【作者】 邓伟；

【导师】 李先国；

【作者基本信息】 中国海洋大学 ， 海洋化学， 2013， 博士

【摘要】 陆架海作为陆地与大洋的过渡带，在陆源有机质的转运及埋藏中具有重要作用。黄、东海是西太平洋最大的边缘海，因其高的生产力和碳埋藏速率，加之大量的入海污染物对生态系统形成巨大的压力，这一海域已成为海洋地球化学研究的热点区域。海洋沉积环境中脂肪烃（AHs）和多环芳烃（PAHs）的研究对于揭示有机质来源、环境污染以及评价其潜在生态风险有着重要的科学意义和应用价值。本论文对南黄海、东海表层沉积物中的正构烷烃、类异戊二烯、复杂混合物（UCM）及多环芳烃等多种烃类标志物进行了系统的研究，旨在了解研究区域内沉积有机质来源、石油污染状况、PAHs的污染源及潜在生态风险。主要结论如下：（1）南黄海表层沉积物中有机碳（TOC）含量整体呈现泥质区高于沿岸的分布趋势，最高值出现在东北地区，含量最低的是苏北沿岸。东海沉积物TOC整体含量低于南黄海，济州岛西南泥质区高于沿岸地区，陆架中部含量最低；沿岸地区TOC分布呈现南部高于北部的特征。有机碳的分布受到沉积物的来源、粒径以及水文条件等因素控制。从C/N分析，南黄海沉积有机质呈现陆源和海源共同影响的特征。由于受到现代黄河与老黄河物质的影响，苏北沿岸以及山东半岛南部地区具有较高的C/N值。东海的C/N值整体低于南黄海，沿岸地区偏低的C/N值主要与人为活动、细菌以及土壤有机质有关。（2）南黄海表层沉积物中正构烷烃（C14^C35）的含量在0.42².00μg·g^-1之间，平均值为1.01±0.34μg·g^-1；东海地区的正构烷烃含量在0.36¹.79μg·g^-1之间，平均值为0.94±0.39μg·g^-1。研究区域正构烷烃以双峰型分布为主，前峰群主峰碳C16/C17/C18，后峰群主峰碳C29/C31。短链正构烷烃（C14^C21）无明显奇偶优势，表明正构烷烃主要来源于微生物合成或化石燃料输入。长链正构烷烃（C>25）具有奇偶优势，表明研究区域存在明显的陆源输入。总的烷烃参数分析表明，南黄海表层沉积物中有机质的海源与陆源贡献相当，而东海以陆源输入为主。正构烷烃含量与TOC%无明显相关性，主要与正构烷烃的来源多样性有关。（3）高的UCM含量和低的姥鲛烷/植烷（Pr/Ph）比值，表明研究区域受到了不同程度的石油污染，其中以苏北沿岸和浙江北部附近海域污染最为严重。除了细菌的贡献外，UCM主要的是由河流输入与船只排放的石油烃造成。此外，大气沉降也可能是UCM的另一个重要来源。（4）南黄海表层沉积物中多环芳烃（TPAHs）的含量在61³601ng·g^-1之间，平均值为825±716ng·g^-1。平面分布呈现北部高于南部，最高值出现在靠近韩国一侧，可能与海上倾废有关；苏北沿岸地区含量最低。东海表层沉积物中TPAHs含量在128¹643ng·g^-1之间，平均值为771±411ng·g^-1。近岸泥质区高于济州岛西南泥质区，陆架中部含量最低。与世界其他地区相比，研究区域整体上处于中低等污染水平。（5）TOC是控制南黄海沉积物中TPAHs分布的重要因素；东海沉积物中TPAHs的分布除受TOC的影响外，还与复杂的水动力条件、滨岸各类污染源的输入以及黑炭（BC）、颗粒有机碳（POC）分布有关。南黄海TOC标准化的TPAHs分布整体呈现沿岸高于远岸，中部泥质区最低的分布特征。（6）沉积物中的PAHs主要以3环母本多环芳烃为主，占总量的64.1%±9.1%，4环次之。其中济州岛西南泥质区和陆架中部以5、6环的PAHs为主，可能与大气输入有关；研究区域沉积物中的优势组分是菲、荧蒽、芴、甲基菲及芘，表明PAHs与煤燃烧有关。（7）因子分析和分子比值法分析显示，家庭燃煤和煤制焦是研究区域最主要的PAHs输入源。木材燃烧对东海PAHs的贡献率要大于南黄海，这与南北能源及工业结构不同有关。此外，天然气燃烧已成为研究区域沉积物中PAHs的重要来源。与燃烧源相比，石油源对沉积物中的PAHs贡献率很小，主要与石油源PAHs不稳定易分解有关。PAHs污染源的组成与我国当前的能源结构吻合。（8）沉积物中的PAHs在远距离传输过程中发生了降解。南黄海、东海近岸沉积物中的PAHs主要以河流输入为主，同时存在大气沉降的添加，而济州岛与陆架中部地区则以大气沉降为主。（9）采用效应区间中-低值法评价了研究区域沉积物中PAHs潜在生态风险，结果表明PAHs远低于效应区间中值（ERM），整体属于低风险。但有多个站位的芴（F）、菲（Phe）超过了效应区间低值（ERL），可能会对底栖生物造成危害。更多还原

【Abstract】 Continental shelf regions are the transition zones between continent and openocean and play a key role in the transport and storage of terrestrial organic materialsin the ocean. As two of the largest marginal seas in the Western Pacific Ocean, theYellow Sea （YS） and East China Sea （ECS） have attracted many concerns not onlybecause of their high primary productivity and high carbon burial rates, but also as aresult of the rapidly increasing environmental pressure of huge pollutant loadings onthe marine ecosystem. The studies on aliphatic hydrocarbons （AHs） and polycyclicaromatic hydrocarbons （PAHs） in the sediments are of important scientific andpractical significance in revealing the origins of sedimentary organic material andenvironmental pollution as well as their potential threat on marine organisms. In thisdissertation, we present systematic results on the composition characteristics, spatialdistribution patterns, and controlling mechanisms of multiple hydrocarbon biomarkers（n-alkanes, isoprenoid pristane and phytane, unresolved complex mixtures （UCM）,alkyl and parent PAHs） in surface sediments from the South Yellow Sea （SYS） andECS. The study aims to understand the origins of sedimentary organic material（SOM）, sediment contamination status by petroleum