Seasonal variations, source apportionment, and health risk assessment of trace metals in PM2.5 in the typical industrial city of changzhi, China

Studying the source-specific health risks of trace metals in PM2.5 is important for controlling its emission sources that are hazardous to human health. In this study, PM2 5-bound trace metals were analyzed during winter, spring, summer, and autumn in 2018 in Changzhi, a typical industrial city in China. The results revealed that the annual concentration of total trace metals in PM2.5 was 7531.9 ng m(-3) in the study area, and the concentration was maximum in spring (14,781.7 ng m(-3)), followed by autumn (7163.8 ng m(-3)), winter (5237.0 ng m(-3)), and summer (3226.1 ng m(-3)). Dry and continual windy days in spring often led to high concentrations of trace metals in Changzhi. Trace metals with high enrichment factor (>100), such as Cd, Sn, Pb, and Zn, were predominantly released from coal combustion. Four sources, such as coal combustion, traffic emissions, resuspended dust, and industry, were established by positive matrix factorization, with contributions to PM2.5-bound trace metals of 29.5%, 26.6%, 26.3%, and 17.6%, respectively. In terms of their contribution to cancer risk, the top contributor both for children and adults was industry, with 1.50 x 10(-6) and 5.99 x 10(-6), respectively, both of which were higher than the safe level (1 x 10(-6)); coal combustion ranked second (0.49 x 10(-6) and 1.94 x 10(-6) for children and adults, respectively). In addition to the advancement of control measures for pollutants and control of industrial production, more attention should also be given in limiting coal consumption through the use of clean energy (e.g., natural gas).