INTERNATIONAL JOURNAL OF GEOMATICS AND GEOSCIENCES Volume 2, No 1, 2011

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1 INTERNATIONAL JOURNAL OF GEOMATICS AND GEOSCIENCES Volume 2, No 1, 2011 Copyright 2010 All rights reserved Integrated Publishing services Research article ISSN A study on ground water quality of Neyveli area, Cuddalore district, tamilnadu Department of Geology, Lecturer, Jawahar Science College, Neyveli. sumapathy_ney@yahoo.com ABSTRACT The suitability of water for different purposes like drinking, industrial water and irrigation are assessed due to its extensive development for the above said purposes. Drinking water standard is based upon, presence of objectionable taste, odors or colors along with the presence of substances with adverse physiological effects. The portability of drinking water is mainly based on recommended permissible limits of certain parameters, when water exceeds the permissible limit it is unfit for human consumption. The Neyveli area falls within the Cuddalore sand stone formation. The study area lies between and North latitudes and and East longitudes. Thirty six water samples were collected in two seasons (Summer and North East Monsoon) and hydrogeochemical characters were determined. The analyzed hydrogeochemical data indicates that the important geochemical processes occurring within the formation. The geochemical processes in the study area exhibits evaporation process in Gibbs plot. The USSL classification, Doneen plot reveals that the quality of the water. Keywords: Cuddalore Sand Stone, Gibbs plot, Neyveli, Hydrogeochemical Studies. 1. Introduction Freshwater is the most important resource of life. Population growth in water scarce regions will only increase the value of the existing water. Though water is the most widespread substance to be found in the natural environment, it is not uniformly distributed all around the globe. Huge amounts of water are bound up in the composition of different minerals of the Earth's crust, mantle and core. Only % of total water can directly satisfy human needs. Groundwater constitutes the major volume of it. Ground water is one of the components of the hydrological cycle, stored underground in geological layers called aquifers; it is a result of infiltration of rainfall and surface water, with which it maintains a close relationship. Water is vital for drinking, sanitation, agriculture, industry and countless other purposes. In contrast to the diminishing resource, global demand for water is rising. In the coming years the ground water utilization is likely to increase manifold for the expansion of irrigated agriculture and to achieve national targets of food production. The important large scale extraction sites in this basin are Neyveli Lignite Corporation (NLC) and the boreholes of New Veeranam Schemes (NVS). The open cast mining of Lignite requires heavy pumping at the rate of 9,000 to 10,000 m 3 hr 1 as water table condition has to be brought down below the level of mining. The vagaries in monsoon and insufficient surface water flow conditions have lead to Submitted on July 2011 published on September

2 increase of agricultural and domestic extraction (Aravindan et al. 2004). The increase of human population and the economic activities in this region has grown; the demand for large scale supplies of freshwater from various competing end users has increased. In this scenario deep aquifers have been bored in the coastal region, increasing the fragility of the system, aiding the movement of the seawater into this freshwater aquifer. Hydrogeochemistry of groundwater is determined by its chemical and biogeochemical constituents, sediments, lithologic content and its temperature which is of a great importance in determine its suitability of a particular ground water for certain utilities i.e. public water supply, irrigation, industrial application, cooling, heating, power generation etc. The quality of ground water is resultant of all biogeochemical process and reactions, that are acting on the water from the moment it has condensed in the time, and discharged by a well (or) spring (Vijayakumar et al. 2010). 2. Study area Neyveli lies between the Ponniyar river basin at North and Vellar river basin at South. In this area a small ephemeral river called Paravaranr basin within an area of 760 sq. km. Since it has not been included in either of the above mentioned adjacent river basins this basin has been now taken up as a separate basin for the present study. Neyveli have two mines and two ash pond. The Neyveli water is to connect the Walaja tank and Perumal tank. The Neyveli lies between the latitudes and North and longitudes and East (Figure 1). Figure 1: Location map of the study area 50

