60 rainwater samples of Badarpur, Assam, India Variables

PC 1

PC 2

PC 3

PC 4

Pb

.720

-.335

.199

.366

Zn

.117

.315

.827

.350

Cr

.796

-.298

-.291

.004

pH

-.769

-.136

-.151

.467

EC

.224

.555

-.592

.478

NO3-

.251

.846

.033

-.222

Eigen value

1.870

1.342

1.182

.753

%Variance

31.166

22.361

19.706

12.543

%Cumulative Variance

31.166

53.526

73.232

85.776

Table 82 Loadings of varimax rotatedvariables on four significant PCs for 60 rainwater samples of Badarpur, Assam, India Variables

VF 1

VF 2

VF 3

VF 4

Pb

.850

-.069

-.002

.277

Zn

.019

.114

-.062

.950

Cr

.831

.166

.096

-.282

pH

-.497

-.757

.174

.013

EC

072

.086

.958

-.077

NO3-

-.208

.778

.378

.193

Eigen value

1.709

1.231

1.105

1.102

%Variance

28.483

20.513

18.419

18.361

%Cumulative Variance

28.483

48.996

67.415

85.776

343

Chapter 4 Results Table 83 Loadings of variables on eight significant PCs for 206 rainwater samples of Bongaigaon, Assam, India Variables

PC 1

PC 2

PC 3

PC 4

PC 5

PC 6

PC 7

PC 8

Pb

-.383

.466

.115

-.243

.610

-.232

.096

-.339

Cd

.489

.441

-.335

.390

.043

.066

.460

-.168

Ni

.452

-.260

.246

-.063

.499

.578

.198

.164

Zn

-.693

.377

.073

.086

.180

.346

-.217

.253

Cr

.298

-.034

.756

.340

-.051

.033

-.277

-.357

Co

.587

.261

.239

-.038

.242

-.504

-.102

.446

pH

.176

.294

.330

-.737

-.371

.139

.231

-.043

EC

-.497

.157

.495

.350

-.225

-.084

.475

.212

NO3-

.292

.770

-.105

.098

-.210

.265

-.311

.039

Eigen value

1.866

1.394

1.186

1.014

.948

.863

.769

.609

%Variance

20.736

15.490

13.174

11.265

10.535

9.585

8.550

6.769

%Cumulati ve Variance

20.736

36.227

49.401

60.666

71.201

80.786

89.336

96.105

344

Chapter 4 Results Table 84 Loadings of varimax rotated variables on eight significant PCs for 206 rainwater samples of Bongaigaon, Assam, India

Variables

VF 1

VF 2

VF 3

VF 4

VF 5

VF 6

VF 7

VF 8

Pb

-.005

.048

.018

.988

.025

.035

-.033

-.057

Cd

.949

-.004

.164

.001

.076

-.056

-.047

.075

Ni

.066

-.102

-.070

-.055

.063

.038

.099

.973

Zn

-.395

.392

.575

.334

-.249

-.202

-.199

.059

Cr

-.033

.076

.033

-.039

.089

.003

.979

.099

Co

.086

-.062

.049

.021

.982

.042

.089

.064

pH

-.040

.018

.077

.029

.041

.984

.002

.037

EC

-.006

.969

-.050

.043

-.052

.028

.088

-.108

NO3-

.301

-.131

.859

-.041

.127

.162

.097

-.110

Eigen value

1.162

1.133

1.113

1.098

1.066

1.044

1.036

.998

%Variance

12.906

12.588

12.363

12.198

11.842

11.605

11.507

11.094

%Cumulati ve Variance

12.906

25.494

37.857

50.056

61.898

73.503

85.011

96.105

345

Chapter 4 Results Table 85 Loadings of variables on eight significant PCs for 138 rainwater samples of Dolaigaon, Assam, India Variables

PC 1

PC 2

PC 3

PC 4

PC 5

PC 6

PC 7

PC 8

Pb

.472

.224

-.036

-.248

-.557

.526

.250

.060

Cd

.330

.483

-.399

.334

-.279

-.325

-.240

.381

Ni

.711

.032

.168

.179

.439

-.102

.219

-.029

Zn

-.323

.069

.640

.515

-.044

.131

.239

.364

Cr

-.075

.608

-.037

-.521

.341

-.170

.363

.199

Co

.150

.677

-.012

.360

.289

.365

-.196

-.316

pH

.556

-.201

.383

-.338

.211

.158

-.458

.297

EC

-.059

-.394

-.639

183

.382

.383

.131

.293

NO3-

.712

-.326

-.021

.213

-.118

-.223

.284

-.142

Eigen value

1.790

1.420

1.156

1.064

.988

.793

.702

.615

%Variance

19.888

15.779

12.846

11.825

10.979

8.815

7.802

6.836

%Cumulati ve Variance

19.888

35.667

48.513

60.338

71.316

80.131

87.934

94.769

346

Chapter 4 Results Table 86 Loadings of varimax rotated variables on eight significant PCs for 138 rainwater samples of Dolaigaon, Assam, India Variables

VF 1

VF 2

VF 3

VF 4

VF 5

VF 6

VF 7

VF 8

Pb

.077

.045

.024

.072

.983

-.053

.066

-.049

Cd

.075

.114

.024

-.042

.067

-.053

.985

-.022

Ni

.816

.233

.158

.260

-.047

.043

.016

.044

Zn

-.053

.030

-.057

-.054

-.054

.985

-.053

-.082

Cr

-.056

.057

.974

-.030

.026

-.059

.026

-.071

Co

.024

.971

.058

-.032

.046

.029

.114

-.032

pH

.161

-.035

-.033

.968

.075

-.056

-.043

-.052

EC

.011

-.030

-.070

-.049

-.049

-.081

-.022

.989

NO3-

.819

-.189

-.257

-.015

.164

-.122

.090

-.029

Eigen value

1.382

1.055

1.053

1.019

1.013

1.008

1.001

1.000

%Variance

15.353

11.717

11.698

11.318

11.252

11.195

11.125

11.111

%Cumulati ve Variance

15.353

27.070

38.768

50.086

61.338

72.533

83.659

94.769

347

Chapter 4 Results Table 87 Loadings of variables on seven significant PCs for 141 rainwater samples of BGR Township, Assam, India Variables

