青岛市PM2.5化学组分特征及综合来源解析

Characterization of Chemical Composition and Comprehensive Source Apportionment of PM_(2.5) in Qingdao

为明确青岛市环境受体中PM_(2.5)的化学组分特征及来源,该研究于2016年在青岛市7个点位采集了PM_(2.5)样品,分析了PM_(2.5)中的无机元素、水溶性离子、碳等组分的质量浓度,采用CMB模型估算法,估算了青岛市的一次源类、二次源类对PM_(2.5)的贡献,并结合排放源清单及系数分配得到综合的PM_(2.5)源解析结果。结果表明:青岛市环境受体中PM_(2.5)平均质量浓度为62μg/m^3。PM_(2.5)中占比较高的组分是OC(16.44%)、SO_4^(2-)(15.07%)、NO_3^-(11.27%)、NH_4^+(8.86%)和EC(5.21%)。OC/EC的年平均值为3.62,说明存在二次有机气溶胶污染;SO2-4/NO-3的年平均值为2.71,夏季明显高于其他季节。冬季重污染过程中主要离子呈现出累积的现象。夏季二次硫酸盐的贡献上升为第一位(24.7%);机动车尘四季的贡献均较高(17.5%~20.5%),燃煤在冬季(15.1%)、秋季(13.3%)贡献高,扬尘在春季(16.5%)、冬季(15.6%)贡献高。

PM2.5 samples in seven sites were collected during four seasons of 2016 to study the characterization of chemical composition and source of PM2.5 in Qingdao. The mass ancentration of elemental compositions,water-soluble ions and carbon in PM2.5 samples were analyzed. The contributions of primary and secondary emission source to PM2.5 were estimated with CMB（ chemical mass balance） method. The comprehensive sources to PM2.5 were obtained by combining the emission inventory and coefficient distribution. The results showed that the average concentration of PM2.5 in Qingdao was 62 μg/m^3. The major chemical compositions in PM2.5 were OC（ 16. 44%）,SO4^2-（ 15. 07%）,NO3^-（ 11. 27%）,NH4^＋（ 8. 86%） and EC（ 5. 21%）.The annual average ratio of OC/EC was 3. 62,meaning secondary organic aerosol pollution occurred. The annual average ratio of SO4^2-/NO3^- was 2. 71 and that in summer was obviously higher than other seasons. During heavy pollution in winter,the major ions were accumulated. Secondary sulfate was the primary source to PM2.5 in summer（ 24. 7%）. The contributions of traffic emissions（ 17. 5%-20. 5%） were in a high level during the whole year. The contributions of coal burning were higher in winter（ 15. 1%） and autumn（ 13. 3%）,while that of re-suspended dust were higher in spring（ 16. 5%） and winter（ 15. 6%）.