【作者】 曹治国；

【导师】 刘静玲；

【作者基本信息】 北京师范大学 ， 环境科学， 2010， 硕士

【摘要】 作为持久性有机污染物（persistent organic pollutants, POPs）中的一种,多环芳烃（polycyclic aromatic hydrocarbons, PAHs）具有致癌、致畸、致突变的“三致”效应,PAHs的环境行为,污染来源,环境风险是近年来研究的热点。PAHs对河流的污染严重威胁着水环境健康。由于人为胁迫造成的环境压力在全国各大流域中居于首位,加上海河流域降水量少,“有河皆干有水皆污”,已成为海河流域目前水环境最突出的特征。但尽管海河流域多年来在全国八大流域中一直污染最为严重,到目前为止,海河流域持久性有机污染物的污染方面的研究还仅仅局限在北京、天津地区。因此开展对于海河流域其他河流POPs污染的研究,具有科学意义和现实意义。本文以水环境状况相对较好的滦河和水污染非常严重的漳卫南运河为研究对象,对两条河流中PAHs的污染分布、污染来源以及生态风险进行了分析研究。在春汛期间,研究了滦河流域USEPA优先控制的16种PAHs的分布和来源。共布设了11个采样点,在2008年4月,采集了11个地表水水样,11个表层沉积物样品。地表水中PAHs的浓度范围为9.8 ng·L^–1至310 ng·L^–1,沉积物中PAHs的浓度为未检出（not detected, ND）至478 ng·g–1。结果表明,农村地区采样点（5个） PAHs的平均浓度低于城市地区采样点（6个） PAHs的平均浓度,可以把农村地区PAHs的含量当作背景值,把城市地区PAHs的含量当作该地区污染的最高值。地表水中PAHs的组成以3- （38.4%）,4-环（60.7%）为主,而沉积物中PAHs的组成以3- （27.4%）,4- （38.5%）,5-环（15.8%）为主,由此可以看出3-,4-环PAHs是滦河流域PAHs污染的主要成分,高环PAHs更趋向于富集在沉积物中。运用了分子比值模型对PAHs的来源进行了辨析。结果表明,化石燃料、木材的燃烧是滦河流域PAHs污染的主要来源,在瀑河口和大黑汀两个采样点,也在一定程度上受到石油污染的影响。在枯水季节,研究了滦河流域USEPA优先控制的16种PAHs的分布特征,污染来源和生态风险。为了进一步做深入研究,在丰水季节研究的基础上,把采样点增加到了20个,并且增加了对水体潜在污染源——岸边土壤中PAHs的研究。地表水、沉积物、岸边土壤中PAHs的含量分别是:37.3-234 ng·L-1,20.9-287 ng·g-1,36.9-378 ng·g-1,由此可见,沉积物种PAHs的含量略高于岸边土壤。对PAHs组成结构的分析表明,2-,3-环PAHs是地表水中PAHs的主要组成成分,4-,5-,6-环PAHs是沉积物和岸边土壤中PAHs的主要成分,显示出沉积物和岸边土壤中PAHs的组成特征相似,而与地表水中PAHs的组成大不相同,高环PAHs倾向于富集在固体介质中,这与丰水季节的研究结果基本一致。从空间分布特征上看,污染比较严重的样点主要集中在中下游地区,这个分布特征与滦河流域城市的分布特征一致。农村地区和河口地区PAHs的污染相对比较轻,这种河口污染较轻的现象,与国内其它河流如长江、珠江、海河河口地区污染严重的特点完全不同。干流、支流的污染程度并没有大的差别。从结构上看,不同采样点地表水中PAHs呈现出相似的组成特征,但农村地区和城市地区沉积物、岸边土壤中PAHs呈现不同的组成特征,由于农村地区和城市地区PAHs污染来源不同,并且水体中不同环的PAHs在地表水和沉积物之间进行了分配,所以岸边土壤更能准确的反映PAHs的原始来源状况。在毒性当量因子（toxic equivalency factors, TEFs）和风险商值方法（risk quotient, RQ）的基础上,本研究提出了新的生态风险评价方法,能更精敏、准确、全面的评价PAHs的生态风险,同时提出了新的生态风险等级划分标准。结果表明,滦河流域水体PAHs总体呈现低风险水平,只有S9 （承德市）处于中等风险状态。虽然PAHs环数越高毒性越强,但研究表明,滦河流域中低环PAHs呈现出的生态风险高于高环PAHs,这主要是由于滦河流域中低环PAHs在PAHs组成中占主要成分,高环PAHs污染并不严重。同时,水体PAHs呈现的生态风险高于沉积物和岸边土壤,所以地表水PAHs的污染首先应引起关注。本研究表明,岸边土壤PAHs能更好的反映PAHs的原始污染来源,所以利用岸边土壤PAHs数据,分别利用分子比值模型和主成份分析法（principal component analysis, PCA）与多元线性回归（multiple linear regression, MLR）相结合的方法对滦河流域PAHs进行源解析。结果表明,滦河流域PAHs的污染呈现以化石燃料和生物燃料燃烧为主要来源的特征。研究了漳卫南运河流域地表水中USEPA16种优先控制的PAHs的分布特征、污染来源和生态风险。4月、10月地表水中PAHs总量分别在31.7-74.5 ng·L-1、45.3-99.0 ng·L-1之间,与国内外其他河流相比,整体处于较低污染水平,同时也要低于滦河流域地表水PAHs的污染浓度。四女寺污染最严重,河口污染最轻。这个空间分布特征与滦河流域相同。整体上看,10月份PAHs浓度比4月份略有增加。从16种PAHs单体的组成来看,漳卫南运河PAHs以2-、3-、4-环为主。用本研究提出的生态风险评价方法进行生态风险评价的结果表明,4、10两个月份最高风险商值（RQ∑PAHs（MPCs））值均为0,最低风险商值（RQ∑PAHs（NCs））值分别在34.7-111.0,20.4-88.8之间,平均值分别为58.4,49.8。∑PAHs在7个采样点均呈现低生态风险,且4月份生态风险略高于10月份,风险最高值出现在4月份的四女寺,最低值出现在10月份的河口。源解析结果显示,漳卫南运河流域PAHs的含量和分布主要受煤炭及薪柴燃烧的影响,四女寺和河口地区受到一定的石油污染的影响。滦河流域和漳卫南运河流域PAHs的污染呈现出一些类似的特征,比如PAHs浓度水平与国内外其他流域比起来处于相对较低水平;PAHs组成以中低环PAHs为主;从空间分布来看,河口污染较轻,中下游地区较重;两个流域PAHs的污染都主要来自于化石燃料和生物燃料的燃烧,但同时也受到一定程度石油来源PAHs的污染。同时,通过对比滦河、漳卫南运河、天津海河也发现,常规污染非常严重的漳卫南运河地表水PAHs污染要比常规污染相对较轻的滦河地表水PAHs浓度要低,天津海河无论常规污染和PAHs污染都非常严重。这初步说明,不同种类的污染物具有不同的分布特征和迁移转化机理,不同类型的污染在同一流域并非相伴发生;城市的分布对PAHs的分布有决定性的影响;对流域水体进行污染水平评价的同时要指明参评的污染物种类,同时应尽可能对各个类型的污染物进行全面的评价。更多还原

