【作者】 夏重欢；

【导师】 谢周清； 林群声；

【作者基本信息】 中国科学技术大学 ， 环境科学， 2011， 博士

【摘要】 在过去的若干年里,我国面临着海洋污染这个环境问题的巨大挑战。由于我国社会经济的高速发展,以及许多工厂、发电厂、污水处理系统的排污条件不符合国家环境法规,我国的环境污染情况日益严重。大量的污染物从陆地涌入近海,加剧了我国近海海洋生态系统的恶化。近几年,污染物在海洋生物体内的积累效应受到了愈来愈多的关注,因为这种效应不仅会危及生物体本身的生命,而且考虑到食用海产品是人类暴露环境污染物的重要途径,这种效应最终将可能威胁到人类的健康。为了回应这一关注,本研究旨在了解不同种类的海洋鱼类体内各种有机和无机污染物的现有水平。与此同时,初步评估暴露这些污染物对普通民众的健康造成的潜在不利影响。在食物链中,鱼类处在较高的营养级,从而增加了其在水生环境中对污染物的暴露水平,因而体内含有高浓度的污染物。所以,除了具有商业价值和可供人类消费外,鱼类还是良好的环境污染生物指示物。在全球范围内,许多研究已经报道了海鱼体内含有高浓度的环境污染物,其中包括有机氯化合物,溴代阻燃剂(例如多溴联苯醚和六溴环十二烷)和金属元素,并指出它们可能对人类健康产生威胁。本研究于2008年在我国东部九个沿海城市(大连、天津、青岛、上海、舟山、温州、福州、泉州和厦门)获取了两种近海海鱼,分别是大黄鱼(Pseudosciaena crocea)和银鲳鱼(Pampus argenteus),并对所有样品进行了一系列有机氯农药(OCPs),多氯联苯(PCBs),多溴联苯醚(PBDEs),六溴环十二烷(HBCDs)以及若干痕量元素的检测。此外,对获取的另一种海鱼,小黄鱼(Pseudosciaena polyactis),也分析了痕量元素。主要研究结果摘要如下：在被检测的所有有机氯农药中,滴滴涕(DDTs),六六六(HCHs),六氯苯(HCB)和氯丹类化合物在所有海鱼样品中均有检出,浓度相对较高,是最主要的残留农药。特别是DDTs的含量,尽管与我国之前监测的数据相比已有明显的降低趋势,但较其他国家和地区所报道的结果约高了一个数量级,表明我国沿海区域已进入全球滴滴涕污染最严重地区的行列之中。通过对DDTs的残留成分分析,推断DDTs的主要来源是历史上的过量应用,而小部分的新源可能来自于三氯杀螨醇和含有DDT的渔船用防污油漆的使用。HCHs浓度较之前的数据亦有大幅度降低,但是高比例的γ-HCH说明了林丹的近期使用。主成分分析(PCA)显示在所研究的几个地区中,大连附近海域是OCPs污染最严重的区域。癌症和非癌症风险评估预示,OCPs致使食鱼消费者患癌症的风险很高,尤其是DDTs,而产生非癌症类疾患的可能性不是很大。建议每日膳食消费大黄鱼不得超过9g,每月不要多于1餐,而每日消费鲳鱼不得超过67g,每月不要多于9餐。本研究检测了三十六种PCB的同系物,其中十一种属于类二嗯英PCB。结果显示,PCBs的总浓度处于全球水平的低端,主要与我国使用PCBs时间短,用量少有关。在各PCB同系物中,PCB 18,29,52,66,101,104,138,153,180和194是主要组成成分。类二嗯英PCBs (dl-PCBs)的总浓度与PCBs的总浓度呈现显著的正相关性,表明PCBs的总浓度可以解释80%左右dl-PCBs勺总浓度的变化。相比银鲳鱼,大黄鱼的生物蓄积性较强,体内PCBs浓度更高,这可能是由它们不同的摄食习惯和生活习性引起的。不同城市间的PCBs浓度水平不存在显著性差异,PCA分析显示PCBs在各个采样点的来源类似,大连和温州地区可能存在其他的源。风险评估结果显示,癌症风险值大于10-6,说明消费者由于暴露类二噁英PCBs而罹患癌症的风险超过每百万人出现一个的概率。相反,非癌症危害商数都小于1,即非癌症效应不明显。PBDEs在所有样品中均有检出,但是浓度值相对很低,尤其低于大量使用五溴联苯醚的北美地区。从地理分布上看,PBDEs最高值出现在厦门。大黄鱼体内PBDEs的浓度水平显著高于银鲳鱼,这与摄食习性等因素有关。从全球其他地区海鱼体内检测得到的常见的PBDE同系物分布模式为BDE47> BDE99, BDE100>BDE153, BDE154。与此相比,本研究得出的结果有些不同。本研究中BDE47和BDE154是最主要的同系物,约占PBDEs总含量的60%以上。BDE154比例相对较高可能是由高溴化的PBDE同系物降解而致,例如BDE183和BDE209。由食鱼而估算得到的PBDEs日均摄入量不到产生作用剂量的万分之一,表明由PBDEs产生的潜在健康风险是可以忽略的。HBCDs在所有样品中均有检出,反映了我国沿岸地区环境中HBCDs的广泛存在。HBCD的总浓度相对很低,远远低于密集使用HBCDs的欧洲地区。在被检测的3种HBCD同分异构体(α-,β-和γ-HBCD)中,α异构体呈现出非常显著的优势性,体现了它较强的生物蓄积性。空间分布上,HBCDs最高值出现在北方地区的大连,最低值出现在温州。通过食用鱼类估算得到的HBCDs日均摄入量远低于产生效应浓度,说明针对HBCDs而言,食用大黄鱼和银鲳鱼是安全的。本研究也对甲基汞(MeHg)和其他痕量元素(总汞、硒、镉、钻、铬、铜、铁、锰、镍、铅、锶和锌)进行了分析。汞、铁和镍的浓度属于全球范围的低值,其他元素的结果与全球浓度值范围一致。除了16%的样品中镉的含量超过了欧洲委员会法规推荐的标准值,其他元素值均低于国际标准浓度。从人体健康的角度来看,这些元素的日均摄入量没有超过美国环保署建立的参考剂量浓度,因此危害商数均小于1,说明它们不会对消费者的健康产生显著影响。总体而言,这项研究扩充了目前我国海鱼体内各种环境污染物浓度水平的信息量,并提供了人类通过食用鱼类而暴露这些污染物的初步健康风险评估。尽管痕量金属元素和溴代阻燃剂造成的风险不显著,但是对这几类污染物在近海海洋生态系统中的连续监测是非常有必要的。此外,建议相关部门除了提供关于鱼类消费量的建议,必须立即采取一些措施来降低环境中DDTs的浓度。更多还原

【Abstract】 Marine pollution has posed a grave challenge to China over the past years. Due to China’s double-figure annual economic growth and the failure of factories, power plants., sewage systems and other sources to obey environmental regulations, pollution in China has risen sharply. Large amounts of contaminants are filtering from the land into the sea, which caused the coastal marine ecosystem to get worse. In recent years, global public concern over accumulation of pollutants in marine organisms has increased because it would not only threaten life themselves, but may also lead to adverse health effects to population considering seafood consumption is an important route of human exposure to environmental contaminants.In response to this concern, the present study aimed to determine the current levels of various organic and inorganic pollutants in different species of marine fish. At the same time, the potential health risks derived from the exposure to these contaminants for the general