叶菌唑的光解和土壤降解特性

Photolysis and soil degradation of metconazole

为明确叶菌唑的环境降解规律,采用室内模拟实验方法,研究了叶菌唑在不同条件下的光解和土壤降解特性.结果表明,在紫外灯照射下,不同p H时,叶菌唑在中性条件下的光解速率最快;环境物质二价铁离子、三价铁离子、硝酸根离子和亚硝酸根离子对叶菌唑的光解均具有抑制作用.叶菌唑在3种不同土壤中的降解顺序为南京黄棕壤>东北黑土>江西红壤,降解半衰期分别为35.9、51.7、60.3 d,属于中等降解农药;土壤含水量(20%—60%)越高,叶菌唑降解速率越快,当土壤含水量为饱和含水量的80%时,微生物生长将受到抑制,降解速率减慢;土壤中微生物和有机质能加快叶菌唑的降解,在微生物和有机质存在的条件下叶菌唑降解速率分别提高1.1倍和2.3倍.研究结果可为叶菌唑的合理使用和环境安全性评价提供科学依据.

In order to understand the environmental degradation of metconazole, photolytic and soil degradation of metconazole under different conditions were investigated by the indoor simulation method. The results showed that the photolytic rate of metconazole was the fastest under neutral conditions. Environmental matters such as ferric ions, ferrous ions, nitrate and nitrite inhibited the degradation of metconazole. The degradation rate of metconazole in three types of soils followed the order of Nanjing yellow-brown soil 〉 Northeast black soil 〉 diangxi red soil, and their degradation half lives were 35.9, 51.7 and 60.3 days respectively, which indicated metconazole belongs to medium degradation pesticides. The degradation rate of metconazole accelerated with the increase of soil moistrue （ 20%--60% ）, but decreased when the moistrue reached 80% of the saturation content due to the inhibition of microbical growth. The organic matters and microorganisms of the promoted the degradation of metconazole. The degradation rates of metconazole were improved by 1.1 and 2.3 times in the presence of microorganisms and organic matter. The results provided a scientific basis for rational use and environmental safety assessment of metconazole.