2) Akkithimmanhalli Lake changed to Corporation Hockey stadium. ..... ground water in hard rock terrain of north eastern parts of Kalahandi district Orissa.
Chapter 01 1.1 1.2 1.3 1..4 1.5 1.6 1.7 1.8 1.9 1.10 1.11 1.12 1.13 1.14 1.15 1.16 02 2.1 2.2 2.3 03 3.1 3.2 04 4.1 4.2 4.3 4.3.1 4.3.2 4.4 4.4.1 4.4.2 05 5.1 5.2 5.3 06 6.1 6.2 6.3 6.4
CONTENTS Title INTRODUCTION Introduction to water Water resources in India Threats to water resources Lake Chemical Characteristics of lakes Significance of urban lakes Lakes in India Environmental Status of Lakes in India Overview of Karnataka lakes Lakes of Bangalore Major Types of Lakes Encroachment of lakes Overall impact of anthropogenic activities on lakes Ground water Radon Hydrological applications of radon Review of literature Lakes Ground water Radon Relevance of the study Scope of the study Objectives of the study Study area Bangalore Ground water related problems Sankey Tank Restoration actions Legal land encroachment tangle Malathahalli Lake Pollution sources Flora and fauna of the two lakes Materials and Methods Sample collection Radon estimation Bacteriological analysis. Results and discussion Dissolved oxygen pH Electrical Conductivity Total Dissolved Solids (TDS) 1
Page No. 01 02 03 04 04 05 05 06 07 08 09 09 11 11 13 15 17 21 26 28 29 30 32 36 37 38 38 39 39 41 42 44 45 47 49 52
6.5 6.6 6.7 6.8 6.9 6.10 6.11 6.12 6.13 6.14 6.15 6.16 6.17 6.18 6.19
Colour Turbidity Biochemical Oxygen Demand (BOD) Chemical Oxygen Demand (COD) Water Temperature Carbon dioxide Total Alkalinity as CaCO3 Total Hardness Calcium Magnesium Chlorides Nitrate Phosphate Sulphate Fluoride
Potassium Sodium Silica Iron Fecal Coliform Correlation Matrix for physico-chemical Parameters Radon Annual effective dose / Effective Dose Equivalent Rate Summary and conclusion Recommendation Limitations and future line of work References Websites referred 10.1 List of Tables Table No. Description General information about the study area 4.1 Irrigation by different sources (area and no. of structures) 4.2 Basic information of Sankey tank 4.3 physico-chemical analysis procedures and respective 5.1 standards Classification of water based on EC data for irrigation 6.1 TDS in water is classified by Catrol (1962) 6.2 TDS groundwater is classified by Hem’s classification (1970) 6.3 Temperature Conditions for Aquatic Organisms 6.4 Important compounds responsible for alkalinity 6.5 Typical alkalinity ranges. (mg/l CaCO3) 6.6 U.S. E.P.A. Classification of lakes based on alkalinity 6.7 Classification of water samples based on total Hardness 6.8 List of Figures 6.20 6.21 6.22 6.23 6.24 6.25 6.26 6.27
07 08 09 10
2
55 56 59 60 61 65 67 70 72 74 76 79 82 85 87 90 92 95 97 99 100 100 104 105 107 109 110 115 Page No. 32 32 36 41 51 54 54 64 68 69 69 72
Figure No. 1.1 1.2 1.3 4.1 4.2 4.3 5.1 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 6.10 6.11 6.12 6.13 6.14 6.15 6.16 6.17 6.18 6.19 6.20 6.21 6.22 6.23 6.24 6.25 6.26 6.27 6.28 6.29 6.30 6.31 6.32 6.33 6.34 6.35 6.36 6.37
Description Distribution of water on earth % wise distribution of lakes in Karnataka % wise size of lakes in Karnataka Mean Monthly Rainfall of Bangalore District (mm) Growth of bore wells in Bangalore city Location map and sapling sites of the study area Diagrammatic view of Radon monitor in water Variation in DO values between the two lakes DO variation in bore wells around the two lakes pH variation in the two lakes pH variation in the ground water around the two lakes EC variation in the two lakes EC variation in ground water around the two lakes TDS variation in the two lakes TDS in groundwater samples around the two lakes Colour variation in the two lakes Colour variation in borewell samples around the two lakes Turbidity of the two lakes Turbidity variation in ground water around the two lakes BOD in the two lakes COD variation in the two lakes Thermal stratification in lake water bodies. Water Temperature variation inside the two lakes Bore well water temperature around the lakes CO2 in the two lakes Bore well CO2 variation around the two lakes Total Alkalinity graph for the two lakes Total alkalinity of bore wells around the lakes Total Hardness as CaCO3 in lake water samples Hardness in ground water around the two lakes Ca concentration in the two lakes Ground water Ca concentration around the two lakes Mg concentration in the two lakes Mg in ground water samples Chloride variation in the two lakes Chloride concentration around the two lakes Nitrate concentration in the two lakes Nitrate concentration around the two lakes Phosphate concentration in the two lakes Phosphate in GW around the two lakes Sulphate concentration in the two lakes Sulphate in GW around the two lakes Fluoride concentration inside the two lakes Fluoride concentration in bore wells around the two lakes 3
Page No. 01 08 08 31 34 35 44 46 46 48 49 50 51 53 54 56 56 58 58 60 61 62 64 65 66 66 68 69 71 72 73 74 75 76 78 79 81 82 84 85 86 87 89 89
Potassium concentration around the two lakes Potassium concentration in bore wells around the two lakes Sodium concentration inside the two lakes Sodium concentration in bore wells around the two lakes Silica concentration inside the two lakes Silica concentration in bore wells around the two lakes Iron concentration in the two lakes Iron concentration around the two lakes Fecal coliform count inside the two lakes Radon analysis in Sankey tank Radon analysis in Malathalli Lake Radon analysis in ground water around the two lakes List of Annexures Annexure No. Description Correlation Matrix for Sankey Tank I Correlation Matrix for Malathalli lake II Physico chemical analysis of Sankey tank (March 2012) III Physico chemical analysis of Sankey tank (April 2012) IV Physico chemical analysis of Sankey tank (May 2012) V Physico chemical analysis of Malathalli lake (March 2012) VI Physico chemical analysis of Malathalli lake (April 2012) VII Physico chemical analysis of Malathalli Lake (May 2012) VIII Physico Chemical Analysis of Ground Water samples IX around Malathalli Lake Physico Chemical Analysis of Ground Water samples X around Sankey Tank List of Plates Plate No. Description Early Morning view of Sankey tank 11.1 A view of Sankey Tank after rejuvenation 11.2 Ducks swimming in the Sankey Tank 11.3 Duck Shelter feed structure in the middle of Sankey Tank 11.4 Duck Shelter feed structure in the middle of Sankey Tank 11.5 Part of Sankey Tank developed into a park 11.6 A view of Sankey Tank water after its restoration 11.7 Restoration work in progress at outlet of the Malathalli Lake 11.8 A view of sewage entering into Malathalli Lake 11.9 Surface water collection from the Malathalli Lake 11.10 Samples showing end point for phosphate analysis 11.11 Fecal coliform Colonies grown on the membrane filter paper 11.12 A view of Eutrophication in the Malathalli Lake 11.13 A view of Sewage treatment plant near Malathahalli lake 11.14 Rejuvenation work in progress in the Malathalli Lake 11.15 6.38 6.39 6.40 6.41 6.42 6.43 6.44 6.45 6.46 6.47 6.48 6.49
4
90 91 93 94 96 96 97 98 99 102 102 103 Page No. 116 117 118 119 120 121 122 123 124 125
Page No. 126 126 126 127 127 127 128 128 128 129 129 129 130 130 130
CHAPTER -1 INTRODUCTION 1.1: Introduction to water Water is the most abundant substance, covering more than 70 percent of the earth’s surface and existing in many places and forms: mostly in the oceans and polar ice caps, but also as clouds, rain water, rivers, freshwater aquifers, and sea ice. Water is also found in the ground and in the air we breathe and is essential to all known forms of life. It makes up two thirds of our bodies. In fact, between 50 and 90 per cent of the weight of any living being is water. Great civilizations have risen where water supplies were plentiful, such as on the banks of rivers and major waterways; Mesopotamia, the so-called cradle of civilization, was situated between two major rivers. Large metropolitans like London, Paris, New York, and Tokyo owe their success in part to their easy accessibility via water and the resultant expansion of trade. Water is used for domestic purposes for cleaning, cooking bathing, and carrying away wastes, and in agriculture for irrigation, power generation, industries, navigation, recreation and many other reasons. On the planet, water is continuously moving through the cycle involving evaporation, precipitation, and runoff to the sea, thus influencing the earth’s climate.
Fig: 1.1: Distribution of water on earth
1
Water is in a constant state of motion as explained in the hydrological cycle. The very act of condensation usually requires a surface, or nuclei, water may acquire impurities at the very moment of condensation. Additional impurities are added as the liquid travels through the remainder of the hydrological cycle and comes in contact with materials in the air and on or beneath the surface of the earth. Human activities contribute further to the impurities in the form of industrial and domestic wastes, agricultural chemicals and other less obvious contaminants. However, it is the water quality in the intermediate stage, which is of greatest concern, because it is the quality at this stage that affects human usage.
1.2: Water resources in India India by virtue of its geographical position and varied terrain and climatic zones, is blessed with many rivers, which supports a rich diversity of inland and coastal waterbodies. The annual precipitation including snowfall, which is the main source of water in the country is estimated to be of the order of 4000 cu.km. For the purpose of monitoring rainfall, the country has been divided into 35 meteorological subdivisions. The resources potential of the country, which occurs, as natural run-off in the rivers is about 1869 cu.km as per the basin wise latest estimates of Central Water Commission, considering both surface and groundwater as one system. GangaBrahmaputra-Meghna system is the major contributor to the total water resources 2
potential of the country. Its share is about 60 percent in the total water resources potential of the various rivers (National Informatics Centre 2009). A survey conducted by the Ministry of Environment and Forests (MoEF) in 1990 showed that wetlands occupied an estimated 4.1 million hectares of which 1.5 million hectares were natural and 2.6 million hectares man-made (excluding paddy fields, rivers and streams) and mangroves occupying an estimated 0.45 million hectares. About 80% of the mangroves were distributed in the Sunderbans of West Bengal and Andaman and Nicobar Islands, with the rest in the coastal states of Orissa, Andhra Pradesh, Tamil Nadu, Karnataka, Kerala, Goa, Maharashtra and Gujarat. A preliminary inventory by the Department of Science and Technology, recorded a total of 1193 wetlands, covering an area of about 3,904,543 ha, of which 572 were natural (Scott and Pole, 1989).
1.3: Threats to water resources Most often human interactions with water involve fresh streams, rivers, marshes, lakes, and shallow groundwaters. As is true of all organisms, our very existence depends on this water; we need an abundance of fresh water to live. Globally, there are increasing problems related to the availability of freshwater. Less than 1% of all water on Earth is available for human consumption. This precious resource is not only being overexploited but also is seriously degraded due to anthropogenic activities involving indiscriminate disposal of pollutants in water bodies, which has rendered it unfit for sustenance of life. According to the United Nations Environment Program (UNEP), close to one quarter of the world’s population may soon suffer from chronic water shortages. The most significant threats to water resources are from point sources (sewage, industrial effluents, etc.) and from non-point sources (agriculture, urban, etc.) Apart from these, dumping of solid wastes, chemical spills, thermal pollution, acid precipitation, mine drainage, etc. also contribute. Pollution of any form first affects the chemical quality of the water and then systematically destroys the community, 3
disrupting the delicate food web in these aquatic ecosystems. Understanding the implications of each of these threats requires characterisation of aquatic ecosystems involving detailed understanding of the ecology.
1.4: Lake A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Natural lakes are generally found in mountainous areas, rift zones, and areas with ongoing glaciation. The word lake comes from Middle English lake ("lake, pond, waterway"), from Old English lacu ("pond, pool, stream"), from Proto-Germanic lakō ("pond, ditch, slow moving stream").In lake ecology , the environment of a lake is referred to as lacustrine.
1.5: Chemical Characteristics of lakes Water chemistry is an important indicator of a lake’s condition. Numerous materials are dissolved in lake water or suspended in the water column, and many more insoluble forms are associated with the lake sediment. Many are present in more than one form and can be transformed through chemical or biological processes into different forms. Concentrations of various elements provide information about biological processes, nutrient loading, contaminant input, trophic status, stratification, and many other variables. Among the most commonly sampled chemical characteristics are dissolved oxygen, nitrogen, and phosphorus. These are the three elements most important for biological processes. Lakes have numerous features in addition to lake type, such as drainage basin (also known as catchment area), inflow and outflow, nutrient content, dissolved oxygen, pollutants, pH, and sedimentation. Changes in the level of a lake are controlled by the difference between the input and output compared to the total volume of the lake. Significant input sources are precipitation onto the lake, runoff carried by streams and channels from the 4
lake's catchment area, groundwater channels and aquifers, and artificial sources from outside the catchment area. Output sources are evaporation from the lake, surface and groundwater flows, and any extraction of lake water by humans. As climate conditions and human water requirements vary, these will create fluctuations in the lake level.
1.6: Significance of urban lakes Groundwater recharge and discharge. Rain water harvesting. Flood control and stream flow maintenance. Pisciculture. Emergency water supply for fire fighting. Role in biogeochemical cycles. Wildlife habitat especially fishes and birds. Lung space-clear and cool air. Recreation – education, boating, swimming, walking and jogging on the lake bund.
