Identification of key controlling factors of groundwater chemistry and probabilistic health risk assessment using kernel density estimation

·Cl-Na. Groundwater samples were categorized into seven groups by the SOM method: Group I (73%)-freshwater, and Groups II-VII containing excessive total iron, fluoride, sulfate, chloride, arsenic, and nitrate, respectively. Hydrogeochemical graphical method and PMF model demonstrated that natural processes acted as the main controlling factor governing the groundwater chemistry (>66.4%), among which 27.3% accounted for the fluoride and arsenic pollution caused by geogenic processes. Anthropogenic factors also played a significant role (≥11.9%), primarily responsible for the elevated nitrate levels. Long-term ingestion of contaminated groundwater may increase the likelihood of both non-carcinogenic and carcinogenic health effects, particularly among children. Groundwater arsenic concentrations in southern Baicheng demand particular attention, as they represent both the primary contributors to health risks and the most sensitive parameters for carcinogenic/non-carcinogenic risk assessments. These insights facilitate targeted regional groundwater management and remediation strategies.