ISSN: 2347-3215 Volume 2 Number 5 (May-2014) pp. xx-xx www.ijcrar.com
Water Quality Assessment in Parts of the Niger Delta Region of Nigeria Part II D.E.Egirani*1, M.T.Latif2 and N.R. Poyi3 1
Faculty of Science, Niger Delta University, Wilberforce Island, Nigeria School of Environmental and Natural Resources, Universiti Kebangsaan Malaysia, Malaysia 3 Nigerian Institute of Mining and Geosciences, Jos, Nigeria 2
*Corresponding author email:
[email protected] KEYWORDS
Water quality, Niger Delta Region, Assessment, bacteriological, physical and chemical
A B S T R A C T Anthropogenic sources- haphazard effluent discharges and natural sourceswaterlogging and incessant flooding remain the major sources of deteriorating water quality in the Niger Delta Region of Nigeria. This study investigates community water quality assessment and management in the south-southern Niger Delta Region of Nigeria. A total of 14 community water samples, harvested rain water, (surface water i.e. river and pond water) and ground water samples were collected and analyzed for their physico-chemical and bacteriological constituents. The chemical data set generated were subjected to theoretical models and graphical interpretation. The results indicate that these community waters are suitable for drinking purpose, especially where the Escherichia coli and total coliforms do not exceed the international and regional recommended limits of 0 per 100ml of sample. In addition, the community waters are excellent for livestock, recreational and irrigation purposes. Possible sources of community water contamination have been suggested. Adequate land use planning, legislation and implementation of environmental laws are required in this region to have effective surface water and ground water resource management.
Introduction The wholesomeness of water for human consumption remains one of the first concerns of regional legislation. Water is crucial for human health, wellbeing and industrial development [1-2]. Water quality is dependent on physical, chemical and bacteriological characterization of available water resources [2-3].
Water demand exceeds supply in many parts of the world [4]. As of 2004, 1.1 billion people lack access to improved water sources [5-8]. The health and well-being of humans and ecosystems depend heavily on the quality of the water resources available through proper land use planning and
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enactment of robust legislation [9-10]. It also supports global food production by providing the fundamental resource upon which agriculture, livestock production, recreation, irrigation, fisheries and aquaculture depend [11-13]. The main public concern in recent years has been the damage to human health that is caused by contaminated water through environmental pollution [14-16].
southern Niger Delta Region of Nigeria (NDR) have not been fully documented. Surface and groundwater quality assessment and management are major issues having profound impact on communities in the Niger Delta Region of Nigeria [NDR] [40]. Despite the region s abundant water resources, water quality is threatened by deteriorating environmental conditions and lack of water resource management [41-43]. The problems of environmental pollution in the Niger Delta Region of Nigeria poses direct consequences to surface and ground water resources [44]. These contaminants arise from anthropogenic sources- haphazard effluent discharges and natural sourceswaterlogging and incessant flooding [4549]. Contaminants can enter aquifers by infiltration of surface water through soil, sediments, rock and surface runoff to the point where direct contamination occurs. The sanitary status of drinking water in communities of the NDR is poor. Water wells are in the environs of contaminant sources such as sewage ditches (carrying wastewater from homes, landfills and village dry toilets). Drinking water supply in numerous of these communities could be unhealthy and not meeting regulatory standards [42, 50].
1. Further concerns with water quality are the impacts of water pollution and contamination on the ecosystem and the cost of drinking water treatment [17-18]. New waste-water treatment facilities have helped to safe drinking water [19]. Nevertheless, pollution from agricultural sources and dissolved organic carbon are issues in the United Kingdom and many countries [2021]. Regulatory guidelines that promote good water quality are critical in the management of water resources [22]. Water pollution also occurs when rain water runoff from urban area, industrial area, agriculture land and mining operations makes its way back to receiving water courses (i.e. river, lake or ocean) and into the ground [23-24]. Water quality standards for surface waters vary significantly due to different environmental conditions, ecosystems and intended human uses. Variation in water quality for ground water is significantly influenced by interaction with rock chemistry [25]. The water quality index (WQI) and other theoretical models are used to monitor water quality changes in water supply over time [26-30]. An assessment of water quality is very important for knowing its suitability for various purposes [31-32]. Water quality studies have been widely considered in literature [33-39].
3. Bacterial contamination of drinking water is a major contributor to water-borne diseases such as diarrhea, nausea, gastroenteritis, typhoid fever and dysentery [51-52]. Total bacterial count, total coliforms and Escherichia coli are common signs of water contamination with disease causing pathogens [54]. Sources of total and fecal coliform in groundwater can include infiltration of domestic or wild animal fecal matter, effluent from leaking septic systems or sewage discharges and vegetal matter runoff [55]. According to the WHO standard for public drinking water, total coliforms and fecal coliforms in 100 mL of water must
2. However, surface and ground water quality assessment and management in the
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both be below detectable levels [56]. The Canadian Drinking Water Quality Guideline for total coliforms and Escherichia coli is also none detectable per 100 mL. Total coliforms are naturally found in both fecal and non-fecal environments, so they are commonly present in both surface water and groundwater under the direct influence of surface water sources [57]. The guideline for total bacteria count is less than 100 CFU mL 1 [58]. In communities around south-southern Niger Delta Region of Nigeria, there are public, private water wells and numerous surface water sources which are used for water supply [23].
