新农药硫肟醚在土壤中降解的影响因子研究

Factors influencing the degradation of insecticide HNPC-A9908 in the Soil

在实验室条件下对新农药硫肟醚（O-（3-苯氧苄基）-2-甲硫基-1-（4-氯苯基）丙基酮肟醚）在土壤中降解的影响因子进行了研究。结果表明，在20d的培养时间内，随着土壤含水量的增加，硫肟醚的降解速率加快。当土壤含水量增加到80％（质量分数）时，其降解率达到最大（46．73％），然后随土壤含水量增加反而下降。随着土壤温度的升高，硫肟醚在土壤中的降解速率增加。30℃时降解速率达到最大（47．83％），以后温度继续升高，其降解速率呈现出下降趋势。在5—100mg／kg的质量比范围内硫肟醚在土壤中的降解速率随其质量比的增加而提高；但当质量比继续增加时，硫肟醚的降解速率表现出下降趋势。硫肟醚在土壤中的降解遵循一级动力学方程，其在非灭菌与灭菌土壤中的降解速率常数k分别为8．106×10^-3和1．63×10^-3；半衰期分别为85．5d和425．2d。微生物对硫肟醚在土壤中的降解具有显著的影响。

The present article has made an investigation of novel insecticide HNPC-A9908 [ O-（ 3-phenoxybenzyl）-2-methylthio-1-（ 4- chloro- phenyl） propyl ketone oxime] in the laboratory conditions as to its factors influencing the degradation of the soil quality. The results have shown that the degradation rate of HNPC-A9908 would increase with the increasing soil water-holding capacity. The highest level would be reached when the water-holding capacity reaches 80% within the incubation time of 20 d. Then, the degradation rate would stop and drop with the increase of the water-hold capacity. Further testing results prove that its degradation rate would increase with the enhancing temperature in soil, with its highest level at 30℃. After that, the degradation rate tends to decrease even when the temperature keeps rising. Moreover, the degradation in soil tends to speed up with the concentrations of HNPC-A9908 increased in the range of 5- 100 mg/kg, and then would drop beyond the given concentration, which is proves to be in correspondence with the first-order kinetic equation. The article also proves that the degradation rate coefficient （k） of HNPC-A9908 in sterilized and non-sterilized soil （Changsha silt clay soil） are respectively 1.63 × 10^-3 and 8.106 × 10^-3 , while its half-life is 425.2 d and 85.9 d, thus indicating that microorganisms in the soil are likely able to accelerate the degradation.