1.7: Lakes in India There is no specific definition for Lakes in India. The word “Lake” is used loosely to describe many types of water bodies – natural, manmade and ephemeral including wetlands. Many of them are euphemistically called Lakes more by convention and a desire to be grandiose rather than by application of an accepted definition. Vice versa, many lakes are categorized as wetlands while reporting under Ramsar Convention. India is well known for the huge variance in its lakes, but the data is nebulous. There is no orderly or scientific census of lakes. Though there is a distinction between fresh water lakes and brackish water lakes, just as the lakes of southern peninsular India are distinct from those of the Himalayan region and natural lakes from manmade reservoirs, there is no scientific evaluation. Most of the large reservoirs (formed by 5
construction of dams) have been constructed during the last 50 years. It is, therefore, possible to access their data, though not always easily. Reservoirs include tanks which are, however, not properly accounted though estimated at over half a million in number spread all over the country, predominantly in southern India. The water spread areas of rivers; lakes, reservoirs, and brackish water have not been comprehensively surveyed.
1.8: Environmental Status of Lakes in India The lakes and reservoirs, all over the country without exception, are in varying degrees of environmental degradation. The degradation is due to encroachments eutrophication (from domestic and industrial effluents) and silt. There has been a quantum jump in population during the last century without corresponding expansion of civic facilities resulting in lakes and reservoirs, especially the urban ones, becoming sinks for contaminants. The main causes for the impaired conditions of the lakes could be summarized as hereunder:
Pollutants entering from fixed point sources Nutrients from wastewater from municipal and domestic effluents Organic, inorganic and toxic pollution from industrial effluents Storm water runoff.
Pollutants entering from non- point sources Nutrients through fertilizers, toxic pesticides and other chemicals, mainly from agriculture runoff Organic pollution from human settlements spread over areas along the periphery of the lakes and reservoirs.
6
Other basin-related causes of impairment: Silting of lakes on account of increased erosion as a result of expansion of urban and agricultural areas, deforestation, road construction and such other land disturbances taking place in the drainage basin Diversion of rivers feeding the lakes reducing their sizes. Competition for using lake water such as for drinking, irrigation, hydropower etc, Untreated or inadequately treated domestic and industrial effluents from point sources located all over the basin
1.9: Overview of Karnataka lakes Karnataka state is endowed with numerous rivers, lakes, and streams, and has a coastline of about 320 km. Spatial extent of the state is 1,92,204 sq km (5.35% of the country's total geographical area) with a population of 52 million. The occurrence and distribution of rainfall in the state is highly erratic. It is estimated that nearly 75% of the state’s area is drought prone, and the rain fall has coefficient of variation of variability of more than 30%, which leaves the state exposed to the risk of drought. Karnataka has more than 36,508 big and small tanks. In the Malnad region – Shimoga, parts of Dakshina Kannada and Uttara Kannada, tanks are generally small and a great number only harvest rain. They are not supported by channels which divert stream water. Malnad’s tank accounts for nearly 25% of the total tanks of the state. In the Northern Plateau – Dharwar, Belgaum, Bijapur, Bellary, Raichur, Gulbarga and Bidar, tanks are very few and account for only 15% of the total tanks of the state. In the southern plateau - Chitradurga, Tumkur, parts of Chikmagalur, Hassan, Kodagu, Mysore, Mandya, Bangalore and Kolar there are numerous tanks and they account to 60% of the total tanks of the state.
7
Fig 1.2: % wise distribution of lakes in Karnataka
Fig 1.3: % wise size of lakes in Karnataka
1.10: Lakes of Bangalore Lakes in Bangalore city in Karnataka are numerous, and there are no rivers close by. Most lakes in the Bangalore region were constructed in the Sixteenth century by damming the natural valley systems by constructing bunds. The effect of urbanization has taken some heavy toll on the Beautiful lakes in Bangalore. The lakes in the city have been largely encroached for urban infrastructure and as result, in the heart of the city only 17 good lakes exist as against 51 healthy lakes in 1985.Urban development has caused 16 lakes getting converted to bus stands, Golf courses, playgrounds and residential colonies, and few tanks were 8
breached under the malaria eradication programme. In recent years, the Management of Lakes traditionally done by the government agencies witnessed experimentation by the Lake Development Authority with a limited public–private sector participation in respect of three lakes, which has proved controversial and resulted in almost a reversal of the policy.
1.11: Major Types of Lakes In the broader sense, Bangalore lakes can be classified into two major categories; 1) SEWAGE FED LAKES- Those lakes whose water source is rain as well as sewage, but major contribution for input of water is sewage only. e.g. Malathalli lake. 2) RAIN FED LAKES- For these lakes water input is from rain only and less contribution can be from ground water also. e.g. Sankey tank.
1.12: Encroachment of lakes Most of the lakes have vanished due to encroachment and construction activity for urban infrastructure expansion. The city once had 280-285 lakes of which 7 cannot be traced, 7 are reduced to small pools of water, 18 have been unauthorizedly encroached by slums and private parties and 14 have dried up, which are leased out by the Government. 28 lakes have been used by the Bangalore Development Authority to distribute sites and build extensions for residential areas. The remaining lakes are in fairly advanced state of deterioration.
Some of the major lakes that disappeared over the years are 1) Shoolay Lake changed to Football stadium. 2) Akkithimmanhalli Lake changed to Corporation Hockey stadium. 3) Sampangi Lake changed to Kanteerava Sports Complex. 4) Dharmanbudhi Lake changed to Kempegowda Bus Station. 5) Challaghatta lake changed to Karnataka Golf Association. 6) Koramangala lake changed to National Games Complex in Ejipura. 9
7) Siddikatte Lake has now become KR Market. 8) Karanji tank is the Gandhi Bazar area. 9) Kempambudhi is now a sewerage collection tank. 10) Nagashettihalli lake changed to Space department. 11) Kadugondanahalli lake changed to Ambedkar Medical College. 12) Domlur Lake changed to BDA layout. 13) Millers Lake changed to Guru Nanak Bhavan, Badminton Stadium. 14) Subhashnagar Lake changed to Residential layout. 15) Kurubarahalli Lake changed to Residential layout. 16) Kodihalli Lake changed to Residential layout. 17) Sinivaigalu Lake changed to Residential layout. 18) Marenahalli Lake changed to Residential layout. 19) Shivanahalli Lake changed to Playground, Bus stand. 20) Chenamma tank changed to a burial ground, Banashankari 2nd Stage. 21) Puttennahalli tank changed to J.P. Nagar 6th Phase. 22) Jakkarayanakere is converted into a sports ground. 23) Kamakshipalya Lake is converted into a sports ground. 24) Baalayyana Kere (kamakshipalya) is converted into a sports ground. 25) Dasarahalli tank is converted into Dr. B.R Ambedkar Stadium. 26) Kaikondrahalli Lake is now an apartment complex (SJR watermark).
The lakes of the city have been largely encroached for urban infrastructure, and as result, in the heart of the city only 17 good lakes exist as against 51 healthy lakes in 1985. According to a scientific study carried out by the Centre for Ecological Sciences (CES), Indian Institute of Science, Bangalore, the water bodies of the city have reduced from 3.40 per cent (2,324 ha (5,742.7 acres)) in 1973 to just about 1.47 per cent (1,005 ha (2,483.4 acres)) in 2005 with built up area during the corresponding period increasing to 45.19 per cent (30,476 ha (75,307.8 acres)) from 27.30 per cent (18,650 ha (46,085.2 acres)). 10
The adverse results of such large change are reported to be 1) Frequent flooding and micro–climatic changes in the city. 2) Undesirable impact on the diversity of flora and fauna. 3) Decrease in the number of migratory birds. 4) Fishing community and washer-men will be robbed of their livelihood.
1.13: Overall impact of anthropogenic activities on lakes Deterioration of lake water quality Sedimentation and Shrinkage Decrease in productivity to support flora and fauna Loss of aesthetic values and decrease in tourism potential Existing tanks should be deweeded and aquatic life must be developed; Affects the ground water sources Growing mosquito menace Renders the water unfit for recreational purposes Causes serious health hazards Climate change Shortage in drinking water Illegal encroachments and slum development leading to lake pollution
1.14: Ground water Water is a very complex substance and its unique properties are essential for life. Its physical properties shape the hydrosphere and are an essential part of the water cycle and climate. Its thermodynamic properties determine evaporation and the thermal gradient in the atmosphere. The many types of precipitation involve a complex mixture of processes such as coalescence, super cooling and supersaturation. Some of the precipitated water becomes groundwater, and groundwater flow includes phenomena such as percolation, while the conductivity of water makes electrical and electromagnetic methods useful for tracking groundwater flow. 11
When rain falls to the ground, the water does not stop moving. Some of it flows along the land surface to streams or lakes, some is used by plants, some evaporates and returns to the atmosphere, and some seeps into the ground. Water seeps into the ground much like a glass of water poured onto a pile of sand. As water seeps into the ground, some of it clings to particles of soil or to roots of plants just below the land surface. This moisture provides plants with the water they need to grow. Water not used by plants moves deeper into the ground. The water moves downward through empty spaces or cracks in the soil, sand, or rocks until it reaches a layer of rock through which water cannot easily move. The water then fills the empty spaces and cracks above that layer. The top of the water in the soil, sand, or rocks is called the water table and the water that fills the empty spaces and cracks is called ground water. Water seeping down from the land surface adds to the ground water and is called recharge water. Ground water is recharged from rain water and snowmelt or from water that leaks through the bottom of some lakes and rivers. Ground water also can be recharged when water-supply systems (pipelines and canals) leak and when crops are irrigated with more water than the plants can use. At least some ground water can be found almost everywhere. The water table may be deep, such as under a hillside, or shallow such as under a valley. The water table may rise or fall depending on several factors. Heavy rains or melting snow may increase recharge and cause the water table to rise. An extended period of dry weather may decrease recharge and cause the water table to fall. Groundwater is a highly useful and often abundant resource. However, over-use, or overdraft, can cause major problems to human users and to the environment. The most evident problem (as far as human groundwater use is concerned) is a lowering of the water table beyond the reach of existing wells. Wells must consequently be deepened to reach the groundwater; in some places (e.g., California, Texas and India) the water table has dropped hundreds of feet because of extensive well pumping. In the Punjab region of India, for example, groundwater levels have dropped 10 meters 12
since 1979, and the rate of depletion is accelerating. A lowered water table may, in turn, cause other problems such as groundwater-related subsidence and saltwater intrusion. Love Canal was one of the most widely known examples of groundwater pollution. In 1978, residents of the Love Canal neighborhood in upstate New York noticed high rates of cancer and an alarming number of birth defects. This was eventually traced to organic solvents and dioxins from an industrial landfill that the neighborhood had been built over and around, which had then infiltrated into the water supply and evaporated in basements to further contaminate the air. Eight hundred families were reimbursed for their homes and moved, after extensive legal battles and media coverage. Another example of widespread groundwater pollution is in the Ganges Plain of northern India and Bangladesh where severe contamination of groundwater by naturally occurring arsenic affects 25% of water wells in the shallower of two regional aquifers. The pollution occurs because aquifer sediments contain organic matter (dead plant material) that generates anaerobic (an environment without oxygen) conditions in the aquifer. These conditions result in the microbial dissolution of iron oxides in the sediment and thus the release of the arsenic, normally strongly bound to iron oxides, into the water. As a consequence, arsenic-rich groundwater is often iron-rich, although secondary processes often obscure the association of dissolved arsenic and dissolved iron.
1.15: Radon Health effects of radon, most notably lung cancer, have been investigated for several decades. Initially, investigations focused on underground miners exposed to high concentrations of radon in their occupational environment. However, in the early 1980s, several surveys of radon concentrations in homes and other buildings were carried out, and the results of these surveys, together with risk estimates based on the studies of mine workers, provided indirect evidence that radon may be an important 13
cause of lung cancer in the general population. Recently, efforts to directly investigate the association between indoor radon and lung cancer have provided convincing evidence of increased lung cancer risk causally associated with radon, even at levels commonly found in buildings. Risk assessment for radon both in mines and in residential settings have provided clear insights into the health risks due to radon. Radon is now recognized as the second most important cause of lung cancer after smoking in the general population. The understanding of radon sources and radon transport mechanisms has evolved over several decades. Radon belongs to the noble gas series in the periodic table. There are three natural isotopes of radon namely, radon (222Rn), thoron (220Rn) and actinon (219Rn) resulting from the radioactive decay of the uranium, thorium and the actinium series. from the decay of 226 Ra, the immediate parent from the
238
222
Rn is formed
U series, while its isotope
220
Rn decays from 224Ra, a member of the 232Th series. Actinon results from the decay
of 223Ra from 235U series and is normally neglected because its presence is negligible in atmosphere. Radon being a gaseous element in the natural radioactive series gets diffused into the atmosphere from the earth’s crust. A national reference level for radon represents the maximum accepted radon concentration in a residential dwelling and is an important component of a national programme. For homes with radon concentrations above these levels remedial actions may be recommended or required. When setting a reference level, various national factors such as the distribution of radon, the number of existing homes with high radon concentrations, the arithmetic mean of indoor radon level and the prevalence of smoking should be taken into consideration. In view of the latest scientific data, WHO proposes a reference level of 100 Bqm-3 to minimize health hazards due to indoor radon exposure. However, if this level cannot be reached under the prevailing country-specific conditions, the chosen reference level should not exceed 300 Bqm- 3 which represents approximately 10 mSv per year according to recent calculations by the International Commission on Radiation Protection. When one talk about radon, the immediate interpretation comes to the mind is its radiation effect “lung cancer”. One should also know that radon can be used for many scientific applications. The 14
best known application of radon is its use in earth quake prediction. Being a noble gas the tectonic movements enhances the level of radon in soil hence, can be used as a precursor to an earth quake event. Experiments on mixing and transport of radon in air are made use in atmospheric studies. Sudden fall of radon levels in sea cost areas is an indication for the onslaught of rain in the region. Radon has many roles in ground water studies like (i)
Dating.
