Assessment of hydrochemistry of groundwater in Muthupet coastal region, Tamilnadu, India.

Introduction

Water source have always been a precious commodity for human life. Water is used for a wide variety of purposes, chief among which are domestic, industrial, irrigation, hydroelectric power generation, navigation, recreation and fisheries development. The extent of a water use for any one purpose varies from one country to another and is dependent on a variety of factors like state of economic development, including standard of living; importance and extent of a specific sector like industry or agriculture in the national economy; efficiency of water use; socioculturar practices, and so on (Venkatesh et. al, 2005). An estimate by World Bank report that the year 2025, about 3.25 billion people in 52 countries will live in conditions of acute water shortage (Serageldin, 1995). Indian sub-continent is one of the wettest places on earth (Subramanian, 2000). The groundwater is the major source for domestic and agricultural activities in this study area.

Study area

The study area, Muthupet is situated in Tiruvarur district of Tamilnadu (Fig. 1). The study area is located between latitude 10[degrees]16'00" to 10[degrees]34'00" North and longitude 79[degrees]26'30" to 79[degrees]42'00" East in the survey of India toposheets number 58N/7, N/10, and N/11. The study area receives an average rainfall of 1327.11mm. The maximum and minimum temperature ranges between 28[degrees]C to 34[degrees]C in the months of January to May respectively. Geologically, the study area comprises of alluvium, sandy clay, silt and fluviomarine sediments. Geomorphlolgically, the Muthupet consist of flood plains, delta plain and natural levee.

[FIGURE 1 OMITTED]

Materials and methods

Groundwater samples were collected systematically using clear acid washed polythene bottles form nine locations during february to september 2007 and analyzed for various physico-chemical parameters using standard procedure APHA (1998). The results of the physico-chemical analysis are given in Table .1, 2 & 3. The pH, EC were measured by field kit Total dissolved solids was estimated by calculation method. Sodium and potassium were determined using flame photometer. Calcium, magnesium, chloride and bicarbonate were determined by volumetric titration methods. Sulphate was determined using spectrophotometer. All the concentration are expressed in mg/1 except pH and EC in [micro]S/cm.

Result and discussion

Major ion chemistry

The pH concentration ranges from 6.3 to 7.25, 7.2 to 8.6 and 6.5 to 8.0 in post, summer and premonsoon seasons respectively. In general, pH of water sample is slightly acidic to alkaline in nature. The electrical conductivity values are found to be within the range of 1014-3227 [micro]S/cm at 25[degrees]C in the study area. EC has a direct bearing on the percentage of total dissolved solids (Srinivasan et. al 2000). The concentration of total dissolved solids ranges from 139.91 to 516.13 mg/l in the study area. Calcium and magnesium ions present in groundwater is particularly derived from leaching of limestone, dolomites, gypsum and anhydrites, whereas the calcium ions is also derived from cation exchange process (Garrels 1976). Calcium concentration ranges from 19 to 31 mg/l, 69.6 to 136.3 mg/l and 37.3 to 64 mg/l in post, summer and premonsoon seasons respectively. The concentration of magnesium ranges from 14 to 55.83 mg/l, with an average value of 34.91 mg/l. Sodium concentration is various from 142.6 to 620.1 mg/l in the study period. Sodium is high in summer season particularly in the northwestern parts. Potassium contents ranges from 18.05 to 130.53 mg/l in the study period.

Bicarbonate ion is varies from 26 to 46 mg/l, 69 to 92 mg/l and 34.66 to 73.33 mg/l in the groundwater samples of during post, summer and premonsoon seasons respectively. The high bicarbonate concentration was obtained in well number 6 during summer season. Chloride concentration of groundwater samples in the study area lies in the ranges between 209.5 to 702.46 mg/l and sulphate ion is varies from 151.45 to 713.4 mg/l in the study period. Sulphate ion concentrations are probably derived from weathering of sulfate and gypsum-bearing sedimentary rocks (Elango et al. 2003; Jeevanandam et al. 2006). The nitrate ion varies from 1.9 to 7.8 mg/l in the study period. Nitrogen compounds are present in groundwater in the form of nitrate (NO3) and nitrite (NO2) ions. Nitrite is more toxic to animal and human health than nitrate. Nitrates are extremely soluble in water and can move easily through soil into the drinking water supply (Saba et al. 2006). The fertilizers and domestic wastes are main sources of nitrogen-containing compounds and they are converted to nitrates in the soil.

Hydrogeochemical facies

The piper (1953) trilinear diagram is most useful to understand chemical relationships among groundwater. The chemical quality data of the investigated area are used in piper trilinear diagram for graphical analysis (Fig.2). The groundwater samples falls in Na-Cl segments of the diamond shaped field.

[FIGURE 2 OMITTED]

Irrigation water quality (USSL-United states salinity laboratory, 1954)

The sodium absorption ration (SAR) is useful for judging the quality of groundwater for the use of agricultural purposes (Todd, 1980 and Lawrence, 1982) classified the waters in relation to irrigation based in the ranges of SAR values. Sodium absorption ration is expressed as,

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]

Where the concentration are expressed in equivalent per million (epm).

