Source apportionment and health risk due to PM₁₀ and TSP at the surface workings of an underground coal mine in the arid desert region of northwestern China

The surface operations area of an underground coal mine near Lingwu in Ningxia Hui Autonomous Region was selected for this study. Particulate matter (PM) was sampled in the coal screening plant during the day and night in Spring and Winter, 2019. Twelve trace metals and eight water-soluble ions in particulate matter up to 10 μm in diameter (PM₁₀) and total suspended particles (TSP) were analyzed using ICP-OES and ion chromatography, respectively. The enrichment factor (EF) and positive matrix fraction (PMF) were used to identify potential sources of particulate metals. The forward trajectory model was used to analyze the main migration pathways of particles. Results showed that higher concentrations of PM₁₀ and TSP were found in Spring than in Winter; the concentration of PM at night was lower than during the day. Most of the trace metals in TSP were greater than in PM₁₀, while the content of most water-soluble ions in TSP was lower than in PM₁₀. The EF analysis confirmed that particulate metals were attributable to anthropogenic emission. PMF model results further demonstrated that the main sources of PM in both seasons were regional suspended dust, traffic emission, industrial emission and coal burning. Air mass dispersion analysis showed that PM generated by these operations may spread to eastern and southeastern China within 72 h in Spring, while mainly to southeastern and southern China in Winter. These suggest a need for greater focus on strengthening the monitoring and early warning of the presence of atmospheric PM in southern Shanxi, China. Because of the risks that particulate metals pose to human health, the protection of children should be strengthened around the surface operation area of an underground coal mine. Moreover, monitoring of the concentrations of Cr in PM₁₀ and Mn in TSP in Spring should be strengthened, and the opposite procedure should be adopted in Winter. These findings are useful for providing a theoretical basis for the prevention and control of pollutants in underground mining areas and the construction of cleaner production lines.