Plant-microorganism Combined Bioremediation Of Chlorpyrifos-contaminated Soil

Soil contamination by pesticides is an important problem all over the world. Bioremediation combining plants and microorganisms is increasingly recognized and applied to treat pesticide residues. This approach integrates the advantages of phytoremediation and microbial remediation to accelerate degradation of the pesticides. Plant species Sorghum Hybrid, Lolium multiforum and Medicago sativa, and a bacterium, DSP-A, were used to investigate plant-microorganism combined bioremediation of contaminated soil.The chlorpyrifos-degrading bacterium, DSP-A, was isolated from a soil near a waste water outlet of chlorpyrifos-producing factories in Fuan. The isolate could remove 50.13 % chlorpyrifos in the mineral liquid medium with 100 mg/L chlorpyrifos within 2 days.Three plant species were studied on phytoremediation of chlorpyrifos-contaminated soil. The results showed that their capacities of degradation were different. Sorghum Hybrid was superior to the other two species.The relatively-growing index (RGVI) and seeds vitality of Sorghum Hybrid, Lolium multiforum and Medicago sativa in chlorpyrifos-contaminated soil were studied. The results showed that chlorpyrifos of low concentration could promote seed vitality of Lolium multiforum and Medicago sativa. And Sorghum Hybrid could resist high contamination of chlorpyrifos.The combined bioremediation effect of DSP-A with one of three plant species on chlorpyrifos in the contaminated soil was investigated. The results showed that Plant-microorganism combined bioremediation was better than phytoremediation or microbial remediation. Our study indicated that the best plant combined with DSP-A was Sorghum Hybrid, followed by Lolium multiforum. Factors affecting the combined remediation were studied. Microbial quantity, plant density and soil moisture played important roles in the combined bioremediation of chlorpyrifos .