Assessment of groundwater quality and seawater intrusion along the ...
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JOURNAL OF COASTAL SCIENCES Journal homepage: www.jcsonline.co.nr ISSN: 2348 – 6740
Volume 2 Issue No. 1 - 2015
Pages 6-11
Assessment of groundwater quality and seawater intrusion along the coastal aquifer around Kalpakkam, Tamil Nadu, India *G. Kanagaraj, S.G.D. Sridhar, A.M. Sakthivel Department of Applied Geology and Centre for Environmental Sciences, School of Earth and Atmospheric Sciences, University of Madras, Guindy Campus, Chennai 600 025, India
ABSTRACT
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The chemical characteristics of thirty three groundwater samples around Kalpakkam region were studied during post monsoon (PSM) and pre monsoon (PRM) season (2011). The hydro-geochemical data were processed with reference to World Health Organization (WHO) standards. The dominance of anions and cations were in the order of Cl- > HCO3- > NO3- > SO4 and Na+ > Mg > Ca > K. The northeastern part of the study area has EC values above permissible limit during both seasons, which may be attributed to the proximity of backwater and saline intrusion. The groundwater of the study area is characterized by the dominance of strong acids (Cl) exceeds weak acids (HCO3 and SO4) during both seasons of the year 2011, as 90.9% and100% based on the hydro-chemical facies. These have been almost certainly derived from natural chemical weathering of rock minerals, ion exchange and to some extent by anthropogenic activities such as application of fertilizers. 39.4% and 51.5% of the total samples collected were found to have higher seawater ratio, indicating a large proportion of groundwater affected by seawater intrusion. Most of the ions are positively correlated with Cl-, especially with Na and Mg indicating that such ions are derived from saline water intrusion and chemical weathering along with leaching of secondary salts, that clearly indicates natural as well as anthropogenic activities. The association of the ion in factor I representing Ca, Mg, Cl and Na indicate leaching of secondary salts, or backwater recharge. The groundwater quality was found suitable for drinking purposes.
Received 1 November 2014 Accepted 16 March 2015 Available online 20 March 2015 Keywords Geochemistry Seawater intrustion SPSS Piper diagram Factor analysis Kalpakkam
*Corresponding author, E-mail address: [email protected] Phone: 044-22202724, © 2015 – Journal of Coastal Sciences. All rights reserved
1. Introduction Water is an essential and vital component of our life support system. Geochemical processes occurring within the groundwater and reactions with aquifer minerals have significant effect on water quality. Groundwater also plays an important role in agriculture, for irrigating the crops. The coastal aquifers suffer saline water intrusion that becomes a worldwide concern (Eragil, 2000; Cheng and Ouazar, 2004; Mhamdi et al., 2006; Zekri, 2008; Franco et al., 2009; Nasab et al., 2010; Mondal et al., 2010a). Groundwater chemistry based on hydrochemical data is useful for providing preliminary information on water types, classification of water for various purposes as well as identification of different aquifer and study of different chemical processes (Karanth, 1987; Saxena et al., 2003; Jalali, 2007; Sarwade et al., 2007). The industrial waste water, sewage sludge, solid waste materials are currently being discharged into the environment indiscriminately. These materials enter into the freshwater aquifers, resulting in the pollution of irrigation and drinking water (Forstner and Wittman, 1981). The seawater intrusion is a main cause of high salinity, and groundwater generally demonstrates high concentration not only in total dissolved solids (TDS) but also in cations and anions (Richter and Krietler, 1993) as well as the increase of selective trace element (Saxena et al., 2004; Mondal et al., 2010b). Seawater intrusion is defined as the migration of saline water from the sea into freshwater aquifer that are hydraulically connected with the sea. 6
Seawater intrusion leads to the salinization of fresh water aquifers along the coastlines. In highly populated coastal regions with greater dependence on groundwater, the withdrawal usually exceeds the recharge rate resulting in seawater intrusion. The density of seawater is marginally higher than that of freshwater. When seawater intrusion is a main cause of high salinity, groundwater generally exhibits high concentrations not only in total dissolved solids (TDS) but on some specific chemical constituents, such as Cl-, Na+, Mg2+, and SO42- (Richter and Kreitler, 1993) as well as accumulation of selected trace elements (Saxena et al., 2004; Mondal et al., 2010b). The coastal groundwater system is fragile and its evolution will help in the proper planning and sustainable management. Interpretation of hydrochemical data suggests that calcium carbonate dissolution, ion-exchange processes, halite dissolution, silicate weathering, and irrigation return flow are responsible for the groundwater chemistry in the area. The water quality assessment studies in the nearby coastal aquifers were carried out by several authors (Sivakumar and Elango, 2008; Sasidhar and Vijay Kumar, 2008; Karmegam et al., 2010; Chidambaram et al., 2011; Seshadri et al., 2013). But, the present study area lacks a detailed approach on groundwater geochemistry. So, the present research investigates the hydrogeochemical processes that control the groundwater chemistry of the study area including its suitablity for drinking purpose. This will lead to ORIGINAL
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improved understanding of the hydrogeochemical characteristics of 3. Methodology the coastal aquifers along the Kalpakkam coast. For the assessment of groundwater quality, 33 ground water samples 2. Study area and Geology were collected during January 2011 (post-monsoon) and June 2011 (pre-monsoon) from the bore well and dug wells. These samples The study area lies between 80˚3ʹ and 80˚13ʹ30ʺ E longitude and were collected in 1 liter capacity polyethylene bottles. The pH, from 12˚20ʹ30ʺ to 12˚48’30” N latitude. It is situated about 70 km temperature, electrical conductance (EC), and total dissolved solids South of Chennai. The area is bounded by Bay of Bengal on the east, (TDS) were measured in-situ using portable bore well logger (Multi Edaiyur backwaters on the north and Buckingham canal on the west. probe system, YSI 556 MPS). The samples collected were analyzed in The average annual rainfall in the study area is 1237 mm. The the laboratory for concentration of major ions. The Ca2+, Mg2+, CO3, topography of the study area is slightly undulating with sand bars HCO3 were determined titrimetrically (APHA, 1985). The Na+, K+ and depressions. The regional gradient is towards the eastern side. were estimated using Flame photometer. The anions Cl-, NO3, SO4 The altitude varies between less than a meter to 13 m above MSL. were determined using Ion Chromatography. The statistical analysis The geology of the area consists of Archean basement at the bottom, were carried out using SPSS software. which is made up charnockites and overlain by recent alluvium. The depth of hard rock varies from 12 to 20 m below the ground surface. 4. Results and Discussion The weathered/fractured charnockite and the alluvium form the major aquifer system of the study area. Lenses of clays and clay The results of the analysis are presented in Table 1 for the study area pockets were encountered in the alluvial formations. The thickness during post and pre monsoon of the year 2011. Groundwater in the of the sandy formations varies from 3 to 12 m. The shallow aquifer is study area is generally have pH ranging from 6 to 8 during postunconfined in nature. The study area and sample location shown in monsoon season, while in the pre-monsoon it ranges from 6.1 to 7.7. figure 1. They are within the permissible limit in both the seasons based on
