Effect Of Plant Rhizosphere Effect On The Remediation Of PAHs Contaminated Soil By Plant Microorganism Combined

PAHs are a widespread class of persistent organic pollutants in the environment,which not only reduces the quality of the environment but also endanger human health.Because soil is the main carrier of PAHs in nature,the soil remediation of PAHs contaminated soil has become the focus and hot spot of domestic and foreign experts and scholars.This study takes PAHs contaminated soil as the object of study,focuses on the degradation of PAHs in the rhizosphere of plants and the mechanism of microbial reaction in the rhizosphere.Firstly,the paper studied simulated soil contaminated by PAHs and long-term contaminated farm soil contaminated by PAHs,samples through time points,used chemical analysis method to analyze the degradation of PAHs under synergistic action of root exudates and microorganisms.The results show that:Mycobacterium M1 as the degradation bacteria of PAHs have the potential for application in soil remediation;the addition of root exudates of rye has the promotion effect on the PAHs in the soil of Mycobacterium M1 degradation,and when the concentration of TOC of the root exudates of the rye was 80 mg/kg,the effect is the best.Secondly,the paper used the laboratory root box experiment to study plant combined with microbial degradation of PAHs contaminated soil,analyzed the spatial and temporal distribution of PAHs in root exudates and microbial degradation.The results show that:the synergistic effect of the root exudates of soybean,ryegrass and alfalfa and the M1 of Mycobacterium are good for PAHs degradation,the synergistic effect of the root exudates of alfalfa and the Mycobacterium Ml is the most significant;in the root box experiment,the degradation of PAHs is different in space,that is:the effect of degradation of soybean rhizosphere is better than the non root zone,the effect of degradation of ryegrass and alfalfa rhizosphere is better than close root zone and far root zone,and the effect of degradation in close root zone is better than far root zone.Finally,used molecular biology method to study on effect of rhizosphere effect on the number and activity of microorganisms of simulated contaminated soil and in-situ contaminated soil.The results show that:the tolerance of microbial to PAHs in in-situ contaminated soil is stronger;number and activity of microorganisms in the rhizosphere are higher than that of the non rhizosphere,the rhizosphere effect promotes the growth and activity of microorganisms.To sum up,it is a feasible method to improve the efficiency of PAHs contaminated soil by screening highly effective PAHs degrading bacteria and specific PAHs phytoremediation.However,the adaptability of degrading bacteria and plants to soil contaminated soil is still a key limiting factor.In the future research,the degradation bacteria and plants that can adapt to many environmental conditions should be developed,To achieve better degradation effect.