PC 1

PC 2

PC 3

PC 4

PC 5

PC 6

PC 7

Pb

.561

-.079

-.111

.725

.090

.008

-.242

Cd

.123

.688

.422

.135

.139

.404

-.241

Ni

.780

-.119

.078

-.047

.234

-.349

.250

Zn

-.334

.538

.258

.425

-.136

-.124

.559

Cr

.520

-.009

.519

-.353

-.418

.205

.077

Co

.717

.067

-.336

-.053

.096

.339

.297

pH

-.112

.561

-.566

-.261

.332

.141

.083

EC

-.155

-.265

.536

-.088

.752

.034

.073

NO3-

.306

.686

.085

-.213

.023

-.500

-.249

Eigen value

1.964

1.645

1.261

.976

.960

.729

.660

%Variance

21.826

18.274

14.010

10.846

10.670

8.101

7.332

%Cumulati ve Variance

21.826

40.100

54.110

64.955

75.625

83.726

91.059

348

Chapter 4 Results Table 88 Loadings of varimax rotated variables on seven significant PCs for 141 rainwater samples of BGR Township, Assam, India Variables

VF 1

VF 2

VF 3

VF 4

VF 5

VF 6

VF 7

Pb

.204

.016

.003

.932

.081

-.074

-.047

Cd

.017

.039

.199

.080

.919

.082

.162

Ni

.620

.263

.417

.291

-.294

.263

-.038

Zn

-.113

-.057

.039

-.046

.149

-.039

.975

Cr

.314

.818

.114

-.196

.233

-.085

-.091

Co

.885

-.022

-.044

.141

.086

-.146

-.115

pH

.295

-.746

.181

-.323

.226

-.145

-.005

EC

-.071

.015

-.091

-.064

.070

.968

-.036

NO3-

.022

-.039

.931

-.020

.214

-.115

.046

Eigen value

1.414

1.302

1.138

1.129

1.124

1.083

1.006

%Variance

15.710

14.465

12.639

12.547

12.486

12.032

11.181

%Cumulative Variance

15.710

30.174

42.813

55.360

67.846

79.878

91.059

349

Chapter 4 Results Table 89 Loadings of variables on seven significant PCs for 103 rainwater samples of Kolkata, West Bengal, India Variables

PC 1

PC 2

PC 3

PC 4

PC 5

PC 6

PC 7

Pb

.527

-.213

.272

.541

-.085

.384

.355

Cd

-.086

-.452

-.599

-.150

.423

.056

.467

Ni

.872

-.015

-.082

-.034

.018

.061

-.168

Zn

.260

.583

-.404

.189

.490

.179

-.275

Cr

-.675

.091

.224

.525

.284

.143

-.044

pH

.233

.541

.413

-.055

.276

-.463

.433

EC

.019

-.230

.616

-.481

.425

.373

-.120

NO3-

-.196

.641

-.125

-.299

-.296

.511

.291

Eigen value

1.662

1.355

1.219

.951

.851

.821

.736

%Variance

20.777

16.942

15.233

11.890

10.641

10.266

9.202

%Cumulati ve Variance

20.777

37.719

52.952

64.841

75.482

85.748

94.950

350

Chapter 4 Results Table 90 Loadings of varimax rotated variables seven significant PCs for 103 rainwater samples of Kolkata, West Bengal, India Variables

VF 1

VF 2

VF 3

VF 4

VF 5

VF 6

VF 7

Pb

-.081

.980

-.033

-.052

-.020

.012

.021

Cd

-.018

-.024

.011

-.057

.989

-.024

-.106

Ni

-.735

.330

.329

-.175

-.100

.053

.006

Zn

-.036

-.033

.965

.096

.016

-.084

.069

Cr

.929

.062

.115

-.059

-.079

.035

-.036

pH

-.035

.021

.067

.033

-.106

.029

.990

EC

.003

.014

-.079

-.025

-.024

.995

.028

NO3-

.034

-.058

.088

.985

-.057

-.025

.033

Eigen value

1.414

1.078

1.071

1.021

1.009

1.003

.999

%Variance

17.677

13.480

13.390

12.763

12.619

12.533

12.488

%Cumulati ve Variance

17.677

31.158

44.547

57.310

69.928

82.462

94.950

Table 91 Loadings of variables on eight significant PCs for 82 rainwater samples of Kharagpur, West Bengal, India Variables

PC 1

PC 2

PC 3

PC 4

PC 5

PC 6

PC 7

PC 8

Pb

.685

.339

.119

-.280

.052

.000

.413

.354

Cd

.193

-.005

.267

.868

.228

.183

.224

-.029

Ni

.466

.123

-.647

-.053

.404

-.211

.092

-.198

Zn

-.436

.306

.268

-.155

.748

-.083

-.075

-.064

Cr

.003

.562

-.581

.057

-.104

.482

-.038

-.190

Co

.350

-.549

.153

-.283

.282

.593

-.149

.054

pH

.152

.509

.625

-.233

-.174

.091

.109

-.436

EC

-.668

.503

-.070

-.021

.017

.216

.089

.353

351

Chapter 4 Results NO3-

.560

.526

.164

.180

-.004

-.092

-.547

.199

Eigen value

1.821

1.630

1.359

1.030

.898

.733

.577

.562

%Variance

20.233

18.112

15.102

11.439

9.981

8.144

6.416

6.247

%Cumulati ve Variance

20.233

38.345

53.448

64.887

74.868

83.012

89.428

95.675

Table 92 Loadings of varimax rotated variables on eight significant PCs for 82 rainwater samples of Kharagpur, West Bengal, India Variables

