丙溴磷、氯氰菊酯和百菌清在露地和温室芹菜上的农药残留降解动态评价

Degradation dynamics of residues of profenofos,cypermethrin and chlorothalonil on celery in open field and greenhouse

[目的]为确保丙溴磷、氯氰菊酯和百菌清在芹菜上的使用安全性,比较研究了其在芹菜上的农药残留降解动态差异,并结合我国农药安全管理制度提出使用建议。[方法]通过露地和温室试验,得到推荐剂量(丙溴磷450 g a.i./hm^(2)、氯氰菊酯1125 g a.i./hm^(2)、百菌清2490 g a.i./hm^(2))和2倍推荐剂量(丙溴磷900 g a.i./hm^(2)、氯氰菊酯2250 g a.i./hm^(2)、百菌清4980 g a.i./hm^(2))下3种农药在芹菜上的原始沉积量和降解规律。基于气相色谱技术建立丙溴磷、氯氰菊酯和百菌清残留量检测分析方法,分析试验数据。[结果]丙溴磷、氯氰菊酯和百菌清按照推荐剂量在芹菜上使用,露地条件下,原始沉积量分别为22.69、0.84、18.18 mg/kg,药后1 d残留量分别为17.55、0.61、14.76 mg/kg,半衰期分别为3.5、2.0、4.3 d;温室条件下,原始沉积量分别为39.88、0.98、26.81 mg/kg,药后1 d残留量分别为48.38、1.83、29.32 mg/kg,半衰期分别为3.1、1.1、4.2 d。按照2倍推荐剂量使用,露地和温室条件下,3种农药的原始沉积量都明显增大,丙溴磷和百菌清半衰期延长,而氯氰菊酯的半衰期露地条件下变化不大,温室条件下无变化。[结论]丙溴磷、氯氰菊酯和百菌清3种农药在芹菜上的残留降解规律符合一级动力学方程,半衰期分别为3.1~4.2、1.1~2.2、4.2~7.4 d,残留量随施药剂量增大而增加,相同施药剂量,温室残留量比同期露地高,降解率普遍较露地低。结合最大残留限量值及芹菜采收期,在种植过程中不建议使用丙溴磷,建议推广使用氯氰菊酯,百菌清严格按照推荐剂量使用,且每季芹菜仅可使用1次。

[Aims]The dissipation dynamics of profenofos,cypermethrin and chlorothalonil on celery were compared and studied to ensure the safe use of them on celery,and recommendations for use were made in line with China's Pesticide Safety Management System.[Methods]Through experiments in open field and greenhouse,the original deposition and degradation laws of the three pesticides at recommended doses(profenofos 450 g a.i./ha,cypermethrin 1125 g a.i./ha,chlorothalonil 2490 g a.i./ha)and twice the recommended doses(profenofos 900 g a.i./ha,cypermethrin 2250 g a.i./ha,chlorothalonil 4980 g a.i./ha)on celery were obtained.Gas chromatography technology was used to establish analytical methods for detecting residues of profenofos,cypermethrin and chlorothalonil.The test data were analyzed.[Results]Under field conditions,the original deposition of profenofos,cypermethrin and chlorothalonil at the recommended doses were 22.69,0.84 and 18.18 mg/kg,respectively,and their residues on day 1 after application were 17.55,0.61 and 14.76 mg/kg,with half-lives of 3.5,2.0 and 4.3 d,respectively.Under greenhouse conditions,the original deposition was 39.88,0.98 and 26.81 mg/kg,and their residues on day 1 after application were 48.38,1.83 and 29.32 mg/kg,with half-lives of 3.1,1.1 and 4.2 d,respectively.Under field and greenhouse conditions at twice the recommended doses,the original deposition of all the three pesticides significantly increased,and the half-lives of profenofos and chlorothalonil were prolonged,while the half-life of cypermethrin didn't change significantly under field conditions and remained unchanged under greenhouse conditions.[Conclusions]The degradation laws of profenofos,cypermethrin and chlorothalonil on celery comply with first-order kinetic equations,with half-lives of3.1-4.2,1.1-2.2 and 4.2-7.4 d,respectively.The residues increase with the increasing of application doses.Under the same application dose,the residues in greenhouse are higher than those in the field for the same period,with a lower degradation rate.In line with maximum residue limits and interval to harvest,it is not recommended to use profenofos during the cultivation process.It is recommended to promote the use of cypermethrin,while chlorothalonil should be used only once for celery in a season,strictly following the recommended dose.