| Recycling activities of electric and electronic waste (e-waste) are emerging as a global concern as they can contribute to the release of harmful pollutants into environment. Heavy metal and Polychlorinated biphenyls (PCBs) are this kind of harmful pollutants. In this research, we collected soil samples from the farmland around two e-waste recycling sites (dryland region D and paddy soil region P) where the PCBs leaking accident have happened. Concentration and composition of soil pollutants such as heavy metal, PCBs and OCPs were analysed. Combining the use of traditional microbial ecological research methods and PCR-DGGE to explore the changes of microbial ecosystem and community structure under contamination stress. The main conclusions are as follows:(1) D and P regin were both contaminated by heavy metal. In D region, concentration of Cd was one time higher than the National Environmental Quality Standard level III (NEQS III). Concentration of Cu,Pb,Zn exceeded NEQS II. Concentration of Pb,Zn in D1(the sampling site that was nearest to the recycling site) was 2 and 5 times higher than NEQS III, respectively. In P region, concentration of Cd was one time higher than NEQS III, Concentration of Cu exceeded NEQS II. There were slight contamination of Pb and Zn at the same time.(2) The average concentration of PCBs around the D region was 1.31 mg·kg-1, the highest concentration reached to 1.67 mg·kg-1 . The concentratin of PCBs decreased with the increasd of the distance from recycling site. In P region, average concentration of PCBs was just 9.70μg·kg-1. in D region PCBs was mainly composed of 3,. But in P region, the main composition were4,5,6-chlorinated PCBs. Both farmland was contaminated by organochlorine pesticide, but the concentration was very low. In D region, the average content of Hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT) were 22.4μg·kg-1 and 0.5μg·kg-1, respectivily. In P region, the content of HCH and DDT were 16.3μg·kg-1 and 6.6μg·kg-1, respectively. Evident transform had happened on the HCH and DDT in soil.(3) In D region, there was a significant correlationship between concentration of PCBs and Cu, Cd, and also between Pb, Zn, indicating that they come from the same source, respectivily. In P region, there was a significant correlationship between Cd and Pb. Indicating that they come from the same source.(4) Analysis of soil respiration and enzymes activity showed that in Dryland region, when getting close to the recycling site, soil microbial activity increased. The PCBs may have a positive effect on the microbial activity. In the paddy soil, soil respiration and enzymes fluctuated from site to site, but have no significant correlationship with the pollutants in soil. In D region, Urase activity showed a significant correlationship with the concentration of Cu and Cd, indicating that the decrease of urease activity may caused by the effect of Cu and Cd in the soil. Urease may be suitable for the assay of the effect of heavy metal contamination.(5) Microbial account show that in dryland, when getting close to the recycling site, number of soil bacteria and actinomycete increased the Shannon diversity index of bacteria increased, But that of soil actinomycete decreased at the same time. PCA result show that, when getting close to the cycling site, the difference of the character of soil microbial community between sampling site and background site increased. This may caused by the gradience of PCBs and Cu in the soil. In paddy soil, number of bacteria and actinomycete in different sampling site are similar, number of fungi fluctuated acutely.There was some different between the community structure of different sampling site in paddy soil, but no obvious trend was observed.(6) Clone and sequence of the specific band on the DGGE gel of dryland showed that most of the specific clone belongs to the Proteobacteria and Bacteroidetes, we also found that many clones were highly similar with the sequences of microbes that are related with organic compound degradation. Bacteria belong to this two phylum may play a very important role in the microbial ecosystem in PCBs contaminated soil, and also in the transformation and degradation of PCBs pollutants.
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