Driving factors and health risks of spatiotemporal variations of heavy metal pollution in groundwater of pyrite mining areas in the middle and upper reaches of the Yangtze River in China

Groundwater heavy metal contamination from mining activities is a major concern, yet driving mechanisms and health risk differences caused by spatiotemporal variability remain unclear. This study investigated a typical pyrite mining area in middle and upper reaches of the Yangtze River in China, collecting 354 shallow groundwater samples during the 2023 wet and dry seasons to assess driving factors and health risk of nine heavy metals (Fe, Mn, Cu, Zn, Hg, As, Cd, Pb, Se) at spatiotemporal variability. Results showed most heavy metal concentrations were significantly higher in the dry season. Fe had the highest average concentration (41.04 mg/L), and Hg showed the most intense fluctuations. This seasonal difference exhibited a clear distance-attenuation effect: dry-season enrichment was pronounced in near-mine zones (<100 m) but weakened with increasing distance. Random Forest models revealed drivers in the wet season were diverse, including SO 4 2− , TDS, pH, and distance. In contrast, they were concentrated in the dry season, dominated by TDS, SO 4 2− , and pH. The human health risk of groundwater around mining areas was higher for adults than for children, and it is greater in the dry season than in the wet season. This study elucidated the spatiotemporal mechanisms and health risk of groundwater contamination in mining areas, identifying the dry season and near-mine zones as critical nodes for risk management. Fe, Mn, As, and Cd were identified as priority elements for health risk management. These findings provide a scientific basis for developing precise and sustainable groundwater management strategies. • Dry season groundwater heavy metals higher than wet season. • Contamination seasonal differences shows attenuation with distance from the mine. • Heavy metal drivers shift from diverse wet-season to concentrated dry-season. • Dry season and near-mine zones are key spatiotemporal nodes for risk management. • Fe, Mn, As and Cd are prior controlled pollutants for groundwater in mining areas.