(ii)
Ground water movements
(iii)
Aquifer characteristics etc.
Two thirds of the total effective radiation dose to the average humans from all natural sources comes from radon and its progeny. Radon in homes is more concentrated and far more dangerous than outdoors. The National Academy of Sciences estimates that the outdoor radon causes only 800 out of the total of 21,000 lung cancer deaths in the US each year. But radon decay products, radioactive solid particles, much smaller than household dust, float in the air and get trapped in our lungs, trachea, and bronchi. At 4 pCi/L each liter of air contains 70,000 radon atoms. But less than 1% of the inhaled atoms get trapped and we thus accumulate in our airways about 600,000 radioactive particles every hour. They shoot out alpha particles that can pose severe health risk to the people.
1.16: Hydrological applications of radon 222
Rn occurs naturally in all groundwater systems the concentrations have been used
for range of applications. These concentrations may vary considerably between aquifers depending on lithology and geologic structure. Radon concentrations in stream water are usually several orders of magnitude lower than concentrations in groundwater. Radon is easy to sample and analyze. The great potential lies in the study of rapid mixing processes occurring on time scales from hours to days. Over short time scales, increase in radon concentration has been related to aquifer 15
residence time, and used to measure infiltration rates. Comparisons between radon concentrations in groundwater with those in surface waters receiving aquifer discharge have enabled locations groundwater discharge to be identified, and determination of discharge rate. Recently Radon concentration has been used to infer flow rates through fracture rock aquifer and as portioning tracer in the contaminated studies. The short half life of
222
Rn limits its applications in most regional flow systems,
where residence times exceed a few weeks. The large variability of
222
Rn
concentrations in groundwater, independent of dissolved 226Ra concentrations, further supports the idea that controls on
222
Rn concentrations in a given aquifer are
dependent on local aquifer characteristics (Krishnaswamy et al., 1982). radioactive noble gas. It is produced from
226
222
Rn is a
Ra in the radioactive decay. When
rainfall or surface water infiltrate into rock or soil, the concentration of groundwater increases due to radioactive decay of
222
Rn in the
226
Ra in soil or rock. After the
rainfall or the surface water infiltrate into rock or soil, about 3 weeks later, the rate of 222
Rn supply by radioactive decay of
the concentration of concentration of
222
226
Ra will be in a state of balance. At this time,
222
Rn in the groundwater reaches a stable state. Therefore, the
Rn in groundwater is much higher than surface water.
222
Rn in
surface flow comes from riverbed sediment or is recharged by groundwater; however, 222
Rn in the riverbed sediment is very scarce and can be omitted. Groundwater is the
only source of 222Rn in the surface flow.
222
Rn diffuses into the river, transfers to the
atmosphere due to radioactive decay and gas exchange.
16
Chapter 2 Review of literature 2.1: Lakes Rao et al., (1982) studied the physicochemical parameters and zooplankton diversity of perennial tank, Hutchammankere located near Anekal in Bangalore district for the period of two years. Increase in temperature was found to be favorable for zooplankton multiplication. Turbidity was found to affect phytoplankton production but had less influence on zooplankton. Thus, an inverse relationship was obtained between phytoplankton and zooplankton in relation to turbidity because of the grazing effects of zooplankton over phytoplankton. Chakrapani (1996) compared the physicochemical analysis and zooplankton diversity of 19 urban and 24 non-urban lakes. The zooplankton diversity of some of the urban and non-urban lakes was compared with the earlier study. The changes in the populations have indicated the influences of pollution on these lakes. Biological analysis indicated that lakes such Anekepalya, Bellandur, Chilkkahulimam, Harohalli, Kengeri, Kalkere, Nagavara, Nelamangala, Puttenahalli, Rachenahalli, Rampura,
Tavarakere,
Ulsoor,
Varthur,
Vengaiah,
Yellahehalli,
and
Yellamallappuchetty were threatened ecologically and unsuitable for human usage. Seasonal distribution of the population structure of zooplankton was studied in connection with physicochemical parameters in an experimental perennial fish culture pond in Calcutta, West Bengal by Sarkar and Choudary (1999). A significant multiple correlations involving the fluctuations of zooplankton number and concentration changes of dissolved oxygen, temperature, total alkalinity, total nitrogen, phosphate and pH was observed. Thus, the study confirms the influence of these abiotic factors on zooplankton population. Venkataraman et al., (2001) studied the faunal diversity of the wetlands in the Indian Botanical Garden, Haora, and West Bengal and found that the faunal diversity was dependent on the plants as well as the size of the wetland concerned and inversely related to anthropogenic activities. 17
The impact of urbanization on Bellandur Lake, Bangalore was studied by Chandrasekhar et al., (2003), which revealed higher values of alkalinity, BOD and COD and low levels of dissolved oxygen indicating the polluted nature of the lake. The urbanization of surrounding areas had let to the discharge of domestic sewage and industrial effluents into the lake, which contributed to the observed trends. Hydrobiological studies of lake Mirik in Darjeeling, Himalayas was studied by Jha and Barat (2003). The pH of the lake was found to be acidic in nature and other physicochemical parameters and plankton analysis confirmed that the lake was polluted due to contaminants let into the lake, though the values were diluted due to heavy monsoons. The study indicated that the lake cannot be used as a scarcity alternative for drinking water supply. The physicochemical and zooplankton analysis of the Shendurni river, Kerala was studied by Sahib (2004). The dissolved oxygen levels were observed to be highly saturated and a direct correlation between dissolved oxygen level and zooplankton populations were observed. A study on the physicochemical limnology and productivity of Jaisamand lake, Udaipur was conducted by Sharma and Sarang (2004). A positive correlation of water clarity with pH, total alkalinity, Electrical Conductivity, net primary productivity and gross primary productivity was observed. At the same time, a negative relationship was found for free carbon dioxide and nitrate. The decline in zooplankton population in the lake was due to the predatory effect of fish species tilapia. Awasthi and Tiwari (2004) studied the seasonal trends in abiotic factors in Govindgarh lake, Rewa, Madhya Pradesh and observed an inverse relationship between dissolved oxygen and temperature and opined that the lake was polluted. The lake was perennial and alkaline in nature. The parameters found to show marked seasonal variations include temperature, transparency, pH, dissolved oxygen, free carbon dioxide, alkalinity, calcium, chloride, nitrite and phosphate. Pandey and Verma (2004) studied the influence of catchment on chemical and biological characteristics of Baghdara lake and Udai Sagar lake in Southern Rajasthan. The two lakes were of constrasting features with Baghdara lake receiving 18
runoff from undisturbed woodlands ad Udai Sagar lake receiving runoff from urbanized regions. The physicochemical and biological analysis of both the lakes revealed that Udai Sagar lake was polluted and reaching eutrophic condition, whereas Baghdara lake was unpolluted. The study also shows that the dredging of sediment containing phosphorus as a restoration measure for eutrophic lakes was effective. G. Jeelani A. Q. Shah (2006) worked on geochemical characteristics of water and sediment from the Dal Lake, Kashmir Himalaya to monitor the natural and anthropogenic influences on the water and sediment chemistry of the Lake. They found that Lower pH, high TDS, EC and NO3 values in the Gagribal basin and in some patches of other basins were due to anthropogenic inputs in the form of sewage from surrounding population, houseboats, hotels, etc. Their data suggested that the Dal Lake is characterized by differential natural and anthropogenic influences. Aboud S. Jumbe et.al. (2008) studied 21 Bangalore lakes to get their ecological status particularly through the special prospective of human encroachment and pollution. They identified that the main pressure on the urban lakes is due to encroachment, eutrophication, sedimentation, weed infestation, untreated sewage and industrial effluent discharge, sand mining and deforestation around them. This pressure is largely attributed due to rapid and uncontrolled expansion of build-up area and unsustainable agricultural practices, i.e. anthropogenic activities. They concluded that the solution of this problem is to strictly enforce the laws and regulations of lakes and mass awareness about conservation of lakes. Bela Zutshi, et al. (2008) studied the impact of anthropogenic activity on the lake ecosystem in Bangalore Karnataka .They found that anthropogenic activities especially discharge of untreated industrial effluents and sewages into lakes results in depletion of DO, high chlorophil, TDS, BOD, Phosphates, NH3 and high alkalinity, which contributed to algal bloom and leads to mortality of fishes. They also found that because of man induced pollution, the diversity of phytoplankton and zooplanktons has drastically altered and declined as in majority of the lakes.
19
Bindiya et. al. (2008) made an attempt to get the picture of environmental degradation of Malathalli lake, Bangalore, India by assessed the physico-chemical parameters such as pH, dissolved oxygen, BOD, suspended solids, total dissolved solids, alkalinity, hardness, nitrates, phosphates, sulphates, sodium, potassium, fluorides and chlorides. They found that the lake is contaminated with organic pollution .DO has been found less than 3.5 mg/l which is not suitable for sensitive fish species, only few exotic species can survive in these conditions. The results obtained were average BOD is 6.0 mg/L. The pH is also above permissible limit at 8.9 showing alkaline nature of the lake. The chloride-bicarbonate ratio of 2.2 confirmed the seriousness of the status of pollution in the lake. Sankar Narayan Sinha and Mrinal Biswas (2011) studied the physic-chemical characteristics of the water quality of a Lake in Kalyani, West Bengal for a period of one year to assess the pollution status of the lake. They calculated water quality index using twelve physico-chemical parameters and found that the lake is atrophic as evidenced by shallow depth (2-4m), low transparency (14-34 NTU), low dissolved oxygen (2.5-6.0 mg/L) and higher concentrations of other nutrients such as phosphates, nitrates, sulphates and chlorides. They concluded that High value of WQI of the lake indicated high degree of pollution that makes water of this lake unsuitable for human consumption as well as for fish culture unless it is treated and disinfected properly. Durga Madhab Mahapatra et al. (2011) worked on assessment of treatment capabilities of Varthur Lake, Bangalore, India and their results revealed Alkalinity, TDS, conductivity and hardness values were higher when compared to earlier studies. Their study revealed that the lake behaves as an anaerobic and aerobic lagoon with a residence time of 4.8 days, treating the wastewater to a considerable extent. Rafiullah M. Khan et al., (2012) worked on physico chemical analysis of Triveni lake water of Amravati district in Maharashtra, India to obtain a picture of water quality inside the lake. They conducted physic-chemical analysis from December 2010 to November 2011 and their finding revealed that lake water is of better quality for 20
drinking purpose in winter and summer seasons in spite of fact that significant seasonal variation in some physicochemical parameters was observed.
2.2: Ground water Flourisis, one of the major problems due to excess Fluoride content has been investigated thoroughly by extensive research on ground water in Bhopal India by Suresh,et.al (1996). Mellout B. Azmon et.al (1997) have worked on salinization of ground water in Israel. According to them, aquifers near to seas are prone to be polluted with high salt concentration. They found that most of the aquifers near to seas in the study area posses salt concentration above permissible limits. High fluoride content in ground water Anigal district of Orissa has been reported by Das et.al (1999). Rengarej et.al (1999) made an attempt to assess the ground water quality in sub-urban region of Chennai city and found that all the samples exceeded the recommended limits for drinking water. Singh et.al. (2001) made an attempt to study ground water quality at Ponta Sahib Himachal Pradesh and their study indicated that some modifications or remedial measures are to be taken in the existing water supply as the water quality was unsatisfactory in most of study areas. Shyamala et al., (2002) worked on Physicochemical Analysis of Bore well water samples of Telungupalayam Area in Coimbatore District, Tamilnadu, India. They found that the pH, chloride ion, total hardness, calcium and COD values are well within the permissible limits. They also reported that TDS of one sampling station was well above the desirable limit and the average of alkalinity has exceeded the desirable limits which are due to improper drainage system of the dyeing units. They concluded that the water quality in the study area is fit for domestic and drinking purpose but need treatments to minimize the contamination especially the alkalinity.
