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Degradation of Herbicides in Soils and Their Effect on Biological Indicators for Soil Quality

Author: YaoBin
Tutor: XuJianMing
School: Zhejiang University
Course: Soil chemistry and the environment
Keywords: Atrazine Butachlor Metsulfuron Degradation Temperature Water Microbial biomass Microbial diversity
CLC: X592
Type: PhD thesis
Year: 2003
Downloads: 666
Quote: 5
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Abstract


The extensive use of pesticides, the soil in many areas of China by a certain degree of pollution, and has a large, wide range and dispersion characteristics. Atrazine, butachlor and metsulfuron three herbicides widely used in China, researchers have carried out in-depth research of the three types of herbicides in soil physical, chemical and biological behavior , but the degradation characteristics of the three categories of herbicides under certain controlled conditions and their impact on soil microbiology indicators relative lack of. Butachlor neutral, weakly alkaline atrazine Tianjin and weakly acidic metsulfuron three different types of commonly used herbicides for the study, some control conditions, the degradation of the herbicide in the soil dynamic law its biological indicators of herbicide pollution response, trying to reveal the biological characterization of soil quality indicators contaminated soil remediation process environmentally friendly processes and mechanisms of evolution to regulate environmental conditions for using natural microorganisms rely on soil activity improve rather quickly situ remediation of contaminated soil technology to provide a theoretical basis. Achieved major results are as follows: 1. Degradation of atrazine in soil under controlled conditions at different temperatures and different water content under controlled conditions to study the herbicide atrazine in three soils in the the yellow the tendons mud Tian, ??bruising mud fields and short coated mud Tian population dynamics law . The results show that: (1) when the soil moisture content of 40% of field water holding capacity at different temperatures (15 ℃, 25 ℃, 35 ℃) incubation conditions, the total amount of atrazine residue in the soil over time changes satisfy the first order kinetics equation C = the Coe -kt . With the increase in temperature, the atrazine degradation accelerated soil degradation half-life is shortened. 15 ℃, 25 ℃ and 35 ℃ atrazine degradation half-life in the the yellow the tendons mud Tian, ??bruising paddy field and light coating of mud Tanaka were 31.2 ~ 59.2d 15.0 25.6d and 10.5 ~ 32.7d. From the test results, higher temperatures the middle of the soil environment degradation rate of atrazine residues than fast low-temperature environment. (2) 35 ℃ incubation conditions, soil moisture content from 40% field water holding capacity increased to 60% of field water holding capacity, increased the rate of degradation of atrazine herbicide in the soil. Regulate soil temperature and soil moisture conditions in the production practice to improve soil microbial activity and promote the degradation of the herbicide. 2. Butachlor in soil degradation studies under controlled conditions at different temperatures and different water content control conditions, herbicide butachlor in the the yellow the tendons mud Tian, ??the bruising mud fields and short coated paddy field soil population dynamics of law. The results show that: (1) temperature butachlor in soil degradation, three temperatures (15C, 25'C, 35C) in the same soil water content (40% of field water holding capacity) under the incubation conditions, small metolachlor herbicides dynamic of regularity: the higher the temperature, soil butachlor degradation faster the degradation half-life is shortened; 15'C, 25C and 35'C temperatures> Factory metolachlor in the the yellow the tendons mud Tian, ??bruising the degradation half of the clayey soil and light painted mud Tanaka were 13. l ~ 105d, 11.7 ~ 21. Zd and 10.5 ~ 26d: the butachlor total residues in the soil change over time to meet the first-order kinetics equation C = C;; e-''. Butachlor residues from the test results, the soil environment of the higher temperature than the low-temperature environment in the fast degradation rate. (2) soil moisture has a significant effect on the degradation of butachlor in soil, measured results shows the the 35C incubation conditions, with soil moisture increases the speed of degradation of butachlor in soil. 40% of field water holding capacity conditions under the alachlor in the yellow the tendons mud Tian, ??bruising mud fields and short coated mud Tanaka DI. Were as follows: 16. Zd, m. sd, 32.7d; 60% field water holding capacity conditions under DT alachlor in the corresponding three soil; . Were as follows: 15. id, 9. gd, 13. sd. 3. Herbicide contamination biological indicators of soil environmental quality atrazine, butachlor and A metsulfuron three herbicides to 10mg. kg-'concentration in soil fertilized biological indicators of soil environment to a certain extent, the test showed that the effects of herbicides on biological indicators of soil environment is changing over time. *) The soil herbicide contaminated soil microbial biomass carbon significantly reduced, especially in the early stage of incubation, the impact of herbicides on the disabilities soil microbial biomass. When herbicides in soil degradation, biomass carbon decreased. The same herbicide in different soil microbial biomass carbon impact. Atrazine herbicide on the tested soil microbial biomass carbon impact of the order for the: light painted mud field> purple clayey soil> yellow tendons paddy field; butachlor: pale painted mud field> yellow the tendons mud Tian purple mud Tian; metsulfuron as : purple mud Tin> pale painted mud Tian Huang tendons paddy field. The same soil, different herbicides on microbial biomass carbon is not the same yellow tendons mud Tanaka herbicides on soil microbial biomass carbon order: metsulfuron> butachlor> atrazine; bruising paddy field : metsulfuron> atrazine> butachlor; the light painted mud Tian: butachlor> A phosphorus Long> atrazine; (2) soil microbial biomass nitrogen decreased significantly after herbicide pollution, especially In the early stage of incubation, the impact of herbicides on soil microbial biomass nitrogen. When herbicides in soil degradation, biomass nitrogen decreases. Same herbicides in different soils, the degree of influence of the soil microbial biomass nitrogen. Atlas ocean tested soil microbial biomass nitrogen affect the order as: bruising mud Tian> pale painted mud Tian yellow tendons mud Tian: butachlor: pale painted mud Tin> Tin bruising mud yellow tendons mud Tian; A phosphorus Long for: short the painted mud Tian> purple clayey soil> yellow tendons paddy field. Studies have shown that different herbicide was applied to the same soil microbial biomass carbon is not the same, atrazine, butachlor and A phosphorus Long three herbicides applied into the Yellow tendons mud field on the order of microbial biomass carbon as follows:> butachlor> metsulfuron atrazine. Three of the test herbicides applied into the bruising paddy field soil microbial biomass nitrogen order: metsulfuron> butachlor> atrazine. The three n tested herbicides applied into the light painted mud Tin on soil microbial bio?

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