[Source Analysis and Composition Characteristics of Water-soluble Ions During Spring Festival in Ningbo]

Water-soluble ions and some trace gases during the Spring Festival in Ningbo were observed using an ion online gas composition and aerosol monitoring system. Combined with meteorological elements data, the source analysis and composition characteristics of water-soluble ions and trace gases were analyzed. The average concentration of ρ(PM_2.5) during the observation period was 33.1 μg·m^-3, and there was light pollution. The order of concentration of water-soluble ions was NO₃^->SO₄^2->NH₄⁺>K⁺>Cl^->Na⁺>Ca²⁺>Mg²⁺. The secondary inorganic ions ρ(NO₃^-), ρ(SO₄^2-), and ρ(NH₄⁺) were the most water-soluble ions, which were 12.5, 10.5, and 7.2 μg·m^-3, respectively. According to the PMF source analysis, firecracker combustion, secondary generation (background, industrial source), and dust sources were the major sources of fine particles during the observation period, and their contribution rates of PM_2.5 were 21.9%, 64.5%, and 13.6%, respectively. When the secondary generation was the main pollution, NH₄⁺ accounted for 92.2% of the cations. When firecracker combustion was the main pollution from New Year's Eve to the second day, the proportion of K⁺ions significantly increased. Dust sources were affected by regional transport from the northwest direction. When the dust source was the main pollution, the proportion of K⁺+Ca²⁺and Na⁺+Mg²⁺ increased.