VF 1

VF 2

VF 3

VF 4

VF 5

VF 6

VF 7

VF 8

Pb

-.011

-.078

.156

.072

.166

.186

.000

.936

Cd

-.031

-.009

-.013

.004

-.002

.079

.996

3.009 E-5

Ni

.209

.035

.887

-.032

-.190

.057

-.036

.190

Zn

-.050

.967

.005

-.023

.105

-.010

.000

-.079

Cr

.946

-.059

.161

-.073

.045

.078

-.021

-.018

Co

-.091

-.039

.010

.983

-.051

-.043

.000

.067

pH

.026

.094

-.135

-.049

.946

.126

-.003

.160

EC

.482

.451

-.534

-.333

-.162

-.109

-.094

.072

NO3-

.064

-.022

.070

-.042

.124

.965

.087

.178

Eigen value

1.188

1.162

1.145

1.093

1.016

1.012

1.010

.986

%Variance

13.200

12.908

12.718

12.143

11.289

11.244

11.217

10.957

%Cumulati ve Variance

13.200

26.108

38.826

50.969

62.257

73.501

84.718

95.675

352

Chapter 4 Results Roof Collection Table 93 Loadings of variables on six significant PCs for 98 rainwater samples of Irongmara, Assam, India Variables

PC 1

PC 2

PC 3

PC 4

PC 5

PC 6

Pb

.096

.709

.180

.089

-.543

.303

Cd

.051

.615

.344

.241

.546

-.328

Ni

.873

.021

.065

-.157

-.038

-.071

Zn

.663

-.119

-.120

.065

.421

.562

Cr

-.058

-.032

.915

.036

.010

.204

Co

.475

.092

-.243

.753

-.186

-.161

pH

.135

.697

-.323

-.503

.089

-.019

EC

.679

-.262

.295

-.316

-.214

-.343

Eigen value

1.921

1.459

1.257

1.016

.859

.705

%Variance

24.013

18.238

15.715

12.696

10.738

8.815

%Cumulative Variance

24.013

42.251

57.966

70.662

81.400

90.215

Table 94 Loadings of varimax rotated variables on six significant PCs for 98 rainwater samples of Irongmara, Assam, India Variables

VF 1

VF 2

VF 3

VF 4

VF 5

VF 6

Pb

-.012

.030

.959

.103

.058

-.051

Cd

-.035

.049

.066

.065

.974

-.006

Ni

.776

-.104

.111

.158

.063

.378

Zn

.166

-.013

-.056

.097

-.010

.962

Cr

.101

.850

.194

-.262

.211

.010

Co

.112

-.074

.099

.935

.072

.114

pH

.100

-.694

.411

-.341

.298

.075

353

Chapter 4 Results EC

.925

.110

-.076

.003

-.075

-.015

Eigen value

1.520

1.236

1.162

1.108

1.101

1.090

%Variance

18.999

15.452

14.530

13.849

13.760

13.625

%Cumulative Variance

18.999

34.451

48.981

62.830

76.590

90.215

Table 95 Loadings of variables on seven significant PCs for 93 rainwater samples of Bongaigaon, Assam, India Variables

PC 1

PC 2

PC 3

PC 4

PC 5

PC 6

PC 7

Pb

.606

-.170

-.211

.576

-.212

.326

-.218

Cd

-.333

-.105

.438

.663

.416

-.269

-.016

Ni

.262

.617

.588

-.020

-.222

-.166

.162

Zn

.266

-.555

.468

-.131

.264

.394

.399

Cr

.582

.161

-.094

-.262

.670

-.086

-.300

Co

.720

-.131

.468

-.046

-.249

-.204

-.147

pH

.480

.396

-.508

.229

.140

-.124

.497

EC

-.179

.756

.244

.070

.125

.509

-.113

Eigen value

1.736

1.500

1.347

.917

.882

.685

.605

%Variance

21.706

18.753

16.832

11.457

11.023

8.560

7.566

%Cumulati ve Variance

21.706

40.459

57.290

68.748

79.771

88.331

95.897

354

Chapter 4 Results Table 96 Loadings of varimax rotated variables on seven significant PCs for 93 rainwater samples of Bongaigaon, Assam, India Variables

VF 1

VF 2

VF 3

VF 4

VF 5

VF 6

VF 7

Pb

.040

-.045

.971

.031

.036

.144

-.026

Cd

-.011

.029

-.027

-.054

.042

-.085

.992

Ni

.837

.374

-.162

-.059

-.050

.151

.048

Zn

.061

-.093

.040

.046

.986

-.092

.044

Cr

.068

.026

.035

.978

.046

.141

-.055

Co

.776

-.273

.322

.215

.182

-.131

-.080

pH

.028

.003

.145

.146

-.097

.959

-.092

EC

.069

.969

-.041

.030

-.090

-.006

.027

Eigen value

1.318

1.167

1.099

1.034

1.031

1.016

1.008

%Variance

16.475

14.582

13.738

12.922

12.885

12.694

12.602

%Cumulati ve Variance

16.475

31.057

44.795

57.717

70.601

83.296

95.897

Table 97 Loadings of variables on seven significant PCs for 82 rainwater samples of Dolaigaon, Assam, India Variables

PC 1

PC 2

PC 3

PC 4

PC 5

PC 6

PC 7

Pb

-.162

.651

-.088

-.528

.306

-.182

.230

Cd

-.486

.093

.336

.485

.580

.245

.073

Ni

.656

-.257

.111

-.043

.459

-.486

-.143

Zn

.479

.191

.365

-.528

.072

.499

-.074

Cr

.735

-.140

-.168

.290

.037

.195

.515

Co

.022

.362

.746

.163

-.314

-.309

.254

pH

-.075

-.616

.605

-.216

.002

.046

-.035

355

Chapter 4 Results EC

.481

.575

.111

.412

-.051

.075

-.384

Eigen value

1.699

1.396

1.230

1.121

.748

.720

.563

%Variance

21.238

17.445

15.373

14.014

9.352

9.003

7.041

%Cumulat ive Variance

21.238

38.684

54.057

68.071

77.423

86.426

93.467

Table 98 Loadings of varimax rotated variables on seven significant PCs for 82 rainwater samples of Dolaigaon, Assam, India Variables

