This study investigated the hydrochemical characteristics and human health risks of groundwater in a pollution accident site. By collecting 27 samples, the content of the heavy metal(oid)s (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) was tested, statistical analysis of heavy metal ion concentration was conducted, and the Nemerow comprehensive contamination index was determined. The health risk assessment was conducted based on the test results, and correlation analysis, as well as principal component analysis, were used to resolve the possible sources of heavy metal contamination. The results showed that the total hardness and total dissolved solids were significantly higher, and the potassium permanganate index and ammonia nitrogen content were higher in some samples. The heavy metal content was higher than the Class III groundwater quality standard (GB/T14848-2017). The health risk assessment showed that the total health risks posed by the eight heavy metal(oid)s in the study area through drinking water and dermal contact exceeded the maximum acceptable level. In general, the health risk is slightly higher for adults than for children. The groundwater in the abandoned mines has unsafe levels of heavy metal(oid)s for human health, but the normal drinking water remains safe for surrounding residents. Carcinogenic heavy metal(oid)s are the main source of health risks in the region, and the impact of Cr on human health requires further attention.

In order to understand the pollution degree and source of potentially toxic elements (PTEs) in groundwater around the accident site and evaluate their harm to human health, 22 groundwater samples were collected around the accident well, and the contents of As, Cd, Cr, Cu, Hg, Ni, Pb, Zn, CH₂Cl₂ and C₂H₄Cl₂ were determined. On the basis of water quality evaluation, the source apportionment method combining qualitative and quantitative analysis was used to determine the main sources of PTEs in the region, and the health risk assessment model was used to evaluate the health risk of PTEs to the human body. The results show that pH, TDS, Th and COD all exceed the standard to varying degrees, among which TH is the index with the largest number exceeding the standard. The quality of the groundwater environment in the study area is at a very poor level, and the F value is between 7.25 and 8.49. The exposure results model showed that there was no non-carcinogenic risk of PTEs in the study area, and the health risk of oral intake in the exposed population was greater than that of skin contact. Compared with adults, children were more vulnerable to the health risk stress of PTEs in groundwater. The total carcinogenic risk is higher than the total non-carcinogenic risk. As, Cd and Cr are the primary factors causing carcinogenic health risks in this area. Principal component analysis (PCA) was used to analyze the sources of PTEs in groundwater, and three principal components were extracted. It was preliminarily determined that PTE pollution was mainly related to agricultural sources, anthropogenic industrial sources and industrial sedimentation sources. The results of positive definite factor matrix analysis (PMF) were basically similar to those of PCA, but PMF further clarified the contribution rate of three pollution sources, among which agricultural sources contributed the most to the accumulation of PTEs.