Surfactants Enhance Plant-microbe Remediation Of DDTs-contaminated Soils

The organic pollution in facility agriculture soil is becoming more and more serious in our country.DDT is persistent in soil which bring potential risk to human health through food chain.It also affects agricultural exports and international market to a certain degree.Bioremediation of DDT contaminated argricultural soil has been one of the focuses both at home and abroad because it possesses advantages like high efficiency and environment friendly.In order to improve the effect of remediation of DDT contaminated agriculture soil,we selected high efficient DDT-degrading bacteria and designed surfactants enhance plant-microbe remediation technology.The results showed that DDT could improve the microremediation and phytoremediation efficient.In the study,the biodegradation and the plant absorption of DDT in different combination remediation were research by field experiment.The optimal surfactant-enhanced plant-microbial remediation technique was determined.The results showed that the optimum conditions for plant-microbial remediation were surface-System,the main results are as follows:(1)The DDT-degrading bacteria were isolated and purified from the farmland soil by enrichment cultivation method.The degradation rate of DDT by the high efficient DDT-degrading bacteria-Arthrobacter globiformis was 78.58 % under the contration of 10mg·L-1DDT during 24 h.(2)The experiment of mixed surfactants enhance plant-microbe remediation of DDTs contaminated soils was carried out.The results showed that when the concentration of biosurfactant was 100mg·kg-1,the treatment of mixed surfactants +rape-C+N bacteria had the highest degradation rate of DDT(58.65%).The degradation rate of DDT of treatments mixed surfactants(300mg·kg-1 soil)+ rape-C and mixed surfactants(40mg·kg-1 soil)+ rape-N was 54.73% and 54.60% respectively.(3)The experiment of biosurfactants enhance plant-microbe remediation of DDTs contaminated soils was carried out.The results showed that when the concentration of biosurfactant was 5mg·kg-1,the treatment of biosurfactant + rape-N bacteria had the highest degradation rate of DDT(62.83%).The degradation rate of DDT of treatments biosurfactant(5mg·kg-1soil)+ rape-C and biosurfactant(20mg·kg-1soil)+ rape-C was58.83% and 58.78% respectively.(4)The content of DDT in overground parts and root of plant were determined.The results showed that DDT in the overground parts of the rape was below the detectable limit,while that in the ryegrass was high.The DDT degradation rate of the ryegrass soil was low,which indicated that DDT removal in soil was mainly caused by the microorganism.The treatments(5 mg·kg-1biosurfactant/soil + rape + N bacteria and 100mg·kg-1 mixed surfactants/soil + rape + C+N mixed bacterium)have the highest DDT degradation rate and the lowest plant adsorption.This indicated that in low DDT pollution agricultural land,we can remediate the polluted soil and at the same time the rape may be planted.