Tracing groundwater salinization using geochemical and isotopic signature in Southeastern coastal Tamilnadu, India

Attempt has been made to discriminate groundwater salinity causes along the east coast of India. A total of 122 groundwater samples (61/season) were collected for two diverse seasons (Pre Monsoon and Post Monsoon) and analyzed for physical and chemical components along with stable isotopes. The Piper diagram proposes samples along the coast predisposed by saltwater incursion. Ionic ratio plots recommend groundwater discriminatory by changing geochemical signatures. The statistical correlation suggests impact of saltwater incursion, anthropogenic and rock water interaction as sources for dissolved constituents in groundwater. The thermodynamic stability plot suggests higher silicate dissolution, weathering and ion exchange prompting water chemistry nevertheless of seasons. The δ18O and δ2H increases towards the sea suggesting enrichment attributed to the sea water influence and rainfall influences along the southwestern parts of the study area. •The study deals with salinization sources of coastal groundwater in Southeastern coastal aquifers.•The Piper diagram proposes samples along the coast predisposed by saltwater intrusion.•Ionic ratio plots recommend groundwater biased by changing geochemical signatures.•Correlation analysis predicts sea water, rock water interaction and anthropogenic sources influencing groundwater.•The δ18O and δ2H increases towards the sea suggesting enrichment attributed to the sea water influence.