氟铃脲水解与土壤降解研究

Research on the hydrolysis and soil degradation of hexaflumuron

采用室内模拟方法,研究了东北黑土、江西红壤和南京黄棕壤中氟铃脲在好气、渍水、灭菌条件下的降解特性及pH值、温度、Cu2+和表面活性剂十二烷基磺酸钠(SDS)对水解的影响。结果表明,氟铃脲的水解和土壤降解均符合一级动力学方程。氟铃脲在碱性条件下的水解速率比在中性和酸性条件下快。水解速率随温度升高而加快,平均温度效应系数为1.11。水解活化能与温度无相关性,活化熵与温度则显著相关。在35℃、pH值为9的条件下Cu2+显著促进氟铃脲水解,SDS则表现为抑制作用。氟铃脲在东北黑土中降解最快,其次是南京黄棕壤和江西红壤,不同处理条件下降解速率从大到小为渍水、好气、灭菌。氟铃脲在土壤中降解主要为微生物降解,厌氧微生物起重要作用。

The given paper is aimed to present our investigation and analysis of the influences of the degradation characteristic features of hexaflumuron in three different types of soils, the black soil in China Northeast, the red soil in Jiangxi and the loess, or the yellow-brown soil in Nanjing under the aerobic, anaerobic and aseptic conditions in the laboratory conditions. Our research has also been done aiming at the observation and analysis of the effects of different temperatures, different pH values and concentrations of copper ion （Cu 2＋ ） and surfactant （sodium dodecyl sulfate, SDS） on the hydrolysis of hexaflumuron in the aqueous solutions. The results of our research have shown that, both the hydrolysis and degradation in the soils of hexaflumuron tend to follow the first-order kinetics law in all the above-mentioned cases. In addition, we have conducted the hydrolysis in the alkaline condition in the most prompt way, in comparison with those in the acid and neutral solutions. As a result, we have found the hydrolysis rate can be expected to get accelerated with the temperature rising, under the effect of temperature coefficient being 1.11. The activation entropy has indicated a significantly negative correlation with the temperature, though no obvious correlation has been found between the activation energy and temperature in our study. Nevertheless, in buffer solution of pH=9 at 35 ℃, the hydrolysis rate of hexaflumuron has proved to be remarkably accelerated with the increase of Cu 2＋ concentration in the range of 25 500 μg/L. Moreover, we have found that, the sodium dodecylsulphate turns out playing an inhibitory function while the restraining degree can be enhanced with the increase of the concentration of SDS in the range of 100-900 mg/L. Among the three types of soils, hexaflumuron can be made well observing the following sequence： the yellow-brown soil of Nanjing 〉 the black soil of northeast 〉 the red soil of Jiangxi, respectively. Thus, the results we have gained prove that the alkaline condition and higher amount of organic matter content in the soil really have significant effects on the degradation of hexaflumuron. Meanwhile, the clay content in the soil tends also contributes to the acceleration of the rate of soil degradation. To be more accurate, the order of rating under different processing conditions proves to be in the following descending order： anaerobic 〉aerobic〉sterilization, respectively, which indicates that the process of hexaflumuron has been made degraded mainly by the biodegradation in the soils and the activities of anaerobe are likely to exert positive influence on the soil degradation of hexaflumuron.