Assessment of groundwater geochemistry and lead contamination in Kabini interstate River Basin, Western Ghats India

The study examined the seasonal groundwater water quality in the Kabini River Basin, to assess its suitability for drinking and irrigation. Groundwater samples were analyzed for physicochemical parameters, major ions and heavy metal Pb 2+ and the results were evaluated against BIS (2012). The monsoon season exhibits comparatively low pH value in DW samples (4.2-6.6 DW). Moreover, TDS and EC values in the down-stretch part of the basin exceeded the permissible limits in all samples, suggesting the enhanced solute dissolution and influence of human activities, particularly agricultural discharge. The calcium, magnesium, sodium, potassium, sulphate, nitrate, chloride and bicarbonate are well within the limit guidelines while the heavy metal Pb 2+ (0.01-0.9 mg/L) surpass the safe limit reflects the industrial pollution risk and pesticides induce contamination. Integrated Water Quality Index (IWQI) shows 18% DW and 75% BW samples fall within poor category, classifying overall region as ranging from “poor” to “unsuitable” category. Irrigational suitability analysis shows that 33% of monsoon and 56% of non-monsoon samples have favorable sodium level. During monsoon season, adults exhibited mean ILCR of 1.3E-02 via ingestion and 6.9E-05 via dermal pathway whereas children show 1.4E-02 through ingestion and 9.5E-02 through dermal exposure. In non-monsoon season adults ILCR reduced to 3.2E-03 for ingestion and 1.7E-05 for dermal pathways with corresponding values for children of 3.5E-03 and 2.3E-02 respectively. The study identifies key contamination hotspots, emphasizing the need for immediate regulatory intervention and improved water treatment infrastructure.