Fig. 1 Geomorphology of study area with location of groundwater samples
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WHO (2004). EC is one of the measurement of strength and mineralization of natural water. In the study area, EC ranges from 138 to 7312µS/cm during post-monsoon, while in the pre-monsoon it ranges from 100 to 3940 µS/cm. TDS range from 89 to 4258 mg/l during post-monsoon season, whereas, during pre-monsoon it ranges from 133 to 8054 mg/l. According to WHO (2004) TDS is above permissible limit in both the seasons. TDS increases after rains that dissolve minerals from overlying rocks (minerals) during infiltration. Parameter EC pH TDS Ca Mg Na K HCO3 SO4 Cl NO3
Post monsoon Minimum Maximum 138 7312 6 8 89 4258 5 600 3 240 6 520 1 30 20 465 8 425 13 2048 3 58
Pre monsoon Minimum Maximum 100 3940 6.1 7.7 133 8054 6 620 1 430 11 1750 1 72 30 738 8 104 28 4815 1 182
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to 58 mg/l whereas, it ranges between 1 and 182 mg/l during premonsoon samples. Based on the WHO (2004), Cl, HCO3 are above permissible limit in most of the samples, but SO4 and NO3 are within permissible limit. It indicates that most of the samples are not suitable for drinking purpose as well as agriculture uses. World Health Organisation Standards (2004) Sl No.
Parameters
Acceptable Limit
Permissible Limit
1
pH
6.5-8.5
No relaxation
2
TDS
500
1000
3
EC
1400
-
4
Na
-
200
5
Ca
100
200
6
Mg
50
100
7
K
20
42
8
Cl
250
1000
9 10
SO4 NO3
250 45
400 No relaxation
Table 2 World Health Organisation Standards (2004) for drinking water
Table 1 Minimum and maximum values for different parameters of the study 4.3. Box and Whisker plot area for post and pre monsoon seasons. All parameters are reported in mg/l, except EC (µs/cm), pH in pH scale. Box plots can be used to compare groundwater quality data
4.1. Major cations The ascendancy of cations is as follows Na > Mg > Ca > K during post and pre-monsoon seasons. Sodium ion concentration in the postmonsoon season varies from 6 to 520 mg/l while it ranges between 11 and 1750 mg/l during pre-monsoon. Sodium concentration plays an important role in evaluating the groundwater quality for irrigation because sodium causes an increase in the hardness of soil as well as a reduction in its permeability (Tijani, 1994). Calcium ion concentration in the post-monsoon season varies from 5 to 600 mg/l while it ranges between 6 and 620 mg/l during pre-monsoon samples. Magnesium ion concentration in the post-monsoon season varies from 3 to 240 mg/l while it ranges between 1 and 430 mg/l during pre-monsoon samples. Potassium ion concentration in the post-monsoon season varies from 1 to 30 mg/l whereas; it ranges between 1 and 72 mg/l during pre-monsoon samples. Comparing the WHO (2004), Na, Ca, Mg and K concentrations were above permissible limit in most of the samples. The WHO standards for anions and cations are presented in Table 2.
(generally for the same parameter) between wells. The plots are constructed using the median value and the inter-quartile range (25 and 75 cumulative frequency measured as central tendency and variability). They are quick and convenient way to visualize the spread of data. The chemical composition of the groundwater samples is shown in the box plot (Figure 2 and 3). The abundance of the major cations is in the order of Na > Ca > Mg in both seasons. The abundance of major anions is in the order of HCO3 > Cl > SO4 during January 2011, and they have been pictorially represented in the box plot.
4.2. Major anions The ascendancy of anions is as follows Cl > HCO3 > NO3 >SO4 during post and pre-monsoon seasons. Chloride ion concentration in the post-monsoon season varies from 13 to 2048 mg/l while it ranges between 28 and 4815 mg/l during pre-monsoon samples. Cl- is higher due to the impact of saline water and base ion exchange reaction (Freeze and Cherry, 1979). Bicarbonate ion concentration in the post-monsoon season varies from 20 to 465 mg/l while it ranges between 30 and 738 mg/l during pre-monsoon samples. Higher concentration of bicarbonate indicates the contribution of silicate and carbonate for chemical weathering. Sulphate ion concentration in the post-monsoon season varies from 8 to 425 mg/l while it ranges between 8 and 104 mg/l during pre-monsoon samples. Fig. 2 Box and Whisker’s plots for Post monsoon season Nitrate ion concentration in the post-monsoon season varies from 3 8
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This shows that most of the sample points lie below the equiline with few of the samples lie above the equiline. Majority of the groundwater samples illustrate silicate weathering during June (2011) compared to post monsoon season. This process might have increased the calcium, magnesium, and bicarbonate ion contents in the groundwater of the study area during the said seasons. 4.5. Gibbs Plot
Fig. 3 Box and Whisker’s plots for Pre monsoon season
Reactions between groundwater and aquifer minerals have a significant role in water quality, which is also useful to understand the genesis of groundwater. Groundwater chemistry in the study area is regulated by diverse processes and mechanisms. The chemical relationships of groundwater based on the lithology of aquifer have been studied following the plot derived by Gibb’s (1970). Three kinds of fields are recognized in the Gibb’s diagram, namely, precipitation, evaporation/crystallization, and rock-water interaction. The weathering dominated water has high Ca and HCO3concentration, and the evaporation/crystallization dominated water is characterized with high Na+ and Cl- contents. In the cation plot, (Figure 5) most of the water samples fall outside the plot and few of the water samples fall in the rock-water interaction and evaporation, for both the seasons of the study area. During both the seasons, the increase in evaporation increases the salinity and the concentration of the ions such as Na and Cl that increases with increasing TDS.
