天津大沽排水河沉积物典型持久性有机污染物的分布特征与来源解析

Distribution and Source Analysis of Classic Persistent Organic Pollutants in Sediments from Dagu Drainage Canal,Tianjin,China

分别使用气相色谱质谱仪和气相色谱仪对2010年5月采集的天津市大沽排水河8个沉积物样的16种多环芳烃(PAHs)和7种有机氯农药(OCPs)进行了调查,结果表明,沉积物中PAHs的总含量范围为370～5607ng·g-1,平均浓度为2041ng·g-1,OCPs的总含量范围为42.2～680ng·g-1,平均浓度为222ng·g-1。对其组成特征及来源进行了分析,结果表明,沉积物中PAHs主要以3～4环为主,5～6环较少,沉积物中PAHs主要来自化石燃料的燃烧或交通源贡献,以及少量石油产品的输入。滴滴涕(DDT)及其代谢产物的含量明显低于林丹类物质(HCHs),HCHs有新的输入,DDT没有新的输入,其降解方式主要是厌氧降解。

In May,2010,8 sediment samples were collected from Dagu Drainage Canal after dredging.The 16 US EPA priority polycyclic aromatic hydrocarbons（PAHs） and 7 kinds of organochlorine pesticides（OCPs） were extracted by Soxhlet extractor,and then purified by passing through glass column filled with 1：2 alumina：silica with anhydrous sodium sulfate（1 cm） at the top of the column,and measured by GC-MS and GC,respectively.The composition profile and possible source of PAHs,hexachlorocyclohexane（HCHs）,and dichlorodiphenyltrichloroethane（DDT） and its metabolites were discussed.The results showed that the concentrations of total PAHs and OCPs in the sediment samples ranged from 370 to 5 607 ng·g-1 and 42.1 to 680 ng·g-1,respectively,with the average concentrations being 2 041 ng·g-1 and 222 ng·g-1.There was no specific spatial distribution for PAHs and DDT and its metabolites,however,HCHs was obviously higher in the lower reach of the canal,manifesting possible point source along the lower reach.The PAHs with 3～4 rings were the dominant PAHs compared to those with 5～6 rings,the ratio of LMW（lower molecular weight PAHs,2～3 rings）/HMW（higher molecular weight PAHs,4～6 rings）,InP（indeno-（1,2,3-cd） pyrene）/[InP ＋ BgP（benzo（ghi）perylene）] and Flu（fluoranthene）/[Flu ＋ Pyr（pyrene）] indicated that fuel-burning was the main source of PAHs in sediments.Principal component analysis method gave similar results that the combustion of fossil fuels or traffic source was the main source of PAHs in sediments,with a few coming from anthropogenic releases of oil.The composition profile of OCPs in sediments suggested new lindane input but no new input of DDT.The degradation of DDT was mainly anaerobic degradation as indicated by DDD/DDE ratio being larger than 1.0.