西安市秋季大气细粒子（PM2．5）中化学元素的浓度特征和来源

目的]研究西安市秋季大气细粒子（PM2.5）中化学元素的浓度特征及来源。方法]于2009年10月利用微流量采样器采集西安大气中PM2.5样品,分析其元素浓度特征及来源。结果]西安市秋季大气中PM2.5质量浓度的平均值为168.44μg/m3,最小值为53.29μg/m3,最大值达358.16μg/m3,高于北京、珠江三角洲;PM2.5中S、Zn、K、Cl、Ca、Fe的质量浓度均超过1.0μg/m3,处于较高污染水平;PM2.5中K与有机碳（OC）、元素碳（EC）的相关性较高,相关系数分别为0.76和0.75（P〈0.0001）,说明OC、EC与K具有相同的来源,生物质燃烧对OC、EC有一定的贡献;元素的富集因子分析表明,K、Ca、Fe、Ti、Mn和Cr主要来源于地壳或岩石风化等自然源,而S、Zn、Cl、Pb、Br、Mo、Cd和As主要受人为污染源的影响,而受土壤扬尘等自然源的影响较小,其中Cd的富集因子最大,主要来源于金属冶炼等人为污染;燃煤、生物质燃烧、机动车尾气排放、冶金化工、扬尘等是该区秋季PM2.5的主要来源。结论]该研究为城市环境污染治理提供了理论依据。

Concentration Characteristics and Sources of Chemical Elements in Atmospheric Fine Particles (PM_(2.5)) in Autumn in Xi'an City

Objective]The aim was to study the concentration characteristics and sources of chemical elements in atmospheric fine particles (PM2.5) in autumn in Xi'an City.Method]By means of min-volume sampler,PM2.5 samples in atmosphere in Xi'an were collected in October 2009,and the concentration characteristics and sources of elements in PM2.5 were analyzed.Result]The average mass concentration of PM2.5 in atmosphere in autumn in Xi'an City was 168.44 μg/m3 which was higher than that of Beijing and Pearl River Delta area,and the minimum and maximum value were 53.29 and 358.16 μg/m3,respectively.The mass concentration of S,Zn,K,Cl,Ca and Fe in PM2.5 was above 1.0 μg/m3,with high pollution level.In addition,K had obvious correlation with organic carbon(OC) and element carbon(EC),with the correlation coefficients of 0.76 and 0.75(P < 0.000 1) respectivdly,and it showed that OC and EC had the same source as K,namely biomass burning had certain contribution on OC and EC.Enrichment factors analysis revealed that K,Ca,Fe,Ti,Mn and Cr came from earth crust,rock weathering and other natural sources,while anthropogenic pollution sources had great effects on S,Zn,Cl,Pb,Br,Mo,Cd and As which were affected by soil dust and other natural sources slightly,among them,Cd had the highest enrichment factor and mainly came from metal smelting.Besides,coal combustion,biomass burning,vehicle emissions,metallurgical and chemical industry and dust were the main sources of PM2.5 in autumn in Xi'an.Conclusion]The study could provide theoretical foundation for the control of urban environmental pollution.