为了分析北京市大气细颗粒物中有机质的污染水平及其来源，作者对2005年夏季北京市PM10 和PM2.5中有机物的浓度、族组成及其饱和烃组分的组成和分布特征进行了研究，运用分子地球化学参数对污染源进行了示踪研究；同时分析了正构烷烃单分子碳同位素组成特征和分布规律。结果表明：夏季北京大气颗粒物中有机物浓度较高，各个采样点的饱和烃均不同程度地受到了高等植物等现代生物和化石燃料不完全燃烧产物两种来源的影响；藿烷的分布表明其受汽油燃烧产物的影响比较大，而甾烷的分布表明燃煤和发动机润滑油的排放对它的影响大致相当；低碳数部分正构烷烃δ13C值呈现出清洁区<交通干道区<商业区<工业区这一趋势，表现出各个功能区所受到的污染源影响的不同。

In order to analyze the pollution level and the source of organic matter in atmospheric particulates in Beijing city, the authors had researched on the concentrations of organic matter, the group components, the compositions and distribution of aliphatic from PM10 and PM2.5 sampled in Beijing city during summer in 2005. The tracing study on pollutant source using some molecular geochemical parameters was conducted; The characteristics and distributions of the carbon isotopic compositions of n-alkane series from atmospheric particulates in Beijing city during summer have been studied as well. The results are concluded as follows: the concentrations of organic matter in atmospheric particulates in Beijing city during summer were high, the saturated hydrocarbons from each sampling area may be derived from both modern higher plants and incomplete combustion of fossil fuels to some extents; the distribution of hopanes clearly showed the impact of gasoline combustion exhausts; the distribution of steranes suggested that the influence of coal burning and engine lubricants on them was similar; the δ13C values of n-alkane series with low carbon numbers increase from cleaning zone, traffic zone, business zone to industry zone because of the influence of different pollutant source.