天津地区表层土壤和河流沉积物中甾烷与五环三萜烷的分布特征及污染源分析

Distribution and sources of steranes and pentacyclic triterpanes in surface soils and bottom sediments from Tianjin

分析了天津地区表层土壤和具有代表性的河流沉积物中甾烷和五环三萜烷系列化合物的组成与分布特征,讨论了这类化合物的来源及环境意义。分析表明,在天津地区不同环境功能区表层土壤和河流沉积物中均检测到了甾烷和五环三萜烷系列化合物,但样品之间其含量存在明显的差别;表层土壤与河流沉积物中甾烷、五环三萜烷化合物的组成与石油中的基本一致,样品间这类化合物在饱和烃中的相对含量与正烷烃CPI之间有较好的负相关关系,表明它们主要来源于石油及副产品,可以根据样品中甾、萜化合物与正构烷烃的比值来反映饱和烃中石油烃污染源的贡献。论文根据样品中甾烷、五环三萜烷化合物与正构烷烃的比值,并结合正烷烃CPI参数初步分析了天津地区不同环境功能区表层土壤和河流沉积物中饱和烃污染物的污染源。

Contents and distribution of steranes and pentacyclic triterpanes in surface soils and river bottom sediments from Tianjing were investigated. Their sources and environmental geochemical significance as indicators to source of Hydrocarbon contamination in general were discussed. Steranes and pentacyclic triterpanes were detected in all soil and sediment samples. The concentrations of these compounds varied among the samples collected from different locations. The compositive difference of steranes and penta-cyclic triterpanes between the samples and crude oil was not remarkably different. There was a negative correlation between the concentration ratio of steranes and terpanes to normal alkane and carbon predominance index (CPI) of normal alkane, suggesting that steranes and pentacyclic triterpanes detected in the samples were mainly from crude oil or its products. The contribution of crude oil to saturated hydrocarbon contamination of the samples was estimated based on the concentration ratio of steranes and terpanes to normal alkane. This approach, together with CPI calculation, were used to possible sources of saturated hydrocarbon compounds in soil and sediment samples collected from various location in Tianjin.