Hydrogeochemistry and quality evaluation of groundwater and its impact on human health in North Tripura, India.

Groundwater contamination becomes an alarming threat to the provision of ecosystem services and natural resources. A very high level of groundwater contamination has been observed in the northeastern states particularly in North Tripura district. Therefore, the present study considered the region as a case study to evaluate the hydrogeochemical facies, heavy metal pollution and irrigation indices, and their impact on human health. For the investigation, we have collected a total of 35 groundwater samples from North Tripura district. Hydrogeochemical facies through Piper plot reflect Ca-Mg-HCO and Na-HCO as dominant water types. Gibbs plot identifies the dominance of rock-water interaction process in groundwater hydrochemistry. Geochemical plots indicate the dominance of silicate weathering, ion exchange and carbonate dissolution processes in groundwater mineralisation. The order of trace metal contaminations follows Fe > As > Zn > Mn > Cu > Pb. Results of heavy metal indices suggest above 80% samples are at high risk due to high Fe contamination. The risk of the heavy metal indices is associated with rising elevation in southern part of North Tripura. Findings of health risk assessment study imply that children face much carcinogenic and non-carcinogenic risks than adults because of unsafe levels of Fe and As. Multivariate statistical tools are applied to unravel interrelationships among all ions and trace metals as well as probable hydrogeochemical processes in groundwater. Results of Wilcox and USSL plots suggest 77% samples meet irrigation suitability criteria. Besides, the analysis suggests a better insight to identify hydrogeochemical processes controlling groundwater chemistry and the suitability of groundwater for irrigation and drinking purposes. The study also suggests treatment and sustainable management of groundwater resources is compulsory to reduce trace metal contaminations before public use.