VF 1

VF 2

VF 3

VF 4

VF 5

VF 6

VF 7

Pb

-.009

.934

.131

.060

-.014

-.149

.006

Cd

.002

-.008

-.089

.059

-.086

-.078

.985

Ni

.042

-.036

.059

-.015

.968

.159

-.090

Zn

.074

.103

.949

.034

.054

.086

-.096

Cr

.108

-.126

.084

-.030

.167

.952

-.083

Co

.096

.033

.037

.979

-.015

-.028

.057

pH

-.585

-.462

.323

.224

.208

-.192

.105

EC

.906

-.065

.159

.178

.107

.062

.034

Eigen value

1.192

1.120

1.067

1.049

1.031

1.010

1.009

%Variance

14.900

13.994

13.341

13.111

12.888

12.621

12.612

%Cumulat ive Variance

14.900

28.894

42.235

55.347

68.235

80.855

93.467

356

Chapter 4 Results Table 99 Distribution of rainwater collection sites in different clusters CLUSTER

SITES

1

Irongmara, Dolaigaon, Badarpur

2

Kolkata

3

Kharagpur, Bongaigaon, BGR Township

Table 100 Comparison of Rainwater Quality (Direct Collection) with Indian Standard Specifications For Drinking Water IS: 10500

SL NO.

PARAMETER

Present Study (Rainwater)

Requirement (Acceptable Limit)

1

pH value

6.64

6.5-8.5

2

Electrical Conductivity

17.9

Not Mentioned

3

Nitrate (as NO3), mg L-1, Max Lead (as Pb), mg L-1, Max

1.48

4

5

6

Method of Test, Ref to Part of Part 11 IS 3025

45

No relaxation

Part 34

0.009

0.01

No relaxation

Part 47

0.004

0.003

No relaxation

Part 41

0.0038

0.02

No relaxation

Part 54

7

Zinc (as Zn), mg L-1, Max

0.02

5

15

Part 49

8

Chromium (as Cr), mg L-1, Max Cobalt (as Co), mg L-1, Max

0.0217

0.05

No relaxation

Part 52

0.0045

Not Mentioned

9

357

Cadmium (as Cd), mg L-1, Max Nickel (as Ni), mg L-1, Max

Permissible Limit in the Absence of No Alternative Source relaxation

Chapter 4 Results Table 101 Comparison of Rainwater Quality (Roof Collection) with Indian Standard Specifications For Drinking Water IS: 10500

SL NO.

PARAMETER

Present Study (Rainwater)

Requirement (Acceptable Limit)

1

pH value

6.32

6.5-8.5

2

Electrical Conductivity

29.84

Not Mentioned

3

Lead (as Pb), mg L-1, Max

0.0104

4

Cadmium (as Cd), mg L-1, Max Nickel (as Ni), mg L-1, Max

6

7

5

8

9

358

Permissible Limit in the Absence of No Alternative Source relaxation

Method of Test, Ref to Part of Part 11 IS 3025

0.01

No relaxation

Part 47

0.0044

0.003

No relaxation

Part 41

0.0071

0.02

No relaxation

Part 54

Zinc (as Zn), mg L-1, Max

0.2652

5

15

Part 49

Chromium (as Cr), mg L-1, Max Cobalt (as Co), mg L-1, Max

0.0079

0.05

No relaxation

Part 52

0.0058

Not Mentioned

pH value

6.32

6.5-8.5

No relaxation

Part 11

CHAPTER 5 Discussion Conclusion Recommendation

Chapter 5 Discussion Rainwater Quality in Direct Collection pH Samples of rainwater were collected from seven different locations. These locations are Irongmara and Badarpur in Cachar and Karimganj districts, respectively, of south Assam; Bongaigaon, Dolaigaon and BGR Township in Bongaigaon district of western Assam; and Kolkata and Kharagpur in West Bengal. The last two sites have a conglomeration of industries such as cement plants, steel plants, aluminium factory, carbon factory etc. The analytical results show that pH of rainwater of the seven sampling sites in direct collection samples ranged between 5.35 to 6.64 indicating slightly acidic to alkaline nature of rainwater as compared to the reference level of 5.6 (Charlson and Rodhe, 1982). The pH of natural controlled by

precipitation is

dissolved CO2. The pH is also greatly influenced by the

addition of acidic components generated by civil and industrial activities (Primerano et al., 1998). In pollution free areas, pH value for natural rainwater is around 5.6 due to carbonic acid produced from CO2– water equilibrium. When pH value ranges from 5 to 5.6, it can be considered that rainwater has enough buffering capacity, so it is not an impacted site; but when pH value is less than 5, there is evident anthropogenic source contributing to the acidity of rainwater (Jaeschke, 1986). The mean pH over a three year observation period of 2011-2013 was 5.35 at Dolaigaon, which is slightly acidic than the reference level; while it was 5.52 at Irongmara, and 5.63 at Bongaigaon, which are very close to the reference value. Further, rainwater pH values, in the absence of common basic compounds such as NH3 and CaCO3 may be expected to range from 4.5 to 5.6 due to 359 | P a g e