and PAHs, the sources andpotential ecological risk of PAHs in the study areas. The main conclusions aresummarized as follows:1. The content of total organic carbon （TOC） in the surface sediments from the SYSshowed an overall pattern of lower values near the coast and higher values in the mud area. The highest values occurred in the northeast part of the study area, and thelowest values were found off the Jiangsu coast. The average TOC content in thesamples from the ECS was relatively lower than that from the SYS. The highest levelappeared in the mud area to the southwest of Cheju Island while the lowest TOCcontent was found in the middle shelf, and higher level occurred in the inner shelfregion. The distribution pattern of TOC in the inner shelf was characterized byincreasing southward along the shoreline. In the study areas, the distribution of TOCis affected by many factors, such as sediment sources, grain-sizes, hydrodynamicconditions, and so on. The C/N ratio suggests that SOM in the SYS is derived fromboth terrestrial plants and marine organism. The terrestrial input dominates the sourceof organic material in the northern part of the study areas and Jiangsu coastal area,caused by inputs of materials from the modern Huanghe River and the old Huanghedelta, respectively. In comparison, the values of C/N in the ECS are lower than that inthe SYS. In coastal area, lower C/N ratios could be primarily attributed toanthropogenic influences, microorganism and soil-derived organic matter.2. Concentrations of n-alkanes （C14^C35） were from0.42to2.00μg·g^-1in the SYSsurface sediments and varied from0.36to1.79μg·g^-1in the ECS surface sediments,with mean values of1.01±0.34μg·g^-1and0.94±0.39μg·g^-1, respectively. In mostsamples, the n-alkanes had a bimodal distribution which is maximized at C16, C17orC18in the first mode and at C29or C31in the second mode. The short-chain （C14^C21）n-alkanes showed no noticeable even/odd preference, suggesting that microbialactivity or fossil inputs is the primary source. The profile of long-chain（C>25）n-alkanes with an elevated odd to even carbon preference revealed the occurrence ofprominent terrestrial inputs in the study area. Overall, bulk hydrocarbon parameterssuggest that SOM in surface sediment in the SYS is derived from both terrestrial andmarine sources, while that in the ECS is predominantly come from terrestrial sources.There is no significant correlation between the contents of n-alkanes and TOC%in thestudy areas, primarily because of the diversity of sources of n-alkanes.3. The presence of elevated levels of UCM and relatively low Pr/Ph ratios in mostsites revealed a petroleum contamination in the study areas, especially in the coastal areas of Jiangsu and south Zhejiang. With the exception of bacterial contribution, themajority of UCM is related to anthropogenic input of petroleum residues likely due tothe local river discharge and shipping activities. In addition, atmospheric deposition isprobably another important source for UCM.4. Concentrations of PAHs （TPAHs） varied from61to3601ng.g^-1in the SYSsurface sediments, with mean values of825±716ng.g^-1. TPAHs showed an overallpattern of lower values in the north part and higher