[Elemental Composition Characteristics of PM_2.5 and PM₁₀, and Heavy Pollution Analysis in Hefei]

Through the collection of atmospheric PM_2.5 and PM₁₀ samples in Hefei in 2018, combined with high-precision testing of elements in these samples, the elemental composition of PM_2.5 and PM₁₀ was studied during heavy pollution episodes and under non-pollution conditions. The main pollutant sources and causes of heavy pollution in Hefei are also discussed based on an analysis of the differences in the element composition of atmospheric particles. The results showed that, among the 16 elements detected, the mass concentrations of Si, Al, Mg, and Ca during heavy pollution episodes were lower than during non-polluted conditions. This may have been caused by a reduction in ground dust emission caused by calmer winds during heavily polluted conditions. In comparison, the mass concentrations of S, Na, K, Cl, Ti, Fe, P, Cu, and Ni were higher during heavy pollution episodes than during non-pollution conditions, and the difference was greatest for S. The proportion and enrichment factors for S were also greatly increased during heavy pollution events, indicating that its emission from coal burning is the main source of pollution in Hefei. The heavy metal content was low, however, and the enrichment factor was high, the main sources of which may be garbage incineration, motor vehicles, and industrial emissions.