Chapter 5 Discussion natural sulfur compounds alone (Charlson and Rodhe, 1982; Gulsoy et al., 1999; Okay et al., 2002). Viewed against these findings, pH at Dolaigaon, Bongaigaon and Irongmara reflect the relatively unpolluted nature of these two sites. On the other hand, the highest mean pH of 6.64 was recorded at Kolkata, followed by 6.06 at Kharagpur. Rainwater pH was found to be distinctly alkaline in several cities of India such as Agra (pH 7.01- 7.05) (Saxena et al., 1991; Kumar et al., 2002), Lucknow (pH 6.5-8.7) (Singh et al., 2007), and Varanasi (pH 6.3-7.9) (Pandey and Singh, 2011). Further, rainwater pH in Dhanbad was found to be on the alkaline side of the reference level of 5.6 during non-monsoon and early monsoon period, while it tended to be acidic during monsoon (Singh et al., 2007). In the present study, pH at Kolkata and Kharagpur remained consistently alkaline in both pre-monsoon and monsoon. The alkaline pH at Kolkata and Kharagpur is also comparable with the rainwater pH recorded in several other Indian cities such as Nagpur (Salve et al., 2008), Tirupati (Mouli et al., 2005), Pune (Safai et al., 2004) and Asansol (Banerjee, 2008). It may be noted that many of these cities are in the Indo-Gangetic plain and high loading of alkaline, especially Ca2+ and Mg2+ rich atmospheric suspended particulates of crustal origin is likely to be neutralizing the acidic components (SO2 & NOx) that are generated by anthropogenic activities (Singh et al., 2007; Prathibha et al., 2010). Similar neutralization of acidic components are also known from other parts of India. Incidences of alkaline precipitation have been reported from different parts of the world such as Monterrey, Mexico (Lara et al., 2010), Lhasa, Tibet (Zhang et al., 2003) and other areas. However, 360 | P a g e

Chapter 5 Discussion the mean pH values during 2011-2013 of 5.89 and 6.02 at Badarpur and BGR Township, respectively, are also towards the alkaline side, although Irongmara, which is not very far from Badarpur, and Dolaigaon and Bongaigaon, which are very close to BGR Township, have lower pH. This raises the possibility that neutralization of the carbonic acid generated natural acidity of rainwater may also be contributed by anthropogenic activities. Badarpur has a cement factory, while the paper mill at Panchgram is also less than 5 km away. BGR Township is very close to the Bongaigaon refinery. While cement dust could possibly contribute alkalinity to rainwater pH, burning of fossil fuel at the refinery is likely to make rainfall further acidic, rather than making it alkaline, as is observed in BGR Township. However, it is to be remembered that rainwater chemistry is not only influenced by local natural and anthropogenic sources, but is also derived from long distance transport (Berg et al., 1994; Al-Khashman, 2009). Rainwater samples that were directly collected from the rain (without roof contact) also showed lower values of pH during the months of March, April and May. It is due to the reason that the first flush of rainwater contains higher nutrient load if it rains after a long spell of dry period. In rainy periods, when precipitation is greater or there are consecutive days of rainfall, the concentration of solids in the collected rainwater decreases considerably.

361 | P a g e

Chapter 5 Discussion Electrical Conductivity (EC) Electrical conductivity of direct collection rainwater samples is observed to be highest at Kolkata and it is found to be least at Kharagpur. Increase in EC is likely to be due to the entry of more cations and anions into the atmosphere of industrially developed areas like Kolkata, although low EC at Kharagpur, which is also an industrial area, calls for more detailed studies for offering an explanation. However, EC can show extremely wide variations even in an industrial area, as has been shown for Dhanbad, where EC values could be as low as 4 and could shoot up to 178. The time of collection (first flush or later), the season (non-monsoon, early monsoon or late monsoon)

and

other

factors

are

known to

influence

the ionic

composition and abundance in rainwater (Singh et al., 2007). Nitrate Nitrate concentration in rainwater (direct collection) is found to be highest at Dolaigaon and lowest at Bongaigaon. The nitrate concentration ranged between 0.99 mg L-1 in Bongaigaon and 1.48 mg L-1 in Dolaigaon. The mean nitrate concentration during 2011-2013 are: Irongmara 1.46 mg L-1, Badarpur 1.24 mg L-1, Bongaigaon 0.99 mg L-1 , Dolaigaon 1.48 mg L-1 , BGR Township 1.21 mg L-1 , Kolkata 1.12 mg L-1, Kharagpur 1.41 mg L-1. The highest mean nitrate concentration in rainwater (direct collection)

was

recorded at Dolaigaon, while the lowest is at Bongaigaon. NO₃ˉ / H⁺ ratio contributes to nitrate in rainwater samples. Increased concentrations of NO3in rain water could be due to emission of N oxides from the combustion of fossil fuel and biomass burning (Pandey et al., 1992; Ceron et al., 2008).

362 | P a g e

Chapter 5 Discussion However, comparisons of the nitrate levels obtained in the present study with those recorded in other parts of India revealed that those recorded in the present study were very low and not a casue of any concern.

Heavy Metals Critical levels of heavy metals were observed (Pb: 0.009 mg L-1; Cd: 0.004 mg L1 in some study locations) which is in agreement with the earlier reported findings (Ubuoh et al., 2012). The result of analyses in the rainwater samples and comparison with Indian drinking water quality values indicates a few departures for parameters like pH and Cd. It is observed that the mean concentration of all the heavy metals studied were generally within

the

acceptable

limits

for

drinking

water

by

Indian

Standard

Specifications for drinking water IS: 10500 with only exception in case of pH and Cd which are below and above their permissible limits. The high mean concentrations of heavy metals suggested anthropogenic activities (Singh et al., 2007; Prathibha et al., 2010; Umeobika et al., 2013). Pb concentration is detected to be highest at Kolkata. It is expected to be due to the vehicular emission and it is obvious due to catalytic technology of the vehicles. Pb seems to have a separate source and obviously it is the traffic circulation which is largely responsible, besides other sources like small scale lead battery manufacture, lead-containing paints and such other sources. Similar observations have been made by Kanellopoulou (2001). However, lead concentrations in the ambient air has likely gone down after the introduction of unleaded gasoline in India around 2004-2005. The maximum

363 | P a g e

Chapter 5 Discussion concentration of Pb was found at the sampling site in month of March-May which may reflect the accumulation of dust in the atmosphere during the long low rainfall period of December-January.

