【摘要】 于2017年1—5月（取暖季）在西宁市区、郊区、农村设置采样点采集PM_2.5样品,利用离子色谱法测定PM_2.5中水溶性无机离子浓度。结果表明:取暖季西宁大气PM_2.5日均质量浓度为（55.98±52.66）μg/m³,呈现明显的市区>郊区>农村的浓度变化特征。PM_2.5中水溶性离子质量浓度之和占PM_2.5质量浓度的36.3%,水溶性离子平均浓度大小为SO₄^2->NO₃^->NH₄⁺>Na⁺>Cl^->C₂O₄^2->Ca²⁺>F^->K⁺>Mg²⁺;取暖季西宁大气硫氧化率（SOR）和氮氧化率（NOR）平均值分别为0.21、0.13,表明SO₄^2-、NO₃^-主要由二次转化形成,PM_2.5中NO₃^-/SO₄^2-（质量浓度比）为0.75,阳离子与阴离子电荷摩尔数比值为0.89,表明燃煤是PM_2.5主要贡献源,颗粒物总体呈酸性。后向轨迹分析表明,重污染期间西宁PM_2.5及其中水溶性离子的浓度变化不仅受本地污染源的影响,也受外来气团输送的影响。更多还原

【Abstract】 The PM_2.5 samples were collected at urban,suburb and rural area of Xining from January to May（heating season）of 2017.The water-soluble inorganic ions in PM_2.5 were determined by ion chromatography method.The results showed that during heating season,the daily mean mass concentration of PM_2.5 was（55.98±52.66）μg/m³ in Xining,which presented significantly characteristics of urban>suburb>rural area.The total mass concentration of the water soluble ions determined in this study accounted for 36.3%of PM_2.5,the average concentration of water-soluble ions occurring the following sequence:SO₄^2->NO₃^->NH₄⁺>Na⁺>Cl^->C₂O₄^2->Ca²⁺>F^->K⁺>Mg²⁺.The average sulfur oxidation rate（SOR）and nitrogen oxidation rate（NOR）of Xining atmosphere were 0.21,0.13separately,which meant the SO₄^2-,NO₃^-in PM_2.5 were mainly formed by secondary transformation,NO₃^-/SO₄^2-（mass concentration）of PM_2.5was 0.75and the mole ratio of anion charge to cation charge was 0.89,demonstrating that coal combustion was still the dominating source of PM_2.5and the particle were generally acidic.Backward trajectory analysis indicated that the PM_2.5and water soluble ion in Xining during heavy pollution were not only influenced by the local pollution sources,but also affected by foreign air transportation.更多还原