4.4. (Ca+Mg) vs (HCO3+SO4) diagram In the (Ca+Mg) vs (HCO3+SO4) diagram, explained by Datta and Tyagi (1996) the ionic concentrations falling above the equiline are due to carbonate weathering, whereas, those falling along the equiline are caused by both carbonate weathering and silicate weathering (Lakshmanan et al., 2003). (Ca+Mg) vs (HCO3+SO4) scatter diagram of the study area is shown in figure 4.
Fig. 5 Gibb’s plot for post monsoon and pre monsoon season
4.6. Hydrochemical Facies One of the most useful graphs for representing and comparing geochemistry in water quality analysis is the trilinear diagram of Piper (1953) and is shown in figure 6. The diagram is divided into three major divisions. The percentage of total cations is plotted on the left triangle; while the percentage of total anions is plotted on the right triangle. These two triangles are then projected into the central diamond shaped area parallel to the upper edges of the central area (Todd, 1980). During the post-monsoon (January 2011) 90.9% of Strong acids (Cl) exceeds weak acids (HCO3 and SO4), 78.8 % Alkaline earth (Ca+Mg) exceeds alkalies (Na+K) and 63.6% Mixed type (CaNa-HCO3); during the pre-monsoon (June 2011) 100% of Strong acids (Cl) exceeds weak acids (HCO3 and SO4), 66.6% Alkaline earth (Ca+Mg) exceeds alkalies (Na+K) and 63.6% Mixed type (Ca-NaHCO3). The reason is that the groundwater that pass through igneous Fig. 4 Relationship of (Ca+Mg) Vs (SO4+HCO3) for groundwater samples during post monsoon and pre monsoon season
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rocks dissolves only small quantities of mineral matters because of contamination in groundwater which usually originates from urban the relative insolubility of the rock composition. and agricultural activities, but still an association of NO3 and K is mainly due to the impact of potash fertilizers in groundwater. Parameters
Post monsoon
Pre monsoon
Component
1
2
3
1
2
3
Ca
.979
-.004
.043
.979
.054
.014
Mg
.982
-.003
.063
.991
.017
-.095
Na
.782
.529
.128
.971
.084
.158
K
.666
.593
.101
.071
.078
.746
Cl
.964
.156
.002
.998
-.033
.000
HCO3
.579
.369
.529
.103
.834
.332
SO4
.939
.049
.009
.182
.797
.425
NO3
-.065
.846
-.153
-.077
.115
.795
pH
-.053
-.165
.918
-.141
.847
-.240
Table 3 Factor analysis of geochemical parameters during post and premonsoon season
5. Conclusion Fig. 6 Piper diagram for post monsoon and pre monsoon season
4.7. Factor Analysis Factor analysis is a statistical method used to describe variability among observed, correlated variables in terms of a potentially lower number of unobserved variables called factors. Factor analysis can recognize several pollution factors reasonably, but the interpretation of these factors in terms of actual controlling sources and processes is highly subjective. The purpose of factor analysis is to interpret the structure within the variance, covariance matrix of a multivariate data collection. Factor analysis can be applied to investigate groundwater contamination (Kanagaraj et al., 2013). Factor analysis rendered three significant factors explaining 87.1% of the total variance during post and pre-monsoon (2011) as shown in Table 3. The association of the ion in Factor I representing Ca2+, Mg2+, Cl- and Na indicate leaching of secondary salts, or backwater recharge. Factor II is represented by NO3 and K indicating the impact of Nitrate and Potassium fertilizer. NO3 is one of the extensive contamination in groundwater, which usually originates from urban and agricultural activities, but still an association of NO3 and K is mainly due to the impact of potash fertilizers in groundwater. Factor III shows the influence of pH in the hydro-geochemical environment. It is associated with positive loadings of HCO3 which indicates the weathering process. A consequence of this incongruent dissolution is a rise in pH and in the HCO3 concentration of the water (Freeze and Cherry, 1979). In pre-monsoon three factors were extracted with 84.4% of total data variance (TDV). The association of the ion in Factor I representing Ca2+, Mg2+, Cl- and Na indicate leaching of secondary salts, or backwater recharge. The concentration of Na and Cl can be attributed to the intrusion of seawater into the aquifer system which increases the concentrations of these ions. Factor II shows the influence of pH in the hydro-geochemical environment. It is associated with positive loadings of HCO3 which indicates the weathering process. A consequence of this incongruent dissolution is a rise in pH and in the HCO3 concentration of the water (Freeze and Cherry, 1979). Factor III indicates NO3 and K indicating the impact of Nitrate and Potassium fertilizer. NO3 is one of the extensive 10
Groundwater in the study area is alkaline in nature. In area having more clay content, the TDS generally increases with recharge. Based on the box and whisker plots, the abundance of the major cations is in the order of Na > Ca > Mg in both the seasons, and the abundance of major anions is in the order of HCO3 > Cl > SO4 during January 2011. Majority of the groundwater samples illustrate silicate weathering during pre monsoon compared to post monsoon season. This process might have increased the calcium, magnesium, and bicarbonate ion contents in the groundwater of the study area during the post season. The Gibb’s plot indicate that most of the water samples fall outside the plot and few of the water samples fall in the rock-water interaction and evaporation during both the seasons of the study area. During all the seasons the increase in evaporation increases the salinity and the concentration of the ions such as Na and Cl increases with increasing TDS. During the post-monsoon (January 2011) 90.9% of Strong acids (Cl) exceeds weak acids (HCO3 and SO4), 78.8% Alkaline earth (Ca+Mg) exceeds alkalies (Na+K) and 63.6% Mixed type (Ca-Na-HCO3); during pre-monsoon (June 2011) 100% of Strong acids (Cl) exceeds weak acids (HCO3 and SO4), 66.6% Alkaline earth (Ca+Mg) exceeds alkalies (Na+K) and 63.6% Mixed type (Ca-Na-HCO3). The reason is that the groundwater that pass through igneous rocks dissolves only small quantities of mineral matters because of the relative insolubility of the rock composition. Factor II is represented by NO3 and K indicating the impact of Nitrate and Potassium fertilizer. NO3 is one of the extensive contaminate in groundwater, which usually originates from urban and agricultural activities but the association of NO3 clearly indicates the impact of potash fertilizers in groundwater. In general, it is observed that the leaching of secondary salts, seawater intrusion, weathering and anthropogenic impacts are the dominant controlling factors during both the seasons of the study area.
