戊唑醇在土壤中的光降解行为动力学研究

Kinetics of tebuconazole photodegradation behavior in soil

以高压汞灯为光源, 研究了戊唑醇在土壤中的光化学降解行为及各种因素对光降解的影响。结果表明, 戊唑醇在高压汞灯下的光降解符合化学反应一级动力学方程。戊唑醇在不同类型土壤中的光解速度为砂姜黑土〉河潮土〉红壤〉棕壤〉紫泥土, 这与土壤有机质和黏粒含量有关；随土壤含水量增加, 戊唑醇的光解速率加快, 主要是因为水分增加了农药分子在土壤中的移动性；中性环境较酸或碱性环境更有利于戊唑醇的光解；当土壤中戊唑醇的浓度为20~100 mg·kg-1时, 其光解速率与浓度呈负相关关系；表面活性剂十二烷基苯磺酸钠和十六烷基三甲基溴化铵对戊唑醇的降解均具有光猝灭作用；不同添加剂量的尿素对戊唑醇的光解几乎均表现出光猝灭作用, 氯化钾则表现为敏化作用。高压汞灯下, 戊唑醇在土壤中降解半衰期为10~22 min。

Kinetics of tebuconazole photodegradation in soil and the associated influencing factors were investigated under high-pressure mercury lamp. The results show that tebuconazole photodegradation in soil matches with the first order chemical reaction series. The order of tebuconazole photodegradation rate in different soils is as follows： lime concretion black soil 〉 river cultivated fluviogenic soil 〉 krasnozem 〉 brown earth 〉 purple soil. The order is closely related with organic matter and clay content of the soil. Tebuconazole photodegradation accelerates with increasing soil moisture, because that water enhances pesticide molecule mobility in soils. Tebuconazole is more rapidly photodegraded in neutral than in acid and alkaline soil conditions. Negative correlations exist between photodegradation rate and tebuconazole concentration of 20~100 mg·kg-1. Surfactants, DDBS and HDTMA have photoquenching effect on tebuconazole photodegradation. Urea photoquenches tebuconazole photodegradation, while KCl exhibits photosensitizing effect. Degradation half-life of tebuconazole in soil is 10~22 minutes.