Abstract: g author [Abstract]　Objective　To investigate the factors affecting the degradation of niclosamide in the soil, so as to provide the evidence for the assessment of the environmental safety in the field snail control with niclosamide. Methods　A high performance liquid chromatography was established for the determination of niclosamide in the field. Then, the degradation of niclosamide was investigated in soils with different moistures (10%, 30%, 50%, 70% and 90%), temperatures [(15 ± 1), (25 ± 1), (35 ± 1) ℃], initial concentrations (1, 5, 10 mg/kg) and in sterilized and non-sterilized soils. In addition, the degradation of niclosamide was fitted with the first-order kinetics equation, and the degradation half-life was calculated. Results　The niclosamide residues gradually decreased over time in soils with different moistures, and a higher rate of degradation was seen in soils with a higher moisture. The degradation half-life of niclosamide reduced from 4.258 d in the soil with a 10% moisture to 2.412 d in the soil with a 90% moisture. The niclosamide residues gradually decreased over time in soils with different temperatures, and a higher rate of degradation was seen in soils with a higher temperature. The degradation half-life of niclosamide reduced from 4.398 d in the soil with a temperature of (15 ± 1) ℃ to 2.828 d in the soil with a temperature of (35 ± 1) ℃. The degradation half-lives of niclosamide were 3.212, 3.333 d and 3.448 d in soils containing niclosamide at initial concentrations of 1, 5 mg/kg and 10 mg/kg, and > 30 d and 3.273 d in sterilized and non-sterilized soils. Multiple linear regression analysis revealed that soil microorganisms (P = 0.010), moisture (P = 0.000) and temperature (P = 0.002) affected the half-life of niclosamide degradation. Conclusion 　The degradation of niclosamide in soils fits the first-order kinetics equation, and presence of microorganisms, a high temperature and high moisture may accelerate the degradation of niclosamide in the soil.

Key words: Niclosamide, Degradation, Soil, Half-life

摘要： 目的　了解灭螺药氯硝柳胺在土壤中降解的影响因素，为评价氯硝柳胺现场灭螺的环境安全提供参考依据。方法　建立土壤中氯硝柳胺含量检测的高效液相色谱法，并分析氯硝柳胺在不同含水量（10%、30%、50%、70%、90%）、不同温度[（15 ± 1）、（25 ± 1）、（35 ± 1） ℃]、不同初始浓度（1、5、10 mg/kg）及灭菌和未灭菌土壤中的降解。采用一级反应动力学方程对氯硝柳胺降解进行拟合，计算其降解半衰期。结果　随着时间延长，氯硝柳胺残留量在不同含水量土壤中逐渐降低；土壤含水量越高，降解越快，氯硝柳胺在10%～90%含水量土壤中的降解半衰期由4.258 d下降为2.412 d。在不同温度土壤中，氯硝柳胺残留量随时间延长而逐渐下降；温度越高，氯硝柳胺降解越快，氯硝柳胺在（15 ± 1）～（35 ± 1） ℃土壤中的降解半衰期由4.398 d下降为2.828 d。1、5、10 mg/kg初始浓度氯硝柳胺在土壤中的降解半衰期分别为3.212、3.333、3.448 d，氯硝柳胺在灭菌和未灭菌土壤中的降解半衰期分别为> 30 d和3.273 d。多元线性回归分析发现，土壤中微生物（P = 0.010）、含水量（P = 0.000）和温度（P = 0.002）对氯硝柳胺降解半衰期均有影响。结论　氯硝柳胺在土壤中的降解符合一级反应动力学方程，土壤中存在微生物、温度高、含水量增加可促进氯硝柳胺在土壤中的降解。

关键词: 氯硝柳胺, 降解, 土壤, 半衰期