渤海石油污染：来自表层沉积物中生物标志物的证据

Petroleum contamination in the surface sediments of the Bohai Sea:evidence from the sedimentary biomarker records

通过对渤海表层沉积物中饱和烃的分布、来源和分子组成特征的系统分析,探讨了沉积物中生物标志物对石油污染的指示意义。研究表明,沉积物中色谱不可分辨的混合物(UCM)和正构烷烃的分布及组成特征显示出沉积物不同程度地受到了石油烃输入和细菌微生物作用的影响,其中以渤海湾沿岸区域最为明显。渤海湾近岸区和黄河口附近沉积物中正构烷烃平均碳链长度(ACL)低于其他地区,姥鲛烷/植烷(Pr/Ph)也普遍低于1.0,表明可能受到来自于石油平台开采活动、船舶航行、河流输入的石油烃的影响。C27-18α(H)-三降藿烷(Ts)与C27-17α(H)-三降藿烷(Tm)的比值(Ts/Tm)、C31升藿烷22S/(22S+22R)和αααC29甾烷20S/(20S+20R)的比值表明该区域沉积物中有机质成熟度较高,可能受到外来石油烃输入及其衍生物的影响。通过与周边环境中生物标志物分子组成特征的对比发现,沉积物中甾烷和萜类化合物主要来源于石油及其衍生物。将饱和烃各参数进行归一化处理,得到了石油污染的综合替代性指标,并初步圈定了石油污染相对较重的区域。

On the basis of the examination of the distribution, sources and molecular composition of the aliphatic hydrocarbons in surface sediments of the Bohai Sea, the sedimentary biomarkers of those hydrocarbons and their indication for the petroleum contamination was elucidated. The occurrence of unresolved complex mixtures and the distribution and compositional patterns of the n-alkanes in the sediments indicated the presence of a widespread pe- troleum contamination, especially for the coastal Bohai Bay. The n-a｜kane average chain length （ACID in the sam ples from the offshore Bohai Bay and Huanghe River estuary was significant lower than those from the other re- gions, coupling with the lower ratios of Pr/Ph （〈1.0）, which suggesting the potential impact of the offshore oil exploration, shipping activity and fluvial input for the petroleum residue input. The conventional diagnostic ratios of the petroleum biomarkers, such as Ts/Tm, homohopanes S/（S＋R） and αααC29 sterane S/（S＋R） ratios indica- ted a presence of mature constituents in the sediments, implying the contribution of crude oil or its products. By comparing the molecular composition to the samples from the surrounding environmental setting, the steranes and terpanes in the sediment samples was mainly derived from the crude oil and/or its products. After normalization of the aliphatic hydrocarbon parameters, the petroleum hydrocarbon index （PHI） was achieved. The PHI has figured out four divided regions as the relatively intense contaminated regions with a total area of 1.22×10^6 km^2 , account- ing for 240% of the study area.