Seasonal variations and health risk assessment of trace elements in the Badigad River, lesser Himalayas, Nepal

The consumption of contaminated river water can have severe effects on human health. This study aims to investigate the trace elements (TEs) content and their health risk assessment in the Badigad River Basin in the lesser Himalayas of Nepal. In total, 44 water samples were collected from 22 different sites during the pre-monsoon and monsoon seasons, and 25 TEs were analyzed. Correlation matrix and principal component analysis (PCA) were used to analyze the potential relationship between the measured TEs and their source tracking. Furthermore, the water quality index (WQI), metal index (MI), and cancer index (CI) were evaluated. The TEs content in all samples were found to be within the WHO recommended guideline for drinking and domestic purposes. The dominancy order of the TEs was observed as Sr > Ba > Li > Rb > Zn > Cr > Sc > Mn > Ti > Cu > As > Ni > Co > U > V > Pb > Cs > Ga > Y > Tl > Th > Zr > Bi > Cd > Nb. The PCA analysis suggested that TEs could have natural, anthropogenic, and mixed origins. The WQI indicated that the river water is safe from a human health perspective. The MI suggested that Badigad River can be considered safer for drinking purposes, and the cancer index (CI) showed that all the reported TEs are at low-risk levels. The findings of this study could be useful for government agencies in developing more sustainable water management policies in the region. However, it is suggested that further investigations should be conducted in terms of other hydrogeochemical variables, including major ions, at spatiotemporal levels for the sustainability of the river basin.