[Source and Health Risk Assessment of Heavy Metals in Groundwater of Datong Basin]

The identification of distribution characteristics, pollution sources, and potential human health risks of heavy metals in groundwater is crucial for the scientific planning and rational development of groundwater resources in arid-semiarid regions. In this study, 46 groundwater samples were collected and analyzed using hydrogeochemical modeling and multivariate statistical analysis methods to reveal the pollution characteristics and speciation distribution of 11 heavy metals （As, B, Pb, Sb, Tl, Mn, Ba, Cd, Co, Cr, and Al） in the Datong Basin. The absolute principal component-linear regression （APCS-MLR） model and health risk assessment model （HRA） were employed to determine the sources and health risk levels of heavy metals in groundwater. The results showed that： ① As, B, Pb, Sb, and Tl in groundwater exceeded the Class Ⅲ groundwater quality standards, indicating severe pollution, while Mn showed mild pollution, with heavy metal concentrations generally higher in the central region compared to those in the southern, eastern, and western regions. ② The predominant speciation forms of As, B, Pb, Sb, and Tl were HAsO₄^2-（91.71%）, H₃BO₃（97.61%）, PbCO₃（88.08%）, Sb（OH）₆^-（99.81%）, and Tl⁺（94.84%）, respectively, with pH being one of the key factors affecting the distribution of heavy metal species. ③ The main sources of heavy metal pollution were soil migration sources （Co, Cd, and Cr）, industrial sources （Al, Pb, Sb, and B）, mining sources （Tl and Mn）, and natural sources （Ba and As）, with industrial sources accounting for the largest proportion （34%）, followed by natural sources （29%）, mining sources （20%）, and soil migration sources （18%）. The health risk assessment results for specific sources of heavy metals indicated that industrial activities and natural sources were the main contributors to the carcinogenic risk for adults （54.68%） and children （67.51%）, with As posing the highest carcinogenic risk. Mining activities were the major contributor to non-carcinogenic risk （56.69% for adults, 56.97% for children）, with higher risks associated with Tl and As.