| Soil contaminated by e-waste has attracted worldwide attention due to the rapid growth of e-waste and the social,environmental and health issues caused by extensive e-waste recycling.Shantou Guiyu town as one of the country's most important e-waste dismantling area,its crude dismantling and imperfect e-waste management system led to the soil contamination in electronic waste disposal sites and the surroundings,The main pollutants are persistent organic pollutants(POPs)and heavy metals,and the co-contamination by these compounds pose a serious threat to the region's ecological and environmental safety.In order to explore the rhizosphere effects on the distribution and composition of POPs and heavy metals and soil microbial community in e-waste contaminated soil,the rhizosphere and non-rhizosphere soil samples of 14 kinds of vegetables in the vicinity of the waste area were collected and studied.The present research may p rovide clues and fondamental knowledge for the soil eco logical risk assessment and bioremediation.The main results are as follows:The arithmetic mean concentrations of C u,Cr and Pb in the non-rhizosphere soil were 4.6,2.3 and 2.7 times than the soil background value,and the arithmetic mean concentration of C u and Pb is 1.6 times and 2 times than the maximum allowable value of secondary standard of soil environmental quality in C hina.There was no correlation between C u and C r and Pb heavy metals in non-rhizosphere soils,while Cr were significant correlated with Pb(p <0.01),indicating that the soil Pb and Cr pollut ion may have homology,C u pollution is caused by another source of pollut ion.The significantly correlation between TOC and C u,C r,Pb in rhizosphere soil(p <0.01),confir ming the important role of soil TOC in the greater adsorption capacity and adsorption capacity of rhizosphere soil.By the analying PBDEs,N BFRs and DPs,it was acquired that the concentration of PBDEs was the highest,followed by N BFRs and DPs.The DPs content was close to the soil background value,indicating that the electronic waste products in this study area did not contain DPs.The concentrations of PBDEs,NBFRs and DPs in rhizosphere soils were generally higher than those in non-rhizosphere soils.BDE209 and DBDPE were the domiant compounds with highest concentrations,accounting for more than 70% of the POPs in rhizosphere soil,BDE47 is the main low brominated PBDEs monomer.The rhizosphere of most vegetables(cabbage,etc.)helps degradating low brominated N BFRs,but only helps enriching high brominated N BFRs.The content of soil pollutants in the rhizosphere soil of the sweet potato and radish leaves is lower than that of the non-rhizosphere pollutants,which may be related to a bigger root surface area of the sweet potato leaves in the soil,indicating its advantage in soil remediation.The microbial community structure was studied by high-throughput sequencing technology,and 26 species of bacteria and 832 species were identified.It was found that there was a significant difference in the abundance of microorganis ms between the two lines of Bacteroidetes and Verrucomicrobia in the rhizosphe re and non-rhizosphere samples.It was found that the microbial diversity in the rhizosphere soil was not affected by the contamination,while the microbial diversity of non-rhizosphere soil was affected by TBB,TBE,DBDPE and Pb and the abundance of non-rhizosphere microbes was more affected by pollutants.This suggests that plants can reduce the effects of pollutants on microorganisms and that they have a protective effect on microbes.In addition,plants could increase the number of microorganisms,promo te microbial activity,enhance microbial metabolis m,improve mineralization capacity of microorganisms toward pollutants and help joint remediation of plant-microbial in contaminated soil. |
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