【作者】 施晨辉；

【导师】 朱国念；

【作者基本信息】 浙江大学 ， 植物保护， 2009， 博士

【摘要】 以丙炔噁草酮为对象,研究了该药剂在环境和植物样品中的残留分析方法,并利用此检测手段研究了丙炔噁草酮在实验室内的土壤吸附、土壤降解、水解、光解等行为特性,比较了丙炔噁草酮在稻田环境中的降解特性。研究结果将有助于进一步了解丙炔噁草酮在环境中的迁移和转化过程,系统评价其在环境中的归宿和潜在危害,从而为该药剂的注册登记和安全合理使用以及最终消除可能产生的环境污染提供科学依据。主要结果如下：本文建立了一种测定水、土壤、稻苗、稻米样品中水稻田除草剂丙炔噁草酮残留的气相色谱分析方法。前处理方法以QuEChERS方法为基础进行优化,节约了溶剂用量、样品前处理时间与人工,将此方法应用于除食物蔬菜样品外的环境样品检测的前处理。使用带ECD检测器的Agilent6890气相色谱仪进行检测,测得检测器对丙炔噁草酮的最小检出量为1.0×10-12g,各类样品的最低定量检出限均为0.01 mg/kg.水、土壤、稻苗、稻米样品中丙炔噁草酮的添加回收率范围为82.9-112.0%,标准偏差范围为0.2-6.2%。本气相色谱条件下该方法准确度、精密度及灵敏度均达到农药残留检测的要求。丙炔噁草酮在土壤中的吸附能力为黄红壤>壤土>青紫泥,Kd值分别为103.35、97.45、76.52,属于较易吸附类型。吸附自由能△G均小于40KJ/mol,说明其在土壤中的吸附以物理吸附为主。土壤中的有机质含量与丙炔噁草酮的吸附Kd值成显著正相关,pH值、阳离子交换量及粘粒含量对其影响较小丙炔噁草酮在青紫泥和黄红壤中属于较难降解类型,在壤土中属于中等降解类型,降解半衰期分别为277.3d、233.6d、182.4d。土壤中的有机质含量与丙炔噁草酮降解半衰期成显著的负相关,粘粒含量、pH值及阳离子交换量对其影响较小丙炔噁草酮在pH=9.6、pH=7.1、pH=5.0缓冲溶液中水解半衰期分别为3.7 d、192.5d、147.5d,碱性环境中水解速率比在中性和酸性环境中迅速。分解产物经GC-MS检测,其碎片信息表明丙炔噁草酮在溶液中发生水解反应时,母体的杂环内酯键水解开环,有产物N-(2,4-二氯-5-β-丙炔氧苯基)-N’-(2,2-二甲基丙酰基)-肼甲酸生成。紫外灯照射下丙炔噁草酮的光解速率远大于氙灯,半衰期分别为3.09min、1.43h。增加光照强度、升高光解时溶液体系温度均能加快丙炔噁草酮在模拟太阳光(氙灯)下的光降解反应速度。光解反应溶液体系中丙酮含量的增加对丙炔噁草酮的光解有促进作用,而乙腈含量增加对光解反应略有抑制,甲醇对丙炔噁草酮的光降解几乎没有影响；二氧化钛的存在及含量的增加,能显著促进丙炔噁草酮的光解作用。丙炔噁草酮在缓冲溶液中的光解反应,根据光解产物质谱信息可知母体苯环上的脱氯作用是其主要作用机理,5-叔丁基-3-(4-羟基-3-β-丙炔氧苯基)-1,3,4-恶唑啉-2-酮或5-叔丁基-3-(3-p-丙炔氧苯基)-1,3,4-恶唑啉-2-酮或5-叔丁基-3-(2-羟基-5-β-丙炔氧苯基)-1,3,4-恶唑啉-2-酮均可能是其主要的光解产物。施用在水稻田的丙炔噁草酮,在大田环境中迅速消解,远快于室内的降解试验结果。其原因除药剂本身的降解以外,降雨和土壤吸附可能是丙炔噁草酮在田水中迅速消解的重要因素；大田土壤中丙炔噁草酮消解迅速的主要原因则可能是雨水冲刷的流失和稻苗的吸收有关。更多还原

