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Monitoring the groundwater chemical composition and identifying the presence of pollutants is an integral part of any comprehensive groundwater management strategy. The present study was conducted in a part of West Tripura, northeast India, to investigate the presence and sources of trace metals in groundwater and the risk to human health due to direct ingestion of groundwater. Samples were collected from 68 locations twice a year from 2016 to 2018. Mixed Ca–Mg–HCO3, Ca–Cl and Ca–Mg–Cl were the main groundwater types. Hydrogeochemical methods showed groundwater mineralization due to (1) carbonate dissolution, (2) silicate weathering, (3) cation exchange processes and (4) anthropogenic sources. Occurrence of faecal coliforms increased in groundwater after monsoons. Nitrate and microbial contamination from wastewater infiltration were apparent. Iron, manganese, lead, cadmium and arsenic were above the drinking water limits prescribed by the Bureau of Indian Standards. Water quality index indicated 1.5% had poor, 8.7% had marginal, 16.2% had fair, 66.2% had good and 7.4% had excellent water quality. Correlation and principal component analysis reiterated the sources of major ions and trace metals identified from hydrogeochemical methods. Human exposure assessment suggests health risk due to high iron in groundwater. The presence of unsafe levels of trace metals in groundwater requires proper treatment measures before domestic use.

A hydrogeochemical assessment was carried out in Jirania Block of west district of Tripura, India, to evaluate the geochemical processes and groundwater suitability for drinking and irrigation purposes. Twenty-two groundwater samples were collected at different lithologies in the study area during post-monsoon period. The collected samples were analyzed for major ions and heavy metals using the standard protocols. The analyzed parameters were used for various geochemical plots and indices to classify the groundwater quality. The order of dominance of cations is Ca 2+ > Mg 2+ > Na + > K + and HCO 3 − > Cl − > SO 4 2− > NO 3 − for anions. Higher concentration of Fe and Mn was observed in most of the samples, which are above the acceptable limit of BIS standard. Correlation analysis and factor analysis were applied to unravel the relationship between ions and to identify the possible geochemical processes in groundwater. The interpretation of analytical data, plots and indices reveals that the weathering, mineral dissolution and ion exchange reactions are the major controlling factors for the groundwater geochemistry. The quality of the groundwater is suitable for drinking and irrigation purposes to the local community in this assessment period.

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