21
Sandeep Pandey and Shweta Tiwari (2003) worked on Physico-chemical analysis of ground water of selected area of Ghazipur city. Their study revealed that almost all physico-chemical parameters were within the permissible limits laid by BIS. They concluded that the ground water can be used for domestic purpose but they also recommended that microbial analysis should also be carried out to get the precise picture of ground water potability in Ghazipur city (UP) India. Shashidhara and Balasubramanya (2004) made an effort to understand the present water demand, water supply status of Bangalore and also the role of ground water and its quality in the study area. They surveyed 101 households with a structured questionnaire methodology. The study revealed that the groundwater usage is about 38% even inspite of 100 % coverage in pipe water supply; Supply demand gap is around 1MLD; Groundwater level before year 2000 was around 150 ft and at present it has gone up to 400-500ft due to overdraft. Prakash and Somashekar (2004) studied the water quality of Anekal taluk of Bangalore district India by analyzing the water samples from various locations for physico-chemical and biological parameters. They found that in 81.48% of water samples were not suitable for domestic purposes as showed at least one of the parameter beyond the acceptable limit of BIS. They concluded that groundwater quality is gradually getting deteriorated and it may deteriorate further with time. So public should be made aware of the water quality importance and hygienic conditions before use. Neelakantarama et al. (2004) conducted a study of nitrate content in Jayamangali Subbasin in parts of Tumkur and Bangalore districts, which is underlain by gneisses, granites, schists and dolorite dykes. The study revealed that average nitrate concentration is 31.22 and 60.6 ppm in pre-monsoon and post-monsoon seasons respectively. Overall they found that 94.17 % of wells show seasonal variation. Anand et-al (2005) made an effort to understand the dependency of urban population on ground water in Bangalore, kolar and Chennai. They found that growth of bore wells in Bangalore city has increased from 5,000 to 450,000 in last three decades. During last five years, more than 100, 000 tube wells have been drilled in Bangalore 22
city to meet growing demands. In Kolar city, the study found 68% per cent dependency on groundwater but 97 per cent of it is non-potable. Neither the city Municipal Corporations nor the private suppliers of the state have been able to meet the growing demand in urban areas. A brief study on Chennai city revealed the dependency of groundwater on surrounding villages due to which the depth of water table has increased from 60-80 to 120-130 feet, thus making the water un-potable. Kumaresan and Hegde (2005) investigated Tumkur and Kolar district of Karnataka India for the presence of fluoride. They found that fluoride content in about 24% of the dug well samples and 61% of the bore well samples were more than 1.5 ppm. It was also observed that, there is a tendency of increase in fluoride concentration with depth. They guessed that fluoride is geogenic and it is probably released by the fluoride bearing minerals like fluorite and apatite, which occur as accessory minerals in the younger granites. They also proposed some remedial options like setting up of defluoridation plant, tapping alternative water source or quality improvement through dilution by practicing Rain Water Harvesting. Jasroti and Rajinder Singh (2005) estimated the ground water potential around Devak-Rui watersheds Jammu district (J&K) by analyzing various parameters like rainfall, runoff, infiltration, evaporation, transpiration, ground water recharge, discharge and movement. They found that precipitation was the main source of groundwater recharge. The other sources which replenish the groundwater are seepage from canal system, return flow from the applied irrigation, subsurface inflow from the adjoining region, recharge from the river system etc. They concluded with the final outcome that the net annual groundwater availability in the command and non command areas was together about 7438 ham. Nayak et al. (2005) studied the occurrence of high nitrate and fluoride content in ground water in hard rock terrain of north eastern parts of Kalahandi district Orissa. The study revealed that the main hydrological unit in the study area comprises of granite, charnokite, khondalite, and the thickness varies from few meters to a maximum of 15 meters. They found that ground water occurs under unconfined condition in the weathered mantle and under semi confined to confined in the deeper 23
fracture zone. They found that the ground water in the Precambrian terrain in study area is normal due to natural recharge to the phreatic aquifer. They also found that water quality in two patches mainly in Kesinga, parts of Bhawanipatna and Nerla blocks with EC more than 750μS/cm at 25˚C. 13 out of 15 ground water samples showed high content of nitrate above permissible limit of 45ppm and 4 out of 5 ground water samples showed Fluoride content higher than permissible limit of 1.5ppm; They concluded that ground water in most of the parts Kesinga block and its surroundings is unsuitable for domestic use. Sadashivaiah et.al (2006) worked on Hydrochemical Analysis and Evaluation of Groundwater Quality in Tumkur Taluk, Karnataka State, India. They found that the type of water that predominates in the study area is Ca-Mg-HCO3 type during both pre and post-monsoon seasons of the year 2006, based on hydro-chemical facies. On the basis of sodium adsorption ratio, residual sodium carbonate, sodium percent, salinity hazard, they concluded that ground water quality is suitable for irrigation. Arunabh Mishra and Vasishta Bhatt (2007) worked on Physico-Chemical and Microbiological Analysis of Under Ground Water in V.V Nagar and Nearby Places of Anand District,Gujarat, India. The study showed that the quality of water samples subjected to study was acceptable from majority of physico-chemical parameters while as per the bacteriological standards, the water needs to be treated before using it in domestic applications. Akhilesh Jinwal and Savita Dixit (2007) studied the Pre- and Post-Monsoon variation in Physico-Chemical Characteristics in Groundwater Quality of Bhopal "The City of Lakes" India. They found that the water quality was better in Post-monsoon season than Pre-monsoon season and concluded that the extent of pollution occurred due to over exploitation of ground water, urbanization and anthropogenic activities. Usha et al., (2008) carried out a study on assessment of ground water quality of Hebbal lake Bangalore and their study showed that positive correlation of TDS with Chloride, Ca, Mg ion concentrations and TH also showed positive correlation with Ca and Mg ion concentrations. 24
Chhaya Wagh et.al (2009) studied the physico-chemical analysis of ground water in Pravara area, district Ahmednagar, Maharashtra. They found that the ground water from few sampling stations is within permissible limit according to WHO and ISI standards. Rajendra Prasad et al., (2009) worked on Hydrochemical Characteristics and Evaluation of Groundwater Quality of Tumkur Amanikere Lake Watershed, Karnataka, India. They found that the type of water that predominated in the study area is Ca-Mg-Cl type. They also reported that all the water samples in the study area fall under hard to very hard water category. Venkateswara Rao et al. (2009) conducted a study on Spatial distribution of ground water quality information at Rajahmundry and its surrounding areas of Visakhapatnam, India. Their results revealed that pH increases from pre-monsoon to post-monsoon. Similarly the TDS values are decreasing from pre-monsoon to postmonsoon. The concentration of cations namely Ca, Mg, Na have recorded an increasing trend. The anions also indicated similar behavior. They concluded that besides the type of formation the ion exchange phenomena and the drainage network activity in the post-monsoon period contributed to the increase of these parameters. Udayalaxmi et al., (2010) worked on geochemical evaluation of groundwater quality in selected areas of Hyderabad, A.P., India. Their study revealed that groundwater in the entire region is too hard for drinking and they attributed the main cause river Musi, which acts as a carrier of domestic and industrial effluents. They also found that In and around Nacharam and Mallapur, the effluents discharged from the several industries are responsible for polluting the groundwater in the region, and in regions such as Jamai Osmania, Lallaguda and Lalapet are very densely populated and it is the domestic sewage in this area that is the primary cause of groundwater contamination. Nirdosh Patil et.al. (2010) studied the physico-chemical characteristics of ground water of Gulbarga city (Karnataka). Their study revealed that the overall water quality of Gulbarga city is very poor and unsuitable for drinking purposes. They recommended that top priority should be given to water quality monitoring and 25
indigenous technologies should be adopted to make water fit for drinking after treatment such as desalination and defluoridation. Prasanna et al. (2011) worked on Hydrogeochemical analysis and evaluation of groundwater quality in the Gadilam river basin, Tamil Nadu, India. The geochemical studies of the aquatic systems of the Gadilam river basin showed that the groundwater is near-acidic to alkaline and mostly oxidizing in nature. Higher concentration of Sodium and Chloride indicated leaching of secondary salts and anthropogenic impact by industry and salt water intrusion. Spatial distribution of EC indicates anthropogenic impact in the downstream side of the basin. They also found that few of the groundwater samples in the study area were unsuitable for domestic and drinking purposes. Suna et al., (2011) worked on fluoride contamination status of ground water in Karnataka India and found that Fluoride is highly sporadic and localized in eastern and southeastern Karnataka. The geological strata near the wells influence the fluoride content in phreatic groundwater. They also recommended biological defluoridation as the best alternative over conventional methods.
2.3: Radon Extensive studies have been conducted on the hydrological behavior and radiological significance of Radon and Radium around the world. Radium, radon and thoron are important radionuclides in the uranium and thorium decay series. (Birchard and Libby,1980; Hermansson et al. 1991). Several reports on the presence of dissolved radon in groundwater from northern India are also available (Vivek et al. 2002). Cecil et al., (1991) measured 222Rn and 226Ra concentrations in the bore well samples in Chickies quartzite of southern Pennsylvania, USA and found that radon and radium concentrations ranged from 3.2 to 907 Bq/l 0.004 to 4.44 Bq/l respectively. Kozin Ki et al. (1995) showed that the aquifer materials were the source of the dissolved
222
Rn in study of the Kirkwood- Cohansy system in southern New Jersey.
The majority of the wells contained 222Rn concentrations between 7 and 70 Bq/l. Concentration of
222
Rn were approximately two orders of magnitude greater than the 26
concentrations of dissolved
226
Ra in the groundwater samples, indicating that the source of the
222
Rn was not dissolved
226
Ra within this aquifer system and the data
correlated to the depth and the chemical composition of the water samples.. Choubey (1997) recorded radon concentrations in soil, air and groundwater in Bhilangana Valley, Garhwal Himalaya using an LR-115 plastic track detector and radon emanometer. His found that the measured radon concentrations varying from 1 KBq/m3 to 57 KBq/m3 in soil , 5 Bq/l to 887 Bq/l in water and 95 Bq/m3 to 208 Bq/m3 in air, the recorded values were quite high due to associated uranium mineralization in the area. Joseph and Rhett (1998) analyzed water samples collected in 1995 in the fluvial aquifers of the White River Basin were analyzed for radon and found that radon concentrations in the shallow wells ranged from 140 to 1,600 pCi/L (picocuries per liter). The analyses of the samples from the deep wells by them indicated that radon concentrations decrease with depth within the fluvial aquifers; the median concentration was 210 pCi/L. Virk et al., (2001) found radon concentrations ranging from 3.0–8.8 Bq/l in the groundwater samples from tube wells in Bathinda and Gurdaspur districts of Punjab, India. The radon concentration recorded in natural springs of Uttarkhand, West Bengal, Sikkim, and Bhutan by Virk (2002). The lowest and highest concentration recorded is 0.1 and 441.2 Bq/l (Swastik Burtu village near Gangtok, Sikkim) respectively. Due to high radon concentration in natural springs, the residents in the city and villages around Gangtok are likely to be exposed to radiation hazards following Consumption of potable spring water. Relatively higher concentrations of radon (25–92 Bq/l) were reported by Choubey et al., (2003) for groundwater from Quaternary alluvial gravels associated with uranium-rich sediments in the Doon Valley of the outer Himalayas.
27
Chapter 3 Relevance of the study Lakes and tanks are known to be ecological barometers of the health of the city as they regulate the micro-climate of the health of the centre. Inland water bodies have a profound effect on the ground water table and ground water quality of the nearby aquifers because of direct interaction between surface and ground water. Ground water is directly recharged by these inland surface water bodies and hence the quality of surface water will directly affect the nearby ground water aquifers. The presence of a lake in any region greatly influences the life of the people adjacent to it. Environmentally, lakes have a great significance due to following reasons: 1) Sources of water: surface and recharge of groundwater, for drinking and irrigation. 2) Supports livelihoods. 3) Food and nutrition. 4) Act as flood control measures. 5) Recreation. 6) Lakes are ‘natural infrastructure’ for climate change adaptation.
3.1: Scope of the study The environmental conditions of any lake system depend upon the nature of that lake and its exposure to various environmental factors. Their fragile ecosystem must maintain the state of environmental equilibrium with the existing surroundings particularly from a special prospective of human encroachment and pollution. Developmental pressures and increasing human population has made the lakes of the study area vulnerable to sewage flow, solid waste dumping, etc., in turn exerting pressure on the percolation and infiltration processes responsible for the groundwater recharge (Ravikumar et al., 2011).
However, the city’s population has already
touched 7.5 million with a daily floating population of 15 lakh and at present Bangalore spreads over 500sq km. If current projections are correct, Bangalore will 28
spread over 1500 sq km area by 2025 to accommodate a 10 million plus population. This is the ever rising concern in the race to save existing lakes of the city. Hence, the present work has been carried out with a focus to evaluate comparatively the prevailing water quality and potability of two lakes, Malathalli lake (viz., sewage fed lake) and Sankey tank (viz., rainfed lake) in addition to groundwater samples around these two lakes by analyzing physico-chemical and biological parameters in addition to radon estimation in both surface and groundwater samples. Further, effort has been made to understand the effect of urbanization and anthropogenic pressure on lake water quality, the study has been stressed on Sankey tank which lies in highly urbanized and Malathalli Lake is situated less urbanized area. Effort has also been made to obtain the overall picture of water quality of Sankey tank which is restored and maintained by BBMP; and Malathalli Lake which is under restoration by BDA.
3.2: Objectives of the study To analyze the physico-chemical and bacteriological parameters in the surface waters of Sankey tank and Malathalli lake. To analyze the physico-chemical parameters in the groundwater samples around Sankey tank and Malathalli lake. To estimate radon activity in surface waters of Sankey tank and Malathalli Lake and in groundwater samples in the surrounding area. To arrive at comparative study of water quality in and around Sankey tank and Malathalli lake.
