酰胺类除草剂对土壤微生物活性的影响以及P450对酰胺类除草剂的降解行为研究

【作者】 邵波；

【导师】 刘维屏；

【作者基本信息】 浙江大学 ， 环境科学， 2003， 硕士

【摘要】 本文研究了四种酰胺类除草剂丙草胺、丁草胺、乙草胺和异丙甲草胺对两种土壤酶（过氧化氢酶，多酚氧化酶）的影响。实验结果表明，四种酰胺类农药浓度变化0、1、10、50、100μg．g^-1对土壤两种酶活性影响程度有所不同，对过氧化氢酶的影响大于多酚氧化酶，其中丙草胺最为明显；高浓度组对这两种酶的影响大于低浓度组，成为主要影响。可利用过氧化氢酶对乙草胺、丙草胺、丁草胺和异丙甲草胺农药的敏感性，将它作为指标酶去考察或判断农药对土壤生态环境的污染程度，尤其是丙草胺对土壤的污染程度。 本文同时研究了四种酰胺类农药丙草胺、丁草胺、异丙甲草胺和异丙甲草胺对土壤呼吸的影响以及变化规律。结果表明，土壤呼吸强度对异丙甲草胺等四种酰胺类农药较为敏感，在农药施入的初期，即对土壤的呼吸有强烈的抑制作用，抑制程度达22％～35.2％。随着培养时间的延续，受抑制的土壤呼吸强度将逐渐恢复，并出现一定的刺激效应，一个月（34天）后与对照无明显差异。通过土壤呼吸影响评价，得出四种酰胺类农药即异丙甲草胺、乙草胺、丙草胺和丁草胺，危害系数＜20均属于低毒或无实际危害的农药，即对土壤微生物的危害都较小。 本文从水稻中提取细胞色素P450，选择酰胺类除草剂丁草胺、异丙甲草胺及其对映异构体做为供试农药，研究水稻细胞色素P450对这两种除草剂的代谢动力学，考察水稻细胞色素P450对丁草胺和异丙甲草胺的降解性能。实验结果表明，水稻细胞色素P450s能很快降解丁草胺和异丙甲草胺及其对映异构体农药，降解半衰期14.68～150.52min之间。随着农药浓度的增加(20μgml^-1、30μgml^-1、40μgml^-1)，降解速率下降，其相应的半衰期延长。降解速率丁草胺＞异丙甲草胺＞异丙甲草胺S-isomer。更多还原

【Abstract】 Influence of Chloroacetanilide herbicides pretilachlor , butachlor, acetochlor and metoalchlor on soil catalase and polyphenol oxidase activities was investigated at concentration of 0.1 .10.50. 100|4g. g-1 respectively. Results show that herbicides have different effects on this two soil enzymes, they have stronger effect on catalase than on polyphenol oxidase, particularly for pretilachlor; the higher concentration of herbicides the more effect to land enzyme. So we can use catalase as index enzyme, to explore and judge the effect of pesticide to soil ecological environment.The effects of these four Chloroacetanilide herbicides to soil respiration were also studied in this paper. Results show that soil respiration had high sensitivity to four Chloroacetanilide herbicides. At the beginning of apply, soil respiration was inhibited by the herbicides strongly, inhibition degree is 22.0%~35.2%. The soil respiration can recover gradually, and also show some stimulation effect, and they have no apparent effect after 34 days. Judging by soil respiration, we can conclude that Chloroacetanilide herbicides are low toxicity or no actual harm-ness pesticide, in other words that they are almost harmless to soil microorganism.Cytochrome P450 was extracted from rice, and metabolic kinetics of cytochrome P450 to butachlor, metoalchlor and their enantiomers are studied. The results show that cytochrome P450 can degrade butachlor, metoalchlor and their enantiomers rapidly, the degradation half-life-time between 14.68 to 150.52min. The degradation rate lower as the pesticide concentration higher (20ug ml"1, 30ug ml"1 and 40ug ml"1), the corresponding half-life-time longer. The degradation rate of these herbicides followed the order: butachlor> metoalchlor> metoalchlor S-isomer.更多还原