Chemical Evolution Characteristics and Health Risks Assessment of Surface Water–Groundwater in Large-Scale Coal Mining Areas of the Inner Mongolian Plateau Under Mining Activities

Mining can significantly affect the spatial distribution and temporal evolution of groundwater chemistry. From July to August 2024, the research team collected 26 surface water and groundwater samples in the Shengli Coal Mine area of the Mongolian Plateau, conducting comprehensive hydrogeochemical analyses on surface water flowing through the mining area, groundwater within the mining area, seepage water, and groundwater outside the mining area. The results indicate that groundwater in this region is notably affected by human activities such as mining operations. Specifically, in surface water flowing through the mining area, concentrations of total dissolved solids (TDS), sulfates, nitrates, and nickel showed significant increases. Compared to groundwater systems in other areas of the Mongolian Plateau, nickel levels in the mining area’s groundwater were significantly higher, while nitrate levels exhibited the opposite trend. A significant positive correlation was observed between metal element concentrations in surface water and groundwater. The study found that abnormal distributions of heavy metals such as beryllium (Be), thallium (Tl), and tin (Sn) may originate from point-source pollution caused by mining activities. Furthermore, concentrations of manganese (Mn), arsenic (As), and antimony (Sb) in the groundwater of this area exceeded relevant regulatory limits, with arsenic being particularly prominent. The levels of arsenic in both surface water and groundwater may pose carcinogenic risks to human health. This study shows that nearly half of the sampled water bodies in the area require purification treatment to meet drinking water standards, highlighting the urgent need for further attention to water quality safety issues. The conclusions derived from this research provide theoretical support for understanding the long-term evolutionary mechanisms of groundwater in mining areas, while also offering important insights for improving groundwater environmental management and ensuring water resource security in mining regions.