29
Chapter -4 Study area 4.1: Bangalore Bangalore urban district was formed in the year 1986. Bangalore urban district especially, Bangalore city being capital city of Karnataka is central point for running the state administration. It is now known as BBMP, is the biggest urban area with an areal extent of 850sq.km. Bangalore, the fastest growing city in Asia, has recently attained the fame of ‘Silicon City”, due to its progressive trend in Information technology. The city, which was known as Garden City, is losing its lung space (greener patches) due to rapid urbanization and multifaceted industrial development. Now, after the IT boom the city has suddenly overgrown its size and the district administration is facing a challenging task for providing necessary infrastructures to the related economic activities, trade, commerce and housing facilities. Especially, the enormous pressure on water supply needs scientific planning and effective management of water resources, particularly ground water in the district. The district is located in the southeastern part of Karnataka. It is having an area of 2174 sq.km and is located between the north latitude 12°39' 32’’: 13°14' 13’’ and East longitude 77°19’44’’: 77°50'13’’. Bangalore city have undulating topology with varying altitudes with a mean altitude of 920m (3,020 ft) MSL. The district is bounded in all the directions by Bangalore rural district except in southeast, where the district is bounded by Dharmapuri district of Tamil Nadu state. The district is divided into three taluks namely Bangalore north, Bangalore south and Anekal taluks and is very well connected to all parts of the country and to different parts of world through air ways (With newly built international Air port), railways and road ways. There are 699 villages in the district with 122 grampanchayats. Major part of the district is drained by Shimsha and Kanva rivers of Cauvery basin i.e., Bangalore north and South taluks (Catchment area of 468 sq.km which includes Nelamangala and Magadi taluks of Bangalore rural also). Anekal taluk is drained by South Pennar river of Ponnaiyar basin, which takes its birth from Nandi hills and 30
flows towards south (Catchment area is 2005 sq.km which covers Devanahalli and Hoskote taluks of Bangalore rural district also. Ground water is the major source of irrigation in the district along with few tanks and lift irrigation schemes. Paddy and Ragi are the major crops grown in the district along with other subsidiary crops such as Maize, Cereals and Groundnut. Predominant geological formations are Granite, Gneiss. Ground water quality shows the presence of chemical constituents more than permissible limit (EC, F, AS, Fe, NO3) and the water is of Sodium Chloride type. Bangalore urban district receives 831mm rainfall annually. During the year 2005, Bangalore urban district received actual rainfall of 1342.7 mm in 69 rainy days. Of the total rainfall, contribution from southwestern monsoon is 54.18% and 26.53% is from northeastern monsoon. In addition to this, Pre-monsoon showers contribute significant rainfall of 18.53%. A perusal of the departures of actual rainfall from respective normal reveals that the Pre-monsoon season rainfall is highly variable. In case of monsoon season, the rainfall is either normal or above normal in most years. Post monsoon rainfall is also highly variable on annual basis. Typical monsoonal climate prevails in the district with major contribution of rainfall during southwest monsoon. In general, pre-humid to semi arid climatic conditions prevail in the district. Average temperature is around 23.1°C.
Fig 4.1: Mean Monthly Rainfall of Bangalore District (mm)
31
Table 4.1: General information about the study area i) Geographical area
2174 Sq.Km
ii) Number of tehsils/ blocks/ taluks
Three taluks, Bangalore North, Bangalore South and Anekal
iii) Number of panchayats/ villages
122/699
iv) Average annual Rainfall (mm)
831 mm
Table 4.2: Irrigation by different sources (area and no. of structures) Dug wells
581 ha
628 dug wells
Tube wells/Bore wells
10814 ha
12756 wells
Tanks/Ponds
2369 ha
517 structures
Net irrigated area
13764 ha
4.2: Ground water related problems All the three taluks constitutes urban agglomeration in the district. Bangalore city is located on a high mound of 900 mamsl with Arkavathy in the west and Ponnaiyar in the east. It is mainly covered under BBMP with 6 City Municipal corporations and one Taluk municipal corporation with an urban population of 57, 59,987. Urbanization has increased rapidly in the last two decades paving way for layouts and industries, which have wiped out many tanks and lakes, which were helpful in maintaining the ground water level. In urban area of Bangalore district, main problems affecting ground water are 1. Sewage pollution and Industrial pollution. 2. High Nitrate concentration in ground water. 3. Over exploitation of ground water resources. Rapid urbanization, IT boom, related economic activities, trade and commerce have exerted enormous pressure and this has increased the sewage waste into the lakes. Improper environmental planning has given room for establishment of new residential layouts without proper sewerage system and even if such systems have been provided, the same have not been connected to trunk sewers of BWSSB. The municipal effluents from such natural drains leading to tanks and lakes deteriorate the 32
quality of the water. Sedimentation of the pollutants has not only reduced the surface area of the water which in turn has increased evaporation rate, but has also reduced ground water levels on account of poor permeability with more and more silt, clay deposits, trash and toxic waste accumulation in the lakes year after year. Sewage pollution is seen in the western part of the city where the entire sewage is let into Vrishabhavathi river valley and most of the tanks are also polluted from sewage source due to haphazard urbanization. As per CGWB studies, most of the open wells/borewell situated in the vicinity of Vrishabhavathi river is polluted due to sewerage discharging into the river. However, impact assessment of artificial recharge structures in Bangalore University has shown that, there is improvement in the quality of ground water in and around Vrishabhavathi valley. Regarding industrial pollution, study of CGWB shows that, in Industrial belt of Peenya, Rajajinagar and Hoskote area, Ground water is slightly alkaline and indicated high concentration of chloride and magnesium in ground water and high nitrate in all the industrial belts of Peenya, Hoskeote, Rajajinagar and Kanakapura road. However water is free from bicarbonates. Nitrate concentration is the single major constraint for suitability of ground water for drinking is concerned. Major part of the shallow ground water i.e., 45 % of the area is affected by high nitrate content which may be due to natural sewage and industrial pollution whereas; deeper aquifer is not affected to that extent by high nitrate content. Over exploitation of ground water Resources: Rapid and unplanned urbanization has taken its toll on water resources of the district, especially the ground water with increased exploitation by bore wells dug up in all possible terrains. In view of the stage of the ground water development to the tune of 196- 200% and over exploitation of ground water resources water level has gone deeper thereby leaving the only solution of building up of ground water resource through artificial recharge and rainwater harvesting.
33
Fig 4.2: Growth of bore wells in Bangalore city during 2009 (Source: BWSSB, 2010)
Lakes of Bangalore occupy about 4.8% of city’s geographical area (640 sq. km) covering both urban and rural areas. Bangalore lakes have several direct use values apart from replenishing the groundwater table and influencing climate of the city. The lakes in Bangalore form a chain of hydrological connections through them. The flow of the water runs from north to south-east as well as south-west along the natural gradient of the land. During monsoon, the surplus water from the upstream lake flows down into the next lake in the chain and from there further down. This connectivity did not allow an overflow of water out of the lake into surrounding areas as the additional quantity of seasonal waters, thus, transferred to other lakes. The system, hence, served as an excellent flood controller. Supported by a network of storm water drains, these lakes, thus, trapped and stored rainwater and served as the means of rainwater harvesting for agriculture, drinking and washing (Deepa et al. 1998, Kiran and Ramachandra 1999, Ramachandra et al. 2001). Nowadays, due to rapid urbanization, almost 135 lakes have disappeared from the map of Bangalore. Lack of proper management strategies is the major factor that has led to the deterioration of lakes. Existing lakes too are under great pressure. Today the figure rests at 81, of these only 34 are recognized to be live lakes. In terms of number of water bodies, the reduction is as high as 35.09 percent, while in terms of 34
water spread area, it shows an 8.66 percent decrease. Sedimentation also has reduced the impounding capacity of lakes. The shallowness of water has increased evaporation rate. This has reduced groundwater levels on account of poor permeability with more and more silt, clay deposits, trash and toxic waste accumulation in the lakes, year after year and degeneration of groundwater quality. The water table has receded considerably and the water, which was available at a depth of 80 to 90 feet, has now increased to 400 to 500 feet and at some places it has completely vanished. There are around 2000 urban lakes in the State which were basically constructed to meet urban needs of the concerned towns. A fully fledged survey / demarcation / classification of lakes in the BMRDA area is yet to be completed, latest satellite imageries coupled with Toposheet of Survey of India, information have indicated that approximately 18260.48 ha of water spread in 2789 lakes in BMRDA area exists. Out of the above lakes, those falling in the BDA area, number 608 with water spread area of 4572.73 ha (Chakrapani 1988, Kiran & Ramachandra 1999, Kiran et al. 1998, Krishna et al. 1996).
Fig4.3: Location map and sapling sites of the study area
35
4.3: Sankey Tank Sankey tank, a manmade lake or tank is situated in the western part of Bangalore in the middle of the suburbs of Malleshwaram, Vyalikaval and Sadashiva Nagar in the Aramane nagara ward (ward no. 35). The lake covers an area of about 15 ha (37.1 acres). As per topo sheet, Area is 12.79 ha and perimeter is 2041.89 m. At its widest, the tank has a width of 800 m (2,624.7 ft). Sankey tank was constructed by Col. Richard Hieram Sankey (RE) of the Madras Sappers Regiment, in 1882, to meet the water
supply
demands
of
Bangalore.
The
tank
was
also
known
as
Gandhadhakotikere, as the Government Sandalwood Depot used to be located near the lake. Table 4.3: Basic information of Sankey tank Location
Bangalore District, Karnataka
Coordinates
13°01′N 77°34′E to 13.01; 77.57
Lake type
Freshwater
Primary inflows
Rainfall and city drainage
Catchment area Basin countries Surface area Max. depth Shore length Surface elevation
1.254 km (0.8 mi) India 15 ha (37.1 acres) 9.26 m (30.4 ft) 1.7 km (1.1 mi) 929.8 m (3,050.5 ft)
Islands Settlements Valley Current status Outlet
1 Bangalore Vrishabhavathy Polluted one outlet on the southern corner
History Sankey reservoir was constructed in 1882 and the works cost Rupees 575000. It was linked to the Miller's tank and Dharmambudhi tank and was built as a safeguard against water shortages, such as that experienced in the Great Famine of 1875-77. The quality of water was not very good and when Lord Connemara, Governor of Madras visited in July 1888 it was commented upon by a local wit: "The men who
36
are thrown off their horses and killed on the spot at Bangalore are the only ones that are allowed by doctors not to have died from drinking bad water".
Threats The threats posed to the survival of the lake, which were also identified by the local people (morning joggers) using the lake, refer to Contamination of water with sewage flowing in from seven points, which are connected to storm water drains Choked drains with garbage and sewage Leaking sewage pipes connected to a public toilet at a park Decrease in the biological oxygen demand and high BOD content due to sewage Reduction number of ducks, fish and migratory birds due to polluted condition of the lake waters
4.3.1: Restoration actions The tank was converted into a park by the Bangalore Water Supply and Sewerage Board (BWSSB) and the Bruhat Bangalore Mahanagara Palike (BBMP) with funds provided by the Government of Karnataka. In addition, the following were also implemented. Removing encroachments Alum purification treatment to absorb toxic elements and germs Nursery towards the north. Paved Walkways Landscaped parks Special tank for idol immersion during Ganesh Chaturthi festival Restoration of swimming pool
37
4.3.2: Legal land encroachment tangle In 2004, local builders’ proposal to construct a multistory building in the Sankey tank bed was challenged by petitioners in the Karnataka Lok Adalat (Peoples Court, an adjunct of the High Court). But the Court was informed by the Bangalore Mahanagar Palike (BMP) that it had not sanctioned any plan for the proposed building and that it would take immediate action to prevent any such steps by the developer taken without a no-objection certificate from the Ministry of Environment and Forests. The Lok Adalat ordered the Forest Department to repossess 0.52 ha (1.3 acres) of land belonging to it from the real estate developers who had set out to build an apartment block there. The Lake Development Authority also recommended that no construction or development activity should be allowed within a distance of 100 m (328.1 ft) from lakes in order to ensure that the water bodies in the city are not encroached and their conservation and protection are not stalled. The Karnataka State Pollution Control Board (KSPCB) informed the court that the proposal of Abhishek Builders and Mantri Developers to build an 18–floor luxury apartment block near the Sankey Tank has been turned down as gross violations were noted under the Air (Prevention and Control of Pollution) Act and the Water (Prevention and Control of Pollution) Act.
4.6: Malathahalli Lake Malathalli Lake is located on the western fringe of Bangalore city, adjacent to the Bangalore University campus at Kengeri in Malathalli Village. The lake is situtated in the ward Herohalli ward (ward no.72) and is located at about 11 kms from the heart of the city. It is situated between north latitude 13°50’ and 13° 55’ and East longitude 77° 34’ and 77° 36’. The new B.D.A. layout, namely Visvesvaraya layout (8th Block) is located towards west and block 9 in the eastern side of the lake. The lake is irregular in shape and covers approximately 25.9ha and perimeter being approximately 2900 meters. Malathahalli Lake is 20.62 ha. The total area of the Malathalli Lake including boundary line and bunds is about 29.274 ha. As per Topo 38
sheet, the total area is 24.26 ha and perimeter is 2756.42 ha. The shore line length of the lake is 2,700m and length of the bund is 436m. The water shed area of the Malathahalli Lake is 6.18sq.km. The main source of water is rainwater, and the inlets are at the north and northeast of the lake. Malathalli lake falls in the Vrishabhavathi lake valley and Byramangala lake series. The catchment area of the lake is about 625ha. Digitized lake boundary from Toposheet No. 57H/5 using ArcGIS gave the area of 27.53 ha. It was observed that the lake area has reduced from 27.53ha. to 25.95ha. The highest point was 900m above sea level and lowest point was 840m above MSL.
4.4.1: Pollution sources Malathalli Lake is affected by several sources of pollution including washing of clothes, animals, vehicles and even bathing, especially on the northern and eastern banks of the lake. These activities lead to pollution of the lake by soaps, detergents and organic matter, and are taking place almost all around the lake. The lake area is also misused as public toilets leading to the unhygienic environment and increasing the organic load in the lake. To the south of the lake, its banks are used as crematorium. Dumping of garbage and other wastes around the lake is taking place, which not only pollutes the lake but also spoils its beauty. To the west of the lake, there is an Areca plantation surrounded by several housing encroachments. The sewage line enters the lake from north-east and eastern banks of the lake. Cattle grazing can be seen to the west and north of the lake. The volume of the lake is decreasing due to the accumulation of silt coming from the run off. There are a number of upcoming layouts around the lake, which may affect the water both quantitatively and qualitatively.
