渤海水体和沉积物中多环芳烃时空分布及来源研究
孙旭
学位类型硕士
导师唐建辉
2021-05-11
培养单位中国科学院烟台海岸带研究所
学位授予单位中国科学院大学
学位授予地点中国科学院烟台海岸带研究所
学位名称理学硕士
学位专业海洋化学
关键词多环芳烃污染水平渤海垂直混合季节变化
摘要随着我国工业化和城市化水平的不断提高，能源消耗量的不断增长，多环芳烃（Polycyclic aromatic hydrocarbons, PAHs）的排放量也在不断增加。PAHs具有长距离迁移性和强亲脂性，还具有致畸、致癌、致突变等“三致”毒理效应，目前已在大气、水体、土壤、沉积物乃至生物体和人体内都有所检出。近岸海域是连接陆地和远洋的纽带，沿海城市频繁的工业和人为活动排放的污染物导致近岸海域生态环境退化，对生态系统和人类健康构成威胁。本研究以渤海海域为研究背景，以美国环保署（USEPA）优先控制的15种PAHs为研究对象，分别于2019年6月（春夏季）、8月（夏季）和11月（秋季）通过科考航次采集渤海表底层海水样品，并于2019年6月采集渤海表层沉积物样品。本文首次系统调查了PAHs在渤海水体中的空间分布特征及季节变化趋势，探究了PAHs在水体两相介质（溶解相和颗粒相）以及表层沉积物中的浓度水平、组成特征和空间分布，并简要探究了该海域PAHs的主要输入途径。研究得出的结论如下：一、渤海水体中PAHs的时空分布特征与来源：PAHs在渤海水体中的分布广泛检出，总浓度范围在3.16 - 87.9 ng/L之间；水平分布特征表现为近岸高、中部低的特点，这说明陆源输入是渤海水体PAHs最主要的来源。研究结果与国内外其他海域相比，渤海PAHs属于中等污染水平。通过估算储量发现，渤海水体中PAHs的储量远低于邻近城市PAHs的排放量。春秋季节，PAHs在渤海水体中的垂直分布没有表现出明显的浓度水平差异，这与强烈季风作用下渤海水体垂直混合均匀有关。但在夏季，渤海中部海域表层水体中的污染物浓度较高，与底层水体中PAHs浓度形成了明显差异，说明冷水团和温跃层的形成可能阻碍了水体的垂直交换，导致污染物的层化现象。季节变化上，PAHs总浓度春季（6月）>高于秋季（11月）>高于夏季(8月)。夏季浓度降低可能与PAHs高温挥发至大气中有关，同时禁渔期船舶数量的减少也可能是导致这一现象的原因。而秋季PAHs浓度增大与环境温度降低导致燃煤供暖排放有关。这说明PAHs的某些污染源有着明显的季节性特点。渤海水体中PAHs来源分析表明木材等生物质的燃烧、石油等化石燃料燃烧、工业废水和生活污水排放以及船舶溢油是主要来源。二、渤海表层沉积物中PAHs的分布特征与来源：渤海海域表层沉积物中的PAHs检出浓度在7.23 - 168 ng/g dw之间，整体上属于轻微-中等污染水平。表层沉积物中PAHs的储量估算约为226吨，表明渤海表层沉积物是PAHs蓄积的重要介质。近岸河流输入的大量泥沙可能是导致污染物在此累积的一个重要原因。表层沉积物中的PAHs浓度与TOC含量正相关，表明TOC含量对于沉积物中PAHs等有机污染物污染水平和分布特征具有重要的意义。沉积物PAHs来源解析结果与水体中相似，石油、煤炭等化石燃料和生物质燃料的燃烧源是主要的来源。PAHs作为一种非故意生产排放的持久性有毒污染物，在日常的工业生产和人类生活活动中都会不经意时产生。陆源污染是渤海PAHs的主要来源，水体和沉积物是PAHs最重要的受体。PAHs在水体中主要存在于溶解相，且以低环PAHs为主；而在表层沉积物中以高环PAHs为主。这说明在水体中水溶性较强的PAHs容易随着高温挥发和洋流移动转移到其他地区，稳定性更强的高环PAHs则容易吸附或富集在颗粒物上，最终沉降进入沉积物中，形成高浓度累积。因此，通过本研究可以进一步了解PAHs在海洋系统中的环境行为，为海洋环境中有机污染物的监测和治理工作提供参考依据。
其他摘要With the gradually improvement of industrialization and urbanization, and thesoaring increase of energy consumption, the emissions of polycyclic aromatichydrocarbons (PAHs) are also increasing. PAHs have long-distance migration potentialand show strong lipophilicity, as well as teratogenic, carcinogenic and mutagenicproperties. They have been widely detected in the atmosphere, water, soil, sediment,and even organisms and humans. The coastal sea connects the land and the ocean. Hugeamounts of pollutants are discharging into coastal sea by extensively industrial andhuman activities from coastal cities and have caused the deterioration of water qualityand have endangering the health of ecosystem and human health. Fifteen priority PAHswere analyzed in the seawater and sediment from three research cruises on the BohaiSea in June, August and November 2019, respectively. The spatial distributioncharacteristics and seasonal variations of PAHs in the seawater were investigated forthe first time in the Bohai Sea, and the phase distributions were discussed for PAHsbetween two phases (dissolved and particle phase). This paper also studied theconcentration levels, composition profiles and distribution characteristics of PAHs inthe surface sediments, and briefly analyzed the main input pathways of PAHs in theBohai Sea. The conclusions of the study are as follows:PAHs were widely detected in the seawater with a range of 3.16-87.9 ng/L.Horizontally, high levels were found in nearshore and low in the central of Bohai Sea,indicating a dominant land-based source of PAHs. Compared with other studies aroundthe world, the overall PAH levels in the Bohai Sea are at medium levels. The estimatedreserves of PAHs in the seawater are much lower