The assessment of the impact of abandoned mine water on the underwater environment is critical for protecting and restoring the groundwater environment. Taking the abandoned coal mining area in the west of Zhangqiu District as the engineering background and comprehensively considering the regional groundwater chemical characteristics data during the wet and dry seasons, the main characteristics of the ions, hydrochemical types, and ion correlations of the abandoned mine water with the regional groundwater components were analyzed using mathematical statistics, correlation analysis, and Piper diagrams. An impact assessment was conducted on the water quality index values of the groundwater monitoring point. Furthermore, this research establishes an evaluation method of abandoned mine water in a regional groundwater environment based on the improved Nemero index method and matter element theory. Overall, the groundwater pH is weakly alkaline in Zhangqiu District. The groundwater Ca²⁺ is the dominant cation, while HCO₃⁻ and SO₄²⁻ are the dominant anions. The main ion concentration during the dry season is slightly greater than during the wet season. The main hydrochemical type of groundwater during the wet and dry seasons is HCO₃-Ca. In addition, there is a correlation between NO₃⁻ and F⁻, which may be caused by human activities. The groundwater environment is classified as level IV and severely polluted.

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.