4.4.2: Flora and fauna of the two lakes Following were the different types of plants seen in and around the lake: Ipomoea fistulosa, Calotropis, Lantana, Datura, Bambusa, Ficus religiosa, Acacia, Cocus nucifera, Typha, Cassia auriculata, Cassia renegira, Delonix religia, Croton 39
sparciflorus, Pongamia,Hypnus, Peltoforum, Polygonum, Azardichta indica, Musa, Duranta, Psidium, Chara, Nitella,Vallisneria, Elodea, Hydrilla and a variety of grasses. Following were the different types of animals seen in and around the lake Birds - Phalaerocorax fuscicollis (large cormorant), Egretta garzetta (egret), Dicrurus paradiseus (drongo), Ardeola grayii (pond heron), Halcyon smyrnensis (kingfisher), Milvus mygrans (kites), Columba livia (pigeons), Corvus splendens (crows). Animals - Bos gaurus (cattle), Calotes versicolor (garden lizard), Rattus rattus (rodents), Rana tigrina (frog), Bufo malanostictus (frog). Insects Periplaneta americana (cockroach), Poecilocerus piclus (grasshopper), Gryllus domesticus (crickets), Oryctes rhinoceros (beetles), Papilio species (butterflies), Musca domestica (house fly),Drosophila melanogaster (drosophila), Oechophylla smaragdina (ants), mosquitoes, millipedes, centipedes and water striders.
40
CHAPTER 5 Materials and Methods 5.1: Sample collection Random sampling has been adopted to collect groundwater samples. The samples were collected in polythene containers of 2 liters capacity for physicochemical analysis after pumping out sufficient quantity of water from the source such that, the sample collected served as a representative sample. Water samples were collected in 2-litre plastic containers previously cleaned with 1:1 HNO3. The analysis of water samples was carried out by following standard methods (APHA, 2005). The parameters such as pH, Temperature (Water and Air), Electrical Conductivity, Total Dissolved Solids and Dissolved oxygen were analyzed in the sampling spots, while for other parameters, the samples were transferred to the laboratory (APHA, 2005). The sampling points were selected so as the water samples represent the entire lake. The geographic location of all the sampling points was noted down using GPS. Both ground and lake water was assessed by the analysis of physicochemical such as pH, colour, turbidity, electrical conductivity, total dissolved solids, alkalinity, chlorides, total hardness, calcium hardness, nitrates, sulphates, iron, fluorides) etc., using standard methods (APHA, 2005). Table 5.1: physico-chemical analysis procedures and respective standards Sl. No
Characteristics
Analytical method
Unit
BIS limits (1998) Desirable Permissible
1
pH
Electrode
-----
6.5-8.5
6.5-8.5
2
Redox potential (Eh)
Electrode
mV
NA
NA
µS/cm
2000
3000
mg/L
1000
2000
mg/L
200
600
C
NA
NA
3 4 5
Electrical Conductivity (EC) Total Dissolved Solids (TDS) Total Alkalinity (as CaCO3)
Conductivity-TDS meter Conductivity-TDS meter Titrimetric Electrode
0
6
Temperature
7
Total hardness (as CaCO3)
EDTA Titrimetric
mg/L
300
600
8
Calcium hardness (as CaCO3)
EDTA Titrimetric
mg/L
75
200
9
Colour
HACH DR/890 Portable Colorimeter
Hazen s
10
25
41
10
Turbidity 2+
EDTA Titrimetric EDTA Titrimetric
NTU
5
10
mg/L mg/L
75 30
200 100
mg/L
200
mg/L mg/L mg/L mg/L
100 10 NA NA 250
10 NA NA 1000
mg/L
45
45
mg/L
1.0
1.5
11 12
Calcium (as Ca ) Magnesium (as Mg2+)
13
Sodium (as Na+)
14 15 16 17
Potassium (as K2+) Bicarbonates (as HCO3-) Carbonates (as CO32-) Chlorides
18
Nitrates (as NO3-)
19
Fluoride (as F-)
ISE (Ion Selective electrode)
20
Phosphates (as PO43-)
Stannous chloride
mg/L
21
Sulphates (as SO42-)
Barium chloride
mg/L
22
Dissolved oxygen (DO)
23
BOD
Modified Winkler's method
24
Free CO2
25
COD
26
Silica
27
Iron
Flame photometric Titrimetric Titrimetric Argentometric
0.3
0.3 400
mg/L
200 NA
mg/L
NA
< 3 mg/L
Titrimetric method
mg/L
NA
COD digester Spectrophotometric method HACH Colorimeter (1,10-Phenanthroline method)
mg/L
NA
NA
mg/L
NA
NA
mg/L
0.3 mg/L
1.0 mg/L
Note: NA – not available
5.2: Radon estimation In case of Radon, the water sample has been collected in the 250 ml glass bottle establishes a closed air – water loop to aid the radon to strip in water. From the field, the sample bottles were transported very carefully to the laboratory for radon analysis. The diagrammatic presentation of radon detector is given in fig 6.1. The ions are collected in energy specific windows which eliminate interference and maintain very low backgrounds. 222Rn activities are expressed in Bq/m3 (disintegration per second per m3) with 2 σ uncertainties. A specially fabricated aerating system is used to air the water sample that free the radon in water. This radon gas is collected through the energy specific windows and counted for the radon concentration. The time elapsed for the sample collection and analysis is corrected with the following equation C = C0e-λt 42
Where C= measured concentration, C0= initial concentration (to be calculate) after the decay correction, t= time elapsed since collection (days). This instrument is helpful in the analysis radon in air and water. The in situ field monitor system is similar to the system proposed by Brunett et al., for the radon in air. The radon in the air is continuously pumped through a desiccant. The purpose of desiccant is to remove moisture. In this case the water sample collected in the 250 ml bottle establishes a closed air – water loop to aid the radon to strip in water. The diagrammatic presentation of radon detector is given in Fig 5.1. The RAD monitor uses a high electric field above a silicon semi conductor that detects the ground potential to attract the positively charged polonium daughters,218Po+(t1/2=3.1 min; alpha energy =6.00 MeV) and 214Po+(t1/2= 164 μs; alpha energy =7.67 MeV), which are counted as a measure of
222
Rn concentration in
air. The ions are collected in energy specific windows which eliminate interference and maintain very low backgrounds.
222
Rn activities are expressed in Bq/m3
(disintegration per second per m3) with 2 σ uncertainties. A specially fabricated aerating system is used to strip the radon in water. The system uses the bubbling air in closed loop. This radon gas after passing through the desiccant which will free from moisture is collect through the energy specific windows and counted for the radon concentration. The time elapsed for the sample collection and analysis will corrected with the following equation C = C0e-λt (1) Where C= measured concentration, C0= initial concentration (to be calculate) after the decay correction, t= time elapsed since collection (days).
43
Fig 5.1: Diagrammatic view of Radon monitor in water
5.3: Bacteriological analysis (fecal coliform test) Membrane filter method has been used to detect the fecal coliform colonies by using MFC-MUG agar, this agar is specific for the cultivation and culturing of fecal coliforms.
PROCEDURE: 100 ml of water sample has been passed through a thin sterile membrane filter (pore size 0.45µm) which has been kept in a special filter apparatus contained in a sunction flask. The filter disc that contains the trapped microorganisms has been aseptically transferred in sterile Petri-plates having a solidified agar surface. Then the plates were incubated for 24 hours at 37°C in an inverted position. Then, the results were tabulated by using this formula. 𝑵𝒐. 𝒐𝒇 𝒄𝒐𝒍𝒐𝒏𝒊𝒆𝒔 𝒊𝒏 𝟏𝟎𝟎 𝒎𝒍 𝒘𝒂𝒕𝒆𝒓 𝒔𝒂𝒎𝒑𝒍𝒆 =
44
𝒄𝒐𝒍𝒐𝒏𝒚 𝒄𝒐𝒖𝒏𝒕 × 𝟏𝟎𝟎 𝒗𝒐𝒍. 𝒐𝒇 𝒔𝒂𝒎𝒑𝒍𝒆 𝒕𝒂𝒌𝒆𝒏
Chapter 6 Results and discussion 6.1: Dissolved oxygen Dissolved oxygen is an important parameter of water quality and is an index of chemical and biological processes taking place in the water (APHA 1985). DO is inversely related with temperature and with the increase in temperature the amount of DO gets decreased (Thomas L. Crisman et.al 1998).
Also, to the degree that
pollution contributes oxygen-demanding organic matter (like sewage or lawn clippings) or nutrients that stimulate growth of organic matter, pollution causes a decrease in average DO concentrations. If the organic matter is formed in the lake, for example by algae growth, at least some oxygen is produced during growth to offset the eventual loss of oxygen during decomposition. However, in lakes where a large portion of the organic matter is brought in from outside the lake, the balance between oxygen production and oxygen consumption becomes skewed and low DO may become even more of a problem. Total dissolved gas concentrations in water should not exceed 110 percent. Concentrations above this level can be harmful to aquatic life. Fish in waters containing excessive dissolved gases may suffer from "gas bubble disease"; however, this is a very rare occurrence. The bubbles block the flow of blood through blood vessels causing death. (Bowling, L. C. 1990) In the present study, In the Malathalli Lake water, the DO concentration varied from 9.47 mg/l in the month of March to 6.7 mg/l in the month of May with an average value of 8.57 mg/l. For Sankey tank the highest value of DO has been found 8.9 mg/l in the month of March and lowest 6.2 mg/l in the month of May with a mean value of 7.26 mg/l. DO concentrations showed slight decrease from March to May in both the lakes, the reason might be due to increase in ambient air temperature during summer, leading to increase in lake water temperature.
45
DO concentration has been found much higher in Malathalli lake compared to Sankey tank, The source for higher DO in Malathalli lake might be due to eutrophic condition of the lake, which lead to increase is phytoplankton and algal biomass of the lake and due to their photosynthetic activity ,the DO level increases. Another source is aeration given to sewage water during various processes in sewage treatment plant. The DO concentration in Malathalli Lake has been found good enough to support aquatic flora and fauna but due to algal toxin the biota can get
DO concentration in mg/l
affected especially fishes as the lake is in a very high eutrophic state.
10 9 8 7 6 5 4 3 2 1 0
9.2
8.9
7.8
7.7
7.5 6.2 SANKEY TANK MALATHALLI LAKE
MARCH
APRIL
MAY
2012
Fig 6.1: Variation in DO values between Sankey tank and Malathahalli Lake
8 7
DO (mg/l)
6 5 4
MALATHALLI LAKE
3
SANKEY TANK
2 1 0 1
2
3
4
5
6
7
8
9
Sample ID
Fig 6.2: DO variation in bore wells around the two lakes
46
10
11
12
DO concentrations have significant effect upon ground water quality by regulating the valence state of trace metals and by constraining the bacterial metabolism of dissolved organic matter. (Seth Rose 1988). The source for DO in ground water can be air gapes, fractures and chemical reactions which release O2 as their final product or byproducts. Bore wells around the lakes showed a significant variation in DO concentration. The DO values ranged from 5.1 to 6.9 mg/l with a mean value of 5.4 mg/l and 3.5 - 7.1 mg/l with an average value of 5.9 mg /l for groundwater samples collected around Sankey tank and Malathalli Lake respectively.
6.2: pH The term “pH” is defined as the negative logarithm of the hydrogen ion (H+) concentration as it conveniently expresses the acidity or basicity of water. Each change of one pH unit represents a ten-fold change in hydrogen ion concentration. The pH scale is usually represented as ranging from 0 to 14, but pH can extend beyond those values. The alkalinity of natural waters is controlled by the concentration of hydroxide and represented by a pH greater than 7. This is usually an indication of the amount of carbonates, and bicarbonates that shift the equilibrium producing [OH-]. Other contributors to an alkaline pH include boron, phosphorous, nitrogen containing compounds and potassium. Most fish can tolerate pH values of about 5.0 to 9.0, but serious anglers look for waters between pH 6.5 and 8.2. The present study showed that pH range for Malathalli Lake ranged from 8.5 in the month of March to 9.5 in the month of May with an average value of 8.7. Sankey tank water showed a range of 8.2 in the month of May to 9.2 in the month of March with a mean value of 8.5 mg/l. All the samples in Malathalli Lake were found above the standard desirable limit except for March samples and in Sankey tank, all the samples were found within the desirable limit of BIS (1998) which is 6.5 to 8.5 except for the samples of March. 47
Ground water samples around Malathalli Lake showed the highest value of 9.8 and lowest value of 7.2 with an average of 8.7 and out of 12 samples, 7 samples were found above the desirable limit of BIS. Around Sankey tank, the pH of the samples ranged from 7.8 to 8.9 with an average of 7.9. Out of 12 samples 3 samples were found above the desirable limit of BIS. The source could be either industrial seepage or geological causes like the ground water at most of the sites is dominated by Ca and OH ions in equilibrium with Ca(OH)2. Human activities have also produced the extremely alkaline ground water found around steel mills and slag dumps. In the study area, 3 samples out of 12 groundwater samples were found exceeding the acceptable limit of BIS. The water tends to be more alkaline when it possesses carbonates (Zafar, 1966; Suryanarayana, 1995). The pH of surface waters is important to aquatic life because pH affects the ability of fish and other aquatic organisms to regulate basic life-sustaining physiological processes, primarily the exchanges of respiratory gasses and salts with the water in which they live. High pH value induces the formation of trihalomethanes, which are toxic, while pH below 6.5 starts corrosion in pipe thereby releasing toxic metals such as zinc, lead, cadmium and copper (Shrivastava and Patil, 2002).
