北京市大气可吸入颗粒物的化学成分和来源

2007年3月至2008年5月，在北京市成府路东口设立采样点，共采集监测周期为一周的PM2.5(直径小于2.5μm的大气可吸入颗粒物)样品56个，用HR-ICP-MS方法测量了15种元素的含量，并在此基础上应用主因子分析法对PM2.5中这些元素的来源进行探讨。同时，在2008年奥运会和残奥会期间开展了24h时间间隔的密集采样，特别分析了机动车限行期间细颗粒污染物的浓度特征。结果表明，2007年春季至2008年春季期间北京市大气PM2.5平均浓度为72.9μg/m3，超过美国环保局（USEPA）制定的PM2.5年平均浓度限值15μg/m3的近5倍。机动车限行期间北京成府路东口采样点大气PM2.5的平均浓度为40.7μg/m3。通过因子分析方法确定北京PM2.5的3种可能来源：①交通排放、工业排放和燃煤,特征元素为Cu、Zn、As、Sn、Sb、Cd、Pb；②本地扬尘和远源沙尘细颗粒；③可能与成土母岩风化有关的土壤颗粒的再悬浮和/或迁移，其方差贡献率分别为41.2%、31.4%和12.2%。

Chemical composition and origin of atmospheric particulate matter in Beijing

From March 2007 to May 2008,56 weekly PM2.5(suspended particulate matter with aerodynamic diameter less than 2.5μm) were collected at the east crossing of Chengfu Road,Beijing,China.The concentrations of 15 elements in PM2.5 samples were measured by HR-ICP-MS.Factor analysis(FA) was performed in order to characterize the chemical properties and the origin of PM2.5.The total mass of 40 intensive daily(24h) PM2.5 samples were measured during the Olympic Games and the Paralympics Games,in order to investigate the pollution level when traffic control was carried out.The results show that the average mass concentration of PM2.5 was 72.9 μg/m3,which was around 5 times higher than that of the limiting value of 15 μg/m3(established by U.S.Environment Protection Agency) from spring 2007 to spring 2008.During the Olympic Games,the average mass concentration of PM2.5 was 40.7 μg/m3.The statistical evaluation of the data identifies three main sources responsible for PM2.5 in Beijing: ①A combination of road traffic,industry emissions and coal combustion,characterized by Cu,Zn,As,Sn,Sb,Cd and Pb;②Soil dust,construction sites and fine dust particles;③Re-suspension and/or mobilization of geogenic soil particles,accounting for 41.2%,31.4% and 12.2%,respectively of the total variance.