50%禾草丹·异丙隆WP在直播水稻田中的消解动态

Residue dynamics of 50% thiobencarb·isoproturon WP in paddy fields

[目的] 评价禾草丹和异丙隆在直播水稻田施用后的生态环境和糙米的安全性。[方法] 进行2年3地田间试验,采用高效液相色谱-串联质谱法（HPLC-MS/MS）测定稻田土壤中禾草丹和异丙隆的消解动态及其在糙米和土壤中的最终残留。[结果] 在0.01～0.5mg/kg添加水平下,禾草丹和异丙隆在土壤和糙米中的平均回收率为80.4%～108.8%,变异系数为0.6%～12.6%。田间试验[结果]表明：禾草丹和异丙隆在稻田土壤中施药2h后的原始沉积量分别为0.141～1.134mg/kg和0.066～0.543mg/kg,半衰期分别为1.1～4.2d和0.4～4.4d。收获期稻田土壤和糙米中两者的最终残留量均未检出。[结论] 禾草丹和异丙隆均属于易降解农药,50%禾草丹·异丙隆WP按推荐剂量（900g a.i./hm2,即1 800g/hm2）施用于直播水稻田中,施药1次,收获的糙米安全。

[Objective]The aim of this study was to evaluate the ecological safety of thiobencarb and isoproturon in rice and soil of paddy fields.[Method]The field trials on dissipation and final residue of50%thiobencarb·isoproturon WP were conducted in three locations for two years.High performance chromatography coupled with tandem mass spectrometry（HPLC-MS/MS）was employed to determine thiobencarb and isoproturon simultaneously.[Result]The average recoveries of thiobencarb and isoproturon in soil and rice samples were ranged from 80.4%-108.8% with the relative standard deviation of0.6%-12.6% when the fortified levels were 0.01-0.5mg/kg.Degradation dynamic trials indicated that the original deposit amounts of thiobencarb and isoproturon in paddy soil after 2hspraying were 0.141-1.134mg/kg and 0.066-0.543mg/kg and the degradation half-lives were 1.1-4.2dand 0.4-4.4d,respectively.The final residues of thiobencarb and isoproturon in paddy soil and rice samples were not detected at harvest.[Conclusion]Both thiobencarb and isoproturon belonged to easily degradable pesticides.The50%thiobencarb·isoproturon WP can be applied to paddy fields at the recommended dosage with safe harvested rice.