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Shihezi University (2010)

The Effect of Phorate on Soil Microbial Activityand Its Degradation in Soil in Arid Area

Peng Zhen Bao

Titre : The Effect of Phorate on Soil Microbial Activityand Its Degradation in Soil in Arid Area

Auteur : Peng Zhen Bao

Grade : Master’s Theses 2010

Université : Shihezi University

Résumé
Phorate as efficient, broad-spectrum organophosphate insecticide, miticide, widely used in the Xinjiang Cotton long-term, resulting in increased risk of contaminated soil environment. For the safety evaluation of the phorate soil application, this paper mainly the of phorate research on the impact of soil microbial activity, the phorate soil digestion characteristics and phorate biodegradable. [Method] With simulation experiments and pot experiments, the soil was applied to the phorate study its impact on the number of soil microorganisms, soil enzyme activity and soil microbial biomass carbon and nitrogen in the soil digestion characteristics. Application the microbial enrichment domesticated method separation, screening phorate degrading bacteria. [Results] 1) pre-test phorate soil fungi, actinomycetes slight inhibition, but soon returned to control levels, significantly inhibited the number of bacteria in the soil. Tomato rhizosphere soil bacteria is greater than the number of non-rhizosphere soil, phorate was applied to significantly increase soil bacteria of the rhizosphere effect R / S the the bacterial rhizosphere effect R / S between 1.52-2.68, fungi, actinomycetes bacteria rhizosphere effect is not obvious. 2) In the laboratory experiment of soil applied into phorate, soil invertase, phosphatase and protease activity was significantly inhibited, and urease activity expressed as inhibition - and promote - recovery. In the pot experiment phorate was applied to the soil to promote soil protease and phosphatase activity, soil invertase activity was manifested as pre-suppression, anaphase-promoting to promote - suppression, tomato, tomato rhizosphere soil urease activity non-rhizosphere soil urease activity inhibition concentration, high concentration promote. Overall, soil enzyme activity in rhizosphere soil gt ; non-rhizosphere soil. 3) application of phorate in the soil, the simulation soil and pot experiment soil microbial biomass carbon and nitrogen was significantly lower than the control, while soil microbial quotient (SMB / SOC), microbial biomass nitrogen and total soil nitrogen ratio (SMB / TN) was significantly lower than the control. 4) the establishment of a gas chromatographic phorate pesticide residues in the soil, phorate residues in soil using ultrasonic extraction with dichloromethane as extraction solvent, the recoveries were 81.3% -102.2% and the relative standard deviation between 5.3% -7.8%, the results show that the the pharmaceutical extraction method chosen by the test, testing methods and testing conditions appropriate and accurate test results can be used for phorate pesticide testing. . 5) degradation of phorate in the soil first order kinetic characteristics 2mg/kg 8 mg / kg, 20mg/kg treatment in the soil half-life were 8.6,8.2 and 7.2d, with the concentration of phorate improve its shorter half-life in soil. Section 30d when 2mg/kg 8 mg / kg, 20mg/kg processing residue in the soil is 0.153 mg / kg and 0.471 mg / kg and 0.839 mg / kg, digestion rate of more than 90%. 6) at pH 7 and 30 ° C, the strains XT1 and XT2 can 500mg / L PHORATE in 5 days of degradation of 83%. 7) In this study, microbial enrichment domesticated, screened two high drop detoxification phorate bacteria XT1 and XT2 by morphological, physiological, biochemical and 16S rDNA sequence homology analysis from the cotton fields of Shihezi University College of Agriculture Experiment Station, the XT2 identified as belonging to the Steinmann Providencia stuartii bacteria (Providencia stuartii). [Conclusion] The soil was applied to phorate change the soil microbial community structure, reduced soil microbial activity. Phorate degradation in arid soil faster, the half-life of 10 days or less. Application the microbial enrichment domesticated method isolated and screened two degradation ability of strain XT1 and XT2, of able 500 mg / L phorate degradation of 83% within five days.

Mots clés : Phorate Rhizosphere Soil microbial Soil enzymes Biological re - restore \\ lice Acres , soil quiet array book

Présentation (Dissertationtopic )

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