某化工场地土壤与地下水中多环芳烃的分布特征及迁移规律

Distribution and migration of Polycyclic Aromatic Hydrocarbons(PAH)in soil and groundwater of a chemical site

选取某化工场地作为研究对象,采集不同深度的原状土壤样品和原状地下水样品,对土壤样品和地下水样品的16种优控多环芳烃进行定量分析,研究不同种类的多环芳烃在包气带和饱和带中的分布特征和迁移规律。研究表明,在平面上,多环芳烃在土壤和地下水中的污染高值区与生产车间分布基本一致;在垂向上,土壤中的16种多环芳烃集中分布在杂填土层,低环和中环的多环芳烃更易向下迁移,并在黏土层产生一定的富集,仅有最低环的萘通过包气带迁移至饱和层中,饱和层中的萘一部分在地下水中扩散,一部分仍继续垂向迁移至更深层的土壤中。通过特定分子间的浓度比值,初步判定场地土壤中的多环芳烃来源为原油的不完全燃烧。

A chemical site was selected to collect undisturbed soil and undisturbed groundwater samples at different depths.Quantitative analyses of 16 types of optimal controlled PAHs in the soil and groundwater samples were carried out to study the distribution characteristics and migration patterns of different types of PAHs in the aerated zone and saturated zone.The results show that the distribution of PAHs in soil and groundwater for high-pollution-value areas was basically the same as that in the production workshop.In the vertical direction,PAHs in the soil were concentrated in the mixed fill soil layer,and the low-ring PAHs and the middle-ring PAHs were more likely to migrate downward,and were enriched in the clay layer to some extent.Only the lowest ring naphthalene migrated to the saturated layer through the vadose zone.Some of the naphthalene in the saturated layer diffused in the groundwater,and some continued to migrate vertically to the deeper soil.Through the concentration ratio of specific components,the source of PAHs in the soil of the site was preliminarily determined as resulted from incomplete combustion of crude oil.