population were also assessed.As well as the commercial values and human consumption, fish have been established as good bio-indicators of environmental pollution because their tissues often contain high contaminant concentrations due to their relatively high position in the food chain and consequent elevated exposure levels in the aquatic environment. Many investigations have reported high concentrations of environmental contaminants including a suit of organochlorine compounds, brominated flame retardants (e.g. polybrominated diphenyl ethers and hexabromocyclododecanes) and metals in marine fish all over the world, and suggested that they may pose a health risk to human body.In this work, two species of marine fish, namely large yellow croaker (Pseudosciaena crocea) and sliver pomfret (Pampus argenteus) collected from nine coastal cities of eastern China in 2008 were analyzed for a series of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs) and a number of trace elements. Additional fish samples namely small yellow croaker(Pseudosciaena polyactis) were also determined for the trace elements.Among the OCPs, dichlorodiphenyltrichloroethane and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB) and chlordane compounds were the predominant and ubiquitous residues. In particular, the concentrations of DDTs were one order of magnitude greater than those from other countries, indicating that the coastal regions of China probably are among the most DDT-polluted areas in the world, although there was a decreasing trend of DDTs by comparing the results of previous studies in the past. The composition of DDTs revealed that the main source of DDTs was due to the heavy historical agricultural and public health usage, and a small proportion of fresh input from the use of dicofol and DDT-containing antifouling paint was possible. While, the high proportion of y-HCH in Chinese coastal environment suggested the continuous use of lindane. The result of principal component analysis (PCA) showed the coast of Dalian was the most heavily polluted area by OCP compounds among the locations investigated in this study. Cancer and noncancer risk assessments suggested a lifetime cancer risk is a possibility, especially from DDTs, while through intake of these pollutants by only fish consumption did probably not cause noncarcinogenic effects in human body. The calculated daily and meal consumption limits were 9g/day and 1 meal/month for croakers, and 67g/day and 9 meals/month for pomfrets, respectively.Thirty-six congener-specific PCBs were determined, in which,11 congeners are dioxin-like PCBs. The total PCB concentrations of the present study were at the low end of the worldwide figures, which may related to the fact of less usage and shorter consumption history of PCBs in China. For individual PCB congener, PCB 18,29, 52,66,101,104,138,153,180 and 194 were the major constituents. Regression analysis showed a strong positive correlation between total dioxin-like PCBs and total PCB concentrations, and that total PCB levels explain 80% variability in dioxin-like PCBs concentrations. Large yellow croakers have a greater tendency to bioaccumulate PCBs than pomfrets, which may be attributed to their different feeding and living habits. No significant difference in total PCB levels among the cities was observed, and the principal component analysis (PCA) regarding PCB profiles indicates that PCB pollutions came from similar sources in the sampling areas and there may be other different PCB sources in Dalian and Wenzhou. The