Bioremediation Of Herbicides Contaminated Rice Fields Using HCH, DDT, Chlorpyrifos And Buprofezin Degrading Bacteria

Bioremediation of pesticide pollution with microbe was regarded as the most perspective methods to the remediation of pollution. Since 1960s, biodegradation researches of xenobiotic in the seriously polluted environments had been widely conducted. A large number of degrading bacteria had been isolated, and some degrading bacteria preparation and matching products had been developed, which were applied to In situ bioremediation.In situ bioremediation plot experiments of pesticide residues in rice soils located at Beitang Village, Yixin City, had been conducted with HCH degrading bacteria BHC-A, DDT degrading bacteria Wax, chlorpyrifos degrading bacteria Dsp-4 and buprofezin degrading bacteria BF3. The result showed that when the bacterial mass of degrading bacteria reached 107CFU/g dry soil, it had good effects on the degradation of pesticides residues, and no matter higher (about 10mg/kg dry soil) or lower (below 0.3mg/kg dry soil) concentration. Bacterial mass of degrading bacteria in soil was the key element of degradation rate of pesticide residues. With the reduction of pesticide concentration, degrading bacteria would decline and disappear after the soil spraying 20-25 days, which had showed that it was safe and efficient to apply In situ bioremediation with bacteria preparation.The effects of application rates of chemical fertilizers and organic fertilizers on degradation of pestide residues in soils with degrading bacteria had been studied using bowl basin experiments. On one hand, smaller amounts of chemical fertilizers could accelerate the degradation of degrading bacteria, but excessive amounts of them could reduce biological activities of degrading bacteria. On the other hand, the degradation rate of four pesticides were 94.58%,95.37%,98.36%,87.38% after 10 days of a rational application of organic fertilizers with four degrading bacteria, which showed that the rational application of organic fertilizers could dramatically enhance the degrading ability of the degrading bacteria.In order to evaluate the influence of the application of degrading bacteria on original microbial community structure in soils, the the changes in the number of three major kinds of culturable microorganism had been analyzed with plate count method, and cluster analysis had also been conducted to microbial community structure in soils with PCR-DGGE. The result showed that the application of degrading bacteria would not exert serious effects on the number of three major kinds of culturable microorganism in soils. It could affect the balance of their amounts within a short period, but not a longer time, which could show that it was safe to apply the degrading bacteria to environment.