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长江流域—河口—近海环境中多环芳烃分布特征及影响因素研究

发布时间:2018-05-20 05:20

  本文选题:多环芳烃 + 沉积物 ; 参考:《南京大学》2017年硕士论文


【摘要】:流域-河口-近海系统受到陆地与海洋的共同影响,系统内存在复杂的物理化学过程,是一个极其脆弱的生态系统。此外,社会经济的发展使得该区域还面临巨大的人类活动压力,大量的污染物被排放到该区域,使得系统内的生态和环境受到了极大的破坏。因此,对于该系统内污染物环境行为方面的研究变得十分重要和紧迫。本研究以长江流域-河口-近海环境作为典型研究区域,分析系统内持久性有机污染物——多环芳烃(Polycyclic aromatic hydrocarbons,PAHs)的赋存情况,揭示系统内PAHs的来源、分布和组成情况,深入探究该系统内PAHs环境行为的可能性影响因素。长江全流域表层水体中溶解相PAHs(DPAHs)的浓度范围为17.7ng/L~110 ng/L,平均值为42.6ng/L。整体看来,流域由上游到下游PAHs具有明显的累积递增的趋势,但是三峡水库出现明显低值,其对于流域DPAHs具有明显的调节作用。这可能是由于三峡水库的蓄水功能对于PAHs具有一定的冲淡效应。流域水体中主要以低环PAHs(2-3环)为主,其含量约为水体中总DPAHs含量的67%。源解析结果显示,流域水体中PAHs主要有四种来源:生物质燃料和煤炭燃烧混合源,石油类物质泄漏源,交通混合源(柴油和汽油发动机)和焦炭源,各污染源的贡献率分别为40.1%、19.6%、17.5%和22.8%。长江中下游流域水体中悬浮颗粒相PAHs(PPAHs)的浓度分布范围为595.91 ng/g—2473.74ng/g(干重),平均浓度约为1369.92ng/g。两湖(洞庭湖和鄱阳湖)出现浓度高值,自两湖往下游PPAHs浓度同样出现累积递增趋势。两湖由于自身的汇水功能,且流域均属于经济快速发展地区,因此,其对PAHs具有一定的汇聚功能。下游河段(自九江站至常熟站)水体中PPAHs含量表现出较为明显的累积效应,尤其是在镇江站出现了最高值。而在常熟站监测到的PPAHs浓度较镇江站和南京站出现了明显偏低的现象,可能是由于该站位靠近河口地区受到河口潮流的影响,对该站位水体中PPAHs具有一定的冲淡效应。中下游河段PPAHs主要是以高分子量为主(4-6环),占据了 PAHs总量的84%以上。长江口及其邻近海域表层沉积物中PAHs的总浓度范围处于26.6-621.6 ng/g(干重)之间,平均浓度约为158.2ng/g。总体看来,PAHs在空间上的分布具有很大的差异性,可将其分为两个部分:长江口区域和杭州湾南部的浙江近岸海域,浓度的高值区出现在杭州湾外的舟山群岛以东海域。长江口区域表层沉积物中PAHs的浓度范围处于27.2-400.9ng/g,平均浓度大约为137.7ng/g;而邻近浙江近岸海域表层沉积物中PAHs的浓度处于27.3-621.6 ng/g,平均浓度约为175.8 ng/g。空间上,PAHs的浓度分布具有由北往南逐渐升高的趋势,这与研究区沉积物粒度粒度的变化趋势较为一致。此外,PAHs的浓度还存在由河口向外海先逐渐减小后逐渐变大的趋势,这可能受河口地区复杂的水动力条件的影响。长江泥沙进入河口后,由于咸淡水混合和潮流的顶托作用在河口地区发生堆积。此外,河口区繁忙的航运活动产生大量的PAHs也在河口区发生沉降,使得河口区PAHs出现高值区。然而,河口地区强劲的动力尤其是长江冲淡水使得大量的PAHs被带到较远的口外地区,在搬运过程中随着沉积物一起发生分选和堆积,最终大量的PAHs与细颗粒沉积物在长江口泥质区发生堆积,使得该区域PAHs出现浓度高值。整个研究区中高分子量PAHs的浓度范围约在12.9-436.3 ng/g,大约占据了 PAHs总浓度的30.3%-89%。研究区内PAHs浓度与沉积物粒度和有机碳含量的分布特征具有一定的相似性,然而,相关性分析结果表明三者之间的相关性并不明显。这可能是由于PAHs的吸附行为是一个复杂的过程,沉积物粒度和有机碳对其均有吸附偏好,且该区域强劲的动力条件也会使得PAHs发生再分配。因此,复杂的控制因素使得三者之间的相关关系变得模糊。源解析结果显示该研究区PAHs主要来自于煤炭燃烧源,石油泄漏源,生物质燃烧源和交通源;4个污染源的贡献率分别为:40.9%,23.9%,23.6%和11.5%。此外,本研究试图估算研究区50000 km2范围内PAHs的沉降通量,年沉降通量约为107.8 t。
[Abstract]:The river basin, estuarine and offshore system are affected by the land and the ocean, and the system is stored in complex physical and chemical processes. It is an extremely fragile ecosystem. In addition, the development of the society and economy makes the region still face enormous human activity pressure. A large number of pollutants are placed in the region, making the ecosystem and environment in the system affected. Therefore, it is very important and urgent to study the environmental behavior of pollutants in the system. This study takes the Yangtze River Basin - estuarine near sea environment as a typical study area to analyze the occurrence of persistent organic pollutants, polycyclic aromatic hydrocarbons (Polycyclic aromatic hydrocarbons, PAHs) in the system, and reveal the occurrence of the system. The source, distribution and composition of PAHs in the system, the possible influence factors of the PAHs environmental behavior in the system are deeply explored. The concentration range of dissolved phase PAHs (DPAHs) in the surface water body of the Yangtze River Basin is 17.7ng/L to 110 ng/L, with the average value of 42.6ng/L. as a whole, and the PAHs in the basin from upstream to downstream has a obvious cumulative increasing trend. However, the Three Gorges reservoir has obvious low value, which has obvious regulating effect on the DPAHs of the basin. This may be due to the water storage function of the Three Gorges reservoir has a certain dilute effect on the PAHs. The main body of the basin is low ring PAHs (2-3 ring), and its content is about the 67%. source of the total DPAHs content in the water body. There are four main sources of PAHs: biomass fuel and coal combustion mixing source, petroleum substance leakage source, traffic mixing source (diesel and gasoline engine) and coke source, and the contribution rate of each pollution source is 40.1%, 19.6%, 17.5% and 22.8%. in the middle and lower reaches of the Yangtze River Basin, the concentration distribution of suspended particulate phase PAHs (PPAHs) is 595.91 ng/g - 2 473.74ng/g (dry weight), the average concentration is about 1369.92ng/g. and