噻虫嗪在土壤表面及水中的光解特性

The Photolysis Characteristics of Thiamethoxam in the Water and Soil Surface

[目的]采用室内模拟试验方法,研究噻虫嗪的光解特性,为科学评价噻虫嗪的环境安全性奠定基础。[方法]在以氙灯为人工光源,光照度为4 000 lx,(25±2)℃恒温条件下进行,高效液相色谱法测定噻虫嗪在土壤表面和水中的残留量。[结果]噻虫嗪的光解特性符合一级动力学方程,在土壤表面的光解半衰期为288.8 h,黑暗对照的变化率5.6%;在水中的光解半衰期为1.8 h,黑暗对照的变化率6.2%。[结论]根据《化学农药环境安全评价试验准则》(2010),噻虫嗪在土壤表面的光解特性等级为"Ⅴ级(难光解)",在水中的光解特性等级为"I级(易光解)"。

[Aims] The photolysis characteristics of pesticide thiamethoxam was studied under laboratory conditions, and lay a foundation for the scientific evaluation ofthiamethoxam environmental safety. [Methods] Determined the residual concentration of thiamethoxam in the water and the soil surface under conditions of radiation by Xe lamp, illumination of 4 000 lx at （25±2）℃. And the residue of thiamethoxam was determined by HPLC. [Results] The photolysis characteristics of thiamethoxam was in line with the first kinetic equation, and the half-life time of 288.8 hours was found in the soil surface and the rate of change of 5.6% in the control of darkness, the half-life time of 1.8 hours was found in the water and the rate of change of 6.2% in the control of darkness. [Conlusions] In accordance with the criterion for chemical pesticide environmental safety assessment in 2010, the photolysis characteristics ofthiamethoxam in the soil surface is ＂V grade （hard photolysis）＂, and is ＂I grade （easy photolysis）＂ in the water.