3 3. Methodology The water samples were collected during May 2009 and November 2009 to broadly cover seasonal variation. The totals of 36 samples were collected at the rate of 18 samples per season. Water samples were collected in well cleaned one litre polythene sample bottles rinsed by 1:5 HCL and then by double distilled water. The sample locations were identified and recorded with help of GPS (Garmin). The samples collected were analysed for major cations like, Ca and Mg by Titrimetry, Na and K by Flame photometer (CL 378); anions, Cl and HCO 3 by Tirimetry, SO 4, PO 4, and H 4 SiO 4 by Spectrophotometry (SL 171 minispec). EC and ph were determined in the field using electrode. The analyses were done by adopting standard procedures (APHA, 1998). 4. Result and Disscussion Groundwater and surface water samples were collected in space and time and analyzed for major ions using standard procedures. The Comparison of chemical composition of the groundwater in Neyveli area collected during two seasons viz. North East Monsoon (NEM) and Summer (SUM) with WHO (1996) and ISI (1995) standards are given in table 1. The total cations (TZ + ) and total anions (TZ ) balance (Freeze and Cherry 1979) is considered to shows the charge balance error percentage. The error percentage in the samples of the present study ranges between ±1% to ±10%. Occurrence of errors in chemical analysis of groundwater is also due to the reagents employed, limitations of the methods and the instruments used presence of impurities in distilled water etc. The correlation coefficient between TZ + and TZ is around 0.6 to 0.9 TDS / EC ratio was ranging from 0.5 to 0.9. The role played by other ions than those considered here for the cations and anions charge balance is less significant. The average, mean, and standard deviation values in different seasons are given in table 1.a and b. The groundwater in the study area is generally odorless and colorless in most of the places. The average temperature at the time of sampling varies from 25 0 C to 31 0 C. Table 1: Comparison of chemical composition of water with WHO (1996) and ISI (1995) standards in mg/l (Except EC and ph). Parameter Ground Water WHO (1996) Highest desirable ISI (1995) EC ph TDS Ca Mg Na K HCO SO Cl Chemical Parameters 51

4 The chemical characteristics and its Maximum, minimum and average values in different seasons in mgl 1 are given in Table 4.1, 4.2 and 4.3. The ph of water is an indicator of its quality and geochemical equilibrium for solubility calculation (hem, 1985). ph indicates the state of equilibrium reaction in which the water precipitates. Groundwater in the study area is generally alkaline in nature with ph ranging from 5.1 to 8.9 with an average of 7.0. ph is lower in SUM and is higher in NEM. It was found fluctuating in certain locations with fewer abnormalities. Electrical Conductivity (EC) is an indirect measurement of ionic strength and mineralization of natural water. EC ranges from 102 to 6621 µs/cm with an average of µs/cm. Electrical Conductivity of pure water is 0.05 µs/cm (Hem, 1991). Highest EC was observed in NEM followed by SUM. Total dissolved solids (TDS) were higher in NEM followed by SUM. Table 2a: Physico chemical parameter of Neyveli ground water samples. (except Ec and ph in mg/l)(sm Summer season) parameter ph Ec Ca Mg Na K Cl HCO 3 SO 4 H 4 SiO 4 TDS Max Min Avg Table 2b: Physico chemical parameter of Neyveli ground water samples. (except Ec and ph in mg/l)( NEM North East Monsoon) parameter ph Ec Ca Mg Na K Cl HCO 3 SO 4 H 4 SiO 4 TDS Max Min Avg Anions Anion chemistry shows chloride is most abundant ion in most locations and in some place it is equal to sulphate. Bicorbonate represents the major sum of alkalinity. Alkalinity in water is the measure of its capacity of neutralization. It is formed mainly due to the action of atmospheric CO 2 and CO 2 released from organic decomposition. Cl is higher, indicating the impact of saline water and Base Exchange reaction (Freeze and Cherry, 1979). Sulfate is found in water due to breaking down of organic substances from fertilizers, weathered soil / water and due to the influence of saline waters (Miller, 1979; Craig and Anderson, 1979; Singh et al. 1994). Chloride is the dominant anion followed by HCO 3 > SO 4 > PO 4 irrespective of seasons 5.2. Cations Sodium is the important and most abundant alkali metal which is highly mobile and soluble in groundwater. Calcium is an important element in many geochemical processes. Minerals like Calcite, Plagioclase and Hornblende are the primary sources for calcium in groundwater. Magnesium in groundwater is mainly due to the leaching of magnesium bearing minerals from mafic and ultramafic rocks like Pyroxenite, Peridotite, Dunite, Anorthosite and gabbros. Potassium in groundwater is generally lesser in groundwater due to its higher solubility (Bouwer, 1978). Sodium is the dominant cation followed by 52

