【作者】 刘惠君；

【导师】 刘维屏；

【作者基本信息】 浙江大学 ， 环境科学， 2005， 博士

【摘要】 酰胺类除草剂是目前广泛应用的芽前阔叶杂草除草剂。本论文研究了四种常用酰胺类除草剂丁草胺、乙草胺、丙草胺、异丙甲草胺的生物化学行为以及异丙甲草胺在生物环境中表现的手性选择性。 研究表明,培养初期丁草胺、乙草胺、丙草胺和异丙甲草胺对土壤过氧化氢酶和脱氢酶活性、对土壤微生物量氮和微生物量碳有不同程度的抑制,但均能很快恢复,四种供试酰胺类除草剂对土壤生态的影响不大,除草剂之间也没有表现出显著差异;培养初期rac-异丙甲草胺和S-isomer高浓度处理均比常规用药量处理对土壤酶、土壤BN和Bc的影响大。随着培养时间的延续,高浓度处理的酶活性和Bc逐渐恢复并高于常规用药量处理;在整个培养周期内,常规用药量处理的BN比高浓度处理的土壤BN高;S-isomer对土壤生态的影响小于其外消旋体的影响。添加稻秆可导致土壤酶活性、土壤BN和Bc的提高,引起土壤微生物区系的变化。稻秆还田有利于减缓外来污染物对土壤生态的影响。 随着供试除草剂浓度的增加（0.0～1.6μmol/L）,脲酶的紫外吸收光谱发生红移,吸收强度减弱。供试除草剂引起脲酶荧光猝灭的主要原因是静态猝灭。各除草剂和脲酶的结合常数及结合位点数:乙草胺K=1.17×10³L/tool,n=0.81;丙草胺K=1.46×10²L/mol,n=0.67;丁草胺K=2.29×10¹L/mol,n=0.50;异丙甲草胺K=1.49×10³L/mol,n=0.84;S—异丙甲草胺K=2.22×100 L/mol,n=0.8941,S-异丙甲草胺对脲酶溶液构象的影响比异丙甲草胺略大些。反相高效液相色谱流动相组成与酰胺类除草剂的容量因子成线性关系,乙草胺、丙草胺、丁草胺、异丙甲草胺的过量热力学焓变^Δ（?）分别为0.0186 kJ/mol、0.0256 kJ/mol、0.0246 kJ/mol、0.0195kJ/mol,四种酰胺类除草剂与脲酶的结合常数K与过量热力学函数^Δ（?）和^Δ（?）存在相关关系。 rac-异丙甲草胺和其S-对映体对大型蚤的24h-LC₅₀分别为69.4 mg/L和51.2mg/L,根据毒性分级为低毒。S-对映体对大型蚤的急性毒性作用大于rac-异丙更多还原

【Abstract】 Acetanilide herbicides are widely used for preemergence control of broad-leaved weeds. The biochemical behavior of four acetanilide herbicides butachlor, acetochlor, pretilachlor and metoalchlor, and enantioselectivity of metoalchlor have been studied in this thesis.The results showed that the soil catalase and dehydrogenase activities, soil microbial biomass N （B_N） and microbial biomass C （B_C） were restrain somewhat by four acetanilide herbicides at the beginning of cultivation, but can recover soon. Four acetanilide herbicides have little effect on soil ecosystem, and no difference was observed among four herbicides. At the beginning of cultivation, soil enzyme and soil microbial biomass of high concentration was lower than low concentration, but higher than low concentration at the end of cultivation. S-isomer has lower effect on soil ecosystem than rac- metoalchlor. The parameters such as soil enzyme and soil microbial biomass are higher in rice-straw amended treatment than unamended. Rice-straw back to soil can reduce the effect of xenobiotics chemicals.According to the results of the UV difference spectrum curve, the UV difference adsorption reduced when herbicide concentration increased from 0.0 to 1.6μmol.L^-1. UV difference spectra were red-shifted and absorb-peaks became lower. It was shown that herbicide quenched the urease fluorescence mainly through a static quenching procedure. The binding constant and the number of binding site were: acetochlor K= 1.17×10³ L/mol , n=0.81 ; pretilachlor K=1.46×10²L/mol , n=0.67 ; butachlor K = 2.29×10¹L/mol, n=0.50; metolachlor K=1.49×10³L/mol, n=0.84; S-metolachlor K=2.22×10³ L/mol, n=0.8941. The linear relationship between the composition of mobile phase of RP-HPLC and capacity factor of four acetanilide herbicides has been obtained. The excess thermodynamic enthalpy （△（H|—）） of acetochor, pretilachor, butachlor and metolachlor were 0.0186 kJ/mol、 0.0256 kJ/mol、 0.0246 kJ/mol、 0.0195 kJ/mol respectively. The relationship between excess thermodynamic function with the binding constant K was suggested.The acute, 24-h LC50 value of rac-metolachlor and S-metolachlor for D. magna was 69.4 and 51.2 mg L^-1 respectively. Both of them were low toxicant based on the classification standard of toxicity. It is demonstrated in chronic test that S-metolachlor is much less toxic to D. magna than rac-metolachlor in low concentration. The data of the chronic toxicity parameters, such as longevity and number of broods per female of D. magna, implied that rac-metolachlor was 10 times more toxic than S-metolachlor. If number of young per female was considered as an evaluation parameter, rac-metolachlor was 100 times more toxic than S-metolachlor. NOEC of rac- and S-metolachlor to D. magna were 0.001 and 0.1 mg L^-1, respectively. Furthermore the environmental factors, such as montmorillonite, humic acid, pH and hardness, all had influence on the toxicity of S- metolachlor on D. magna.V_max of rice cytochrome P450 were as follow: butachlor > pretilachlor > metoalchlor > S- metoalchlor. And so are degradation rate. With the increase of herbicide concentration, the degradation rate decreased. It showed that the metabolism of rice cytochrome P450 is one reason of selectivity of the acetanilide herbicides, and maybe the reason of different effect to kill weed between rac-metoalchlor and S- metoalchlor.更多还原