In

rainy

season

(June-Sept.)

the

concentration of lead was found in decreasing order may be due to continuously washing of atmosphere by rain. This is in accordance with the earlier reported findings at an urban area Raipur (Tripathi and Jha, 2014). Cd and Cr concentrations are detected to be highest at Kharagpur. It is likely to be due to industrial emissions from iron plants, steel plants, fertilizer plant, cement factory and textile industry located at Kharagpur. Ni, Zn and Co concentrations are found to be highest at Irongmara. The cement factory located at Badarpur which is not very far from Irongmara may be contributing these elements from the impurities present in cement dust.

Higher

concentrations of Ni, Zn, Cr and Co were detected in the month of MarchMay and subsequently decreased along with the later spills of rain. A significant amount of metals fall through the rain at the place of their production, although a substantial amount can be easily transferred by the wind and it is possible to be deposited through the rain at long distances from the point of their sources (Smirnioudi et al., 1998; Nurnberg et al., 1984). The metals Cd, Zn come from the industrial areas (Smirnioudi et al., 1998). The highest Cr concentration observed at Kharagpur is probably due to the emission from textile industry and cement factory located at Kharagpur. The highest Co concentration during the sampling period is

observed at

Irongmara. It is probably due to the emission of cobalt from industries such as steel and iron plants located at Silchar and cement factory at Badarpur. Small amounts of cobalt emission also takes place from motor vehicles. 364 | P a g e

Chapter 5 Discussion Other smaller sources of cobalt entering the atmosphere are exhaust fumes, the burning of fossil fuels and agriculture. Rainwater washes out any soluble cobalt species which are there in the atmosphere. However, the mean heavy metal concentration values during 20112013 revealed that Pb concentration is detected to be highest at Kolkata, Cd and Cr at Kharagpur, Ni, Zn and Co at Irongmara, which is not very far from Badarpur, Badarpur has a cement factory, while the paper mill at Panchgram is also less than 5 km away which may be the probable sources of contamination at Irongmara. Other major sources of contamination in this area are the nearby tea factories located at the Silcoorie and Rosekandy tea estates where burning of fossil fuel and coal are the major contributors to the heavy metal contamination. However, it is to be remembered that rainwater

chemistry

is

not

only

influenced

by

local

natural

and

anthropogenic sources, but is also derived from long distance transport (Berg et al., 1994; Al-Khashman, 2009). Statistical Analysis Statistical comparisons among the concentrations of different physicochemical variables such as pH and EC and the different heavy metals in a given site in different years reveal that there were some significant temporal differences among the measured variables in certain sites. However, these differences could be accounted for as a part of the normal annual fluctuations in rainwater chemistry at a given site. On the other hand, intersite differences in the variables revealed some interesting patterns. For example, pH as well as electrical conductivity at Kolkata was significantly

365 | P a g e

Chapter 5 Discussion more alkaline than the other sites. The statistical significance of the differences observed among the pH and EC values obtained at Kolkata with the other sites confirm the validity of the differences and indicate that urban development at Kolkata is most likely to be responsible for the elevated values. Similarly, concentrations of Pb at Kolkata, Cd at Kharagpur, Cr at Kharagpur and Irongmara, and Ni, Zn and Co at Irongmara were relatively elevated than that in the other sites. Multivariate Statistical Analysis The major findings of the multivariate statistical analysis in the form of Principal Components Analysis (PCA) and the subsequent varimax rotated components (varifactors) at the different sites are summarized below: Irongmara: In this site PCA revealed four significant components (PCs) with eigenvalues greater than unity where Pb, Zn, pH, Ni and Co, among others had high loadings. After varimax rotation and resultant ‘cleaning’, positive contribution of pH was significant in Varifactor 1 (VF1) (which is equivalent to PC1), with a strong negative influence of Pb. Varifactor 2 was dominated by EC. The different heavy metals were variously arrayed in the remaining VFs. Thus, in spite of the high concentrations of heavy metals such as Ni, Zn, Cr and Co at Irongmara, the rainwater chemistry of this rural site is still largely governed by its pH, which remains very close to the reference value of 5.6, and its low EC. Badarpur: In the three PC having eigenvalue greater than unity, PC1 was dominated by Pb and Cr, with pH exerting a strong negative influence. EC, nitrate and Zn were important in the other two PCs. After varimax rotation, 366 | P a g e

Chapter 5 Discussion Pb and Cr continue to exert strong influence in VF1, while nitrate and EC are also important in the other VFs with pH exerting a strong negative influence. The industrial development of Badarpur with a cement factory, railway loco shed and some other small industrial units and the heavy vehicular traffic along National Highway that passes through this railway town, appears to have changed the characteristics of its atmospheric properties as reflected in rainfall quality. Thus it has more influence now from heavy metals like Pb and Cr, with the pH playing a negative role and reduced in importance. Bongaigaon, Dolaigaon and BGR Township: In Bongaigaon, VF1 had significant contributions from Cd and Zn, with EC in VF2 and nitrate and Zn in VF3. In Dolaigaon, VF1 had Ni and nitrate, VF2 Co and Cr and VF3 influenced by pH. In BGR township, Co and Ni dominated VF1, Cr with a negative influence of pH in VF2, and nitrate and Ni in VF3. One common factor is nitrate, whose significant contribution in these three western Assam sites could be linked with their proximity to the Bongaigaon refinery. Kolkata and Kharagpur: In both these sites, Cr contributed significantly to VF1, with Pb contributing to VF2 in Kolkata, and Zn in Kharagpur. Thus there is some similarity between these two sites with their urban-industrial nature. The cluster analysis appears to have laid emphasis not merely on the presence or elevated concentration of a given variable, but on the combination, frequency of occurrence and distribution. Consequently, Kolkata

