【摘要】 为研究背景地区大气PM_{2. 5}化学组分季节变化特征及对能见度的影响,本研究于2016年春、夏、秋、冬在济南市七星台采集大气PM_{2. 5}样品,分析其中水溶性离子组分及OC、EC的污染特征并研究其区域传输贡献.结果表明,NH₄⁺、SO₄^2-和NO₃^-三者之和占年均离子总浓度的90. 24%,二次生成的水溶性无机离子污染较为严重. NO₃^-/SO₄^2-呈现出明显的冬高夏低的季节性变化特征.各季节的SO₄^2-和NH₄⁺主要以（NH4）2SO4结合的形式存在. SOC/OC的范围是21. 17%～54. 21%,表明该地区存在较为严重的二次有机污染.四季SOR值均大于0. 1,显示本区域四季均有SO₄^2-的二次生成,四季NOR的值均高于SOR,可知NO2的二次转化强于SO2的二次转化.大气消光系数（Bext）的范围是172. 68～320. 61 Mm-1,年均值为256. 48Mm-1,大气消光系数呈现明显的夏低冬高的季节性趋势.后推气流轨迹显示七星台地区春、夏季主要受长距离传输和海洋源的影响,秋、冬季主要受局地源的影响.对比2008年济南市大气PM_{2. 5}污染特征研究,结果显示机动车对大气环境影响显著提升.更多还原

【Abstract】 In order to study the seasonal variations in the chemical composition of atmospheric particulate matter with diameters less than 2. 5 μm( PM_{2. 5}) and its influence on visibility in background areas,atmospheric PM_{2. 5} samples were collected in spring,summer,autumn,and winter 2016 at Qixingtai in Ji’nan. The pollution characteristics of water-soluble ions components,organic carbon（ OC）,and elemental carbon（ EC） were analyzed,and their regional transmission contributions were studied. The results show that NH₄⁺,SO₄^2-,and NO₃^-were the main components of water-soluble ions,accounting for 90. 24% of the annual total ion concentration. The secondary water soluble inorganic ions were polluted severely. NO₃^-/SO₄^2-presented obvious seasonal variations of high（ low） levels in winter（ summer）. In each season,SO₄^2-and NH₄⁺existed mainly in the form of（ NH4）2 SO4. The value of secondary OC（ SOC）/OC ranged from 21. 17% to 54. 21%,indicating the presence of relatively severe secondary organic pollution in this area. The sulfur oxidation ratio（ SOR） value in all seasons was greater than 0. 1,indicating that the secondary generation of SO₄^2-occurs in all seasons in this region,and the value of nitrogen oxidation ratio（ NOR） in all seasons was higher than the SOR value. The secondary transformation of NO2 in the Qixingtai region was stronger than that of SO2. The range of atmospheric extinction coefficient（ Bext） was 172. 68-320. 61 Mm-1,with an annual mean of 256. 48 Mm-1. The atmospheric extinction coefficient showed an obvious seasonal trend of the lowest（ highest） in summer（ winter）. The backward airflow trajectory shows that the Qixingtai was affected mainly by the long-distance transmission from Northwest China and the ocean in spring and summer and by local sources in autumn and winter. A comparison of the characteristics of atmospheric PM_{2. 5} pollution in Ji’nan in 2008 revealed that the influence of motor vehicles on the atmospheric environment has been significantly improved.更多还原