[Characteristics and Source Apportionment of Water-soluble Ions in PM_2.5 During Winter in Panjin]

In order to study the characteristics and source of water-soluble ions in PM_2.5 in Panjin, PM_2.5 samples were collected at three sites in January of 2017, and the levels of eight ions (Na⁺, Mg²⁺, Ca²⁺, K⁺, NH₄⁺, SO₄^2-, Cl^-, and NO₃^-) were determined by ICS-900 ion chromatograph. The characteristics of PM_2.5, the water-soluble ion concentration, SOR and NOR calculation, and ion balance calculation were investigated, and a principal component analysis was conducted. The results showed that the concentration of PM_2.5 and water-soluble ions followed a descending sequence of park > development zone > the second middle school. SO₄^2-, NO₃^-, and NH₄⁺ were the major components of the water-soluble ions at the three sampling sites. SOR and NOR values were all higher than 0.10, indicating that SO₄^2- and NO₃^- were mainly converted from SO₂ and NO. The ion balance calculation demonstrated that the cationic and anion equivalents in Panjin had great correlation in winter. Further study showed that the atmosphere in the development zone presented as neutral and that in the cultural park and the second middle school presented as partially alkaline. The principal component analysis further indicated that the water-soluble ions were mainly derived from fuel combustion, biomass burning, secondary particles, and re-suspended dust in winter.