In this study, PM_2.5 and its chemical components were compared at an industrial site and a suburban site in Changzhou, China, during the winter of 2016. The average PM_2.5 concentration was higher at the industrial site (113.06 ± 64.74 μg/m³) than that at the suburban site (84.75 ± 41.76 μg/m³), which suggests that severe pollution with higher emissions occurred in the industrial region. The ion balance indicated that PM_2.5 was weakly acidic and neutral at the suburban and industrial sites, respectively. Water-soluble inorganic ions (WSIIs) were the largest contributor to PM_2.5 (suburban 49.8% vs. industrial 36.0%), and carbonaceous components comprised a significant fraction (approximately 30%) of ambient PM_2.5. Correlations between water-soluble organic carbon (WSOC) and eight carbon fractions showed secondary formation, and biomass burning had a significant impact on the carbonaceous species. The nitrogen and sulfur oxidation ratios exceeded 0.10, which further implied the likelihood of secondary transformation. Thirteen elements comprised ~3.0% of the PM_2.5 mass at both sites.

Soot-particle aerosol mass spectrometry (SP-AMS) coupling positive matrix factorization (PMF) was used to characterize the chemical composition and evaluate the sources of water-soluble organic aerosols (WSOA). The results showed that the WSOA originated from three sources. The PMF model identified six sources of PM_2.5, including secondary aerosols, biomass burning, traffic, soil dust, coal combustion, and road dust (industrial emissions), with mass contributions of 45.1% (38.3%), 18.7% (14.0%), 6.4% (15.9%), 13.8% (8.7%), 7.3% (13.3%), and 8.7% (9.6%) at the suburban (industrial) site. To the best of our knowledge, this is the first study to comprehensively study the chemical characteristics and source apportionment of PM_2.5 in suburban/industrial regions.