氰戊菊酯在土壤中的降解及其影响因子研究

研究了氰戊菊酯在青紫泥、乌栅土以及黄泥土3种不同类型土壤中的降解,并探讨了土壤理化性质、外界环境条件等对其降解的影响。结果表明:氰戊菊酯在3种土壤中的降解半衰期分别为25.3、19.4、17.7d,降解速率常数分别为0.0274、0.0357、0.0392,即在青紫泥中降解最慢,黄泥土中降解最快。而经过灭菌后的土壤,其降解明显减缓,半衰期延长。由此可见,土壤中降解过程主要是微生物的作用。影响降解的最主要因素是有机质含量,其次为土壤酸碱度,即有机质含量越高,土壤碱性越强,则其半衰期越短,降解速度越快。除此之外,外界环境条件对氰戊菊酯的降解影响也较大,温度越高,湿度越大,降解越快;另外,药剂的添加浓度对降解也有重要的影响,添加浓度越高,降解速率越慢。

DEGRADATION DYNAMICS OF FENVALERATE AND ITS INFLUENCING FACTORS IN SOIL

Degradation dynamics of fenvalerate in three soils was studied to explore effects of soil properties on degradation. Results show that the half-time of fenvalerate in the soils was 25.3, 19.4, and 17.7 days, and the degradation rate constant 0.027 4, 0.035 7, 0.039 2, respectively, demonstrating that fenvalerate degradated the fastest in huangni soil and the slowest in qingzi soil. Degradation of fenvalerate in soils seemed to be attributed to activities of microbes, as the degradation rate was lower in sterilized soil. The most important factors affecting its degradation rate in soil are organic matter content and pH. Environmental factors also affect fenvalerate degradation rate. The half-time of fenvalerate decreased with rising temperature and moisture, while its degradation rate did with higher initial application rate of the pesticide.