A study on groundwater geochemistry and water quality in layered aquifers system of Pondicherry region, southeast India

Abstract

Geochemical signatures of groundwater in the Pondicherry region, south India, were determined. The coastal aquifers are fragile and this situation becomes more intense in layered aquifer systems like that of the Pondicherry region. In this region, groundwater occurs in alluvium, Lower Cuddalore, Upper Cuddalore, Tertiary, Cretaceous and mixed aquifers. The geochemical signature of groundwater in these formations was studied by collecting 93 groundwater samples. The collected samples from specific formations were analysed for physical parameters, such as electrical conductivity (EC), pH and major ion concentrations, such as Ca, Mg, Na, K, Cl, HCO 3 , PO 4 and SO 4. The results of the analysis were interpreted with geology; the ionic concentrations in the groundwater vary spatially and temporally. The abundance of these ions are in the following order: Na [ Ca [ Mg [ K = Cl [ HCO 3 [ SO 4. Interpretation of analytical data shows that Ca-Na and Cl-SO 4-HCO 3 is the dominant facies in all the formations. Groundwater in the area is generally hard and fresh-brackish in most of the formations and brackish in nature in alluvium formation. The sodium absorption ratio shows that most of the samples are grouped under excellent category to good category in all the formations. The residual sodium carbonate also are in good category in all the formations. Chloro-alkaline indices reveal that the majority of samples show negative values in all the litho units indicating the exchange of Na and K in groundwater with Mg or Ca in rock. Scholler classification of water indicates that longer residence time of water with more prominent base exchange. High EC and TDS values in certain locations of alluvial, Upper Cuddalore and Cretaceous formations prove to be unsuitable for drinking and irrigation purposes.

Evaluation of drinking water quality index (DWQI) and its seasonal variations in hard rock aquifers of Madurai district, Tamilnadu

“…Hence, physico-chemical analysis of water is important to assess the quality of groundwater that influences the suitability of water for domestic, irrigation, and industrial needs Thilagavathi et al 2012;Chidambaram et al 2011;Singaraja et al 2013). Because of the importance of groundwater in drinking purposes a study has been conducted in Madurai district to assess the drinking water quality index.…”

Relevance of water quality index for groundwater quality evaluation: Thoothukudi District, Tamil Nadu, India

“…The PRM samples show signs of poor quality in drinking purpose compared to POM. This may be due to dilution of ions after monsoon, overexploitation of groundwater, direct discharge of effluents and agricultural impact Thivya et al 2013a;Thilagavathi et al 2012).…”

Hydrochemical Facies and Ionic Exchange in Coastal Aquifers of Puducherry Region, India: Implications for Seawater Intrusion

“…1; CGWB 2007). Groundwater is the main source of water supply for domestic, agricultural, and industrial purposes in Puducherry and is extracted by bore wells (Thilagavathi et al 2012). …”

“…41-1035/2012; Date: 23.07.2012] through major research project. We extend our sincere thanks to Department of Earth Sciences, Department of Ecology and Environmental Sciences and Central Instrumentation Facility of Pondicherry University for providing facilities for analysis.…”