Acknowledgement The authors are thankful to University of Madras, especially to Prof. K. K. Sharma, HOD, Department of Applied Geology for the support and infrastructures provided for the study. ORIGINAL
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References APHA, 1985. Standard methods for the examination of water and wastewater 16th Edn, Washington, D.C.American Public Health Association. Cheng, A. H. D., Ouazar, D. 2004. Coastal aquifer management-monitoring modeling and case studies pp 280, USA: Lewis Publishers. Chidambaram. S., Karmegam.U., Prasanna M. V., Sasidhar P., Vasanthavigar M. 2011. A study on hydrochemical elucidation of coastal groundwaterin and around Kalpakkam region, Southern India. Environmental Earth Sciences, 64(5), 1419-1413. Datta, P. S., Tyagi, S. K. 1996. Major ion chemistry of groundwater in Delhi area: Chemical weathering processes and groundwater flow regime: Journal of Geological Society of India, 47, 179-188. Ergil, M. E., 2000. The salination problem of the Guzelyurt aquifer, Cyprus. Water Research, 34(4), 1201–1214. Forstner, U. K., Wittaman. G. T. W. 1981. Metal Pollution in the Aquatic Environment. Springer Verlag, Berali, Heidelberg, pp 255. Franco, R., Biella, G., Tosi, L., Teatini, P., Lozej, A., Chiozzoto, B. 2009. Monitoring the salt water intrusion by time lapse electrical resistivity tomography: The Chioggia test site (Venice Lagoon Italy). Journal of Applied Geophysics 69(3-4), 117-130. Freeze, A. R., Cherry J. A. 1979. Groundwater. Prentice-Hall, Inc Englewood cliffs, New Jersy, pp 604. Gibbs, R. J. 1970. Mechanisms controlling world's water chemistry, Science, 170, 1089-1090. Jalali, M. 2007. Salinization of ground water in arid and semi-arid zones. An example from Tajarak, western Iran. Environmental Geology, 52(1), 1331149. Kanagaraj, G., Sridhar, S. G. D., Muthusamy, S., Jayaprakash, M. 2013. Hydrochemistry and Assessment of Quality of Ground water in Parts of Kancheepuram District , Tamilnadu, India. Research Expo International Multidiciplinary Research Journal, Volume- III, Issue -IV, December. Karanath, K. R. 1987. Quality of ground water. In: K. R. Karnath (Edn.). Ground water assessment development and management. New Delhi, Tata McGraw Hill. pp 217–275. Karmegam., U., Chidambaram, S., Sasidhar, P., Manivannan, R., Manikandan, R., Anandhan, P. 2010. Geochemical Characterization of Groundwater’s of Shallow Coastal Aquifer in and Around Kalpakkam, South India. Research Journal of Environmental and Earth Sciences 2(4). 170-177. Lakshmanan, E., Kannan, R., Senthil Kumar, M. 2003. Major ion chemistry and identification of hydrogeochemical processes of ground water in the part of Kancheepuram district, Tamil Nadu, India. Journal of Environmental Geoscience, 10(4), 157-166. Mhamdi, A., Gouasmia, M., Gasmi, M., Bouri, S., Dhia, H. B. 2006. Evalution of water quality by the geo electrical method: Example of the ElMida plain North Gabes (Southern Tunisia) Comptes Rendus Geoscience 338 (16), 1228-1239. Mondal, N. C., Singh, V. P., Singh, V. S., Saxena, V. K. 2010a. Determining the interaction between groundwater and saline water through groundwater major ions chemistry. Journal of Hydrology, 388, 100-111. Mondal, N. C., Singh, V. S., Puranik, S. C., Singh, V. P. 2010b. Trace element concentration in groundwater of Pesarlanka Island, Krishna Delta, India. Environmental Monitoring and Assessment, 163, 215-227. Nasab, A. A., Boufadel, M. C., Li, H., Weaver, J. W. 2010. Saltwater flusing in freshwater in a laboratory beach. Journal of Hydrology 386, (1-4), 1-12. Piper, A. M. 1953. A graphic procedure in the geo-chemical interpretation of water analyses. USGS Groundwater Note no. 12. Richter, B. C., Kreitler, C. W. 1993. Geochemical techniques for identifying sources of ground water salinization (258). CRC Press. Sarwade, D. V., Nandakumar, M. V., Kesari, M. P., Mondal, N. C., Singh, V. S., Singh, B. 2007. Evolution of seawater ingress into an Indian Atoll. Environmental Geology 52(2), 1475-1483. Sasidhar P., Vijay Kumar, S. B. 2008. Assessment of groundwater corrosiveness for unconfined aquifer system at Kalpakkam. Environmental Monitoring and Assessment, 145(1-3), 445-452. Saxena, V. K. Singh, V. S., Mondal, N. C., Jain, S. C. 2003. Use of chemical parameters to delineation fresh ground water resources in Potharlanka Island, India. Environmental Geology. 44(5), 516–521.
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Saxena, V. K., Mondal, N. C., Singh, V. S. 2004. Identification seawater ingress using Sr and B in Krishna delta. Current Science, 86(4), 586-590. Seshadri, H., Kaviyarasan, R., Sasidhar, P., Balasubramaniyan, V. 2013. Effect of Saline Water Bodies on the Hydrogeochemical Evaluation of Groundwater at Kalpakkam Coastal Site, Tamil Nadu. Journal of Geological Society of India, 82(5), 535-544. Sivakumar, C., Elango, L. 2008. Assessment of water quality in Kalpakkam region, Tamilnadu, Nature Environment and Pollution Technology, l7, (4), 689-691. Tijani, M.N. 1994. Hydrochemical assessment of groundwater in Moro area, Kwar State, Nigeria. Environmental Geology, 24, 194–202. Todd, D. K. 1980. Ground water hydrology 2nd Edn.,Wiley, New York. pp 552. WHO, 2004. Guidelines for drinking water quality recommendations. Vol.1, pp 515, Geneva: WHO. Zekri, S. 2008. Using economic incentives and regulations to reduce seawater intrusion in the Batinah coastal area of Oman. Agricultural Water Management, 95(3), 243-252.