The plot of data on the U.S.S.L diagram (Fig.3a,b & c) in which EC is taken as salinity hazard and SAR as alkalinity hazard, shows that most of the water samples fall in the categories C3 S1, C3 S2 and few samples in C4 S2 indicating medium to high salinity in all seasons and hence moderately suitable for irrigation purposes.

Drinking water quality

To ascertain the suitability of groundwater for drinking and public health purposes, hydrochemical parameters of the study area are compared with the guideline recommended by world health organization (WHO, 1984) and Indian drinking water standard (BIS, 1983) in Table. 4, which shows that groundwater has partial suitability for drinking purposes and public health because the concentration of TDS, Na and S[O.sub.4] in the groundwater are observed to be more than the concentration of recommended limits for drinking purpose.

[FIGURE 3a OMITTED]

[FIGURE 3b OMITTED]

[FIGURE 3c OMITTED]

Conclusions

The groundwater increases its major ions concentration in the summer season in comparison to the post and premonsoon period. This is because of evaporation, precipitation and environment weathering in the study area.

The groundwater nature is explained by the Piper trilinear diagram which indicates that most of the groundwater samples fall in Na, Ca, Mg facies followed by Cl, S[O.sub.4] facies. The groundwater quality of irrigation water is compared based on electrical conductance, sodium absorption ratio show that groundwater moderately suitable for irrigation.

Hydrochemical parameters of the study area are compared with the guideline recommended by WHO and BIS standards shows the groundwater has partial suitability for drinking purposes.

References

[1] APHA. 1998. Standard methods for the examination of water and waste water. American public health association, Washington.

[2] BIS. 1983. Standards for water for drinking and other purposes. Bureau of Indian standards publication. New Delhi.

[3] Elango, L., Kannan, R. & Senthil Kumar., 2003. "Major ion chemistry and identification of hydrogeochemical processes of groundwater in a part of Kancheepuram District, Tamil Nadu, India". Journal Environmental Geosciences, 10-4, 157-166.

[4] Garrels, R. M. 1976. "A Survey of Low Temperature Water Mineral Relations, in Interpretation of Environmental Isotope and Hydrogeochemical Data in Groundwater Hydrology: Vienna". International Atomic Energy Agency. 65-84.

[5] Jeevanandam, M., Kannan, R., Srinivasalu, S., & Rammohan, V. 2006. "Hydrogeochemistry and groundwater quality assessment of lower part of the Ponnaiyar River Basin, Cuddalore district, SouthIndia". Environmental Monitoring and Assessment, 132 (1), 263-274.

[6] Lawrence. F.W., Upchurch. S.B., 1982. "Identification of recharge areas using geochemical factor analysis". Groundwater. 20.

[7] Piper. A.M., 1953. "A graphic procedure in the geochemical interpretation of water analysis". Trans. Am. Geophys. Union. 25, 914-23.

[8] Saba, S., Nalan, K., Umran, Y., Muserref, A., & Mithat, Y. 2006. "Removal of nitrate from aqueous solution by nitrate selective ion exchange resins". Reactive & Functional Polymers. 66, 1206-1214.

[9] Serageldin. I. 1995. Water resources management: A new policy for sustainable future water international. 20, 15-22.

[10] Srinivas. C.H., Pisk. R.S., Venkateshwar. C., Rao. M.S.S and Reddy. R.R. 2000. "Studies on groundwater quality of Hyderabad". Poll. Res. 19 (2), 285-289.

[11] Subramanian. 2000. "Water quantity-quality prospective in South Asia". Kingston international publishers, Surrey, United Kingdom. 256.

[12] Todd. D.K. 1980. Groundwater hydrology, 2nd ed. John Wiley and sons, Newyork, 256p.

[13] Venkatesh. B. 2005. "Interbasin water transfer--A review of international experience". Jour. of Applied hydrology. 4, 30-39.

[14] W.H.O., 1984. Guidelines for the drinking water quality. Recommendation WHO, Geneva, Vol.1.

S. Venkatramanan*, T. Ramkumar, S. Vasudevan, G. Ramesh, I. Anitha mary and V. Vijayakumar

Department of Earth Sciences, Annamalai University, Annamalainagar-608002.

* Corresponding author E-mail: [e-mail]

Table 2: Physico--chemical parameters of the groundwater samples
(Summer).

