Heavy Metal Pollution and Associated Risk Assessments in Inrush Water from Abandoned Coal Mines, Guangyuan, Sichuan, China

Inrush of acidic mine water from abandoned coal mines poses serious threat to groundwater environment by mobilizing heavy metals and lowering pH, thereby endangering ecosystems and human health. In this study, inrush water samples from nine abandoned coal mines in Wangcang, Sichuan, China, were analyzed for eight heavy metals (Cr(VI), Fe, Mn, Hg, As, Zn, Pb, and Cd) using inductively coupled plasma-mass spectrometry (ICP-MS). The ecological risk was assessed through species sensitivity distribution (SSD) based on native aquatic species data, while health risks were evaluated using USEPA exposure models. Results showed that the mine water was acidic (pH 1.6-7.1) with high metal concentrations, particularly Fe, Zn, Mn, and Cd, with mean values of 1048, 11.5, 4.6, and 0.49 mg/L, respectively, exceeding the Chinese Class III groundwater quality standards. The SSD-derived hazardous concentration for 5% of species (HC5) values ranged from 7.08 & times; 103 mu g/L (Hg) to 3.09 & times; 10(5) mu g/L (Pb), indicating that aquatic species were more sensitive to Hg than Pb. Risk quotients (RQs) revealed Fe as the dominant ecological risk factor across all sites. Although non-carcinogenic hazard indices (HIs) remained below 1, carcinogenic risk from Cr(VI), Cd, and As exceeded the 1 & times; 10(-4) threshold, with oral ingestion identified as the primary exposure pathway. The findings indicate substantial ecological and health risks from abandoned mine inflows, warranting targeted remediation of Fe and carcinogenic metals.