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JOURNAL OF COASTAL SCIENCES Journal homepage: www.jcsonline.co.nr ISSN: 2348 – 6740
Volume 2 Issue No. 1 - 2015
Pages 6-11
Assessment of groundwater quality and seawater intrusion along the coastal aquifer around Kalpakkam, Tamil Nadu, India *G. Kanagaraj, S.G.D. Sridhar, A.M. Sakthivel Department of Applied Geology and Centre for Environmental Sciences, School of Earth and Atmospheric Sciences, University of Madras, Guindy Campus, Chennai 600 025, India
ABSTRACT
ARTICLE INFO
The chemical characteristics of thirty three groundwater samples around Kalpakkam region were studied during post monsoon (PSM) and pre monsoon (PRM) season (2011). The hydro-geochemical data were processed with reference to World Health Organization (WHO) standards. The dominance of anions and cations were in the order of Cl- > HCO3- > NO3- > SO4 and Na+ > Mg > Ca > K. The northeastern part of the study area has EC values above permissible limit during both seasons, which may be attributed to the proximity of backwater and saline intrusion. The groundwater of the study area is characterized by the dominance of strong acids (Cl) exceeds weak acids (HCO3 and SO4) during both seasons of the year 2011, as 90.9% and100% based on the hydro-chemical facies. These have been almost certainly derived from natural chemical weathering of rock minerals, ion exchange and to some extent by anthropogenic activities such as application of fertilizers. 39.4% and 51.5% of the total samples collected were found to have higher seawater ratio, indicating a large proportion of groundwater affected by seawater intrusion. Most of the ions are positively correlated with Cl-, especially with Na and Mg indicating that such ions are derived from saline water intrusion and chemical weathering along with leaching of secondary salts, that clearly indicates natural as well as anthropogenic activities. The association of the ion in factor I representing Ca, Mg, Cl and Na indicate leaching of secondary salts, or backwater recharge. The groundwater quality was found suitable for drinking purposes.
Received 1 November 2014 Accepted 16 March 2015 Available online 20 March 2015 Keywords Geochemistry Seawater intrustion SPSS Piper diagram Factor analysis Kalpakkam
*Corresponding author, E-mail address: [email protected] Phone: 044-22202724, © 2015 – Journal of Coastal Sciences. All rights reserved
1. Introduction Water is an essential and vital component of our life support system. Geochemical processes occurring within the groundwater and reactions with aquifer minerals have significant effect on water quality. Groundwater also plays an important role in agriculture, for irrigating the crops. The coastal aquifers suffer saline water intrusion that becomes a worldwide concern (Eragil, 2000; Cheng and Ouazar, 2004; Mhamdi et al., 2006; Zekri, 2008; Franco et al., 2009; Nasab et al., 2010; Mondal et al., 2010a). Groundwater chemistry based on hydrochemical data is useful for providing preliminary information on water types, classification of water for various purposes as well as identification of different aquifer and study of different chemical processes (Karanth, 1987; Saxena et al., 2003; Jalali, 2007; Sarwade et al., 2007). The industrial waste water, sewage sludge, solid waste materials are currently being discharged into the environment indiscriminately. These materials enter into the freshwater aquifers, resulting in the pollution of irrigation and drinking water (Forstner and Wittman, 1981). The seawater intrusion is a main cause of high salinity, and groundwater generally demonstrates high concentration not only in total dissolved solids (TDS) but also in cations and anions (Richter and Krietler, 1993) as well as the increase of selective trace element (Saxena et al., 2004; Mondal et al., 2010b). Seawater intrusion is defined as the migration of saline water from the sea into freshwater aquifer that are hydraulically connected with the sea. 6
Seawater intrusion leads to the salinization of fresh water aquifers along the coastlines. In highly populated coastal regions with greater dependence on groundwater, the withdrawal usually exceeds the recharge rate resulting in seawater intrusion. The density of seawater is marginally higher than that of freshwater. When seawater intrusion is a main cause of high salinity, groundwater generally exhibits high concentrations not only in total dissolved solids (TDS) but on some specific chemical constituents, such as Cl-, Na+, Mg2+, and SO42- (Richter and Kreitler, 1993) as well as accumulation of selected trace elements (Saxena et al., 2004; Mondal et al., 2010b). The coastal groundwater system is fragile and its evolution will help in the proper planning and sustainable management. Interpretation of hydrochemical data suggests that calcium carbonate dissolution, ion-exchange processes, halite dissolution, silicate weathering, and irrigation return flow are responsible for the groundwater chemistry in the area. The water quality assessment studies in the nearby coastal aquifers were carried out by several authors (Sivakumar and Elango, 2008; Sasidhar and Vijay Kumar, 2008; Karmegam et al., 2010; Chidambaram et al., 2011; Seshadri et al., 2013). But, the present study area lacks a detailed approach on groundwater geochemistry. So, the present research investigates the hydrogeochemical processes that control the groundwater chemistry of the study area including its suitablity for drinking purpose. This will lead to ORIGINAL
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improved understanding of the hydrogeochemical characteristics of 3. Methodology the coastal aquifers along the Kalpakkam coast. For the assessment of groundwater quality, 33 ground water samples 2. Study area and Geology were collected during January 2011 (post-monsoon) and June 2011 (pre-monsoon) from the bore well and dug wells. These samples The study area lies between 80˚3ʹ and 80˚13ʹ30ʺ E longitude and were collected in 1 liter capacity polyethylene bottles. The pH, from 12˚20ʹ30ʺ to 12˚48’30” N latitude. It is situated about 70 km temperature, electrical conductance (EC), and total dissolved solids South of Chennai. The area is bounded by Bay of Bengal on the east, (TDS) were measured in-situ using portable bore well logger (Multi Edaiyur backwaters on the north and Buckingham canal on the west. probe system, YSI 556 MPS). The samples collected were analyzed in The average annual rainfall in the study area is 1237 mm. The the laboratory for concentration of major ions. The Ca2+, Mg2+, CO3, topography of the study area is slightly undulating with sand bars HCO3 were determined titrimetrically (APHA, 1985). The Na+, K+ and depressions. The regional gradient is towards the eastern side. were estimated using Flame photometer. The anions Cl-, NO3, SO4 The altitude varies between less than a meter to 13 m above MSL. were determined using Ion Chromatography. The statistical analysis The geology of the area consists of Archean basement at the bottom, were carried out using SPSS software. which is made up charnockites and overlain by recent alluvium. The depth of hard rock varies from 12 to 20 m below the ground surface. 4. Results and Discussion The weathered/fractured charnockite and the alluvium form the major aquifer system of the study area. Lenses of clays and clay The results of the analysis are presented in Table 1 for the study area pockets were encountered in the alluvial formations. The thickness during post and pre monsoon of the year 2011. Groundwater in the of the sandy formations varies from 3 to 12 m. The shallow aquifer is study area is generally have pH ranging from 6 to 8 during postunconfined in nature. The study area and sample location shown in monsoon season, while in the pre-monsoon it ranges from 6.1 to 7.7. figure 1. They are within the permissible limit in both the seasons based on
