淋滤水量对多环芳烃在土壤剖面中纵向迁移的影响研究

为了揭示淋滤作用对多环芳烃(PAHs)在土壤剖面中纵向迁移的影响,选取北京市昌平区一条具有代表性的土壤剖面作为实验样品,进行了PAHs土柱淋滤模拟研究。结果表明:经过淋滤作用后,淋滤水量不同的三个土柱(A1,A2,A3,淋滤水量依次增大)表层土中残留PAHs总量逐渐降低,但不同环数PAHs含量降低幅度存在较大的差别,低环数PAHs受影响程度更大;在淋滤水量相同的情况下,不同环数PAHs的含量均存在随土柱深度的增大而逐渐降低的趋势,但降低程度存在一定差别。由此推测,通过长期淋滤作用,表层土中的PAHs可以向深层土壤迁移,这些认识可以为深层土壤及浅层地下水的多环芳烃污染评价及保护提供合理的理论依据。

Study on Impacts of Leaching Water Amount on Vertical Migration of Polycyclic Aromatic Hydrocarbons in Soils

To reveal the impacts of leaching water amount on the vertical migration of Polycyclic Aromatic Hydrocarbons (PAHs)in soil profile,soil column simulation leaching experiments were designed and soil samples were collected from a repre-sentative soil profile in Changping District, Beijing. The results showed that the mass fraction of PAHs in topsoil(0~5 cm)of three columns(A1,A2,A3,the amount of leaching water increased in turn)obviously decreased after leaching which indicated that PAHs in topsoil of three columns had varying degrees of vertical migration under the impact of leaching water. The greater amount of leaching water,the lower concentration of PAHs remained in topsoil. However, there were significant differences in the de-crease of mass fraction of PAHs with different rings,and PAHs with low rings were more affected. With the same amount of leac-hing water,the mass fraction of PAHs with different rings had a tendency to decrease with increasing of the depth of soil columns, however the reducing degree was a certain difference. It was presumed that PAHs in topsoil can migrate to deep soils,and these knowledge could provide reasonable theoretical basis for the evaluation and protection of PAHs pollution in deep soils and shallow groundwater.