滦河流域多环芳烃的污染特征、风险评价与来源辨析

在滦河上、中、下游和河口地区布设了15个采样点,对滦河流域的河水和表层沉积物中多环芳烃(PAHs)进行了分析.结果表明,水中PAHs总量为9.8～310ng.L-1,表层沉积物中PAHs总量最高达478ng.g-1.城市地区河段中PAHs的浓度高于农村河段中PAHs的浓度,河口地区相对中游地区污染较轻.就组成特征而言,水中PAHs以3环(40.9%)、4环(56.2%)为主,表层沉积物中PAHs以3环(30.0%)、4环(39.3%)、5环(15.8%)为主.总的来讲,3环、4环PAHs是滦河流域PAHs最主要的成分.地表水健康风险评价结果显示,韩家营、瀑河口两个采样点苯并a]芘(BaP)毒性当量值(EBaP)分别为11.8、11.4ng.L-1,超出中国国家环境保护部(CEPA)制定的EBaP=2.8ng.L-1的国家标准,存在不利的健康风险.表层沉积物生态风险评价结果显示,韩家营、上板城、乌龙矶地区的PAHs可能存在着对生物的潜在危害,剩余研究区域不存在生态风险.滦河水和表层沉积物PAHs主要表现为以草、木柴和煤燃烧来源为主的特征,部分样点存在燃油与木柴、煤燃烧的混合来源特征.瀑河口、大黑汀受石油源污染影响明显.

Pollution characteristics,risk assessment and source apportionment of polycyclic aromatic hydrocarbons (PAHs) in sediments and water of the Luan River,China

The distribution of polycyclic aromatic hydrocarbons (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, China. A total of 15 water samples and 15 sediment samples were collected during April 2008. The total PAH concentrations in the water varied from 9.8 to 310 ng·L-1, and those in surficial sediments ranged from the detection limit to 478 ng·g-1 dry weight. The results showed that the concentrations of PAHs in rural areas were lower than those near city zones. The estuary areas were less polluted than the middle reaches of the river. The PAHs were dominated by 3-(40.9%) and 4-ring (56.2%) components in water samples and by 3-(30.0%), 4-(39.3%), and 5-ring (15.8%) compounds in sediments. The 3- and 4-ring PAHs were the most common components in the Luan River. The toxic equivalency factors (TEFs) were used to calculate benzoa]pyrene equivalents (EBaP) for water samples. The values in most stations were much lower than the Chinese Environmental Protection Agency (CEPA) guidelines for drinking water,(2.8 ng·L-1) except Hanjiaying (11.8 ng·L-1) and Baohekou (11.4 ng·L-1). Overall, the surface water resources showed some carcinogenic potential. The result of ecological risk assessment indicated that high potential ecological risk of PAHs was not found in sediments of the Luan River, but potential harmful effects on creatures might exist in Hanjiaying, Shangbancheng and Wulongji. The molecular indices and isomer pair ratios were used to infer the sources of PAHs, and the results suggested that anthropogenic heavy fuel combustion was likely to be the main source. Petroleum PAHs also made a major contribution to PAH pollution at Baohekou and Daheiting.