Arsenic and selected heavy metal enrichment and its health risk assessment in groundwater of the Haridwar district, Uttarakhand, India

This study reports new data characterizing the spatial distribution and associated health risk of As and other heavy metals in groundwater of the Haridwar district in India. Major ion geochemistry, geochemical facies, and the interdependence of several hydro-geochemical characteristics of groundwater has also been established, along with assessing the likely mechanism of As release in the region. Fe was found to be the dominant contaminant in groundwater of the study area followed by Mn, As, Cu, Ni, Pb, Cr, and Cd. As concentrations in groundwater ranged from 0.10 to 102 mu g/L, with 17% of samples surpassing the recommended WHO drinking water limit (10 mu g/L). The heavy metal pollution indices (HPI) and (HEI) values suggested a moderate to low level of heavy metal pollution. Our new measurements show that the majority of the high As-bearing groundwater samples collected from the study area were also found to have comparatively high Fe, HCO3- and low NO3- and SO42- concentrations indicating the prevalence of reductive dissolution of iron oxyhydroxide in the study area. Principal component analysis (PCA) indicates that the processes like silicate and carbonate weathering, ion exchange and reverse ion exchange processes, anthropogenic activities, such as sewage disposal and application of fertilizers, and reduction dissolution of Fe/Mn oxyhydroxides control the aqueous geochemistry and mobility of As in groundwater. The results of HQ and CR computed for As and heavy metals indicated that approximately 25% of groundwater samples were associated with non-carcinogenic health risks caused predominantly by As, Fe, Pb, and Cd contamination, while almost all samples had carcinogenic health risks due to As, Cd, and Cr contamination. The health risks were found to be highest in the Laksar and Khanpur blocks of the district which coincided with the high levels of As in groundwater of these regions.

Automated summary

This study presents new data on the distribution and health risks of arsenic and other heavy metals in groundwater in Haridwar, India. The dominant contaminant in the groundwater was found to be iron, followed by manganese, arsenic, copper, nickel, lead, chromium, and cadmium. The study also identified the likely mechanism of arsenic release and assessed the level of heavy metal pollution and associated health risks. The results show that the heavy metal pollution level was moderate to low, but there were significant non-carcinogenic and carcinogenic health risks associated with arsenic and heavy metal contamination.