【摘要】 用离子色谱法对181份PM_2.5有效样品中NO^-₃、SO₄^2-、NH⁺₄、Cl^-和F^-等5种水溶性离子进行检测分析。结果表明，西安市PM_2.5的年均浓度为（71.04±51.80）μg·m^-3,季节变化特征表现为：冬季>春季>秋季>夏季。五种水溶性离子的年均浓度为（28.24±31.79）μg·m^-3,季节变化特征表现为：冬季>春季>秋季>夏季。各水溶性离子的年均浓度由大到小依次为：NO^-₃>SO₄^2->NH⁺₄>Cl^->F^-。NO^-₃在冬、春、秋三季的占比最高，而在夏季则是SO₄^2-占比最高。SOR和NOR的年均值分别为0.34和0.17,表明SO₂和NO₂向二次离子SO₄^2-和NO^-₃的转化程度较高。随着污染水平的加重，总水溶性离子浓度在PM_2.5中的占比逐渐升高，NO^-₃的浓度及占比逐渐升高，SO₄^2-的占比逐渐降低。NO^-₃/SO₄^2-的年均值为2.13,夏季固定源对大气污染的贡献较大，而在冬、春、秋三季则是移动源占主导作用。更多还原

【Abstract】 Five water-soluble ions, including NO^-₃, SO₄^2-, NH⁺₄, Cl^- and F^-, were detected and analyzed in 181 PM_2.5 effective samples by ion chromatography. The results showed that the annual average concentration of PM_2.5 in Xi’an was（71.04 ± 51.80） μg·m^-3, and the seasonal variation characteristics were: winter > spring > autumn > summer. The annual average concentration of five water-soluble ions was（28.24 ± 31.79） μg·m^-3, and the seasonal variation characteristics were: winter > spring > autumn > summer. Concentrations of ions were ranked as: NO^- ₃> SO₄^2-> NH⁺₄> Cl^- > F^-. NO^-₃ accounted for the highest proportion in winter, spring, and autumn, while SO₄^2- accounted for the highest proportion in summer. The annual average values of SOR and NOR were 0.34 and 0.17, respectively, indicated a higher degree of conversion of SO₂ and NO₂ into secondary ions SO₄^2- and NO^-₃. With the aggravation of pollution, the proportion of water-soluble ions in PM_2.5 increased significantly, the concentration and proportion of NO^-₃ continued to increase, while the proportion of SO₄^2- decreased. The annual average value of NO₃^-/SO₄^2- was 2.13. Fixed sources contributed significantly to atmospheric pollution in summer,while mobile sources dominated in winter,spring,and autumn.更多还原