兰州市排污沟淤泥的有机质特征及来源分析

文章对兰州市西部工业区、生活区、医院等功能区的排污沟上、中、下段淤泥中饱和烃组成与分布特征进行了分析,初步认识了饱和烃的来源和组成特征。分析表明,排污沟淤泥中分布多种类型的饱和烃化合物,主要包括正构烷烃、无环类异戊二烯烷烃、萜类化合物、甾烷等。正构烷烃组成特征均为双峰态后峰型,主峰碳数为C15-C18和C25-C31。样品中检测出27种萜类化合物,其中五环萜类较三环萜类化合物占优势。甾烷化合物主要包括规则甾烷、重排甾烷、孕甾烷,以规则甾烷为主。有机质生物标志物参数表明,排污沟淤泥中有机质具有成熟和不成熟的特征,主要为现生植物、矿物油和化石燃料对烃类化合物的贡献,并且在不同区段由于外源有机物的加入而表现不同,有机质为多源混合来源。人类活动较集中的中段受矿物油和化石燃料燃烧污染程度明显比上游和下游严重。

A Pollution Investigation of Sewage Ditch in Lanzhou City: Analysis of Organic Matter in Silt

This paper refers to an investigation of a main drainage ditch that flows across the west part of Lanzhou City, with its upper section in residential area, mid section in industrial area, and lower section characterized by busy traffic. Chemical analysis of the. silt sampled in different sections of the ditch showed that the organic matter consisted of a series of saturated hydrocarbons including normal alkanes and isoprenoid alkane, terpenoids and steranes. Composition of n-alkanes featured double-peak pattern with back peaks predominance. The carbon numbers of main peaks are C_(15)-C_(18) and C_(25)-C_(31). 27 kinds of terpanes are detected, among which pentacyclic triterpanes are the dominant. As to 'sources of the organic matter contained in the silt, the mass chromatograms obtained has tracked down the combustion of mineral oils and fossil fuels, discharge of domestic waste-water and others mainly caused by human activities.