Similarities and differences in PM 10 and PM 2.5 concentrations, chemical compositions and sources in Hefei City, China.

Atmospheric particulates were sampled in Hefei City, China from October 2016 to January 2017 to compare chemical compositions and sources of PM _2.5 (particle size smaller than 2.5 μm) and PM ₁₀ (particle size smaller than 10 μm). The mean levels of PM _2.5 and PM ₁₀ were 81 and 109 μg/m ³ , which are higher than the health threshold levels regulated by national and international standards. During the sampling period, AQI (Air Quality Index) was strongly correlated with PM _2.5 (Pearson's coefficient r = 0.94) rather than PM ₁₀ concentrations. The PM _2.5 /PM ₁₀ ratios were approximately 0.7, revealing the characteristics of fine particle pollution. Pollution elements (S, Zn, Cu and Pb) took up a large proportion of the composition and had high enrichment factors of 437, 385, 20 and 53, respectively, in PM ₁₀ . Coal combustion and high-tech manufacture industry discharges were suggested to be the main pollution sources of both PM _2.5 and PM ₁₀ . The PM _2.5 /PM ₁₀ ratios of anthropogenic element concentrations were much higher than ratios of earth crust element. As compared to PM ₁₀ , S and Pb in PM _2.5 had larger EFs, indicating that pollution elements were predominantly enriched in PM _2.5 . Furthermore, a paired sample t-test confirmed similar sources of PM _2.5 and PM ₁₀ . Our study provides basic database to evaluate the heavy metal pollution status of atmospheric particulates in Chinese cities.
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