土壤中多环芳烃的垂直分布特征及来源研究——以四川省南充市区为例

Vertical distribution characteristics and sources of polycyclic aromatic hydrocarbons in soils in industrial zone in Nanchong City

为了解土壤垂直剖面PAHs的分布特征及来源,运用气相色谱法对四川省南充市区土壤中PAHs的纵向分布特征进行了分析,并运用聚类分析法对PAHs进行源解析。结果表明,美国环保局优先控制的16种多环芳烃,炼油厂附近土壤剖面中检测出12种,加油站检出14种。土壤垂直剖面中PAHs总质量比随着土壤深度的增加呈下降趋势,最高值出现在10～30cm,而不是表层;50cm以下土层中PAHs质量比和种类数目锐减。低环PAHs在土壤各剖层均被检出,以2环和3环为主,单种PAH以芴、菲和荧蒽为主;而高环PAHs多出现在地表附近的土层。各剖层中PAHs质量比和种类数目的变化表明,低环PAHs比高环PAHs更容易往土壤深层迁移。聚类分析揭示了土壤中PAHs污染源来自于煤的不完全燃烧和石油及相关产品的泄漏、挥发及燃烧。

Soil is one of the important assembling and transiting places of polycyclic aromatic hydrocarbons （PAHs） in the environent. This paper is aimed to present a report on the vertical distribu- tion characteristics and sources of 16 mainly controlled PAHs in soil collected from Nanchong City. Refinery plant and gas station were chosen as the typical sampling sites. The soil samples were collected every 10 cm of distance from the surface to 100 cm underground. Gas chromatography was adopted to detect and analyze the concentrations of PAHs in soils from the sampling sites. Cluster analytical methodology was used to identify the possible sources of PAHs in soil. The study has showed that 12 kinds of the PAHs were detected in the refinery plant soil whereas 14 kinds of the compounds were found in the gas station soil. The total concentrations of PAHs were found to have peak values at layer 10 - 30 cm beneath the surface. Both numbers of PAHs species and concentrations of PAHs in soil samples drop with depth. For the spot of 50 cm from the surface in particular, the concentrations of PAHs rapidly reduce. The analytical results of our investigation have exhibited the vertical distribution characteristics of PAHs in the soil of Nanchong＇ s industrial zone corresponding on Tianjin with heavy industry and some cities abroad. There were only PAHs with 2-ring and 3-ring existed with a high proportion in each profile. The principal PAHs compounds were fluorine, phenanthrene and fluoranthene. It means that low-ring PAHs can reach the deeper layers according to the vertical profiles. On the other hand, high-ring PAHs were only detected in surface soil samples. The content of PAHs changed along the profiles indicating that low-rings PAHs are easier to migrate compared to high-rings PAHs. The cluster analytical results have identified the main sources of PAHs in the soils as the incomplete combustion of coal plus the contribution of leakage, volatilization as well as the combustion of petroleum and related products.