【Abstract】 Method for residual analysis of oxadiargyl in plant samples and environmental samples was studied in this thesis. Using this residue determination method, we studied environmental behavior of oxadiargyl, such as soil adsorption, soil degradation, hydrolysis, and photodegradation in lab. Degradation characteristics of oxadiargyl in paddy field had been also studied and compared with the results obtained in lab. This study contributed to understanding the transference and transformation process of oxadiargyl in environment and to evaluating its fate and potential hazards in environment systematically. Results of this study would provide a scientific basis for registration, safe and reasonable using, and eliminating of possible arising pollution of oxadiargyl. The main conclusions obtained were listed as follows:A gas chromatography analytical method for determining residue of oxadiargyl had been developed. This method developed from QuEChERS. It was proved to economize on solvent, time and labor, and was proved to work well in determining residue of oxadiargyl in plant, water, and soil samples. A Agilent 6890 gas chromatogrphy spectrometry equipped with ECD was involved in this method. The recoveries of oxadiargyl in water, soil, rice straw and grain ranged from 82.9% to 112.0%, and the RSDs ranged from 0.2% to 6.2%. LOQs were 0.001,0.001,0.005, 0.005 mg/kg respectively, and LODs was 0.01 mg/kg. This method had been recommended in the study of oxadiargyl’s photodegradation, hydrodegradation, dissipation and field study for its accuracy, precision and sensitivity.The Kd values of oxadiargyl in yellow/red loam from Tong’an, loam from Ha’ erbin, purplish clayey soil from Wuxi were 103.35,97.45 and 76.52, respectively. Kd values revealed high absorption capability of oxadiargyl. Adsorption free energy(△G) of oxadiargyl in soils were all below 40 KJ/mol, showing that the adsorption largely resulted from the physical action. There had a good positive correlation between adsorption coefficient (Kd) of oxadiargyl in three different kinds of soils and the soil properties OC, while pH, CEC, and clay content had little effect on Kd.For the half-lifes of Oxadiargyl in yellow/red loam, loam and purplish clayey soil were 233.6d,182.4d and 277.3d, respectively. Oxadiargyl had low dissipation rate in yellow/red loam and purplish clayey soil, and had medium dissipation rate in loam. The degradation rate had a good negative correlation with the soil properties OC, while pH, CEC. Clay content had little effect on degradation rate.Oxadiargyl had a relatively high hydrodegradation rate in alkali buffer with half-life of 3.7d at pH=9.6, and had a very low hydrodegadaton rate in acid and neutral buffer with half-lifes of 147.5d at pH=5.0 and 192.5d at pH=7.1. The fragmentation pattern of photoproduct indicated ring-opening reaction occurred in the bone of macrocyclic lactones of heterocycle while oxadiargyl hydrolyzed in solutions, and the oxadiargyl matrix turned to be N-(2,4-Dichloro-5-prop-2-ynyloxy-phenyl)-N’-(2,2-dimethyl-propionyl)-hydrazinecarboxylic acid.The half-life of oxadiargyl photodegradation under UV light was 3.09min. It was much higher than that under Xenon lamp which with a half-life of 1.43h. Lower half-life under simulation of solar radiation(Xenon lamp) would be enhanced with the treatments of strengthening light intensity and increasing temperature. When came to solvents used in study, acetone would result in higher photodegradation rate, and lower rate gained with acetonitrile, and no rate change with methanol. Humic acid in solution would increase the photodegradation rate slightly. But in presence or increasing dosage of TiO2, photodegradation rate would be accelerated sharply. The fragmentation pattern of photoproduct indicated loss of chlorine was the dominant process when oxadiargyl photodegraded in buffer solutions. 5-tert-Butyl-3-(4-hydroxy-3-prop-2-ynyloxy-phenyl)-3H-[1,3,4]oxadiazol-2-one or 5-tert-Butyl-3-(3-prop-2-ynyloxy-phenyl)-3H-[1,3,4]oxadiazol-2-one or 5-tert-Butyl-3-(2-hydroxy-5-prop-2-ynyloxy-phenyl)-3H-[1,3,4]oxadiazol-2-one was the possible photoproduct.Dissipation rates of oxadiargyl in rice paddy field water and soil were much rapider than that in laboratory experiment. In addition to degradation by oxadiargyl itself, rainfall and oxadiargyl being absorbed by soil would be the important factors leading to the rapid disspation rate of oxadiargyl in paddy water. Washing out by rainfall and being absorbed by rice plant would be the main reasons for the rapidly dissipation of oxadiargyl in paddy soil.更多还原