南水北调中线源头淹没区土壤中多环芳烃的赋存分布特征

研究了南水北调中线源头淹没区农田土壤中多环芳烃(PAHs)的分布特征与来源.采集了丹江口水库淅川淹没区(高程170 m以下)8个乡镇的18个农田土壤.以索氏提取法对样品处理后,采用GC/MS对土壤中美国EPA优先控制的16种PAHs进行了检测分析.结果表明,淹没区农田土壤中共有10种PAHs组分检测出,总残留量范围为5.29~173.11 ng·g^-1,平均值为41.89 ng·g^-1,具有致癌作用的组分苯并 蒽(Baa)、 (Chr)和苯并(b)荧蒽(Bbf)含量约占PAHs总残留量的2.4%.个别采样点的PAHs残留量高于荷兰政府规定的无污染土壤的PAHs值(干重:20~50 ng·g^-1),表明淹没区部分农田土壤已受到轻微的PAHs污染.通过使用PAHs环数相对丰度法和Phe/Ant、Fla/Pyr、Ant/(Ant+Phe)和Fla/(Fla+Pyr)等分子标志物指示法来解析PAHs来源,结果显示,淅川淹没区土壤中PAHs的来源主要是煤等化石燃料和草木等植物性燃料的燃烧,少量来源于汽车尾气的排放以及石油产品的泄漏.淹没区农田土壤中PAHs污染存在一定的生态风险,值得进一步关注.

Distribution characteristics of polycyclic aromatic hydrocarbons in the soil from the middle line source area of the south-to-north water diversion project

The distribution characteristics of polycyclic aromatic hydrocarbons (PAHs) in the soil taken from the middle-line source area of the south-to-north water diversion project were studied. Eighteen soil samples were collected from 8 towns in Xichuan inundation zone of Danjiangkou reservoir. After Soxhlet extraction, PAHs (Nap was not detected) in the soil samples were determined using GC/MS. Ten of the 16 EPA priority PAHs were detected in the soil samples. The total PAHs residues were determined between 5.29 to 173.11 ng·g^-1, with an average of 41.89 ng·g^-1. The highly carcinogenic Baa, Chr, and Bbf accounted for 2.4% of the total residues. The PAHs contents in the soil of some sampling points were higher than that of uncontaminated soil (20~50 ng·g^-1 on dry weight basis) suggested by the Netherland government, indicating that parts of the inundated soil had been contaminated by PAHs slightly. Based on the analysis of relative abundances of PAHs rings and the Molecular Markers, it was concluded that the principal source of PAHs in the studied area was combustion products of coal and other fossil fuels, while only a small portion was contributed by vehicle exhaust emissions and spillage of petroleum products. A certain degree of ecological risk of PAHs pollution existed in the study area, calling for further attentions.