北京地区表层土中饱和烃组成特征及成因分析

根据北京地区不同环境功能区62个样品检测结果,分析了研究区表层土壤中饱和烃类化合物的化学组成及其分布特征,并对其来源进行了讨论。结果表明：（1）北京地区表层土壤中分布有多种类型的烃类污染物,已检测到的饱和烃化合物主要包括正构烷烃、无环类异戊间二烯烷烃、单甲基取代支链烷烃（异构与反异构烷烃）、烷基环己烷和甾、萜烷类等系列化合物中的数百种单体化合物;（2）不同环境功能区,同一地区土地使用情况不同或周围环境不同的土壤样品中饱和烃的质量分数和组成特征均存在较大的差别,其中正构烷烃的质量分数为0.25~4.72μg.g-1;（3）随着距离城中心的距离减小,表土中饱和烃质量分数增高,南部地区饱和烃的质量分数高于北部地区;（4）表层土壤中饱和烃的来源比较复杂,主要来自于化石燃料及木材的不完全燃烧产物,部分地区有少量矿物油及其衍生物的输入。

Component characteristics and origin of saturated hydrocarbon compounds of topsoil in Beijing,China

Sixty-two topsoil samples collected in Beijing were detected to analyze the composition and distribution of saturated hydrocarbon compounds,and then their origin was discussed as well.The results showed that：（1） many kinds of hydrocarbon pollutions in the topsoil samples of Beijing were found,mainly including normal alkanes,iso-and anteiso-alkanes,alkyl-hexamethylenes,hopanes and steranes,etc;（2） the concentration and composition of saturated hydrocarbon compounds in the topsoil samples from different geographic locations or from the same geographic location but with different surrounding environment were obviously different,and the concentration of normal alkane was between 0.25 and 4.72 μg·g-1;（3） with decreasing of the distance to the city center,the concentration of saturated hydrocarbon in the topsoil increased,and it was higher in the north than in the south;（4） the sources of saturated hydrocarbon compounds in the topsoil were diversified,which were mainly from incomplete combustion products of fossil fuel or firewood and some areas showed a small amount of mineral oil and its derivatives import.