S.No   pH    EC ([micro]S/cm)   TDS     Ca      Mg     Na       K

 1     7.5         3187         2040   76.3    42.0   620.1   130.5
 2     7.3         2929         1875   106.0   38.7   393.8   76.6
 3     7.4         2773         1775   102.7   44.1   336.4   32.3
 4     8.4         2459         1574   103.3   55.8   357.9   33.9
 5     7.6         3227         2065   136.3   42.7   500.7   62.0
 6     7.7         3021         1934   81.3    24.8   570.8   67.8
 7     7.5         2828         1810   69.7    23.2   514.8   74.9
 8     8.6         3091         1978   78.0    32.5   588.5   93.7
 9     7.3         2421         1550   86.3    38.1   512.7   38.6

S.No   HC[O.sub.3]   N[O.sub.3]   S[O.sub.4]    Cl

 1        87.3          7.0         637.5      526.3
 2        76.3          6.6         656.2      596.6
 3        73.7          6.6         644.6      607.8
 4        82.0          7.2         337.8      677.5
 5        70.0          6.8         713.4      603.4
 6        92.0          7.8         616.5      564.4
 7        88.7          6.7         417.9      702.5
 8        69.0          5.9         660.0      519.6
 9        70.0          5.8         341.0      526.9

Table 2: Physico--chemical parameters of the groundwater
samples (Summer)

S.No   pH    EC ([micro]S/cm)   TDS     Ca      Mg     Na       K

 1     7.5         3187         2040   76.3    42.0   620.1   130.5
 2     7.3         2929         1875   106.0   38.7   393.8   76.6
 3     7.4         2773         1775   102.7   44.1   336.4   32.3
 4     8.4         2459         1574   103.3   55.8   357.9   33.9
 5     7.6         3227         2065   136.3   42.7   500.7   62.0
 6     7.7         3021         1934   81.3    24.8   570.8   67.8
 7     7.5         2828         1810   69.7    23.2   514.8   74.9
 8     8.6         3091         1978   78.0    32.5   588.5   93.7
 9     7.3         2421         1550   86.3    38.1   512.7   38.6

S.No   HC[O.sub.3]   N[O.sub.3]   S[O.sub.4]    Cl

 1        87.3          7.0         637.5      526.3
 2        76.3          6.6         656.2      596.6
 3        73.7          6.6         644.6      607.8
 4        82.0          7.2         337.8      677.5
 5        70.0          6.8         713.4      603.4
 6        92.0          7.8         616.5      564.4
 7        88.7          6.7         417.9      702.5
 8        69.0          5.9         660.0      519.6
 9        70.0          5.8         341.0      526.9

Table 3: Physico--chemical parameters of the groundwater
samples (Premonsoon).

S.No   pH    EC ([micro]S/cm)   TDS     Ca     Mg     Na      K

 1     6.9         1896         1214   37.3   21.9   401.9   98.1
 2     6.5         1676         1073   46.0   28.3   275.8   69.3
 3     6.6         1749         1119   46.3   29.1   265.1   28.6
 4     7.1         1839         1177   51.3   31.7   288.4   32.0
 5     8.1         2231         1428   48.7   33.3   337.9   55.9
 6     7.7         2045         1309   44.7   19.2   523.0   62.4
 7     7.3         2265         1450   40.7   24.7   379.3   70.5
 8     7.1         1969         1260   59.3   26.4   453.0   90.5
 9     7.1         1518         971    64.0   26.3   361.0   34.8

S.No   HC[O.sub.3]   N[O.sub.3]   S[O.sub.4]    Cl

 1        46.7          4.8         320.3      329.4
 2        50.0          4.0         248.5      400.8
 3        62.0          3.7         276.5      469.9
 4        46.0          4.0         314.7      454.9
 5        35.0          5.0         443.9      503.0
 6        51.3          4.3         333.5      321.9
 7        73.3          4.5         433.5      496.4
 8        34.7          4.1         253.6      373.2
 9        47.3          3.8         232.0      249.4

Table 4: Comparisons of the water quality parameters of
groundwater of the study area.

                                          Indian
      Water                  WHO          drinking
      quality                standard     water
S.    parameter in           mg/l         standard
NO.   mg/l                   (1984)       mg/l
                                          (BIS:1983)

 1    pH                     6.5 to 8.5   6.5 to 8.5

 2    TDS                    500 to       500 to 2000
                             1500

 3    Calcium (Ca)           200          75 to 200

 4    Magnesium              150          --
      (Mg)

 5    Sodium (Na)            200          --

 6    Potassium              --           --
      (K)

 7    Bicarbonate            --           --
      (HC[O.sub.3])

 8    Sulphate               250          200 to 400
      (S[O.sub.4])           250 to

 9    Chloride (Cl)          600          250 to 1000

10    Nitrate (N[O.sub.3])   50           45 to 100

      Concentration in study area mg/l

      Postmonsoon    Summer          Premonsoon
S.
NO.   Min--Max       Min-Max         Min--Max

 1    6.25 to 7.25   7.2 to 8.5      6.5 to 8.0

 2    694.43 to      1549.52 to      971.46 to
      1233.7         2065.31         1449.66

 3    19 to 31       69.6 to 136.3   37.3 to 64

 4    14 to 29       23.16 to        19.2 to 33.2
                     55.83

 5    142.6 to       336.43 to       265.13 to
      352.4          620.1           522.96

 6    18 to 50.1     32.3 to 130.5   28.6 to 98.13

 7    26 to 46       69 to 92        34.6 to 73.3

 8    151.5 to       337.8 to        232.03 to
      512.3          713.4           443.9

 9    209.5 to       519.6 to        249.4 to
      390.35         702.4           503.03

10    1.95 to 2.83   5.82 to 7.80    3.73 to 4.98