5 Ca> Mg> K irrespective of seasons. Na is found to be the dominant cation it may be due to the weathering of Alkali feldspars in rocks or due to cation contribution from sea water. Ca ranges from 1 mgl 1 to 60 mgl 1 with an average of mgl 1. Magnesium concentration was ranging from 1 mgl 1 to 53 mgl 1 with an average of 8.4 mgl 1. Potassium ranges from 1 mgl 1 to 74 mgl 1 with an average of 9.58 mgl 1, higher concentration is noted in POM and lower is noted in SUM. Potassium is less concentration than the sodium due to its grater resistance to weathering and formation of clay minerals Water Quality The suitability of groundwater for irrigation purpose is mainly based upon he estimation of the parameters like SAR, Na %, RSC. Total Na concentration and EC are important in classifying the water for irrigation purposes (Wilcox, 1955). Sodium percentage is calculated against major cations and expressed in terms of SAR. Na is an important cation which is in excess deteriorates the soil structure and reduces crop yield. SAR values in all the major litho units ranges from excellent to good category irrespective of seasons. In Wilcox (1955) classification of electrical conductivity, majority of samples in Neyveli area fall in good to permissible range irrespective of seasons. Salinity of groundwater and SAR also determines its utility for agricultural purposes (USSL, 1954). Salinity originates in groundwater due to weathering of rocks and leaching of ions from top soil, anthropogenic sources along with minor influences on climate. The level of Na and HCO 3 in irrigation groundwater affects permeability of the soil and drainage of the aera. Figure 2: USSL diagram in Sum and NEM When SAR (alkali hazard) and specific conductance (Salinity hazard) is plotted in USSL diagram, classification of water for irrigation purpose can be determined. In Alluvium formation (Figure 2) majority of samples fall in C2S1 zone during SUM and indicating medium salinity and low sodium hazard, satisfactory for plants having moderate salt 53

6 tolerance soils. Minor representation of SUM samples are also noted in C1S1,C3S1 and C3S2 zones indicates medium to high salinity waters. Applications of gypsum in these soil increases soil permeability (Goyal and Jain, 1982). In NEM most of the samples fall in C3S2 indicating high to medium salinity and some samples also fall in C2S1, C3S1 and C3S3. Permeability index is an important factor which influences quality of irrigation water, in relation to soil for development in agriculture. Based on permeability index, Doneen (1948) classified the groundwater as class I, class II and class III to find out suitability of groundwater for irrigation purpose. In Alluvium formation (Figure 3), most of the samples irrespective of seasons fall in class II indicating water are moderate to good for irrigation purpose. Certain samples were noted in SUM seasons which fall in class I. Permeability index is an important factor which influences quality of irrigation water, in relation to soil for development in agriculture. Figure 3: Doneen plot Sum and NEM Gibbs (1970) proposed a method for identifying the relationship between water composition and mechanism controlling the chemistry. There are two plots for cations and anions. In alluvium (Figure 4), the plot for cations and anions fall in rock dominant zone and minor representation is noted in evaporation zone irrespective of seasons. 54

7 6. Conclusion Figure 4: Gibbs diagram in Sum and NEM The study of water chemistry in Neyveli area reveals its hydrogeochical behaviour. The reaction of the medium with the aquifer matrix, the utility of water for various purposes and variation in water quality with space and time, etc., has been determined. Rainfall, thickness of the top soil, lithology, structure and anthropogenic activities in the region are control the quality of groundwater. Groundwater is generally near acidic to alkaline in nature. The higher level of TH, CR and Na% etc., give an alarm to the future utility. Leaching of ions followed by weathering and anthropogenic impact controls the chemistry of the groundwater. Rock water interaction is also identified as one of the factor contributing the variation in water chemistry. Reference 1. APHA (1998) Standard methods for the examination of water and waste water,19 th edition. APHA, Washington DC, USASS. 55

8 2. ARAVINDAN S et al (2010). Groundwater Quality in the Hard Rock Area of the Gadilam River Basin, Tamil Nadu, Journal of Geological Society of India, 63, pp (June issue) 3. CHIDAMBARAM, S, et al. (2004) WATCLAST A Computer Program for Hydrogeochemical Studies. Recent trends in Hydrogeochemistry (case studies from surface and subsurface waters of selected countries). Published by Capital publishing Company, New Delhi, pp DONEEN (1948), the quality of irrigation water. California agriculture Dept. 4 11: GIBBS (1970), mechanisms controlling worlds water chemistry science, 170, pp HEM D (1991), study and interpretation of the chemical characteristics of natural waters, 3 rd edition US Geol. Survey, water supply paper Scientific pub, Jodhpur. 7. USSL (1954), diagnesis and improvement of saline and alkali soils, USDA Hand book 60: VIJAYAKUMAR.V (2010), Hydrogeochemistry in part of Ariyalur region, Journal of Applied Geochemist, 12(2), pp WHO (1996) Guide lines for drinking water quality. Genera 1: