Degradation of S-metolachlor in soil as affected by environmental factors
Degradation of S-metolachlor in soil as affected by environmental factors
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环境因素影响土壤中异丙甲草胺的降解
DOI：
10.4067/s0718-95162014005000015
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发表时间：
2014-03-01
影响因子：
3.9
通讯作者：
Wu, X.M
中科院分区：
文献类型：
--
作者：
Long, Y.H;Li, R.T;Wu, X.M
精-异丙甲草胺是一种很有前途的异丙甲草胺替代品;然而，人们担心其在土壤施用后的环境归宿。研究了环境因子对精异丙甲草胺在土壤中降解速率的影响。在60 d的培养期内，通过提取和检测异丙甲草胺在土壤中的残留量，研究了不同条件下异丙甲草胺在土壤中的降解速率。精异丙甲草胺在5种土壤中的降解均符合一级动力学方程，其半衰期（T1/2）为26.3 ~ 40.1d，受土壤有机质含量的控制。精异丙甲草胺在1 ℃土壤中的降解速率随温度的升高而增大。一级半衰期从35 ℃时的23.7天到10 ℃时的64.8天不等。土壤含水量对除草剂降解率的影响顺序为：80%> 60%> 40%> 20%（1 cm）。灭菌土壤中S-异丙甲草胺的降解速率是未灭菌土壤中的3.3倍，表明微生物降解是S-异丙甲草胺在土壤中降解的主要原因。异丙甲草胺的降解速率随初始浓度的增加而降低。这些研究结果可能对S-异丙甲草胺在农业土壤中的环境归趋具有实际意义。环境因素，特别是土壤有机质、温度和湿度，应与精异丙甲草胺的最低有效施用量相结合，以获得满意的除草效果，减少除草剂径流，并最大限度地减少对环境质量的影响。
S-Metolachlor is a promising alternative to metolachlor; however, there are concerns about its environmental fate following soil application. The present study was conducted to investigate the effects of several environmental factors on the degradation rate of S-metolachlor in soil. The rate of S-metolachlor degradation in soil under different conditions was determined by extracting and detecting residual levels over a 60 d incubation period. Degradation of S-metolachlor in the five tested soils followed the first-order kinetics, yielding the half-lives (T 1/2 ) varying from 26.3 to 40.1 d, which was significantly controlled by soil organic matter (OM) content. The degradation rate of S-metolachlor in 1﹟soil increased with increasing temperature. The first-order half-lives ranged from 23.7 d at 35 °C to 64.8 d at 10 °C. Soil moisture content influenced the rate of herbicide degradation in the following order: 80 > 60 > 40 > 20% for 1﹟soil. The degradation rate of S-metolachlor in sterilized soil was 3.3 times slower than in corresponding unsterilized soil, indicating that microbial degradation was the predominant contributors to dissipation of S-metolachlor in soil. The degradation rate of S-metolachlor decreased as the initial concentration increased. These findings might have practical implications for the environmental fate of S-metolachlor in the agricultural soil. Environmental factors, especially soil OM, temperature and moisture, should be considered in combination with the minimum effective application rate of S-metolachlor for achieving satisfactory weed-control efficacy, reducing herbicide runoff, and minimizing effects on environmental quality.