【Abstract】 Polycyclic aromatic hydrocarbons （PAHs） are an environmental concern due to their carcinogenicity, mutagenicity and toxicity. PAHs’behavior, transport, fate, sources and environmental risk to ecological systems have been extensively studied. The concentration and distribution of PAHs in natural water has become a research focus in the world. In China, the Hai River Basin is the most polluted among the eight big river basins. The proverb, "Almost all rivers were dry, almost all water in rivers was polluted." is the most vivid portrayal of the water environment of the Hai River Basin. However, according to recent literatures, currently study on PAHs of the Hai River Basin mainly focused on the areas around Beijing and Tianjin and research about PAHs in other areas could only be seen in a very few reports. Based on these reasons, the Luan River which was relatively less polluted and the Zhangweinan River which was most polluted among all the rivers in the Hai River Basin were chosen as the study objects.In wet season, the distribution of PAHs was studied by determining the levels of 16 PAHs in water and sediment samples of the Luan River; a very important drinking water source for Tianjin and Tangshan in Hebei province, China. A total of 11 water samples, 11 sediment samples were collected during April 2008. The total PAHs concentrations in water varied from 9.8 to 310 ng·L^–1, and those in surficial sediments ranged from not detected （ND） to 478 ng·g–1 dry weight. The results showed that the upstream, downstream areas were less polluted and high polluted sites concentrated in the middle reaches of the river. The concentrations of PAHs in rural areas （5 sites） which could be considered as the‘background’levels were lower than those near city zones （6 sites） which could be regarded as the‘maximum’values. The PAHs were dominated by 3- （38.4%）, 4-ring （60.7%） components in water samples and by 3- （27.4%）, 4- （38.5%） and 5-ring （15.8%） compounds in sediments. High molecular weight PAHs were inclined to be absorbed into sediments. The 3-, 4-ring PAHs were the most common components in the Luan River. The molecular indices and the distribution of different rings were used to infer the sources of PAHs, and the results suggested that anthropogenic heavy fuel combustion was likely to be the main source. And petroleum PAHs had a high contribution to PAHs pollution at Baohekou and Daheiting.In dry season, the distribution and source of 16 polycyclic aromatic hydrocarbons （PAHs） in the Luan River, China, has been investigated.∑PAHs levels ranged from 37.3 to 234 ng·L^–1 in water, from 20.9 to 287 ng·g-1 in sediment and from 36.9 to 378 ng·g-1 in bank soil, respectively, showing the mean concentration of PAHs in bank soil was a little higher than that in sediment. The compositional profile of PAHs revealed that low molecular （2- to 3-ring） weight PAHs were predominant in dissolved phase, and 4-ring and higher molecular （5- to 6-ring） weight PAHs were abundant in bank soil and sediment, showing different composition profile characteristics in different medias. The spatial distribution of PAHs indicated that the most polluted sites all gathered in the middle and lower reaches of the region, which was in accordance with the distribution pattern of cities in the Luan River Basin, and the rural areas and estuary were much less polluted. There was no significant difference between the main river and it’s tributaries on PAHs contamination in water, sediment and bank soil. PAHs in water from different sites showed familiar composition profiles, while PAHs in sediment and bank soil from rural areas and