two lakes (Dongting Lake and Poyang Lake) with high concentration. The concentration of PPAHs also increases gradually from two lakes. The two lakes have their own catchment function, and the basin all belong to the region of rapid economic development. Because of this, they have a certain converging function to PAHs. The downstream reaches (from nine). The PPAHs content in the water body of the river station to Changshu station shows a more obvious cumulative effect, especially at the ZhenJiang Railway Station, and the PPAHs concentration observed at the station in Changshu is obviously lower than that of ZhenJiang Railway Station as well as the influence of the estuarine tidal current in the estuary area. The middle and lower reaches of PPAHs have a certain dilution effect. The main PPAHs in the middle and lower reaches of the river is mainly high molecular weight (4-6 ring), occupying more than 84% of the total amount of PAHs. The total concentration of PAHs in the surface sediments of the Yangtze Estuary and its adjacent sea area is between 26.6-621.6 ng/g (dry weight). The average concentration is about 158.2ng/g. and PAHs in space distribution. It can be divided into two parts: the Yangtze Estuary region and the Zhejiang coastal waters of the southern Hangzhou Bay, the high concentration area appears in the east of the Zhoushan archipelago outside the Hangzhou Bay. The concentration range of PAHs in the surface sediments of the Yangtze Estuary is 27.2-400.9ng/g, with an average concentration of about 137.7ng/g; and near the near Zhejiang. The concentration of PAHs in the surface sediments of the shore is 27.3-621.6 ng/g, the average concentration is about 175.8 ng/g., and the concentration distribution of PAHs is gradually rising from the north to the south, which is in accordance with the grain size of the sediments in the study area. In addition, the concentration of PAHs also changes gradually from the mouth of the estuary to the sea first and then gradually change. The large trend is likely to be affected by the complex hydrodynamic conditions in the estuarine area. As the sediment of the Yangtze River enters the estuary, the mixture of salt and fresh water and the roof of the tidal current accumulate in the estuarine area. In addition, a large number of PAHs in the estuarine busy shipping activities also settle in the estuarine area, making the estuarine area PAHs high value area. However, however, The strong power of the estuarine area, especially the Changjiang River fresh water, makes a large number of PAHs to be taken to the far outside of the mouth area. In the process of transportation, the sediment is sorted and accumulated along with the sediments. In the end, a large number of PAHs and fine sediments are accumulated in the muddy area of the Yangtze Estuary. The high concentration of PAHs in the region is high. The high scores in the whole study area are high. The concentration range of PAHs is about 12.9-436.3 ng/g, and the concentration of PAHs in the 30.3%-89%. research area that occupies the total PAHs concentration is similar to the distribution characteristics of the grain size and organic carbon content of the sediments. However, the correlation analysis shows that the correlation between the three is not obvious. This may be due to the adsorption behavior of PAHs. A complex process, sediment granularity and organic carbon have adsorption preferences, and the strong dynamic conditions in the region also make PAHs redistribute. Therefore, complex control factors make the correlation between the three become blurred. The source analysis results show that the research area PAHs mainly comes from the coal combustion source, the oil leakage source, Biomass combustion source and traffic source; the contribution rate of the 4 sources are 40.9%, 23.9%, 23.6% and 11.5%. respectively. This study attempts to estimate the PAHs settlement flux in the range of 50000 km2 in the study area, and the annual settlement flux is about 107.8 t.
【学位授予单位】:南京大学
【学位级别】:硕士
【学位授予年份】:2017
【分类号】:X592

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