Major geochemical controls on arsenic enrichment in groundwater of the Tosham area, Bhiwani district, Haryana, India

Arsenic contamination in groundwater is a pressing global environmental and public health issue, especially in regions with geogenic sources. However, limited studies exist on the occurrence, distribution, and sources of arsenic contamination in the Tosham block of Haryana, India. This study aims to evaluate the spatial distribution of arsenic in shallow groundwater and to examine possible the geochemical processes influencing its distribution and mobilization in the Tosham area, Bhiwani district, Haryana. A total of 19 paired groundwater and soil samples were collected from hill-influenced zones surrounding the Tosham hills. Groundwater samples from shallow aquifers (18–48 m depth) were analyzed for major cations, anions, and trace elements using atomic absorption spectrometry (AAS), ion chromatography, and inductively coupled plasma–mass spectrometry (ICP-MS), following APHA (2017) protocols. Arsenic concentrations in groundwater ranged from 0.01 to 0.09 mg/l, with a mean of 0.038 mg/l, and approximately 68% of the samples exceeded the World Health Organization’s permissible limit of 0.01 mg/l for drinking water. Iron concentrations ranged from below the detection limit to 0.04 mg/l (mean: 0.008 mg/l). Bivariate plots suggest sulphide mineral weathering and redox driven processes as a major process influencing groundwater chemistry. The results suggest that arsenic enrichment is influenced by geogenic sources linked to sulphide-bearing minerals. This integrated dual-source conceptual framework accounts for the observed spatial heterogeneity and elevated arsenic concentrations in groundwater. Background As levels associated with fluvial sediments are interpreted to be further influenced by geogenic contributions linked to the Tosham Ring Complex (TRC). Weathering of TRC lithologies may have supplied As-bearing detrital material to adjacent sedimentary units, while continued weathering of sulfide-bearing veins within the crystalline basement could represent an additional, low-intensity but sustained source of arsenic to the groundwater system. Effective management of arsenic-contaminated groundwater necessitates an integrated approach combining scientific research, policy frameworks, technological solutions, and active community engagement to ensure sustainable and equitable access to safe drinking water.