Hydrogeochemical Evaluation of Intermittent Alluvial Aquifers Controlling Arsenic and Fluoride Contamination and Corresponding Health Risk Assessment

Identification and management of safe groundwater supply in a high As and F– contaminated region is a major challenge. This study provides comprehensive hydrogeochemical investigation results for a complex hydro-stratigraphy controlled soil aquifer, which is bound between the Shillong plateau and the Himalayan ranges in the North-Eastern region of India. In this study, distinct contaminated regions of As and F– were identified in the post-monsoon (n = 94) and winter (n = 50) seasons groundwater samples. The maximum dissolved concentration of As was measured to be 71 µg L–1 in post-monsoon and 211 µg L–1 in winter season groundwater samples. Maximum F– concentration was measured as 7 mg L–1 in post-monsoon and 6 mg L–1 in winter season groundwater samples. Identified minerals saturation, weathering and dissolution condition results were well corroborated with the hydrogeochemistry, Bivariate plot, Gibbs and Pourbaix diagrams results. Children of age below 18 years old, in total 20% (i.e. 6,511) and 25% (i.e. 3,627) of the residents were found to be more susceptible to arsenic ingestion effect. The results of health risk assessment showed that the population of age below 18 years old are prone to carcinogenic diseases as well as a symptoms of non-carcinogenic health risk due to daily consumption of As contaminated groundwater. The male population was found relatively more prone to As cancer risk than the female population. Overall, this study provides a critical result about the cause of high As and F– concentration in groundwater and their health risk assessment. It seek to address a prime concern for the usage of groundwater source for drinking water in the Brahmaputra flood plain.