Characterization, Influencing Factors, and Human Health Rrisk of Groundwater Fluoride in Southwestern Songnen Plain, Northeast China

Fluoride (F⁻) is widely distributed and potentially hazardous inorganic pollutant in groundwater. Regional studies on its spatial distribution and controlling factors groundwater remain limited, necessitating detailed investigations to support safe water supply strategies. In this study, 205 groundwater samples were collected from shallow, intermediate, and deep aquifers across the southwestern Songnen Plain to assess F⁻ distribution, geochemical behavior, and associated health risks. The average F⁻ concentrations in shallow, intermediate, and deep groundwater were 1.66, 1.33, and 1.01 mg/L, respectively, with 67.5%, 58.7%, and 40.0% of samples exceeding China’s drinking water standard (1.0 mg/L). High-F⁻ waters were predominantly HCO₃-Na type, showing an increasing trend from the periphery to the center of the study area, particularly in the Huolin River Basin and Qian’an County. Geological sources and prolonged groundwater retention times in downstream aquifers contributed to elevated F⁻ levels, while excessive groundwater extraction disrupted clay layers, facilitating vertical mixing of F⁻-rich waters. F⁻ primarily originated from dissolution of F⁻ -bearing minerals, with cation exchange and anion adsorption/desorption influencing its migration. Health risk assessments indicated significant non-carcinogenic risks, especially for infants and children, emphasizing the need for continuous monitoring, effective management, and increased public awareness.