367 | P a g e

Chapter 5 Discussion – the metropolis with industrial development – stands out in a distinct cluster; the three smaller urban centres with considerable industrial activities, namely Kharagpur, Bongaigaon, and BGR Township are clubbed in another; while the three rural/suburban sites of Irongmara, Badarpur and Dolaigaon remain together. It seems that in spite of some industrial development, Badarpur still essentially retains its suburban character. The location of sampling points, weather conditions, and industrial, urban

or

agricultural

activities

have

significant

effects

on

chemical

composition of collected rainwater (Meera et al., 2006). Rainwater Quality in Roof Collection pH of the three study sites in case of roof collection ranged between 6.216.32. pH of roof collection rainwater is detected to be highest at Bongaigaon and lowest at Irongmara. Several factors influence the quality of roof runoff which include characteristics of roof materials, the rainfall event, meteorological factors, chemical properties of the substances and location of the roof (Forster, 1996). Roof interception causes enrichment (compared to free-fall rainwater) in virtually all the water quality parameters as evidenced in the present study which is in agreement with the earlier findings (Adeniyi and Olabanji, 2005). Rainwater collected from roof catchment are mainly polluted by atmospheric deposition. Galvanized iron roof sample at Irongmara showed higher concentrations of Pb, Ni, Co and Zn. The trace Pb ions in samples could be attributed to washings from particulates in the air resulting from automobile and emissions and other activities in the sampling areas (Adekola et. al., 2001). Rainwater collected from roof catchments of Irongmara has higher 368 | P a g e

Zn concentration because galvanized

Chapter 5 Discussion iron roof catchments have higher zinc concentrations. The concentration of Pb and Ni in the new roof was consistently high during the consecutive three years of sample collection. There was however appreciable difference in the concentration in the water collected from aged roofing sheet. The concentration of Zn in the samples from aged roof was also detected to be higher than what obtained in the new roof samples though there was no significant difference. This is an indication that the impinging of rain drops on the roof gradually erodes the material used in the making of the roof (Eletta and Oyeyipo, 2008). Chang (2004) reported that roofs can be a serious source of nonpoint source pollution. It has been observed that pH, EC and Zn were significantly affected by the types of roofing materials. Rural area roof catchments are affected by agricultural activities and had higher concentrations of pH. Davis et al. (2001) reported that industrial and commercial roofs have much higher concentrations of metals than residential roofs. Comparison with Indian drinking water quality values indicates a few departures for parameters like pH

and Cd. Galvanized iron roof sample

recorded concentrations of EC, Pb, Ni, Zn, Cr and Co within the acceptable limits for drinking water by Indian Standard Specifications for drinking water IS: 10500 while the levels of pH and Cd were below and above their permissible limits. The present study revealed that most parameters (pH, EC, Cd, Zn, Cr) showed a significantly lower value in the case of new roofs compared to old roofs where Pb, Ni and Co showed higher values, indicating the influence of age of the roof on the harvested water quality (Meera and Ahammed, 2011). Variations reflects differences in the age of the roofs, air quality of region, characteristics of precipitation etc. (Forster, 369 | P a g e

Chapter 5 Discussion 1996; Wu et al., 2001; Chang et al., 2004). There are variations in the concentration of pollutants of water samples collected from galvanized iron roofs. Additionally, it is found that the concentration of various pollutants were higher in the first spill of rain in comparison with the next spills (Yaziz et al., 1989). The variations in the concentrations with time suggests anthropogenic inputs that is, the concentrations recorded might not be totally as a result of contact with the roofing sheets. Environmental conditions at the time of collection appears to have contributed to the results (Eletta and Oyeyipo, 2008). The level of Pb recorded in the present study in case of roof colletion even though within the acceptable limit for drinking water by Indian Standard Specifications for drinking water IS: 10500 is high. This high Pb level may be attributed to aerial deposition of the metal on the roofs from vehicle emissions as these roofs are located by the roadside (Ebong et al., 2007; Olajire et al., 1997; Zupanic et al., 1997). The high concentrations of Cd and Pb may be attributed to roofing and painting materials, aerial deposition from automobiles and insecticides used within the area which is in agreement with the earlier reported findings (Alegria et al., 1991). The high levels of Zn recorded in this study may be attributed to the roofing material from where sample was colllected. This is in agreement with the findings of Gromaire-mertz et al. (1999) in the study of rainwater harvested from zinc galvanized iron roofs. The high Zn content recorded in this work could be attributed to the roofing materials (Van-Metre et al., 2003). It has also been observed that, the sample collected from galvanized iron roof recorded higher concentrations for the metals than obtained in the 370 | P a g e

Chapter 5 Discussion direct collection rainwater samples thus, it could be inferred that, the roof contributed some of these metals to rainwater harvested from it. These high levels of Zn

and

Cd

recorded in this study may be attributed to the

leaching action by rainwater of Zn from the Zn roof (Good, 1993; Magyer et al., 2008). The high Cd content recorded may be attributed to the metal being a major impurity in Zn, the painting materials used on the roof and pesticides used within the area (Adachi and Kobayashi, 1992; Forster, 1999; Yaziz

et al., 1989). It has also been observed from the results that,

concentrations of the metals analyzed for in samples harvested from the rooftops were relatively higher than their levels in the direct collection rainwater samples. This showed that, the roofing materials may have influenced the levels of these metals in the rainwater harvested from them. These high concentrations of Zn and Pb has rendered the rainwater harvested from galvanized iron roof unfit for human consumption since there are some health implications associated with high Zn in human body (Killburn et al., 1993; Nolan, 2003). The high concentrations of metals recorded in this study may also be attributed to the samples being the first flush after the long dry season since

according

to

(Davis

and

Matthew,

1999).

Concentrations

of

contaminants in roof runoff decrease with increase in the dilution rate. Also, the higher levels of metals in roof runoff than their corresponding levels in the direct collection rainwater samples observed in this work are in agreement with earlier observations (Queck and Forster, 1993). The site to site fluctuations in the level of metals recorded in this study may be

371 | P a g e

Chapter 5 Discussion attributed to variations in the source of the samples and in anthropogenic activities done at each station (Ebong et al., 2012). However, it is seen

that the rainwater collected from the areas

surrounding the industrial areas is contaminated by the emission of the industries and the possible emissions from automobiles. It has also been shown that quality of rainwater can be significantly impaired especially in industrialized areas (Olobaniyil and Efe, 2007). These observations may be due to interaction between the rainwater and the effluents released from the industries. It is also observed that rainwater contamination may not be restricted to industrial areas alone but vehicular emission may also be responsible for this contamination as seen in the results.

