[Characteristics and Sources of Water-soluble Ion Pollution in PM_2.5 in Winter in Shenyang]

In order to explore the characteristics of PM_2.5 and water-soluble ions in Shenyang in winter, the URG-9000D online monitoring system was used to continuously sample PM_2.5 and gas components during 2018. The results indicated that the average concentration of PM_2.5 in Shenyang during the sampling period was 80.67 μg·m^-3, and the total water-soluble ion concentration ranged from 2.68 to 132.79 μg·m^-3. Compared with clean days, the proportion of NO₃^-, SO₄^2-, and NH₄⁺ (SNA) in polluted days increased significantly, reached 43.7% of PM_2.5. The rapid accumulation of SO₂ in a short period of time made atmospheric PM_2.5 explosively increase in Shenyang in winter. A Pearson correlation analysis showed that the correlation coefficients of SNA, Cl^-, and PM_2.5 were all above 0.78, indicating that the main contribution components of winter PM_2.5 in Shenyang were SNA and Cl^-. The apportionment of PMF sources indicated that the sources of pollutants in winter in Shenyang mainly included secondary reaction sources, coal and biomass combustion sources, and dust sources.