Fig. 1 Geomorphology of study area with location of groundwater samples
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WHO (2004). EC is one of the measurement of strength and mineralization of natural water. In the study area, EC ranges from 138 to 7312µS/cm during post-monsoon, while in the pre-monsoon it ranges from 100 to 3940 µS/cm. TDS range from 89 to 4258 mg/l during post-monsoon season, whereas, during pre-monsoon it ranges from 133 to 8054 mg/l. According to WHO (2004) TDS is above permissible limit in both the seasons. TDS increases after rains that dissolve minerals from overlying rocks (minerals) during infiltration. Parameter EC pH TDS Ca Mg Na K HCO3 SO4 Cl NO3
Post monsoon Minimum Maximum 138 7312 6 8 89 4258 5 600 3 240 6 520 1 30 20 465 8 425 13 2048 3 58
Pre monsoon Minimum Maximum 100 3940 6.1 7.7 133 8054 6 620 1 430 11 1750 1 72 30 738 8 104 28 4815 1 182
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to 58 mg/l whereas, it ranges between 1 and 182 mg/l during premonsoon samples. Based on the WHO (2004), Cl, HCO3 are above permissible limit in most of the samples, but SO4 and NO3 are within permissible limit. It indicates that most of the samples are not suitable for drinking purpose as well as agriculture uses. World Health Organisation Standards (2004) Sl No.
Parameters
Acceptable Limit
Permissible Limit
1
pH
6.5-8.5
No relaxation
2
TDS
500
1000
3
EC
1400
-
4
Na
-
200
5
Ca
100
200
6
Mg
50
100
7
K
20
42
8
Cl
250
1000
9 10
SO4 NO3
250 45
400 No relaxation
Table 2 World Health Organisation Standards (2004) for drinking water
Table 1 Minimum and maximum values for different parameters of the study 4.3. Box and Whisker plot area for post and pre monsoon seasons. All parameters are reported in mg/l, except EC (µs/cm), pH in pH scale. Box plots can be used to compare groundwater quality data
4.1. Major cations The ascendancy of cations is as follows Na > Mg > Ca > K during post and pre-monsoon seasons. Sodium ion concentration in the postmonsoon season varies from 6 to 520 mg/l while it ranges between 11 and 1750 mg/l during pre-monsoon. Sodium concentration plays an important role in evaluating the groundwater quality for irrigation because sodium causes an increase in the hardness of soil as well as a reduction in its permeability (Tijani, 1994). Calcium ion concentration in the post-monsoon season varies from 5 to 600 mg/l while it ranges between 6 and 620 mg/l during pre-monsoon samples. Magnesium ion concentration in the post-monsoon season varies from 3 to 240 mg/l while it ranges between 1 and 430 mg/l during pre-monsoon samples. Potassium ion concentration in the post-monsoon season varies from 1 to 30 mg/l whereas; it ranges between 1 and 72 mg/l during pre-monsoon samples. Comparing the WHO (2004), Na, Ca, Mg and K concentrations were above permissible limit in most of the samples. The WHO standards for anions and cations are presented in Table 2.
(generally for the same parameter) between wells. The plots are constructed using the median value and the inter-quartile range (25 and 75 cumulative frequency measured as central tendency and variability). They are quick and convenient way to visualize the spread of data. The chemical composition of the groundwater samples is shown in the box plot (Figure 2 and 3). The abundance of the major cations is in the order of Na > Ca > Mg in both seasons. The abundance of major anions is in the order of HCO3 > Cl > SO4 during January 2011, and they have been pictorially represented in the box plot.
4.2. Major anions The ascendancy of anions is as follows Cl > HCO3 > NO3 >SO4 during post and pre-monsoon seasons. Chloride ion concentration in the post-monsoon season varies from 13 to 2048 mg/l while it ranges between 28 and 4815 mg/l during pre-monsoon samples. Cl- is higher due to the impact of saline water and base ion exchange reaction (Freeze and Cherry, 1979). Bicarbonate ion concentration in the post-monsoon season varies from 20 to 465 mg/l while it ranges between 30 and 738 mg/l during pre-monsoon samples. Higher concentration of bicarbonate indicates the contribution of silicate and carbonate for chemical weathering. Sulphate ion concentration in the post-monsoon season varies from 8 to 425 mg/l while it ranges between 8 and 104 mg/l during pre-monsoon samples. Fig. 2 Box and Whisker’s plots for Post monsoon season Nitrate ion concentration in the post-monsoon season varies from 3 8
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This shows that most of the sample points lie below the equiline with few of the samples lie above the equiline. Majority of the groundwater samples illustrate silicate weathering during June (2011) compared to post monsoon season. This process might have increased the calcium, magnesium, and bicarbonate ion contents in the groundwater of the study area during the said seasons. 4.5. Gibbs Plot
Fig. 3 Box and Whisker’s plots for Pre monsoon season
Reactions between groundwater and aquifer minerals have a significant role in water quality, which is also useful to understand the genesis of groundwater. Groundwater chemistry in the study area is regulated by diverse processes and mechanisms. The chemical relationships of groundwater based on the lithology of aquifer have been studied following the plot derived by Gibb’s (1970). Three kinds of fields are recognized in the Gibb’s diagram, namely, precipitation, evaporation/crystallization, and rock-water interaction. The weathering dominated water has high Ca and HCO3concentration, and the evaporation/crystallization dominated water is characterized with high Na+ and Cl- contents. In the cation plot, (Figure 5) most of the water samples fall outside the plot and few of the water samples fall in the rock-water interaction and evaporation, for both the seasons of the study area. During both the seasons, the increase in evaporation increases the salinity and the concentration of the ions such as Na and Cl that increases with increasing TDS.
