A comprehensive assessment of groundwater for seasonal variation in hydro-geochemistry, quality, contamination and human health risk from Deccan Basaltic region, Western India

Abstract

Groundwater occurrence in hard rock basaltic terrains is restricted to weathered and fractured zones and pockets wherein slow movement of groundwater, prolonged rock-water interactions and higher residence time alter the natural chemistry of groundwater raising water quality issues. The qualitative geochemical analysis, contamination levels and human health risk assessment (HHRA) of groundwater is an integral step in groundwater management in the Deccan Plateau basalt flow region of India. Representative groundwater samples (68) collected from the Shivganga River basin area during pre-monsoon (PRM) and post-monsoon (POM) seasons in 2015 were analyzed for major cations and anions. According to World Health Organization (WHO) EC, total dissolved solids, hardness, bicarbonate, calcium and magnesium surpassed the desirable limit. Boron and fluoride content exceeded the prescribed desirable limit of the WHO. The pollution and drinking suitability were assessed by computing pollution index of groundwater (PIG), groundwater quality index (GWQI), and HHRA particularly for boron and fluoride toxicity. PIG values inferred that about 6% of groundwater has moderate, 24% has low, and 70% has insignificant pollution in the PRM season; while, only 1 sample (3 %) showed high pollution, 6% showed low, and 91% showed insignificant pollution in the POM season. GWQI results indicate that 27% and 15% samples are within the poor category, and only 15% and 18% of the samples fall within the excellent water quality category in the PRM and the POM season, respectively. Total hazard index (THI) revealed that 88% of children, 59% of adults, and about 38% of infants are exposed to non-carcinogenic risk, as THI values (> 1) were noted for the PRM season; while, 62% of children, 47% of adults and 24% of infants, are vulnerable to non-carcinogenic health hazard during the POM period.