Regulation Of Fe-Mn-modified Biochar On The Microecology Of PAEs-contaminated Soil

Dibutyl phthalate(DBP)and di(2-ethyl)hexyl phthalate(DEHP)are commonly used as additives to improve the flexibility of plastic and are widely detected in water,soil and plants.They can exert negative effects on soil micro-ecosystem and even interfere with the growth and quality of plants.Therefore,it is urgent to find a costeffective measure for reducing the bioavailability of DBP and DEHP in soils.Biochar is a pyrogenic carbon materials produced by the biomass,which are mainly utilized in soil remediation processes owing to their high effectiveness in enhancing soil properties,structure,soil microbial survival environment and suppressing pollutant toxicity.In this study,we assessed behavior of 0.5%,1.0% and 2.0% biochar(BC)and ferromanganese modified biochar(FMBC)in the rhizosphere soil of mature wheat polluted with DBP and DEHP.The main results are as follows:(1)Effects of FMBC application on the soil chemical properties of wheat rhizosphere soilCompared with the control(DBP and DEHP contaminated soil),the application of BC and FMBC elevated soil p H and soil organic matter by 5.93-21.9% and 10.7-78.6%,respectively.Similar enhancements in available nitrogen,available phosphorus and available potassium were observed,and FMBC had significant effects on soil properties over BC treatment.(2)Effects of FMBC application on soil enzyme activity of wheat rhizosphere soilCompared to the control,the application of BC and FMBC obviously increased activity of polyphenol oxidase in wheat rhizosphere soil,followed by ?-glucosidase,dehydrogenase,urease and phosphatase.Effects of FMBC on the above soil enzymes was significantly pronounced,compared to BC treatment.(3)Effects of FMBC application on bacterial diversity and community structure of wheat rhizosphere soilAddition of BC and FMBC had little effect on the bacterial diversity and richness of wheat rhizosphere soil,and the changes in relative abundance at the phylum level showed non-systematic.BC and FMBC addition suppressed the relative abundance of Streptococcus and Enterococcus and increased Bacillus,Pseudomonas and Sphingomonas.Compared to the control,FMBC application reduced the complexity of the network structure of the bacterial genera,while strengthened the positive connection between the degrading bacterial genera.Molecular docking illustrated that DBP and DEHP could bind to the residues of carboxylesterase through hydrogen bonds,van der Waals forces,and ?-? T-type interactions.(4)Effect of FMBC application on DBP and DEHP content in wheat rhizosphere soilCompared to the control group,the application of BC and FMBC obviously increased DBP/DEHP content in soils by 18.7-99.5%/18.3-95.5%,and revealed a significant positive correlation with BC and FMBC dosage.Additionally,the ability of FMBC to immobilize DBP/DEHP is superior to that of BC,which may be attributed to the larger surface area and more surface functional groups of FMBC.