and is highly waterlogged saline mangrove belt [63]. Although the. Montmorillonitic heavy clay of the freshwater back swamp is considered thick- in excess of 6 m at most locations; it does not constitute a good aquitard. This is due to the fact that the area is waterlogged almost all the year round. Furthermore, communities in the studied area are located within the freshwater back swamp, thus, making infiltration of surface contaminants into groundwater possible and construction of solid waste disposal system difficult [64, 62]. Also, the degree of surface contamination of groundwater increases towards the southern fringe of this region [42].
4. Most community residents do not have disinfected water supply, and bacterial contamination is regarded as the greatest potential problem affecting drinking water [59, 23]. It is well recognized that inability to protect water sources and inadequate water treatment are the primary reasons for bacterial contamination of portable water [60]. Nevertheless, few quantitative studies of the effects of water sources and their protection on bacterial contamination in the NDR have been carried out [61].
Analyzing physical, bacteriological and chemical constituents of surface and groundwater in this region helps in ascertaining the extent of pollution of these waters and creates a framework for surface and groundwater management [65, 66]. The major physico-chemical and bacteriological properties of interest include pH, temperature, electrical conductivity, total bacterial count, E.coli, T.coli, turbidity, salinity, color, odor, anions and cations [67]. The aim of this study is to determine physico-chemical and bacteriological characterization of water in the southsouthern NDR and qualify them for various uses by communities. The objective of this study is proffer management strategy to reduce ingress of contaminants into the water resources available to communities.
Theoretical concept of water resources in the Niger Delta Region The Niger Delta Region is underlain by different superficial soil deposits ranging from the organic-peaty marine mud, chicoco in the tidal flat, saline mangrove swamp, montmorillonitic silty clay of the freshwater back swamps and the deltaic lateritic soils of the dry plains [62]. These superficial deposits are directly underlain by coastal plain sands of the Benin formation. Most groundwater aquifers in this region are unconfined and are subjected to infiltration by contaminants from the overlying sediments. In addition, the presence of chicoco mud makes it highly undesirable,
Location and Geology of the study area The area selected for this study is located in the southern flank of the Niger Delta Region of Nigeria (Figure 1). The topography is generally low-lying with elevations ranging from below sea level in the southwestern flank of the region to about 40 m further 3
inland. Most of the low-lying areas regularly experience perennial flooding. Thus, flooding and subsequent infiltration of water contaminants into water sources can be attributed to anthropogenic and natural causes [49, 68-71]. Given that 75% of the NDR is wetland with an annual rainfall of 2000-3000mm, flooding may occur due to excessive rainfall, human manipulation of wetland, flood plains in particular and excessive release of water from Niger and Benue Rivers [72-74]. This may result in the overflow of sewage and other contaminants into water courses. Soils are generally hydromorphic and poorly drained. The pristine vegetation has been reduced considerably in the area and replaced by mosaic of secondary re-growth due to agricultural activities and oil exploration.
The subsurface geology in the region reveals a lithostratigraphic subdivision comprising, an upper sandy Benin Formation, an intervening unit of alternating sandstone and shale named the Agbada Formation, and lower shale Akata Formation [Figure 2] [49, 42]. These three units transverse the whole NDR, ranging in age from early Tertiary to recent [77]. The Benin Formation consists predominantly of fresh water continental sands and gravel with intercalations of shale [11]. This has unconfined aquifer properties and constitutes the most productive for water supply in the region. The hydraulic conductivity of the Benin Formation ranges from 4.6- 10.2 cm/s, while the annual water storage and recharge is estimated to be 6.16 -108 m3. The Agbada formation comprises reservoir rocks while the Akata Formation contains the source rocks for crude oil formation and accumulation [78].
Component part of the natural vegetation occurs as fresh water swamp forest, mangrove swamp forest and ever green lowland rainforest which are a major source of timber. A number of rivers and creeks transverse the area.
Theoretical models, graphical interpretation and concepts of water quality data
The Niger River, located in the eastern flank is the major drainage system from which other discrete river systems originate. These river systems include Benin River, Escravos River, Forcados River, Nun River, Orashi River and Ramos River, all in the western part of the NDR [75]. The region is located within the equatorial belt with a humid climate. The average monthly relative humidity is about 79% [76]. Rainfall distribution is typically bimodal with about 90% of rainfall recorded between March and November and yearly rainfall peaks occurring in July and September. The mean temperature for the hottest months (February/March) is 34 oC while that of the coolest month (August) is 28 oC.
Understanding of processes that control natural water composition is required for robust management of water quality. Hydrogeochemistry seeks to determine the origin of the chemical composition of groundwater and the relationship between water and rock chemistry. Natural water composition is determined by chemical analysis, the data from which may be grouped and statistically evaluated. A significant number of techniques and methods, based on differences in chemical properties of water are available to classify, compare and summarize large volumes of data.
