Abstract
Fluoride (F(-)) and arsenic (As) are the two most conspicuous contaminants, in terms of distribution and menace, in aquifers cause health problems. These contaminants in the shallow aquifers of the eastern Henan Plain, posing serious health risks for the local residents. A total of 136 groundwater samples (74 from the dry season and 62 from the wet season) were analyzed to investigate the to assess the levels and mechanisms of high F(-) and As enrichment in groundwater. Statistical and geostatistical methods, including charge balance calculations and health risk assessments, were employed to evaluate the spatial distribution and associated health risks of these contaminants. The results indicate the maximum concentrations of 2.82 mg/L for F(-) and 51.4 μg/L for As, predominantly in the central, eastern, and southern regions of the study area, particularly at depths of 10-40 m. Elevated levels of these contaminants are associated with higher pH and increased Na(+), HCO(3)(-), SO(4)(2-) ions, while Ca(2+) levels are depleted, attributed to fluorite and sulfide-bearing minerals and anthropogenic activities. The northern part shows a higher vulnerability to non-carcinogenic health risks, whereas the southeastern region exhibits greater carcinogenic risks. The hazard index (HI) values exceeding 1.0 suggest significant non-carcinogenic health risks. The study addresses a significant gap by comprehensively examining the co-occurrence and mechanisms of fluoride and arsenic in groundwater, providing critical data for policymakers to enhance and improve water quality management.