【作者】 熊雅琴；

【导师】 杨仁斌；

【作者基本信息】 湖南农业大学 ， 环境工程， 2006， 硕士

【摘要】 双草醚钠盐是一种超高效、低毒、广谱的稻田除草剂。目前国内外对该农药环境行为方面的研究较少，尤其是对农药的水解尚未见报道。本论文主要探讨了水环境中双草醚钠盐水解行为以及其影响因素，并用正交试验设计法研究了影响农药在天然水体中降解的主要环境因素，为进一步研究农药在水体中的行为以及防止和治理农药污染提供了科学依据。主要内容如下： 研究了双草醚钠盐水解动力学进行，结果表明：（1）水体的酸碱度影响双草醚钠盐在水体中的水解，不同pH值的水体中双草醚钠盐的水解速率不同。在pH值为3、5、7、9、11的缓冲溶液中，双草醚钠盐的水解半衰期分别为：2.61、36.67、288.75、266.54、4.10d。这表明在酸性环境中有利于双草醚钠盐的降解，而在中性或者弱碱性条件下水解缓慢，化学稳定性好，而强碱性环境下的水解速度有明显回升。（2）在试验温度范围（15-45℃）内，双草醚钠盐水解速率受温度影响较大，随温度升高而加快。pH4时，双草醚钠盐的温度效应系数为2.10，即在其它条件一定的情况下，温度每提高10℃，水解速率平均增加1.1倍。（3）pH4时，双草醚钠盐水解反应的平均活化能为54.28kJ／mol，平均活化焓为51.76kJ／mol。双草醚钠盐的水解反应的活化能和活化焓与温度之间没有明显相关性。而双草醚钠盐水解反应的活化熵变化随温度升高而减少，表现出显著相关性，其平均活化熵为-98.98kJ／mol·K。（4）不同初始浓度的双草醚钠盐在水溶液中的水解速率快慢的顺序为20mg／L＞10mg／L＞5mg／L，双草醚钠盐的水解反应初始速率随着农药浓度的增大而加快，但是对双草醚钠盐的水解半衰期的影响不大。 研究了环境因素对双草醚钠盐水解的影响，结果表明：（1）腐殖质的存在对双草醚钠盐的水解有促进作用。水溶液中的腐殖酸（HA）和富里酸（FA）可以加快双草醚钠盐的水解反应，并且HA和FA浓度越大，使双草醚钠盐水解得越快。HA和FA浓度从0增大到1000mg／L，双草醚钠盐的水解半衰期分别缩短了52％和39％。（2）利用通入高纯N₂、O₂来调节反应体系氧含量，试验结果表明：溶解氧浓度对水体的氧化还原电位有显著影响。同时，在氧含量为0.1、0.55、5.21、7.56、9.4mg／L的水解半衰期分别为：97.6、74.5、61.3、59.7、41.5h，表明双草醚钠盐的降解速率随着氧含量的升高而加快。（3）在无机盐浓度较低（0.01mol／L）更多还原

【Abstract】 Bispyribac-sodium is a selective, systemic post-emergence herbicide. Its chemical abstracts name is sodium 2,6-bis[(4,6-dimethoxy-2-pyrimidinyl)oxy] benzoate. Bispyribac-sodium has been used widely in world. Previous studies focused mainly on herbicidal efficacy and mechanism of bispyribac-sodium, little information was available about on its degradation principle in the environment, especially in water. In order to extend its use and provide some fundamental data for assessing the bio-environment safety and scientific application of bispyribac-sodium, the degradation behavior and the influencing factors of bispyribac-sodium in different environmental waters, and hydrolysis kinetics in Aqueous solutions were studied in this paper.The main results were summarized as following:Hydrolysis impact on temperature and pH was studied first. The results showed that the pH and temperature were critical factors determining the degradation rate of bispyribac-sodium in aqueous solutions. The hydrolysis of bispyribac-sodium was easily took place in acid water. And the pH was lower the degradation rate was quicker. But bispyribac-sodium was stable in basic and neutral water. In addition, the higher temperature accelerated the hydrolysis rate in acid water. When the pH value was 4, the temperature coefficient was 2.1.The activation energy (Ea) and the activation enthalpy (AH) had no visible relation with the temperature, but the entropy (AS) increased with the increasing temperature, and the mean activation entropy was -98.98 kJ/mol. In addition, the hydrolysis rate of different initial concentration of bispyribac-sodium was in order of 20 mg/L> 10 mg/L>5 mg/L. The hydrolysis rate of bispyribac-sodium increased with initial concentration of bispyribac-sodium enhanced.Influences of Humus, inorganic salts, DO and nitrogenous fertilizers on hydrolysis of bispyribac-sodium were studied. The hydrolysis of bispyribac-sodium were obtained at 298K and the pH 3.The result showed that Humus could promote the更多还原