8.9
9 8.8
8.5
8.5 SANKEY TANK
pH
8.6
8.8 8.7
8.3
8.4 8.2 8 March
April
May
2012
Fig 6.3: pH variation in the two lakes
48
MALATHALLI LAKE
10 9.5 9
pH
8.5 8 7.5
MALATHALLI LAKE SANKEY TANK
7 6.5 6 A
B
C
D
E
F
G
H
I
J
K
L
SAMPLE ID
Fig 6.4: pH variation in the ground water around the two lakes
The acceptable range of pH to aquatic life, particularly fish, depends on numerous other factors, including prior pH acclimatization, water temperature, dissolved oxygen concentration, and the concentrations and ratios of various cations and anions (McKee and Wolf 1963). Alabaster and Lloyd (1980) identified the pH range that is not directly lethal to freshwater fish as 5.0-9.0. With few exceptions, pH values between 6.5 and 9.0 are satisfactory, on a long-term basis, for fish and other freshwater aquatic life. But, some aquatic organisms (e.g., certain species of algae) have been found to live at pH 2 and lower and others at pH 10 and higher (NAS 1972). However, there are few such organisms, and their extreme tolerances are not reflective of the pH tolerated by the majority of organisms occurring in a given aquatic ecosystem.
6.3: Electrical Conductivity EC is actually a measure of the ionic activity of a solution in term of its capacity to transmit current and is expressed in terms of milli Siemens per meter [mS/m] in SI and millimhos per centimeter [mmhos/cm]. Because water is such a good solvent, it almost always has some solute dissolved in it, often a salt. If water has even a tiny amount of such an impurity, then it can conduct electricity far more readily. Electrical conductivity is a measure of water’s capacity to conduct electric current. As most of 49
the salts in the water are present in the ionic form, are responsible to conduct electric
EC (µmho/cm)
current.
2000 1800 1600 1400 1200 1000 800 600 400 200 0
1836.7
1777.9
1762.5
SANKEY TANK 462.5
462.7
March
384.6
April
MALATHALLI LAKE
May
2012
Fig 6.5: EC variation in the two lakes
Electrical conductivity value Malathalli lake water varied from 1777 µS/cm (March 2012) to 1833.7 µS/cm (April 2012) with a mean of 1797.8 µS/cm. For Sankey tank, the EC varied from 395.7µS/cm in the month of May to 551.6 S/cm in the month of March with an average value of 433.1 µS/cm. BIS desirable limit for EC is 500µS/cm. For Malathalli lake the , all the samples were found above the desirable limit of BIS, But for Sankey tank, in the month of April, samples were found above permissible limit but in rest of the months, the EC value has been found well within the desirable limit of BIS. Form the table 5.1, it has been found that Malathalli Lake falls under the category of permissible and Sankey tank falls under the good category for irrigation.
50
1000 900
EC (µS/cm)
800 700 600 500
MALATHALLI LAKE
400 SANKEY TANK
300 200 100 1
2
3
4
5
6
7
8
9
10
11
12
Sample ID
Fig 6.6: EC variation in ground water around the two lakes
For irrigation waters are classified according to electrical conductivity data as follows, (Manivasakam 2003)
Table 6.1: Classification of water based on electrical conductivity data for irrigation EC in µS/cm at 25°C
Class
Sankey
Tank Sankey
Malathahalli
Malathalli
ground
lake (µS/cm)
ground
(µS/cm )
water < 250
Excellent
250 – 750
Good
750 – 2000
Permissible
2000 – 3000
Doubtful
> 3000
Unsuitable
433.1
water
585.75 1797.8
1161.6
Generally, groundwater tends to have high electrical conductivity due to the presence of high amount of dissolved salts. EC value for ground water samples around Malathalli Lake varied from 1018 µS/cm to 1288 µS/cm with an average value of 1161.6µS/cm. For Sankey tank the EC variation has been found from 355 µS/cm to 862 µS/cm with a mean value of 585.75 µS/cm. Electrical conductivity is a decisive parameter in determining suitability of water for a particular purpose. From Table 6.1: it has been found that ground water around Malathalli lake come under the category of permissible and ground water around Sankey tank water falls under the good category for irrigation. 51
6.4: Total Dissolved Solids (TDS) Total Dissolved Solids is a measure of the total ions in solution as it measures the combined content of all inorganic salts, small amount of organic matter and dissolved gasses contained in a liquid in molecular, ionized or micro-granular (colloidal sol) suspended form. It is used as an indication of aesthetic characteristics of drinking water and as an aggregate indicator of the presence of a broad array of chemical contaminants. Total dissolved solids are normally discussed only for freshwater systems, as salinity comprises some of the ions constituting the TDS. The principal application of TDS is in the study of water quality for streams, rivers and lakes; although TDS is not generally considered a primary pollutant (e.g. it is not deemed to be associated with health effects). Primary sources for TDS in receiving waters are agricultural and residential runoff, leaching of soil contamination and point source water pollution discharge from industrial or sewage treatment plants. TDS values will change when ions are introduced to water from salts, acids, bases, hardwater minerals, or soluble gases that ionize in solution. The most common chemical constituents are calcium, phosphates, nitrates, sodium, potassium and chloride which are found in nutrient runoff, general storm water runoff and runoff from snowy climates where road de-icing salts are applied. The chemicals may be cations, anions, molecules or agglomerations on the order of one thousand or fewer molecules, so long as a soluble micro-granule is formed. A high concentration of dissolved ions is not, by itself, an indication that a stream is polluted or unhealthy. It is normal for streams to dissolve and accumulate fairly high concentrations of ions from the minerals in the rocks and soils over which they flow. If these deposits contain salts (sodium chloride or potassium chloride) or limestone (calcium carbonate), then significant concentrations of ions will result. Total solids refer to any matter either suspended or dissolved in water. Everything that retained by a filter is considered a suspended solid, while those that passed through are classified
52
as dissolved solids, i.e. usually 0.45μ in size (American Public Health Association. 1998). The TDS values varied from 921 mg/l (March) to 1113 mg/l (May) with a mean value of 1062.7 mg/l for Malathalli lake water. For Sankey tank water, TDS concentration varied from 192.7 mg/l (May) to 316.7 mg/l (April) with a mean of 265.2. BIS desirable limit for TDS is 1000 mg/l. Malathalli lake water showed TDS above desirable limit in the month of April and May but for Sankey tank all the samples were found well within the standard limit of BIS.
1200
TDS ( mg/l)
1000 800 SANKEY TANK
600
MALATHALLI LAKE
400 200 0 March
April
May
Fig 6.7: TDS variation in the two lakes
For ground water around the Malathalli the maximum value of 908 mg/l and the minimum value of 528 mg/l have been found with an average of 670.4 mg/l. 3 samples out of 12 samples fall under the non-saline category and rest of the samples have been found slightly saline. For Sankey tank the TDS has been found to vary from 213.6 mg/l to 517 mg /l with a mean value of 337.8 mg/l and all the samples have been found under non-saline category.TDS values for the ground water samples around both the lakes have been found well within the desirable limit prescribed by BIS 1998. 53
1000 900
TDS in mg/l
800
700 600 500
MALATHALLI LAKE
400
SANKEY TANK
300 200 100 1
2
3
4
5
6
7
8
9
10
11
12
SAMPLE ID
Fig 6.8: TDS in groundwater samples around the two lakes Table 6.2 TDS in water is classified as above: (Catrol 1962) Range Sankey Tank CLASSIFICATION
TDS in mg/l Inside
lake
(mg/l) Non – saline
Malathalli lake
< 1000
192.7
Ground water
Inside lake
to 213.6 to 517 921 – 1113
316.7
(12 samples)
(27 samples)
(27 samples) Slightly saline
1000 – 3000
Moderately saline
3000 – 10000
Very saline
> 10000
Ground water 528 – 908 (12 samples)
From the Table 6.2 it has been found that, Malathalli lake water was slightly saline category and Sankey tank water has been found to fall under non saline category. Table 6.3 TDS groundwater is classified as above: (Hem’s classification (1970) SERIAL NO. 1 2 3 4 5
LIVESTOCK poultry pigs horses cattle sheep (adult)
TDS (mg/l) 2860 5290 6435 7150 12,900
As per the table 6.3, both lake water as well as ground water around the lakes has been found to be suitable for livestock consumption. 54
6.5: Colour The main causes of coloration are elevated organic activity with algal growth and saturation / presence of soluble minerals in the vicinity of a water body. Suspended and dissolved particles in water influence color. Suspended material in water bodies may be a result of natural causes and/or human activity. Transparent water with a low accumulation of dissolved materials appears blue and indicates low productivity. Dissolved organic matter, such as humus, peat or decaying plant matter, can produce a yellow or brown color. Some algae or dinoflagellates produce reddish or deep yellow waters. Water rich in phytoplankton and other algae usually appears green. Soil runoff produces a variety of yellow, red, brown and gray colors. Weathered rocks and soils, the land-use activity and the type of trees and plants growing within the watershed will influence the types and amount of dissolved and suspended material found in a lake or stream. Color may also be affected by the concentration of natural dissolved organic acids such as tannins and lignins, which give water a tea color. These are formed when plant material is slowly broken down by organisms into very small particles that are dissolved into water. Tannins that are yellow to black in color are the most abundant kind found in lakes and streams and can have a great influence on water color. Naturally occurring organic compounds such as tannins and lignins, derived from the decomposition of plant and animal matter, can give surface water and groundwater a tea-like yellow-brown hue, as well as a musty smell, is known for its "root beer" color. Present study revealed that the water in both the lakes was found coloured and above permissible limit prescribed by BIS. The colour varied from 98.3 hazens in the month of March to 215.3 hazens in the month of May with a mean value of 151.9 hazens in the Sankey tank and in Malathalli lake water, the highest value has been observed in the month of March with a value of 151 hazens and lowest value of 508 hazens in the month of May with a mean of 371 hazens.
55
colour in Hazen units
500 400 300 SANKEY TANK 200
MALATHALLI LAKE
100 0 March
April
May
2012
Fig 6.9: Colour variation in the two lakes
Ground water around Sankey tank showed more colour as compared to ground water samples around Malathalli Lake. The highest colour value for ground water samples around Malathalli Lake was 10 hazens and lowest was zero with an average value of 2.9 hazens. For Sankey tank ground water samples, the highest colour value has been found 46 hazens and lowest has been found 01 hazens with an average of 23 hazens.
Colour (Hazen units)
50 40 30 MALATHALLI LAKE
20
SANKEY TANK 10
0 1
2
3
4
5
6
7
8
9
10
11
12
sample ID
Fig 6.10: Colour variation in borewell samples around the two lakes
6.6: Turbidity Turbidity is an important parameter for characterizing the quality of water. Turbidity in water may be due to wide variety of suspended materials, which range in size from colloidal to coarse dispersions, depending upon the degree of turbulence. 56
The
characteristics of turbidity in surface water supplies are a function of many factors like watershed features, such as geology, human development (i.e., agricultural uses or urban development), topography, vegetation, and precipitation events can all greatly influence raw water turbidity. In drinking water, the higher the turbidity level, the higher the risk that people may develop gastrointestinal
diseases.
This
is
especially
problematic
for
immunocompromised people, because contaminants like viruses or bacteria can become attached to the suspended solid. The suspended solids interfere with water disinfection with chlorine because the particles act as shields for the virus and bacteria. Similarly, the particles of turbidity provide “shelter” for microbes by reducing their exposure to attack by disinfectants and ultraviolet (UV) during sterilization of water. Typical sources of turbidity in drinking water include the following: a. Waste discharges; b. Runoff from watersheds, especially those that are disturbed or eroding or from urban drainage area; c. Growth of phytoplankton, especially Algae or aquatic weeds and products of their breakdown in water reservoirs, rivers, or lakes; d. Humic acids and other organic compounds resulting from decay of plants, leaves, etc. in water sources; and e. High iron concentrations which give waters a rust-red coloration (mainly in ground water and ground water under the direct influence of surface water). f. Air bubbles and particles from the treatment process (e.g., hydroxides, lime softening) g. Human activities that disturb land, such as construction, can lead to high sediment levels entering water bodies during rain storms due to storm water runoff h. Certain industries such as quarrying, mining and coal recovery can generate very high levels of turbidity from colloidal rock particles 57
The values of turbidity varied between 15.6 (March) to 29.6 NTU (April) for Sankey tank with a mean of 32.2 NTU and for Malathalli it ranged from 12 to 66 NTU with a mean of 44.3 NTU. The highest desirable limit for turbidity is 10 NTU prescribed by BIS; hence all the samples from both the lakes showed turbidity values above BIS standards of 1998.