4.4. (Ca+Mg) vs (HCO3+SO4) diagram In the (Ca+Mg) vs (HCO3+SO4) diagram, explained by Datta and Tyagi (1996) the ionic concentrations falling above the equiline are due to carbonate weathering, whereas, those falling along the equiline are caused by both carbonate weathering and silicate weathering (Lakshmanan et al., 2003). (Ca+Mg) vs (HCO3+SO4) scatter diagram of the study area is shown in figure 4.
Fig. 5 Gibb’s plot for post monsoon and pre monsoon season
4.6. Hydrochemical Facies One of the most useful graphs for representing and comparing geochemistry in water quality analysis is the trilinear diagram of Piper (1953) and is shown in figure 6. The diagram is divided into three major divisions. The percentage of total cations is plotted on the left triangle; while the percentage of total anions is plotted on the right triangle. These two triangles are then projected into the central diamond shaped area parallel to the upper edges of the central area (Todd, 1980). During the post-monsoon (January 2011) 90.9% of Strong acids (Cl) exceeds weak acids (HCO3 and SO4), 78.8 % Alkaline earth (Ca+Mg) exceeds alkalies (Na+K) and 63.6% Mixed type (CaNa-HCO3); during the pre-monsoon (June 2011) 100% of Strong acids (Cl) exceeds weak acids (HCO3 and SO4), 66.6% Alkaline earth (Ca+Mg) exceeds alkalies (Na+K) and 63.6% Mixed type (Ca-NaHCO3). The reason is that the groundwater that pass through igneous Fig. 4 Relationship of (Ca+Mg) Vs (SO4+HCO3) for groundwater samples during post monsoon and pre monsoon season
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rocks dissolves only small quantities of mineral matters because of contamination in groundwater which usually originates from urban the relative insolubility of the rock composition. and agricultural activities, but still an association of NO3 and K is mainly due to the impact of potash fertilizers in groundwater. Parameters
Post monsoon
Pre monsoon
Component
1
2
3
1
2
3
Ca
.979
-.004
.043
.979
.054
.014
Mg
.982
-.003
.063
.991
.017
-.095
Na
.782
.529
.128
.971
.084
.158
K
.666
.593
.101
.071
.078
.746
Cl
.964
.156
.002
.998
-.033
.000
HCO3
.579
.369
.529
.103
.834
.332
SO4
.939
.049
.009
.182
.797
.425
NO3
-.065
.846
-.153
-.077
.115
.795
pH
-.053
-.165
.918
-.141
.847
-.240
Table 3 Factor analysis of geochemical parameters during post and premonsoon season
5. Conclusion Fig. 6 Piper diagram for post monsoon and pre monsoon season
4.7. Factor Analysis Factor analysis is a statistical method used to describe variability among observed, correlated variables in terms of a potentially lower number of unobserved variables called factors. Factor analysis can recognize several pollution factors reasonably, but the interpretation of these factors in terms of actual controlling sources and processes is highly subjective. The purpose of factor analysis is to interpret the structure within the variance, covariance matrix of a multivariate data collection. Factor analysis can be applied to investigate groundwater contamination (Kanagaraj et al., 2013). Factor analysis rendered three significant factors explaining 87.1% of the total variance during post and pre-monsoon (2011) as shown in Table 3. The association of the ion in Factor I representing Ca2+, Mg2+, Cl- and Na indicate leaching of secondary salts, or backwater recharge. Factor II is represented by NO3 and K indicating the impact of Nitrate and Potassium fertilizer. NO3 is one of the extensive contamination in groundwater, which usually originates from urban and agricultural activities, but still an association of NO3 and K is mainly due to the impact of potash fertilizers in groundwater. Factor III shows the influence of pH in the hydro-geochemical environment. It is associated with positive loadings of HCO3 which indicates the weathering process. A consequence of this incongruent dissolution is a rise in pH and in the HCO3 concentration of the water (Freeze and Cherry, 1979). In pre-monsoon three factors were extracted with 84.4% of total data variance (TDV). The association of the ion in Factor I representing Ca2+, Mg2+, Cl- and Na indicate leaching of secondary salts, or backwater recharge. The concentration of Na and Cl can be attributed to the intrusion of seawater into the aquifer system which increases the concentrations of these ions. Factor II shows the influence of pH in the hydro-geochemical environment. It is associated with positive loadings of HCO3 which indicates the weathering process. A consequence of this incongruent dissolution is a rise in pH and in the HCO3 concentration of the water (Freeze and Cherry, 1979). Factor III indicates NO3 and K indicating the impact of Nitrate and Potassium fertilizer. NO3 is one of the extensive 10
Groundwater in the study area is alkaline in nature. In area having more clay content, the TDS generally increases with recharge. Based on the box and whisker plots, the abundance of the major cations is in the order of Na > Ca > Mg in both the seasons, and the abundance of major anions is in the order of HCO3 > Cl > SO4 during January 2011. Majority of the groundwater samples illustrate silicate weathering during pre monsoon compared to post monsoon season. This process might have increased the calcium, magnesium, and bicarbonate ion contents in the groundwater of the study area during the post season. The Gibb’s plot indicate that most of the water samples fall outside the plot and few of the water samples fall in the rock-water interaction and evaporation during both the seasons of the study area. During all the seasons the increase in evaporation increases the salinity and the concentration of the ions such as Na and Cl increases with increasing TDS. During the post-monsoon (January 2011) 90.9% of Strong acids (Cl) exceeds weak acids (HCO3 and SO4), 78.8% Alkaline earth (Ca+Mg) exceeds alkalies (Na+K) and 63.6% Mixed type (Ca-Na-HCO3); during pre-monsoon (June 2011) 100% of Strong acids (Cl) exceeds weak acids (HCO3 and SO4), 66.6% Alkaline earth (Ca+Mg) exceeds alkalies (Na+K) and 63.6% Mixed type (Ca-Na-HCO3). The reason is that the groundwater that pass through igneous rocks dissolves only small quantities of mineral matters because of the relative insolubility of the rock composition. Factor II is represented by NO3 and K indicating the impact of Nitrate and Potassium fertilizer. NO3 is one of the extensive contaminate in groundwater, which usually originates from urban and agricultural activities but the association of NO3 clearly indicates the impact of potash fertilizers in groundwater. In general, it is observed that the leaching of secondary salts, seawater intrusion, weathering and anthropogenic impacts are the dominant controlling factors during both the seasons of the study area.