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variables (axes), called the principal components, which are linear combinations of the original variables [41, 94]. PCA is thus concerned only with establishing which linear component exists within the data and how a particular variable might contribute to that component [41, 95-97]. Piper diagram It is a presentation format which reveals the abundance or relative abundance of component ions in surface and groundwater. For ground water, it reveals the groundwater facies. Many water analyses can be plotted on the same diagram and can be used to classify waters and identify mixing of waters. It shows the relative concentrations of six to seven ions in solutions, namely, the captions Ca, Mg, and Na+K, and the anions Cl, SO4, and HCO3 [98, 99].
Figure.1 Map of the Niger Delta Region showing the study location on the left
Pie diagram
Common procedures include simple inspections and comparison of chemical analyses, the preparation of graphs and maps and more extensive statistical analysis [92].
It displays concentration ratios for individual samples. It makes it easier to compare concentration ratios for several different samples compared with a table of numbers The simplest of pattern diagrams are circular diagrams which are primarily used as symbols on the maps-the most common being the pie-diagram. The subdivisions of the area represent proportions of different ions in percentage of meq/L [92].
Principal component analysis
Collins diagram
Statistical model employed in this study includes descriptive and principal component analysis of physical and chemical data aimed at highlighting the range and sources of such constituents [93]. Statistical computations were executed using the statistical software package IBM SPSS statistics 20. PCA is designed to transform the original variables into new, uncorrelated
It displays concentrations (not ratios) of individual water samples. It is a cumulative chart and values are not readily apparent [100].
Figure.2 Borehole lithology in the Niger Delta Region of Nigeria [42]
Schoeller diagram It is the logarithm analysis of major ion analyses in meq/L. It demonstrates different 5
water types on the same diagram. Sample concentrations not ratios are displayed and compared. Similar waters exhibit similar fingerprints [101-102].
ability of the sodium to dominate in soilwater interaction. The lower SAR the less likely the water is to cause structural degradation of susceptible soils (Table 2) [105].
PHREEQC model The geochemical program (PHREEQC Interactive version 3.0.6.7757 from the United States Geological Survey) was used to calculate the distribution of the aqueous species [103]. In addition, the program was based on an ion-associated aqueous program and was designed to perform a wide variety of aqueous geochemical calculations. PHREEQC can determine which solids might precipitate, based on saturation index (SI) (Table 1). The SI is defined as the logarithm of the ratio of ion activity product (IAP) of component ions for a solid in solution, to the solubility product (Ksp) of the solid, SI = log (IAP/Ksp). Negative and positive SI values represent the potential for dissolution and precipitation, respectively [104].
Langelier Saturation Index (SI) It is a relationship between pH, salinity, alkalinity and hardness (Table 3). It assesses the potential of the water to cause scaling and precipitation or corrosion. The Langelier Saturation Index calculator (LSI) helps determine the scaling potential of the water by using the Langelier Saturation Index [105]. Residual sodium carbonate (RSC) It represents the amount of sodium carbonate and sodium bicarbonate in the water and is said to be present in a water sample if the concentrations of carbonate and bicarbonate ions exceed the concentrations of calcium and magnesium ions. Residual alkalinity is usually expressed as mill equivalents per litre (meq/L) of sodium carbonate. When water containing residual sodium carbonate is used on clay soils containing exchangeable calcium and magnesium, sodium from the residual sodium carbonate in the water will replace calcium and magnesium in the soil and may cause structural damage. Residual Sodium Carbonate (RSC) predicts the accumulation of sodium in the soil based on the potential precipitation of calcium/magnesium carbonate (Equation 2):
Sodium absorption ratio (SAR) It indicates the relative proportion of sodium ions in a water sample to those of calcium and magnesium. SAR is used to predict the sodium hazard and potential for sodium to accumulate in the soil. In order to calculate the SARw from water analysis data, it is essential to convert the units from parts per million or milligrams per litre to milliequivalents per litre as provided in Equation 1:
(1)
RSC= (CO3 +HCO3)-(Ca+Mg)
(2)
A negative RSC indicates water is unlikely to cause structural degradation. An RSC greater than 1.25 indicates a potential hazard to soil structure. Additions of a calcium
This parameter qualifies the ratio of sodium to calcium and magnesium in terms of the
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source, such as gypsum, or acidification of the water prior to use may be required.
Turbidity is a measure of the optical ability of suspended sediments to inhibit the penetration of light. This can be caused by various mixtures of organic and inorganic materials. The U.S Public Health Service sets an upper limit of 5 for drinking water. Most industries require water with turbidity of 10 or less, particularly food and brewage manufacturers. Color is caused largely by organic materials in solution.
Table.1 Parameters used in calculating saturation index from phreeqc Ion/parameters Ca Mg Na K HCO3 SO4 Density of water Alkalinity
Conc. (ppm) variable variable variable variable variable variable 1
Ion/parameters Cl NO3 Fe pH Temp. Pe Cl
Conc. (ppm) variable variable variable variable variable 4 variable
variable
Mn
variable
Table.2 Hazard levels for SAR SAR 1.5 -0.5 to -1.5
