Combined Phyto-microbial Remediation Of Chlorinated Organophosphate Contaminated Soils

With the continuous development of human industrialization and modernization,the synthesis and manufacture of various chemical substances are widely used in diverse industrial production.Organic phosphate,as a chemical additive,commonly exists in various environments.This paper took tris（2-chloroisopropyl）phosphate（TCPP）contaminated soil as the research object to enrich TCPP specific degrading bacteria from soil,the plant species with the best degradation effect was selected,and finally the combined bioremediation of plant and microorganism was used to remove TCPP from soil.The main results were as follows:（1）A strain of highly efficient TCPP-degrading bacteria,named DT-6,was selected for enrichment culture and degradation experiments.The bacteria was identified as Ochrobactrum by 16S r DNA sequence analysis and morphological and biochemical identification.The optimum conditions for its growth and degradation were:TCPP concentration of 50 mg·L^-1,temperature of 35°C,p H=7 and inoculum level of 10%,with a 7d degradation rate of 34.59%.（2）Indoor cultivation tests were conducted to compare the degradation rate of soil TCPP,plant growth and TCPP content in plant tissue of perennial ryegrass（Lolium perenne L.）,tall fescue（Festuca elata Keng ex E.Alexeev）,alfalfa（Medicago sativa L.）and common vetch（Vicia dasycarpa Ten.）in TCPP contaminated soil with the concentration of4.20 mg·kg^-1.After 45 d of indoor cultivation,the average removal rates of TCPP from inter-rooted soils were 77.92%,83.13%,91.60 and 82.07%for tall fescue,common vetch,perennial ryegrass and alfalfa,respectively.The removal rates of TCPP from non-inter-rooted soils were 64.74%,69.47%,83.44%and 65.45%,respectively.The content of TCPP in different plant tissues varied significantly,with the highest content in common vetch leaf tissue(15021.01μg·kg^-1)and the lowest in tall fescue root tissue(1328.96μg·kg^-1).（3）The enrichment screened strain DT-6 was combined with plant cultivation screened perennial ryegrass for the combined phyto-microbial remediation of contaminated soil at different concentrations(100,500,1000,5000和10000μg·kg^-1).The experimental results showed that the soil TCPP(100,500,1000,5000和10000μg·kg^-1)was reduced by 30.71%,18.50%,11.86%,8.32%and 5.24%by the treatment with DT-6 strain only.And the combined phyto-microbial remediation of soil TCPP degraded the different TCPP contaminated soils by average values of 91.14%,88.60%,85.21%,84.81%and 70.28%,respectively.