calculated carcinogenic risks (CRs) were greater than 10-6, suggesting that daily exposure to dioxin-like PCBs via fish consumption had a lifetime cancer risk of greater than one in one million. In contrast, the hazard quotients (HQs) of noncancer risks were all less than unity.Although PBDEs were detected in all of the samples, the concentrations were relatively lower than other regions of the world, especially North America where Penta-BDE was extensively used. Geographically, the highest concentration of PBDEs was found in Xiamen, and the PBDE levels in yellow croakers were significantly higher than those in pomfrets in most of the selected cities, a pattern which may be related to the different feeding habits of the two species. The congener profiles of PBDEs were found to be different from the commonly detected pattern in fishes from other regions of the world (i.e., BDE47> BDE99, BDE100>BDE153, BDE154). BDE47 and BDE154 were the predominant congeners in both species, accounting for more than 60% of the total PBDE concentrations. The reasons for the relatively high proportion of BDE154 may be due to the debromination of higher brominated congeners such as BDE183 and BDE209 by these two species. Estimated daily intakes of PBDEs via fish consumption for the Chinese population were 10,000 times lower than the effect level, indicating the potential health risk caused by PBDEs via fish consumption could be neglected.HBCDs were detectable in all samples analyzed, indicating ubiquitous contamination of these compounds in the Chinese coastal environment. The total HBCD concentrations were relatively lower than other regions of the world, especially Europe, where HBCDs are intensively used. Among the three individual HBCD isomers (α-,β-andγ-HBCD) in all fish samples, the a-isomer showed a remarkable predominance, indicating its higher bioaccumulative potential. Geographically, the highest HBCD level present in fish was found in Dalian in northern China, and the lowest occurred in Wenzhou. Estimated daily intakes of HBCDs via fish consumption for the Chinese population were were much lower than the effect levels, suggesting that large yellow croakers and pomfrets were safe to eat according to HBCDs.Methylmercury and trace elements (total mercury, selenium, cadmium, cobalt, chromium, copper, iron, manganese, nickel, lead, strontium and zinc) were also examined. The levels of mercury, iron and nickel were at the low end of the global range, while the results of other elements are globally within the same range of concentrations. Except for cadmium levels in 16% of the samples higher than criterion recommended by the European Commission Regulation, the concentrations of other metals were well below the international standards. From the human health point of view, the estimated daily intake of these metals did not exceed the reference dose established by US EPA, hence the hazard quotients (HQs) were all less than one, indicating a situation of no risk for the consumer.Overall, this study expanded current knowledge of various contaminants levels in marine fish from China and provided a preliminary health risk of these pollutants to human consumers via dietary fish consumption in Chinese coastal cities. Although the risks by trace metals and BFRs were not notable, continuous monitoring of these and other pollutants in the coastal marine ecosystem are remarkably advisable. Moreover, some actions need to be taken to reduce the environmental levels of DDTs besides giving advisory consumption recommendations.更多还原