成都市冬季大气颗粒物组成特征及来源变化趋势

年冬季分别在成都市8个环境受体采样点采集PM₁₀、PM_2.5样品,同时采集颗粒物源类样品,分析上述样品质量浓度及多种无机元素、水溶性离子和碳组分的含量,以对这3 a冬季大气颗粒物浓度、特征组分、来源及变化趋势进行分析. 使用CMB-iteration模型对成都市中心城区的PM₁₀、PM_2.5进行来源解析. 结果表明: 成都市冬季ρ(PM₁₀)在工业区最高,PM_2.5污染呈现区域性特征；冬季PM₁₀的主要来源有扬尘、二次硫酸盐、煤烟尘、二次硝酸盐和机动车尾气尘,上述5类源在2010─2012年的分担率分别为24%～29%、17%～22%、13%～16%、6%～12%、6%～11%；对PM_2.5有重要贡献的源类有二次硫酸盐、扬尘、煤烟尘、二次硝酸盐和机动车尾气尘,这5类源在2010─2012年的分担率范围分别为25%～27%、19%～22%、12%～15%、11%～13%、8%～11%. 二次粒子、扬尘等是成都市大气颗粒物的主要污染源,其中扬尘、建筑水泥尘等以粗粒子为主的源类浓度贡献呈逐年下降趋势,而二次粒子等以细粒子为主的源类浓度贡献则逐年上升,成都市冬季大气细颗粒物污染加重. 

Particulate Composition and Source Apportionment Trends in Winter in Chengdu

Air samples of ambient PM₁₀ and PM_2.5 were collected in 2010,1, and 2012 at eight sites during winter in Chengdu, Sichuan Province. The inorganic elements, water solvent ions and carbonaceous species were measured to identify the sources of the PM10 and PM_2.5. The trends of PM concentration, chemical composition and sources were investigated. The concentration of PM₁₀ was the highest in the industrial region, while PM_2.5 showed regional characteristics. The sources of PM₁₀ and PM_2.5 in Chengdu were determined by chemical mass balance iteration (CMB-iteration) receptor model. The results showed that the important sources of PM₁₀ in winter in Chengdu were suspended dust, sulfates, fly coal combustion, nitrates and vehicle exhaust, with contributions of 24%-29%, 17%-22%, 13%-16%, 6%-12% and 6%-11%, respectively, from 2010 to 2012. The important sources of PM_2.5 were sulfates, suspended dust, fly coal combustion, nitrates and vehicle exhaust, with contributions of 25%-27%, 19%-22%, 12%-15%, 11%-13% and 8%-11%, respectively, from 2010 to 2012. This work indicated that secondary particles and suspended dust were the major sources of PM in Chengdu. Suspended dust and cement dust, which were mainly composed of coarse particles, contributed less year by year, while the contribution of secondary particles, which were mainly composed of fine particles, increased year by year. Fine PM pollution was serious in winter in Chengdu.