than the total PAHs emissions fromneighboring cities. It is inferred that offshore waters are important environmental mediafor the migration and transformation of PAHs in the environment.In the spring and autumn, there are no obvious difference for vertical distributionof PAHs in the Bohai Sea, indicating a well-mixed water mass in the Bohai Sea underthe strong influence of the East Asia monsoon. However, relatively high concentrationsof PAHs were found in the surface water than in the bottom water in the central BohaiSea in summer. This phenomenon was caused by the formation of verticallystratifications of water masses in summer and the thermoclines have hindered thevertical exchange of water bodies. The seasonal variationas showed that totalconcentration of PAHs was higher in June than in November. The low concentrations  &"!IVof PAHs in summer may be due to the fast volatilization of PAHs into the atmosphereunder high-temperature. The decrease in the number of fishing boats during the fishingban period may also lower the PAHs concentration from fishing activities. Theincreased concentration of PAHs in autumn was related to the discrease of ambienttemperature and the emission from coal-fired heating in northern China. Sourceanalysis showed that PAHs in the seawater were mainly from the combustion ofbiomass and fossil fuels, industrial wastewater and domestic sewage, and ship oil spillsand fuel combustion.In surface sediment, concentration of PAHs was ranged from 7.23 to 168 ng/g dw,which showed a slight medium pollution level wordwidely. The estimated reserves ofPAHs in the surface sediments reached to 226 tons, which indicated that the surfacesediments are important sink of PAHs. A positive correlation was found between theconcentrations of PAHs and TOC, indicating TOC content is an important tool forassessing the pollution level and distribution characteristics of organic pollutants suchas PAHs. Source analysis showed that fossil fuels (such as petroleum and coal) andbiomass combustion are the main sources of PAHs in the surface sediments of the BohaiSea.In summary, as a kind of persistent toxic pollutants discharged from unintentionalproduction, PAHs were produced inadvertently in daily industrial and domesticactivities. Land-based pollution is the main sources of PAHs. Seawater and sedimentare the two reservoirs of PAHs in the Bohai Sea. PAHs show different scales ofvariations vertically and seasonally in the Bohai Sea. PAHs mainly exist in the dissolvedphase in water bodies with mainly low-ring congeners; while PAHs in surfacesediments they were mainly consisted of high-ring congeners. This shows that the morewater-soluble PAHs in water bodies are easily transferred to other sea areas along withhigh-temperature volatilization and ocean currents, while the more stable high-ringPAHs are easily adsorbed or concentrated on particulate matter, and finally settle intomarine sediments. Therefore, the results of this study would help us to better understandthe environmental behavior of PAHs in the marine system, and to provide a referencefor the monitoring and governance of the marine organic pollutants.
语种中文
文献类型学位论文
条目标识符http://ir.yic.ac.cnhttp://ir.yic.ac.cn/handle/133337/28842
专题中科院烟台海岸带研究所知识产出

推荐引用方式
GB/T 7714孙旭. 渤海水体和沉积物中多环芳烃时空分布及来源研究[D]. 中国科学院烟台海岸带研究所. 中国科学院大学,2021.


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