济南城区大气PM2.5、PM1.0的污染特征及大气传输

为研究华北平原PM_2.5、PM_1.0的污染特征,于2014年10月至2016年6月在济南城区使用中流量采样器对大气颗粒物样品进行采集,利用离子色谱、碳气溶胶分析仪测定了颗粒物中的水溶性无机离子成分和碳组分。结果表明:济南城区冬季大气细颗粒污染较重,二次离子SO₄^2-、NO₃^-和NH₄⁺是PM_2.5、PM_1.0最主要的水溶性无机离子,且更易富集在PM_1.0中。有机碳和元素碳的质量浓度表现为春夏低,秋冬高;二次有机碳的质量浓度在冬季明显升高,且大多分布在粒径>1 μm的颗粒物中。72 h后向气流轨迹表明,来自河北、内蒙古的长距离传输与山东地区的局地传输对济南大气中PM_2.5和PM_1.0的离子质量浓度有重要影响。济南冬季的消光系数高达789.13 Mm^-1, PM_2.5中的二次粒子NH₄⁺、SO₄^2-和NO₃^-与消光系数的相关性较高,是使大气能见度降低的主要因素。

Pollution characteristics and atmospheric transmission of PM2.5 and PM1.0 in Jinan city

To study the characteristics of PM_2.5 and PM_1.0 in the North China Plain, atmospheric particulate samples were collected from October, 2014 to June, 2016 in Jinan urban area by using mid-volume samplers. Then we determined iron composition of Water-soluble inorganic ions with ion chromatography(IC)and carbonaceous component with thermal-optical transmittance (TOT) carbon aerosol analyzer. It was shown that the fine particle pollution of the atmosphere was serious in winter. The secondary ions SO₄^2-, NO₃^- and NH₄⁺ were the major water-soluble ions of PM_2.5 and PM_1.0, especially easily enriched in PM_1.0. Compared with autumn and winter, concentrations of organic carbon(OC) and elemental carbon (EC) were much lower in spring and summer. The mass concentration of SOC, most of which was distributed in particles with particle size >1 μm, increased obviously in winter. Indicated by the 72 h backward trajectories, long-distance transmission from Hebei and Inner Mongolia, as well as local transmission from Shan- dong had an important influence on the ion mass concentration of PM_2.5 and PM_1.0 in the atmosphere of Jinan. The extinction coefficient of Jinan was up to 789.13 Mm^-1 in winter. The extinction coefficient had a high correlation with secondary particles NH₄⁺, SO₄^2- and NO₃^- in PM_2.5, which was the chief reason of the reduction in the visibility of the atmosphere.