Hydrogeochemical characteristics and its role in controlling arsenic mobilization in a shallow aquifer

The relevance of groundwater hydrogeochemistry to explain the occurrence and distribution of arsenic in groundwater is of great interest. The insightful discussions on the control of shallow groundwater (< 50 m) hydrogeochemistry in arsenic mobilization are known to be a viable tool to explain the arsenic menace in shallow groundwater. The present investigation emphasizes the hydrogeochemical driver and/or control over the reductive dissolution of Fe-bearing host minerals and thereby releasing arsenic into the shallow groundwater of the study area. The study suggests that hydrogeochemical evolution is mainly governed by carbonate minerals dissolution, silicate weathering, and competitive ion-exchange processes in the shallow aquifers (< 50 m). The present study also indicates the prevalence of carbonate minerals dissolution over silicate weathering. The emergence of Cl⁻ concentration in the shallow groundwater founds the possibilities of anthropogenic inputs into the shallow aquifers (< 50 m). The reducing environment in shallow aquifers (< 50 m) of the study area is evident in the reductive dissolution of Fe- bearing shallow aquifer minerals which absorb arsenic in the solid phase and mobilize arsenic onto shallow groundwater. The study opted for many statistical approaches to delineate the correlation among major and minor ionic constituents of the groundwater which are very helpful to understand the comprehensive mechanism of arsenic mobilization into shallow groundwater.