中重度风化的混合溢油的碳氢同位素研究

The accelerating expansion of trade in crude oils has contributed to the increase in frequency of oil spill accidents in China, placing the Chinese marine environment at risk. According to correlative statistic data, oil spills from various ships resulted in a total of 2635 accidents in offshore China between 1973 and 2006, with the total weight of spilled oil reaching 37000 tons. Therefore, it has become a critical environmental issue to improve the supervision and management of oil spills. Identifying the source of an oil spill is an essential part of this process, providing forensic evidence in the investigation of oil spill accidents. However, field samples from real spill cases often consist of a mixture of multiple source oils, which confounds the chemical fingerprints of spilled oils and candidate sources and the chemical fingerprints of spilled oils usually altering in weathering time, increasing the identifying difficulty. Hence, determination of potential sources and quantification of each source contribution become large challenges when mixed oils are involved. .Carbon and hydrogen stable isotopes can be used in the identification of mixed oils after the moderate or severe weathering process. We present a weathering simulation experiment on artificially two or three source mixed oils that is combined with quantitative determination of petroleum hydrocarbons，in order to identify and reveal the quantitative relationships between characteristics of carbon and hydrogen compound specific isotope of weathered samples and the weathering degree of mixed oils. Based on this，efficient indicators of the mixed oils after medium or long term weathering and quantitative models of the contribution ratios of different end-members in mixed-source oils will be established respectively. This research have academic and practical values in the identifications of differentiating sources in an oil spill with medium or long term weathering process, and in tracing the sources of petroleum hydrocarbons in the sediments, also in understanding characteristics of petroleum hydrocarbons in seafloor sediments and the mechanisms of their transport and transformation.

随着石油工业和海上油运的发展，海上溢油事故不断发生，正确判识油类污染的来源是确定环境责任归属、解决责任纠纷的前提。溢油后数种不同背景烃的混合加大溢油鉴别的难度，碳、氢同位素可应用于混合溢油的中重度风化鉴定。分析比较不同沉积环境和母质来源的原油混合物的整体碳同位素及其中、重度风化后油样的饱和烃单体碳、氢同位素参数特征，揭示不同风化程度的碳、氢同位素分布规律，探讨碳、氢同位素组成与风化程度的定量关系，确立混合溢油指纹中重度风化鉴别的高效指标，构建经风化后的混源油中不同油源的原油贡献比例的定量模型。本课题的研究对环境中重度风化溢油中的鉴别，以及对于溢油在水环境底质中的迁移转化机制，追溯底质中的石油烃来源，都具有实际应用价值。

随着石油工业和海上油运的发展，海上溢油事故不断发生，正确判识油类污染的来源是确定环境责任归属、解决责任纠纷的前提。溢油后数种不同背景烃的混合加大溢油鉴别的难度，碳、氢同位素可应用于混合溢油的中重度风化鉴定。分析比较不同沉积环境和母质来源的原油混合物的整体碳同位素及其中、重度风化后油样的饱和烃单体碳、氢同位素参数特征，揭示不同风化程度的碳、氢同位素分布规律，探讨碳、氢同位素组成与风化程度的定量关系，确立混合溢油指纹中重度风化鉴别的高效指标，构建经风化后的混源油中不同油源的原油贡献比例的定量模型。本课题的研究对环境中重度风化溢油中的鉴别，以及对于溢油在水环境底质中的迁移转化机制，追溯底质中的石油烃来源，都具有实际应用价值。.研究结果表明，混合溢油的短期风化的生物标志物指标鉴别研究可以为混合溢油的中重度风化的相关研究提供重要的数据和理论支撑。常用于短期风化的诊断比值对各混合油样的风化具有指示意义，但难以定性鉴别油品是否发生混合。各系列混合油样的甾萜类生物标志物诊断指标与单一油品的相关诊断比值与混染油品比例有关。原油的混合过程影响了混合物中的某些化合物的风化速率，同时导致13CPr 与13CPh的分馏。短期风化影响了溢油的正构烷烃的单体碳氢同位素分馏，短期风化的油源鉴别应谨慎使用烷烃的δ13C和δD。中长期风化对正构烷烃的单体氢同位素分馏的影响较小；正构烷烃的单体碳同位素在中期风化过程中发生明显分馏效应，而长期风化过程对溢油的单体碳同位素分馏的影响趋弱。盐度会影响溢油的正构烷烃的碳同位素分馏，而对溢油的正构烷烃的氢同位素分馏影响不明显。风化过程对单体同位素的分布模式影响较小。风化过程混合溢油的烷烃、芳烃和非烃碳同位素的混合比例影响较小。风化后的碳同位素碳同位素定量模型仍能指示风化前的混合比例。