三峡库区重庆段重点水域沉积物多环芳烃的污染特征及生态风险评价

采用液相色谱法对三峡库区重庆段9个断面沉积物样品的多环芳烃(PAHs)进行了分析。结果表明,三峡库区重庆段沉积物中ΣPAHs质量比范围为68.6~4 226 ng/g,平均质量比为685 ng/g;7种致癌单体Σ7PAHs质量比范围为23.7~1 265 ng/g,平均值为261ng/g,属中等污染水平。沉积物中ΣPAHs质量比最高点位于化工园区下游,其余断面质量比较低且变化较小;化工园区下游以2~3环为主,占总量的50.66%,其余断面以5~6环为主,占总量的25.90%~67.01%。沉积物中PAHs来源主要为木柴、煤燃料的高温燃烧。沉积物质量基准法和质量标准法评价结果表明,化工园区下游沉积物存在生态风险,有必要开展PAHs污染来源调查和底质生态修复研究;其余断面存在潜在生态风险,需加强监测。

Analysis of the contamination characteristics and the eco-risk assessment of PAHs in sediments from the Three Gorges section in Chongqing area

In this paper,we would like to report the results of our observation and monitoring activities of the contamination characteristics and the eco-risk assessment of PAHs in the sediments from the Three Gorges section of Chongqing area with their possible sources being determined by the values of Ant/(Ant + Phe) and Flu/(Flu + Pyr).So far as we know,the contamination situation of polycyclic aromatic hydrocarbons (PAHs) in the area hasn't received necessary attention from the related departments,which may directly affect the water quality of the area.Therefore,the ecological risk of the sediments has to be further assessed by the methods of the sediment quality guidelines (SQGs) and the sediment quality standards (SQSs) of the state.In July,2014,we have collected the ipractical samples at 9 different sites,including the two entry sections,that is,the main urban sections,and the upstream and downstream of the chemical industry parks.As a result,we have found that the ∑PAHs concentrations stand in a range from 68.6 ng/g to 4 226 ng/g with a mean data value of 685 ng/g,which can be regarded as at the middle pollution level as compared with other domestic rivers.As to the ∑7 PAHs of the 7 probable carcinogens,the pollution indexes vary from 23.7 ng/g to 1 265 ng/g with a mean data of 261 ng/g,which can be detected in the spatial variations.And,in contrast,the content concentration rate of PAHs in the sediment sample from the chemical industry park proves to be very serious(4 226 ng/g),that is,25 times as much serious as that from the case study samples from the above said upstream chemical industry park.Whereas the rate of PAHs pollution from the downstream of the chemical industry park has been found dominated by 2-and 3-ring compounds at a percentage difference from 50％ to 66％,while the other constitutent components have been discovered dominated by 5-and 6-ring compounds at a percentage between 25.90％ and 67.01％.As to the ratio between Ant/(Ant + Phe) (＞0.10) and Flu/ (Flu + Pyr) (＞ 0.50),we have found that the wood and coal combustion should account for the major source pollution for the PAHs,while their respective corresponding contents of PAHs serve as Nap,Ace,F1,BaA and DahA with the RCF ＞ 1,implying that the potential biological hazards originate from the downstream of the chemical industry park.At the same time,the content concentration rates of PAHs from the downstream and upstream of the chemical industry park turn out to be greater than FEL and between PEL and FEL,respectively,thus,signifying the frequent or possible hazards should contribute to the water and sediment ecosystem.Thus,a conclusion has to be made that there is an urgent need to make a thorough investigation of the PAHs pollution source and the urgent fundamental research work for the ecological system restoration around the chemical industry park while strengthening the monitoring of the PAHs pollution in the nearby related regions of the Three Gorges area in Chongqing municipality.