4种农药的光解动力学研究

Photolysis Kinetics of Four Pesticides

以氙灯与太阳光为光源,测定了环戊烯丙菊酯、甲基毒死蜱、三唑磷和γ-六六六4种农药在水中的光解特性。结果表明,4种农药的光解规律均符合一级动力学方程,光解半衰期分别为:0.85、3.39、6.56、15.68h(氙灯)与1.51h、9.90h,9.90d、13.86d(太阳光),光解速率大小依次为:环戊烯丙菊酯>甲基毒死蜱>三唑磷>γ-六六六。其中,环戊烯丙菊酯最易光解,其在氙灯下的光解速率约为太阳光下的2倍;甲基毒死蜱与三唑磷次之,氙灯与太阳光下的光解速率比分别为3和36;γ-六六六最难光解,氙灯下的光解速率约为太阳光下的20倍。不同农药对不同光源的敏感性不同,农药在氙灯下的光解特性可基本反映其在太阳光下的光解性,但不同农药在两种光源下的光解速率的相关性不显著。

The photolysis characteristics of four pesticides （bioallethrin, chlorpyrifos-methyl, triazophos and gamma-HCH） in water were studied under Xenon lamp and sunlight. Results showed that the photolysis of all the four pesticides fitted to the first-order dynamic equation. The half-lifes were 0.85 h, 3.39 h, 6.56 h, 15.68 h under xenon lamp and 1.51 h, 9.90 h, 9.90 d, 13.86 d in sunlight respectively. The photolysis rates were as follows：hioallethnn 〉 chlorpyrifos-methyl 〉 triazophos 〉 gamma-HCH. The rate of bioallethrin, under xenon lamp, was the highest among four pesticides, and it was about 2 times that of under sunlight. The rates of chlorpyrifos-methyl and triazophos under xenon lamp were 3 times and 36 times that of under sunlight respectively. The photolysis reaction was very difficult to take place for gamma-HCH in water, and the rate under xenon lamp was about 20 times over that of under sunlight. The sensitivities of different pesticides to different light sources were dissimilar. The photolysis characteristic of pesticide under xenon lamp can reflect that of under sunlight on the whole, but the photolysis rates were not evident correlation for different pesticides under the two illumination conditions.