氟啶胺的水解与土壤降解特性研究

On fluazinam hydrolysis and degradation features in the soil

通过室内模拟试验研究了氟啶胺在不同pH值和温度下的水解动态规律,以及在南京黄棕壤、江西红壤、东北黑土中于好气、渍水、灭菌土壤环境下的降解特性。结果表明,氟啶胺的水解与土壤降解均符合一级动力学方程。氟啶胺在酸性溶液中稳定,在碱性溶液中则水解较快,且25℃下在pH值为5、7、9、11的缓冲液中的水解半衰期分别为141.46 d、43.87 d、5.63 d、4.50 d;水解速率随温度升高而增加,在pH值为7的条件下,15℃、25℃、35℃时水解半衰期分别为73.74 d、43.87 d、29.25 d,平均温度效应系数为1.59,平均活化能为31.10 kJ/mol。氟啶胺平均降解速率从大到小的不同土壤为东北黑土、南京黄棕壤、江西红壤,降解速率受pH值与有机质质量分数的影响;降解速率从大到小的不同处理为渍水、好气、灭菌,厌氧微生物为主要影响因素。

This paper is inclined to make an investigation of fluazinam hydrolysis and degradation features in the soil at different pH values and temperatures. For our research purpose, we have chosen three types of soil samples, including yellow soil from Nanjing, red soil from Jiangxi and black soil from the Northeast of China under aerobic, drowned and aseptic conditions. The results of our investiga- tion prove that both the processes of fluazinam hydrolysis and degra- dation in the soil are fit for the first-order kinetics equation. Whereas the hydrolysis rate at the same temperature goes slow in the acidic so- lution, it tends to increase in the alkaline solution. And at the temperature of 25 ℃, the haff-life of fluazinam degradation at pH = 5, 7, 9, 11 turns to be 141.46 d, 43.87 d, 5.63 d and 4.50 d. Fluazinam hydrolysis rate increases as the temperature rises, and the half-life values in the condition of pH = 7 and the temperatures of 15 ℃, 25 ℃, 35 ℃ prove to be 73.74 d, 43.87 d, 29.25 d, with the average temperature effect coefficient being 1.59, with the average activation energy of 31.10 kJ/mol, and the absolute value of activa- tion entropy of hydrolysis increased with the increase of temperature. The consequential order of fluazinam degradation rate in the soil under different processing conditions proves to be drowned 〉 aerobic 〉 aseptic. Fluazinam degradation rate in the soil tends to increase by 1 -4 times in drowned than in aerobic, showing that the anaerobe plays an obvious role in it. The degradation rate of fluazinam in the soil can be shown in the order from high to low： black soil from Northeast China 〉 yellow soil from Nanjing 〉 red soil from Jiangxi. The linear regression can also be found in the half-life of fluazinam degradation in the soil and soil pH value, the organic matter content, the cation exchange capacity, and, the clay content. As can be seen, in aseptic and aerobic, the half-life of fluazinam degradation in the soil and clay content reveal a nice linear correlation, but in drowned, the half-life of fluazinam degradation in the soil and the pH value turn out to be also well linear-correlated, thus showing that pH value, the organic matter content and the clay content of soil serve as the main factors.