city zones presented different composition profiles. A method based on toxic equivalency factors （TEFs） and risk quotient （RQ） which can be used to access the ecosystem risk of∑PAHs sensitively and accurately was invented and a new ecosystem risk classification of∑PAHs was suggested. The results indicated that the PAHs in aquatic environment of the Luan River resulted in low ecosystem risk and at S9 the ecosystem risk of PAHs in water was moderate. Low and moderate molecular PAHs presented much more ecosystem risk than high molecular PAHs in the Luan River Basin and the mean ecosystem risk in water was higher than that in sediment and bank soil. As it was concluded that the PAHs in bank soil could better reflect the original source of PAHs, the PAHs data of bank soil was used for PAHs source identification. Both diagnostic ratios of selected PAHs and principal component analysis （PCA） with multiple linear regression （MLR） analysis were studied, suggesting mixed sources of fossil fuels combustion and biomass combustion deriving PAHs in the Luan River Basin.In the Zhangweinan River, the distribution and sources of 16 priority dominated polycyclic aromatic hydrocarbons （PAHs） in surface water were investigated. The total concentrations of PAHs ranged from 31.7 to 74.5ng·L^–1 in April with the average value of 56.3 ng·L^–1, from 45.3 to 99.0 ng·L^–1 in October with the average value of 62.9ng·L^–1, which is lower when compared with the PAHs concentration in other rivers in the world. The spatial distribution of PAHs showed that Sinvsi was heavily polluted site and the Estuary was slightly polluted compared to other sampling sites. The temporal distribution showed that concentrations of PAHs in October were higher than those in April. The PAHs were dominated by 2-, 3-, 4-ring components in water samples in April （25.1%, 48.7% and 19.1%） and October （29.9%, 45.5% and 22.9%）. A new ecological risk assessment method was introduced in this study. The values of RQ∑PAHs（MPCs） at all sites were 0 and the values of RQ∑PAHs（NCs） ranged from 34.7 to 111.0 in April with the mean value of 58.4 and from 20.4 to 88.8 in October with the mean value of 49.8, respectively. The levels of ecological risk were generally low, and the risk in April was slightly higher than that in October. The ecological risk was the highest at Sinvsi in April and was the lowest at the estuary in October. The molecular indices and isomer pair ratios were used to infer the sources of PAHs, and the results suggested that anthropogenic heavy fuel combustion might be the main source. And at Sinvsi and Estuary, petroleum had a high contribution to PAHs pollution.Contrast of the two rivers showed that PAHs pollution characteristics such as levels, composition, distribution, ecosystem risk and sources in the two rivers were similar in some aspects. When compared with the Hai River in Tianjin, with PAHs and common pollutants considered, pollution status of the three rivers showed different characteristics and it was preliminarily concluded that different pollutants showed different distribution and transformation features and different kinds of rivers were polluted with different compositions of pollutants. KEY WORDS: polycyclic aromatic hydrocarbons （PAHs）; the Luan River; the Zhangweinan更多还原