values in the south part of the SYS.The highest values occurred in the northeast close to South Korea, could be likelyrelated to the ocean dumping, while the lowest values were found off the Jiangsucoast. The contents of TPAHs ranged from128to1643ng.g^-1in the ECS surfacesediments, with mean valus of771±411ng.g^-1. Among different sampling areas, thehighest level appeared in the inner shelf region while the lowest value was found inthe central shelf, and higher level occurred in the mud area to the southwest of ChejuIsland. PAHs concentrations in the study areas are at the low to moderate levels of theglobal range.5. TOC was identified as an important controlling factor in the TPAHs distributionin the SYS. However, the TPAHs distribution in the ECS was complicated byhydrodynamic condition, coastal pollutants discharge, black carbon （BC） andparticulate organic carbon （POC） in addition to TOC content. The distribution of theorganic carbon-normalized TPAHs in the SYS surface sediments revealed a clearspatial pattern, with high values near the coast and decreased values seaward, and thelowest values occurred in mud area in the central SYS.6.3ringed parent PAHs are the major components of TPAHs in most stations,accounting for64.1%±9.1%of them, followed by4ringed PAHs. Whereas thefraction of high （5to6） ringed PAHs presents as predominance in the mud area to thesouthwest of Cheju Island and central shelf, primarily caused by inputs of atmosphericdeposition. The main compounds of PAHs in the sediments are phenanthrene,fluoranthene, fluorene, methyl phenanthrene and pyrene, which are consistent withsources related to coal combustion.7. The results from diagnostic ratios and factor analysis indicate that domestic coal combustion and coking industry are the predominant sources of PAHs in the studyareas. The impact of wood combustion on the ECS is greater than that on the SYS,mainly related to the difference of energy usage and industrial structure betweenSouth and North China. In addition, natural gas combustion has been become animportant input for PAHs to the sediment of our study areas. Petrogenic source,compared with pyrogenic source, is a small contributor to the PAHs in surfacesediments of the study areas, primarily related to petroleum-derived PAHs are morevulnerable to degradation. The composition of PAHs sources in surface sediments isconsistent with the profiles of current Chinese energy consumption.8. To some extent, sedimentary PAHs have undergone weathering during long-rangtransport to the study areas. In addition to atmospheric deposition, the PAHs arepredominantly introduced into the SYS and the ECS coastal area via fluvial transport,while PAHs in surface sediments from the mud area to the southwest of Cheju Islandand central shelf are dominated by atmospheric deposition.9. The potential ecological risks of PAHs were evaluated on the basis of effectrang-low （ERL） and effect rang-median （ERM）. The results showed thatconcentrations of PAHs were much lower than ERM and the sediment had a lowprobability of ecological risk. However, contents of fluorene and phenanthreneexceeded the ERL value in many stations. They probably pose risks on the marinebenthos.更多还原