Use of Hydrochemistry and Stable Isotopes as Tools for Groundwater Evolution and Contamination Investigations

Abstract

Hydrochemical and isotopic studies in groundwater was attempted in a basin to gain knowledge on geochemical evolution and water quality status. The results of the chemical analysis indicate the sources of ions into the groundwater are from dissolution and leaching from source rocks, cation exchange and anthropogenic activities. The saturation index calcu- lated specify oversaturation of carbonate species and undersaturation of amorphous silica indicating groundwater chemical evolution controlled by water rock interactions. Water type alters from Ca-HCO3 to Na-Cl indicating groundwater chemistry controlled by rock-water interaction and anthropogenic activities. The plots of various ionic ratios point out groundwater chemistry affected by ion exchange process, silicate and carbonate weathering along with anthropogenic activities. The isotopes of δ2H versus δ18O signify ionic concentration increases along the groundwater flow direction along lower elevations. The water type’s classification designate 5 distinct groups ranging from low EC and highly depleted isotopes to very high EC with enriched stable isotopic composition indicating longer residence time of groundwater.