乙草胺在土壤环境中的降解及其影响因子的研究

Degradation and the Influencing Factors of Acetochlor in Soils

采用实验室模拟方法研究了乙草胺在不同土壤中的降解动态。结果表明,在未灭菌的土壤中,乙草胺3种添加浓度(1.25、2.5和5.0mg·kg-1)处理的半衰期为2.8～5.1d,远远小于在灭菌土壤中3种添加浓度处理的半衰期(20.0～25.1d);乙草胺在偏碱的华北褐土中降解较快,2.5mg·kg-1处理的半衰期为4.2d,而在偏酸的东北黑土和湖南红土中降解较慢,半衰期为6.5～10.7d;土壤相对含水量由13%增至27%,乙草胺降解半衰期由7.3d缩短至3.0d;随着环境温度增高(20℃上升至30℃),乙草胺降解速度加快(半衰期由5.7d缩短至3.3d);乙草胺在黑暗条件下降解半衰期为3.8d,而在光照条件下的半衰期为5.2～6.5d。可见,5种试验因子对土壤中乙草胺的降解均有不同程度的影响。其中土壤微生物是影响乙草胺降解的主要因素,有利于土壤中微生物生长的环境因素,如偏碱的土壤、较高的环境温度和土壤湿度等,对土壤中乙草胺的降解有促进作用。

The degradation of acetochlor in soils from different climatic zon e of China was studied in laboratory. The results showed that half-life of ace tochlor was 2.8～5.1 d in non-sterilized soil and 20.0～25.1 d in sterilized soil, when the soil was treated with acetochlor of 1.25 mg·kg-1, 2.5 mg·k g-1 and 5.0 mg·kg-1, respectively. Acetochlor depletion was faster in alka line soil such as cinnamon soil from North China, with half-life time of 4.2 d ,than that in acid soil such as terra nera soil from Northeast China and terra r ossa soil from South China, with half-life time of 6.5～10.7d. Degradation ra te of acetochlor increased with the increase of soil water content and environme ntal temperature. Light intensity also had some influence on the degradation of acetochlor. Microorganism was a critical factor among all the experimental facto rs that variedly influenced acetochlor depletion in soils, and could accelerate greatly the degradation in soil The environmental factors favorable for the grow th of microbes could also enhance the degradation of acetochlor.