甘蔗叶堆肥中3种常用杀菌剂的降解动态研究

为杀灭甘蔗叶残留病原菌且不对农田土壤造成药害,实现甘蔗叶的健康安全还田,开展了甘蔗叶堆肥中常用3种杀菌剂残留动态研究。选择多菌灵、戊唑醇、吡唑醚菌酯3种常用杀菌剂添加到甘蔗叶堆肥中,设置3个浓度5、20、50μg/g,分别在40、50、60℃下进行堆肥;首先优化液质联用参数,建立3种杀菌剂同时检测的方法,然后对降解动态进行研究。结果表明,3种杀菌剂在0.005~0.2μg/m L范围内线性关系良好,R20.999,0.1、2.0、40.0μg/g 3个浓度水平的加标回收率均在80%~105%之间,RSD10%,方法准确性和精密度良好。相同初始添加浓度时,3种杀菌剂在40℃时降解最快,表现为40℃50℃(60℃);同等温度下,当初始添加量增加时,降解速率减慢,相同初始添加浓度下降解速率随温度变高先减慢后加快;改变初始添加量对降解速率的影响更大。多菌灵降解速率明显快于其他两种杀菌剂,初始添加浓度20μg/g时半衰期为18 d左右,可以添加用来堆肥杀菌;戊唑醇和吡唑醚菌酯初始添加浓度20μg/g时半衰期大于50 d。

The Degradation Dynamics of Three Types of Common Fungicides in Sugarcane Leaves Composting

The degradation dynamic of three types of common fungicides in sugarcane was researched in order to return sugarcane leaves to soil safely after the pathogen in the leaf was killed.Three concentration levels of the pesticides including carbendazim,tebuconazole and pyraclostrobin 5 μg/g,20 μg/g and 50 μg/g were added in the compost and incubated at the temperature 40 ℃,50 ℃ and 60 ℃,repeated three times.The degradation dynamics were researched after the detection method was developed.The results showed that the standard calibration curves with R2 more than 0.999 were developed,which showed good linear relationship from 0.005 μ,g/mL to 0.2 μg/mL.The results of spiked recovery in the range 80％-105％ with the RSDs less than 10％ in the level 0.1 μg/g,2.0 μg/g and 40.0 μg/g showed the good accuracy and precision.At the same initial concentrations,the pesticides at 40 ℃ had the most rapid degradation than that under 50 ℃ and 60 ℃.At the same temperature the higher concentration pesticides had a less rapid degradation rate and at the same concentration,there was a slower degradation rate at first and more rapid later on with the temperature rise from 40 ℃ to 60 ℃.The change of initial concentration gave the degradation greater effects.The carbendazim with the shortest half-life in the sugarcane leaves composting left half only 18 days later under 50 ℃,which was suitable for killing pathogens.On the other hands,the half-life of tebuconzole and difenoconazole was more than 50 days when the initial concentration was 20 μg/g.