北京地区冬季气溶胶分级化学成分及来源分析

在北京城区进行冬季大气气溶胶采样,样品采用PIXE方法进行分析,得到大气气溶胶中20种元素的质量浓度。结果表明:元素Mg、Fe、Si这3种元素均呈粗粒模态单峰型分布,且峰值出现在2～4μm,表明它们来自土壤尘;S、Cl、K等3种元素谱分布呈细粒单峰型分布,峰值都出现在0.25～0.5μm范围内,表明这3种元素主要来自燃煤;Cu、Zn、As、Br、Pb等5种元素谱分布呈双峰型谱分布;Ni、Cu、Zn、As、Se、Br、Pb等元素的粗、细模态的富集因子都较大,尤其是细粒模态,表明这些元素更容易在细粒模态上富集,进一步说明这些元素主要来自人为污染源。因子分析结果表明:土壤尘、煤烟尘、工业源和汽车尾气排放源对北京冬季气溶胶有主要贡献。

Size Distribution of Element Concentration of Atmospheric Aerosols and Source Analysis in Beijing in Winter

Atmospheric aerosol samples were collected by cascade sampler in December 2004 and analyzed using PIXE method,which resulted in mass concentration of 20 elements.The results showed that the size distribution of Mg,Fe and Si reached single peaks in coarse mode,the peak value appeared at 2~4 μm.The size distribution of S,Cl,K had single peaks in fine mode,the peak value appeared at 0.25~0.5 μm.The size distributions of Cu,Zn,As,Br and Pb had two peak mode.The enrichment factors of Ni,Cu,Zn,As,Se,Br and Pb were high in both coarse mode and fine mode,which implied the pollution characteristics from human activities.The factor analysis indicated that the soil,coal combustion,industry and motor vehicle contributed to aerosol pollution in winter in Beijing.