The Mechenism Research On The Migration And Transformation Of Polychlorinated Biphenyls In Soil

Polychlorinated biphenyls(PCBs) are polychlorinated compounds forming when hydrogen on the benzene ring of biphenyl is substituted by chlorine. PCBs are among the persistent organic pollutants(POPs) as environmental contaminants, which was paid more attention due to its serious harm to both the human health and ecological environment.First, the characteristics of adsorption/ desorption in soil were analyzed in this paper. The content of the organic matters and the particle size of soil were identified as the main factors that affected the adsorption of PCBs. Based on the analysis, the soil column leaching experiments were performed to simulate dynamic process of PCBs with water infiltration in unsaturated zone. The behaviors of PCBs including adsorption, dispersion and migration under various water conservancy conditions and soil physical and chemical properties were discussed. The results showed that the migration of PCBs was very slow in soil and it became more slowly when the content of the organic matters increased; Under different water conservancy conditions, the water infiltration provided driving force for the migration of PCBs. In that case the migration velocity accelerated as the flow velocity speeded, resulting in the increasing of migration depth of PCBs; The analysis indicated that the migration of PCBs have a positive correlation with the content of the organic matters, as well as with the water conservancy conditions. The migration model of PCBs in unsaturated zone was set up on the basis of experiment data, which could correctly simulate the migration law of PCBs in the soil. Finally, the transform mode of PCBs in the soil was discussed, the conclusion came out that microbial metabolism was a better way and the main factors affecting transformation could be the temperature and electron acceptor and provider.