Effect of saline water bodies on the hydrogeochemical evaluation of groundwater at Kalpakkam coastal site, Tamil Nadu

Geochemical signatures of groundwater in Kalpakkam plant site were used to identify the geochemistry of the unconfined coastal aquifer. Ground water samples collected from 14 borewells around the study area were studied for four different seasons viz. Summer, South-west monsoon, North-east monsoon and Post-monsoon to identify the major geochemical processes activated in the study area. Data obtained through chemical analyses of groundwater samples were used for graphical plots and geochemical calculations. Piper, Chloro alkaline indices and Chadda’s diagram were determined for geochemical classification of the groundwaters. Identified geochemical processes were verified and quantified using hydrogeochemical aqueous speciation model, PHREEQC to find out the Saturation Indices (SI) of the possible minerals of the study area. It was observed that majority of the bore well samples were under saturated with respect to minerals such as Gypsum, Aragonite and oversaturated with respect to dolomite and calcite. Parameters such as ion exchange and reverse ion exchange, saline water incursion were observed due to the presence of saline water bodies in addition to dissolution of minerals.