天津表层土中饱和烃污染物的组成及分布特征

 分析了天津地区主要环境功能区表层土样品中烃类污染物的组成特征.结果表明,不同环境功能区表层土中均分布有多种类型的饱和烃污染物,主要包括正构烷烃,无环类异戊间二烯烷烃,单甲基支链烷烃,烷基环己烷和甾,萜类等.这些化合物在区域上分布广泛,组分变化多样.样品间正构烷烃碳数分布特征差别较大,CPI1为0.76～1.26,CPI2为1.29～7.14,CPI(wax)为0.81～3.24.aaaC_29-甾烷20S/(20R+20S)为0.45～0.72,C₃₁藿烷22S/(22S+22R)为0.54～0.62,均已达到平衡终点.类异戊间二烯烷烃和烷基环己烷的分布特征与原油相近.表明污染源较复杂,主要包括矿物油,化石燃料的不完全燃烧及天然产物的生物化学降解等,不同功能区污染源存在一定的差别.

Composition and distribution characterization of saturated hydrocarbon pollutant in Tianjin surface soil

Base on the measured results of saturated hydrocarbons in 34 surface soil samples collected from various environment domains in Tianjin, the chemical composition, distribution and pollution sources in the surface soils were investigated. The saturated hydrocarbons in the surface soils were dominated by normal alkane, isoprenoid alkane, iso-and anteiso-alkanes, alkyl hexamethylene, hopanes and steranes, which are widely distributed in the area. The normal-alkane compositions were significantly different among samples with CPI1 ranging from 0.76 to 1.26, CPI2 from 1.29 to 7.14, and CPI(wax) from 0.81 to 3.24. The aaaC29-sterane 20S/(20R+20S) values of the samples range from 0.45 to 0.72, and C31 hopane 22S/(22S+22R) from 0.54 to 0.62, all of which reached chemical equilibrium. Among various species, the chemical composition of isoprenoid alkane and alkyl hexamethylene were similar to that of the crude oil, suggesting complicated pollution sources including crude import, combustion products of fossil fuel or firewood and biochemical degradation of organism. The contributions of various sources to soils from various environment domains were different.