Fig 6.11: Turbidity of the two lakes
Turbidity values in groundwater around the Malathalli lake ranged from 0 – 2 NTU with a mean of 1 NTU and 0 to 8 NTU with a mean of 4.4 NTU for ground water around Sankey. So ground water around both the lakes showed turbidity within the
Turbidity in NTU
desirable limit of BIS. 9 8 7 6 5 4 3 2 1 0
MALATHALLI LAKE SANKEY TANK 1
2
3
4
5
6
7
8
9
10
SAMPLE ID
Fig 6.12: Turbidity variation in ground water around the two lakes
58
11
12
6.7: Biochemical Oxygen Demand (BOD) Biochemical oxygen demand is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period. The BOD value is most commonly expressed in milligrams of oxygen consumed per litre of sample during 5 days of incubation at 20 °C and is often used as a robust surrogate of the degree of organic pollution of water. Biochemical oxygen demand is the amount of oxygen required for microbial metabolism of organic compounds in water. In other words, Biochemical oxygen demand is a measure of the quantity of oxygen required by microorganisms (e.g., aerobic bacteria) in the oxidation of organic matter to obtain energy for growth and reproduction. This demand occurs over some variable period of time depending on temperature, nutrient concentrations, and the enzymes available to indigenous microbial populations. Total biochemical oxygen demand (total BOD). The amount of oxygen required to completely oxidize the organic compounds to carbon dioxide and water through generations of microbial growth, death, decay, and cannibalism. Total BOD is of more significance to food webs than to water quality. Dissolved oxygen depletion is most likely to become evident during the initial aquatic microbial population explosion in response to a large amount of organic material. If the microbial population deoxygenates the water, however, that lack of oxygen imposes a limit on population growth of aerobic aquatic microbial organisms resulting in a longer term food surplus and oxygen deficit. Fish and aquatic insects may die when oxygen is depleted by microbial metabolism. Organisms that are more tolerant of lower dissolved oxygen levels may replace a diversity of natural water systems contain bacteria, which need oxygen (aerobic) to survive.
59
BOD(mg/l)
10 9 8 7 6 5 4 3 2 1 0
7.9
8.8
8.3 7.5 5.8
5.8 SANKEY TANK MALATHALLI LAKE
March
April
May
2012
Fig 6.13: BOD in the two lakes
BOD concentration in the Malathalli Lake varied from 6.9 mg/l to 9.3 mg/l with a mean value of 8.2 mg/l. For Sankey tank, BOD ranged from 5.5 mg/l to 8.7 mg/l with an average value of 6.5 mg/l. According to CPCB guide lines, the BOD level in freshwater should not exceed 3 mg/l. If BOD concentration is above this concentration, the water body will be considered as polluted due to organic matter load. For both the lakes, BOD concentration has been found above this standard limit, but Sankey tank showed significantly less concentration of BOD as compared to Malathalli Lake.
6.8: Chemical Oxygen Demand (COD) In environmental chemistry, the chemical oxygen demand (COD) test is commonly used to indirectly measure the amount of organic compounds in water. Most applications of COD determine the amount of organic pollutants found in surface water (e.g. lakes and rivers) or wastewater, making COD a useful measure of water quality. It is expressed in milligrams per liter (mg/L), which indicates the amount of oxygen consumed to chemically oxidize organic matter in a liter of solution. Chemical oxygen demand is a vital test for assessing the quality of effluents and waste waters prior to discharge. The Chemical Oxygen Demand (COD) test predicts the oxygen requirement of the effluent and is used for monitoring and control of discharges, and for assessing treatment plant performance. The impact of an effluent or waste water discharge on the receiving water is predicted by its oxygen demand. 60
This is because the removal of oxygen from the natural water reduces its ability to sustain aquatic life. The COD test is therefore performed as routine in laboratories of water utilities and industrial companies. It is actually the oxygen requirement of a sample for oxidation of organic and inorganic matter. As the oxidisable inorganic matter is usually negligible in comparison with the quantity of the organic matter, COD is generally considered as the oxygen equivalent of the amount of organic matter oxidisable by potassium dichromate.
180 153.8
160
140.6
140.5
COD in mg/l
140 120 100 80
71.5
60
SANKEY TANK MALATHALLI LAKE
38.1
40
21.9
20 0 March
April
May
2012
Fig 6.14: COD variation in the two lakes
COD in Malathalli ranged from 126.6 mg/l in the month of March to 187 mg/l in the month of May with average value of 144.9 mg/l and for Sankey tank the COD value ranged from 25.5 mg/l in the month of May to 70.5 mg/l in the month of March with an average value of 43.9 mg/l. there is not any prescribed limit for COD but the higher levels indicate pollution due to organic as well as organic sources.
6.9: Water Temperature Metabolic rate and the reproductive activities of aquatic life are controlled by water temperature. Water temperature varies with season, elevation, geographic location, and climatic conditions and is influenced by stream flow, streamside vegetation, 61
groundwater inputs, and water effluent from industrial activities. Water temperature also increases when warm water is discharged into streams from industries.
Classification based on Temperature: Preferred Temperature - temperature range at which an organism likes to live. Breeding Temperature - temperature at which organisms reproduce. Fish eggs require colder temperature than what most adults prefer. Lethal Temperature - temperature at which the organism dies. When this occurs we say that the temperature is a limiting factor for that species.
Fig 6.15: Thermal stratification in lake water bodies.
Increase in Water Temperature can lead to Most aquatic organisms are 'cold blooded'; their body temperature changes with the temperature of the environment. Metabolic activity increases with a rise in temperature, thus increasing a aquatic organisms’ demand for oxygen; however; an increase in stream 62
temperature also causes a decrease in DO, limiting the amount of oxygen available to these aquatic organisms. With a limited amount of DO available, the fish in this system will become stressed. The amount of O2 (oxygen) required for life is increased. This is called increasing the BOD (biological oxygen demand). The amount of dissolved O2 that the water can hold is decreased. A sudden change of 5° C (or more) will instantly kill most fish. Any pollutants in the water become more poisonous. Algae 'blooms' (algae population explosions) occur. The rate of rot and decay (decomposition) increases; this requires even more O2. Desirable species of plants die – blue-green algae (scum) multiply. growth of disease-causing organisms
Factors Affecting Water Temperature Cold incoming spring water will cool lakes and streams. Weather conditions (air temperature, sun, and wind) will change water temperature. Man usually warms water by changing stream banks and by pollution discharge (thermal pollution). The greater the amount of water, the slower it is to change in temperature.
Temperature variation showed a slight increase in both the lakes from March to May, might be due to increase in ambient air temperature. The temperature range for Malathalli has been observed from 27.9 °C (March) to 30.5 °C (May) with a mean of 29.4 °C. For Malathalli lake, temperature variation ranged from 28.1 °C (March) to 30.6 °C (May) with a mean temperature of 29.7 °C.
63
Table: 6.4: Temperature Conditions for Aquatic Organism
(Source Michaud, J.P. 1991)
Temperature Conditions for Aquatic Organisms Temp. °C Organism Desirable plants Undesirable plants Lake Trout Brook Trout Game fish Northern, Walleye Bass, Musky Pan fish Rough fish Bullheads & Catfish Carp & other RF Minnows Macro invertebrate Bottom organisms Stonefly, Mayfly Water Beetles, Water Strider
Breeding T
8 10
Preferred T 4 to 25 25 to 30 10 15 18 to 25 18 to 25 18 to 25 19 to 27 19 to 29 30
Lethal T
4 to 27
32
4 to 27 10 to 20 10 to 20
29 29 29
26 26 32 32 32 32 32 32 29 to 37
From the Table 6.4 ,it is evident that most of aquatic organisms especially fishes can tolerate a maximum of 37°C .if the temperature will still go on increasing, that can have lethal effect on aquatic biota. Both the lakes showed viable temperature for most of the aquatic life and thermal stratification phenomena in lakes is also helpful for the aquatic life to tolerate temperature variation.
31
Temperature (°C)
30.5 30 29.5 SANKEY TANK
29
MALATHALLI LAKE
28.5 28 27.5 27 March
April
May
2012
Fig 6.16: Water Temperature variation inside the two lakes
64
Bore well samples around the Malathalli Lake showed a variation from 29.1 °C to 30.3°C with a mean value of 30.5 °C, and for Sankey tank temperature value ranged from 29.9 °C to 30.1°C with a mean value of 29.5 °C.
31.5 31
Temperature (°C)
30.5
30 29.5 MALATHALLI LAKE
29
SANKEY TANK
28.5 28 27.5 27 1
2
3
4
5
6
7
8
9
10
11
12
SAMPLE ID
Fig 6.17: Bore well water temperature around the lake
6.10: Carbon dioxide Inland waters, just as the world’s oceans, play an important role in the global carbon cycle. While lakes and reservoirs typically emit CO2, they also bury carbon in their sediment. The net CO2 emission is largely the result of the decomposition or preservation of terrestrially supplied carbon. What regulates the balance between CO2 emission and carbon burial is not known, but climate change and temperature have been hypothesized to influence both processes. CO2 is a normal component of all natural waters. It dissolves in water in varying amounts and the dissolution depends on the temperature, pressure and mineral content of the water. Polluted waters acquire CO2 by the biological oxidation of organic matter. Free CO2 in water has no much significance and is hardly ever determined. Surface waters normally contain less than 10 mg/l free CO2 while some ground water contain 30 to 50 mg/l .The presence of free CO2 in water has an important consideration because of its corrosive properties. According to Schmassman, free CO2 in water is likely to damage calcareous building 65
materials such as cement (Manivasakam 2003). There has been no prescribed limit for free CO2 in water, for it appears to have no direct physiological effects. It should be remembered that many of the drinks and beverages are charged with CO2. The highest value of CO2 in Malathalli lake has been reported 6.0 mg/l (March) and lowest value of 8.0 mg/l (May) with a mean value of 6.8 mg/l and for Sankey tank, it ranged from 6.0 to 6.3 mg/l with a mean value of 6.2 mg/l.
9 8
CO2 (mg/l)
7 6 5 4
SANKEY TANK
3
MALATHALLI LAKE
2 1 0 March
April
May
2012
Fig 6.18: CO2 in the two lakes
BORE WELL CO2 VARIATION AROUND THE TWO LAKES 35
CO2 (mg/l
30 25 20
MALATHALLI LAKE
15
SANKEY TANK
10 5 1
2
3
4
5
6
7
8
SAMPLE ID
Fig 6.19: Bore well CO2 variation around the two lakes
66
9
10
11
12
For ground water around the Sankey tank, the CO2 values ranged from 10.5 to 30.1 mg/l with a mean of 20.3 mg/l. For groundwater samples around Malathalli Lake, it ranged from 9.5 to 31.8 mg/l with a mean value of 19.1 mg/l. Higher concentration of free CO2 can lead to the corrosion of metallic pipes.
6.11: Total Alkalinity as CaCO3 Alkalinity is a measure of the capacity of water or any solution to neutralize or buffer acids. This measure of acid-neutralizing capacity is important in figuring out how “buffered” the water is against sudden changes in pH. Alkalinity is important to aquatic organisms because it protects them against rapid changes in pH. Alkalinity is especially important in areas where acid rain is a problem. Significant value of alkalinity could be due to the dissolution of minerals in water from mineral rich soil and rocks, certain plant activities, and certain industrial wastewater discharges (detergents and soap based products are alkaline). If an area’s geology contains large quantities of calcium carbonate (CaCO 3, limestone), water bodies tend to be more alkaline. Limestone is a sedimentary rock formed by the compaction of fossilized coral, shells and bones. Limestone is composed of the minerals calcium carbonate (CaCO3) and/or dolomite (CaMg (CO3)2), along with small amounts of other minerals. Limestone is converted to marble from the heat and pressure of metamorphic events. Alkalinity can increase the pH (make water more basic), when the alkalinity comes from a mineral source such as calcium carbonate (CaCO3). When CaCO3 dissolves in water, the carbonate (CO3) can react with water to form bicarbonate (HCO3-), which produces hydroxide (OH-). In addition to rocks and soils, the alkalinity of streams can be influenced by salts, plant activity, and wastewater. The various ionic species that contribute mainly to alkalinity includes carbonate (CO32-) and bicarbonate (HCO3-), hydroxides (OH-), phosphates, borates, silicates and organic acids. In some cases, ammonia or hydroxides are also accountable to the alkalinity (Sawyer et. al., 2000).
67
Table 6.5: Important compounds responsible for alkalinity H
+
Hydrogen ion (acid)
OH H2CO3 HCO3 2CO3 CaCO3 CaMg(CO3)2
Hydroxide ion (base) Carbonic acid Bicarbonate ion Carbonate ion Calcium carbonate (calcite) Dolomite lime
For Sankey tank, TA ranged from 165.5 mg/l (March) to 401.1 mg/l (April) with an average of 277.4 mg/l. The average total alkalinity between March and May for Malathalli lake was 615.9 mg/L with highest value in the month of April 2012 (755 mg/l) and lowest 555 mg/l. The desirable limit is 200 mg/l prescribed by BIS. Malathalli lakes showed Total alkalinity value above desirable limit of BIS. The reason can ground water discharge into the lake because alkalinity around the bore wells has been found significantly high.
800
Total Alkalinity (mg/l)
700 600 500 400
SANKEY TANK
300
MALATHALLI LAKE
200 100 0 March
April
May
2012
Fig 6.20: Total Alkalinity graph for the two lakes
The Total Alkalinity in the ground water samples around the Malathalli Lake ranged between 315 to 524 mg/l with a mean value of 429.5 mg/l, indicating significant 68
alkaline nature of ground water around the lake but all the samples were found above the desirable limit of BIS of 200 mg/l. Ground water samples around the Sankey tank showed the TA values ranged from 361 to 441 mg/l with an average value of 402.2 mg/l and all the samples were found above the desirable limit of BIS of 200 mg/l. 580
Total alkalinity (mg/l)
530 480
430 MALATHALLI LAKE
380
SANKEY TANK 330 280 1
2
3
4
5
6
7
8
9
10
11
12
2012
Fig 6.21 - Total alkalinity of bore wells around the lakes
Table 6.6: Typical alkalinity ranges. (mg/l CaCO3) Rainwater Typical surface water Surface water in regions with alkaline soils Groundwater Seawater
