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研究了南水北调中线源头区降雨径流中多环芳烃的分布特征及来源.根据不同土地利用类型修建了5组径流场收集径流,采用GC/MS对径流中美国EPA优先控制的16种PAHs进行了检测分析.结果表明,3种土地利用类型降雨径流水相中PAHs含量平均值为:耕地(26.53 ng.L-1)>栎林(20.91 ng.L-1)>果园(17.59 ng.L-1);颗粒相中PAHs含量平均值为:耕地(1 073.72 ng.g-1)>果园(652.29 ng.g-1)>栎林(385.46 ng.g-1).耕地和果园两期径流中均检测出高环致癌组分Bap,检出率为30%;与美国EPA 2006年颁布的《国家推荐的优先有毒污染物水质标准》比较发现组分Chr超过标准,超标率为40%,其在样品中的检出率则高达100%.降雨径流量随坡度的增加呈明显的上升趋势,径流两相中总PAHs含量随坡度的增加也呈明显的上升趋势,可见同种利用类型土地径流中PAHs流失量与坡度的大小密切相关.使用分子标志物指示法对研究区径流中PAHs来源进行解析,结果表明研究区径流中PAHs主要来源是煤、木材等燃烧源,少量来源于汽车尾气排放.研究区降雨径流中PAHs污染存在一定的生态风险,值得进一步关注.
The distribution characteristics and sources of polycyclic aromatic hydrocarbons (PAHs) in the runoff of the middle reaches of the South-to-North Water Diversion Project were studied.According to different land use types, five groups of runoff fields were collected to collect the runoff and 16 priority PAHs from runoff were detected by GC / MS The results showed that the average content of PAHs in three types of land use rainfall runoff aqueous was: 26.53 ng.L-1 cultivated land> 20.91 ng.L-1> 17.59 ng.L-1 ). The average content of PAHs in the granular phase was: cultivated land (1 073.72 ng.g-1)> orchard (652.29 ng.g-1)> oak forest (385.46 ng.g-1) All detected high-ring carcinogenic component Bap, the detection rate was 30%. Compared with the “National Recommended Preferential Poisonous Water Quality Standard” promulgated by the U.S. EPA in 2006, the component Chr exceeded the standard, and the exceeding standard rate was 40% The detection rate in the sample was as high as 100% .The rainfall runoff increased obviously with the increase of slope, the total PAHs content in runoff two phases also increased obviously with the increase of slope, showing the runoff of the same utilization type PAHs in the runoff is closely related to the size of the slope.Using the molecular marker method to study the runoff PAHs The results showed that the main sources of PAHs in runoff from the study area were the combustion sources such as coal and wood, and a small amount of PAHs emissions from automobile exhausts.The PAHs in the runoff from the study area had some ecological risks and deserved further attention.