To explore the characteristics and sources of water-soluble inorganic ions in PM_2.5 of Kunming, simultaneously on-line measurements of major water-soluble inorganic ions and gaseous pollutants were performed from April 15 to May 20, 2021 in Xishan district, Kunming city using a Gas-aerosol Collector and Ion Chromatograph (GAC-IC). The results showed that the average mass concentration of PM_2.5 was 25.0±15.0 μg/m³, indicating that the atmosphere of Kunming was at a relatively clean level, and the average mass concentration of water-soluble ions was 8.32±4.83 μg/m³, which accounted for 32.1% of the PM_2.5 concentration. The water-soluble components of PM_2.5 and gaseous precursors showed obvious diurnal variation, with the increase of inorganic ion concentrations at night and the decrease of inorganic ion concentrations during the day after reaching their peak in the morning. The average SOR and NOR were 0.55 and 0.042, indicating that there was an obvious secondary transformation process of sulfate, but not of nitrate, which might be accompanied by the formation of nitrate and the decomposition of NH₄NO₃. The result of positive matrix factorization (PMF) indicated that there were five main contribution sources of water-soluble ions in PM_2.5, which were fossil fuel combustion source and industry (36%), secondary sulfate (27%), biomass combustion (18%), secondary nitrate (16%) and sea salt (3%).

为探究昆明市春季大气细颗粒物(PM_2.5)中水溶性无机离子的污染特征及来源, 利用大气气态污染物和气溶胶连续收集与在线分析装置(GAC-IC), 于2021年4月15日至5月20日在昆明市西山区对PM_2.5中水溶性离子及其气态前体物进行在线测量。结果表明, 观测期间PM_2.5平均浓度为25.0±15.0 μg/m³, 说明昆明市大气处于较清洁水平, 水溶性离子平均浓度为8.32±4.83 μg/m³, 占PM_2.5浓度的32.1%。水溶性离子及其气态前体物呈现明显的日变化规律, 多数情况下体现为夜间浓度升高, 清晨达到高值, 日间浓度降低。SOR均值为0.55, NOR均值为0.042, 说明硫酸盐存在明显的二次转化过程, 但硝酸盐二次转化不明显, 可能同时存在硝酸盐的生成和NH₄NO₃的热解。正交矩阵因子分析(PMF)结果表明, PM_2.5中水溶性离子有5个主要贡献来源, 分别为化石燃料燃烧源和工业排放(贡献率为36%)、二次硫酸盐(贡献率为27%)、生物质燃烧(贡献率为18%)、二次硝酸盐(贡献率为16%)和海盐(贡献率为3%)。