天津地区主要河流表层沉积物中饱和烃的组成与分布特征

Characterization of saturated hydrocarbon in surface sediments from rivers in Tianjin, China

根据不同环境功能区9条河流表层沉积物样品中饱和烃污染物的分析结果,讨论了天津地区河流沉积物中饱和烃化合物的组成与分布特征,初步分析了饱和烃污染物的污染源。结果表明,不同河流表层沉积物中均分布有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、异构与反异构烷烃、烷基环己烷和甾、萜类等。不同河流及同一河流不同河段的表层沉积物中可抽提有机物(EOM)、烃类化合物含量和饱和烃化合物的组成特征均存在明显的差别,其中北塘排污河(北排污河)和大沽排污河(南排污河)沉积物中EOM的含量相对较高,海河及津北地区的潮白新河、蓟运河、永定新河、北京排污河的沉积物中EOM的含量相对较低;北运河、南运河及大沽排污河巨各庄河段的沉积物中烃类化合物含量相对较高,海河、大沽排污河和北塘排污河表层沉积物中烃类污染物的含量相对较低。位于市区北部的河流,靠近市区的河段沉积物中EOM含量有增加的趋势,而位于市区下游的河流,靠近市区的上游河段的沉积物中EOM含量相对较高,下游河段的有所降低。河流中烃类污染物主要来源于矿物油及其衍生物、高等植物蜡和藻类的降解产物,不同河流及相同河流不同河段污染源的相对贡献存在明显的差别。

Surface sediment samples were collected from nine rivers in Tianjin for saturated hydrocarbons analysis. Chemical composition and distribution pattern, as well as possible sources, of the saturated hydrocarbons in the river sediments were addressed. A series of saturated hydrocarbons including normal alkanes, isoprenoid alkane, iso and anteiso alkanes, alkyl hexamethylene, terpenoids and steranes were detected in the samples. There were significant differences in the contents of the extractable organic matter (EOM), hydrocarbon concentration, and the composition of saturated hydrocarbons among the rivers and river segments in the area. Among the samples studied, the contents of EOMs in the samples from Northern and Southern Sewage Channels were higher than those from Haihe River and other rivers in northern Tianjin. The contents of hydrocarbons in the sediment samples from North Canal, South Canal, and Jü gezhuang segment of Southern Sewage Channel were higher than those from Haihe River, other segments of Southern Sewage Channel, and Northern Sewage Channel. Accumulation of pollutants in the sediments from river segments close to urban area was observed. The saturated hydrocarbons in the sediments were dominantly derived from crude import and biochemical degradation of organism including cuticular in vegetable and algae. The contributions of various sources to sediments are different among rivers and river segments studied.