Acknowledgement The authors are thankful to University of Madras, especially to Prof. K. K. Sharma, HOD, Department of Applied Geology for the support and infrastructures provided for the study. ORIGINAL
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References APHA, 1985. Standard methods for the examination of water and wastewater 16th Edn, Washington, D.C.American Public Health Association. Cheng, A. H. D., Ouazar, D. 2004. Coastal aquifer management-monitoring modeling and case studies pp 280, USA: Lewis Publishers. Chidambaram. S., Karmegam.U., Prasanna M. V., Sasidhar P., Vasanthavigar M. 2011. A study on hydrochemical elucidation of coastal groundwaterin and around Kalpakkam region, Southern India. Environmental Earth Sciences, 64(5), 1419-1413. Datta, P. S., Tyagi, S. K. 1996. Major ion chemistry of groundwater in Delhi area: Chemical weathering processes and groundwater flow regime: Journal of Geological Society of India, 47, 179-188. Ergil, M. E., 2000. The salination problem of the Guzelyurt aquifer, Cyprus. Water Research, 34(4), 1201–1214. Forstner, U. K., Wittaman. G. T. W. 1981. Metal Pollution in the Aquatic Environment. Springer Verlag, Berali, Heidelberg, pp 255. Franco, R., Biella, G., Tosi, L., Teatini, P., Lozej, A., Chiozzoto, B. 2009. Monitoring the salt water intrusion by time lapse electrical resistivity tomography: The Chioggia test site (Venice Lagoon Italy). Journal of Applied Geophysics 69(3-4), 117-130. Freeze, A. R., Cherry J. A. 1979. Groundwater. Prentice-Hall, Inc Englewood cliffs, New Jersy, pp 604. Gibbs, R. J. 1970. Mechanisms controlling world's water chemistry, Science, 170, 1089-1090. Jalali, M. 2007. Salinization of ground water in arid and semi-arid zones. An example from Tajarak, western Iran. Environmental Geology, 52(1), 1331149. Kanagaraj, G., Sridhar, S. G. D., Muthusamy, S., Jayaprakash, M. 2013. Hydrochemistry and Assessment of Quality of Ground water in Parts of Kancheepuram District , Tamilnadu, India. Research Expo International Multidiciplinary Research Journal, Volume- III, Issue -IV, December. Karanath, K. R. 1987. Quality of ground water. In: K. R. Karnath (Edn.). Ground water assessment development and management. New Delhi, Tata McGraw Hill. pp 217–275. Karmegam., U., Chidambaram, S., Sasidhar, P., Manivannan, R., Manikandan, R., Anandhan, P. 2010. Geochemical Characterization of Groundwater’s of Shallow Coastal Aquifer in and Around Kalpakkam, South India. Research Journal of Environmental and Earth Sciences 2(4). 170-177. Lakshmanan, E., Kannan, R., Senthil Kumar, M. 2003. Major ion chemistry and identification of hydrogeochemical processes of ground water in the part of Kancheepuram district, Tamil Nadu, India. Journal of Environmental Geoscience, 10(4), 157-166. Mhamdi, A., Gouasmia, M., Gasmi, M., Bouri, S., Dhia, H. B. 2006. Evalution of water quality by the geo electrical method: Example of the ElMida plain North Gabes (Southern Tunisia) Comptes Rendus Geoscience 338 (16), 1228-1239. Mondal, N. C., Singh, V. P., Singh, V. S., Saxena, V. K. 2010a. Determining the interaction between groundwater and saline water through groundwater major ions chemistry. Journal of Hydrology, 388, 100-111. Mondal, N. C., Singh, V. S., Puranik, S. C., Singh, V. P. 2010b. Trace element concentration in groundwater of Pesarlanka Island, Krishna Delta, India. Environmental Monitoring and Assessment, 163, 215-227. Nasab, A. A., Boufadel, M. C., Li, H., Weaver, J. W. 2010. Saltwater flusing in freshwater in a laboratory beach. Journal of Hydrology 386, (1-4), 1-12. Piper, A. M. 1953. A graphic procedure in the geo-chemical interpretation of water analyses. USGS Groundwater Note no. 12. Richter, B. C., Kreitler, C. W. 1993. Geochemical techniques for identifying sources of ground water salinization (258). CRC Press. Sarwade, D. V., Nandakumar, M. V., Kesari, M. P., Mondal, N. C., Singh, V. S., Singh, B. 2007. Evolution of seawater ingress into an Indian Atoll. Environmental Geology 52(2), 1475-1483. Sasidhar P., Vijay Kumar, S. B. 2008. Assessment of groundwater corrosiveness for unconfined aquifer system at Kalpakkam. Environmental Monitoring and Assessment, 145(1-3), 445-452. Saxena, V. K. Singh, V. S., Mondal, N. C., Jain, S. C. 2003. Use of chemical parameters to delineation fresh ground water resources in Potharlanka Island, India. Environmental Geology. 44(5), 516–521.
11
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Saxena, V. K., Mondal, N. C., Singh, V. S. 2004. Identification seawater ingress using Sr and B in Krishna delta. Current Science, 86(4), 586-590. Seshadri, H., Kaviyarasan, R., Sasidhar, P., Balasubramaniyan, V. 2013. Effect of Saline Water Bodies on the Hydrogeochemical Evaluation of Groundwater at Kalpakkam Coastal Site, Tamil Nadu. Journal of Geological Society of India, 82(5), 535-544. Sivakumar, C., Elango, L. 2008. Assessment of water quality in Kalpakkam region, Tamilnadu, Nature Environment and Pollution Technology, l7, (4), 689-691. Tijani, M.N. 1994. Hydrochemical assessment of groundwater in Moro area, Kwar State, Nigeria. Environmental Geology, 24, 194–202. Todd, D. K. 1980. Ground water hydrology 2nd Edn.,Wiley, New York. pp 552. WHO, 2004. Guidelines for drinking water quality recommendations. Vol.1, pp 515, Geneva: WHO. Zekri, S. 2008. Using economic incentives and regulations to reduce seawater intrusion in the Batinah coastal area of Oman. Agricultural Water Management, 95(3), 243-252.
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