Geochemical partitioning of As and Sb in deposited dust from coal mine vents: Implications for mobility and...

This study investigates the geochemical partitioning of arsenic (As) and antimony (Sb) in deposited dust collected from ventilation outlets of ten underground coal mines in Shanxi, with particular emphasis on potential mobility and associated ecological risks. Particle-size distribution, mineralogical characteristics, and bulk geochemical composition indicate that, relative to the corresponding parent coal, the deposited dust is dominated by fine mineral particles and enriched in clay minerals, carbonates, Fe-bearing phases, sulfate minerals, As, and Sb relative to the corresponding parent coal. Sequential extraction, TESCAN Integrated Mineral Analyzer (TIMA), and X-ray photoelectron spectroscopy (XPS) results further show that As is mainly partitioned into the residual (F8), surface-associated (F3), and acid-soluble fractions (F4), whereas Sb is predominantly concentrated in F8 and F4. These operationally defined fractions should be regarded as indicators of potential reactivity rather than direct measures of field mobility. A morphology- and scenario-adjusted risk index (MARI), derived from RI by assigning fraction-specific mobility-potential weights to As and Sb, shows that dust samples containing higher proportions of readily soluble and potentially reactive pools exhibit extremely high baseline relative risk (MARI = 781-813), and that this risk increases further under scenario-based acidic and low-oxygen conditions (MARI = 932-1016). Collectively, these findings suggest that environmental stressors may enhance the potential reactivity and relative ecological concern of As- and Sb-bearing dust, rather than directly demonstrating release at the field scale. Accordingly, effective management should prioritize focus on dust suppression, targeted environmental monitoring, and stabilization of reactive dust particles. Risk assessments should also incorporate operational partitioning and scenario-dependent sensitivity to improve the identification and prioritization of high-risk deposited dust from coal mine ventilation outlets.