Analysis of the Formation of High-Fluoride and High-Nitrate Groundwater in the Datan Area of Chengde and Human Health Risk Assessment

Long-term consumption of water with high levels of fluoride (F-) and nitrate (NO3-) poses serious health risks to humans. This study aimed to analyze and determine the causes of elevated F- and NO3- concentrations in Datan Town, Fengning County, Chengde City, Hebei Province. A total of 91 groundwater samples were collected, 20 hydrogeochemical parameters were analyzed, and a health risk assessment was conducted using the HHRA model. In the study area, 15.38% of F- and 32.97% of NO3- concentrations were elevated, exceeding China's maximum permissible limits for drinking water (1.0 mg/L and 10 mg/L, respectively). The formation of high-F- groundwater was primarily attributed to fluorite dissolution, while increased NO3- levels resulted mainly from human activities. Health risk assessments for ions posing potential human health hazards revealed significant non-carcinogenic risks for F- and NO3- in both adults and children, exceeding acceptable thresholds (HI>1). For carcinogenic risks, all samples exceeded the acceptable threshold (1×10-6), with As playing a dominant role in groundwater carcinogenic risk. This study holds significant importance. It provides a comprehensive examination of groundwater hydrogeochemistry and health risk assessment in the study area, filling a gap in the knowledge of the Chengde Bashang region. It assists decision-makers in the Datan area in formulating long-term plans for groundwater resource development and lays a foundation for subsequent research.