372 | P a g e

Chapter 5 Conclusion Rainwater samples were collected from the pre-monsoon season of March 2010 to post-

monsoon of October 2013, from seven sampling sites namely

Irongmara, Badarpur, Bongaigaon, Dolaigaon, BGR Township, Kolkata and Kharagpur, which characterised typical suburban, urban and industrialised locations respectively. A total of 943 sample were collected during this period from the sampling sites, taking utmost care in sampling and storage.

The analytical results showed that the mean pH over a three year observation period of 2011-2013 was 5.35 at Dolaigaon, which is slightly acidic than the reference level; while it was 5.52 at Irongmara, and 5.63 at Bongaigaon, which are very close to the reference value. On the other hand, the highest mean pH of 6.64 was recorded at Kolkata, followed by 6.06 at Kharagpur. In the present study, pH at Kolkata and Kharagpur remained consistently alkaline in both pre-monsoon and monsoon. The alkaline pH at Kolkata and Kharagpur is also comparable with the rainwater pH recorded in several other Indian cities. EC can show extremely wide variations even in an industrial area, as has been seen in the present study where it is observed to be both highest and lowest in case of an industrial area which is likely to be due to the entry of more cations and anions into the atmosphere of industrially developed areas. The mean heavy metal concentration values during 2011-2013 revealed that Pb concentration is detected to be highest at Kolkata which is expected to be due to the vehicular emission. Cd and Cr concentrations are detected to be highest at Kharagpur. It is likely to be due to industrial emissions from iron plants, steel plants, fertilizer plant, cement factory and textile industry located 373 | P a g e

Chapter 5 Conclusion at Kharagpur. Ni, Zn and Co concentrations are found to be highest at Irongmara. It is expected to be due to the cement factory located at Badarpur which is not very far from Irongmara. Higher concentrations of Ni, Zn, Cr and Co were detected in the month of March-May and subsequently decreased along with the later spills of rain. Cd and Cr at Kharagpur, Ni, Zn and Co at Irongmara, which is not very far from Badarpur, Badarpur has a cement factory, while the paper mill at Panchgram is also less than 5 km away which may be the probable sources of contamination at Irongmara. Other major sources of contamination in this area are the nearby tea factories located at the Silcoorie and Rosekandy tea estates where burning of fossil fuel and coal are the major contributors to the heavy metal contamination. However, it is to be remembered that rainwater chemistry is not only influenced by local natural and anthropogenic sources, but is also derived from long distance transport. pH of the three study sites in case of roof collection ranged between 6.21-6.32. pH of roof collection rainwater is detected to be highest at Bongaigaon and lowest at Irongmara. Galvanized iron roof sample at Irongmara showed higher concentrations of Pb, Ni, Co and Zn. The trace Pb ions in samples could be attributed to washings from particulates in the air resulting from automobile and emissions and other activities in the sampling areas. This is an indication that the impinging of rain drops on the roof gradually erodes the material used in the making of the roof .

The variations in the

concentrations

inputs (that

with

time

suggests

anthropogenic

is,

the

concentrations recorded might not be totally as a result of contact with the roofing sheets. Environmental conditions at the time of collection appears to 374 | P a g e

Chapter 5 Conclusion have contributed to the results.

It has also been observed from the results

that, concentrations of the metals analyzed for in samples harvested from the rooftops were relatively higher than their levels in the direct collection rainwater samples. Additionally, it is found that the concentration of various pollutants were higher in the first spill of rain in comparison with the next spills. It is seen that, the roofing materials may have influenced the levels of these metals in the rainwater harvested from them. The variations in the concentrations

with

time

suggests

anthropogenic

inputs

that

is,

the

concentrations recorded might not be totally as a result of contact with the roofing sheets. The high concentrations of metals recorded in this study may also be attributed to the samples being the first flush after the long dry season. Concentrations of contaminants in roof runoff decrease with increase in the dilution rate. Also, the higher levels of metals in roof runoff than their corresponding levels in the direct collection rainwater samples observed in the present study. After having a critical review of the results, it could be clearly concluded that the quality of rainwater is not contaminant free. It is observed that the mean concentration of all the heavy metals studied were generally within the acceptable limits for drinking water by Indian Standard Specifications for drinking water IS: 10500 with only exception in case of pH and Cd which are below and above their permissible limits. Galvanized iron roof sample recorded concentrations of EC, Pb, Ni, Zn, Cr and Co within the acceptable limits for drinking water by Indian Standard Specifications for drinking water IS: 10500 while the levels of

pH and Cd were below and above their

permissible limits. The high concentrations of Pb, Cd and Zn has rendered 375 | P a g e

Chapter 5 Conclusion the rainwater harvested from galvanized iron roof unfit for human consumption since there are some health implications associated with these metals in human body. It is site specific and represents the atmospheric characteristics of the location of the free fall. The site to site fluctuations in the level of metals recorded in this study may be attributed to variations in the source of the samples and in anthropogenic activities done at each station. It is also observed that rainwater contamination may not be restricted to industrial areas alone but vehicular emission may also be responsible for this contamination as seen in the results.

376 | P a g e

Chapter 5 Recommendations

The following are some of the recommendations which should be taken care of in case of harvestng rainwater for drinking purpose ------------In order to have better quality of harvested water following measures should be adopted. 1. Rooftops and catchment areas must be cleaned before the rainfall season 2. Water samples should be collected and analyzed on regular basis before using for drinking purposes. 3. Care should be taken to ensure that samples were representative of water to be examined and that no accidental contamination occurs during sampling. 4. Thus it is highly recommended that the captured rainwater (both direct as well as roof collection) should be used for drinking purpose only after proper treatment.

377 | P a g e

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