混剂中毒死蜱在水稻及稻田中的残留消解动态研究

为探讨25%异丙威·毒死蜱乳油中毒死蜱在水稻及稻田中的残留消解动态,采用气相色谱-氮磷检测器(GC-NPD)法对水稻及稻田中的毒死蜱残留量进行测定,旨在为该药在水稻上的合理使用提供科学依据。结果表明:毒死蜱在稻田水、土壤和植株中的残留消解动态规律均符合一级动力学方程,消解半衰期分别为1.45~3.48 d、3.16~6.36 d和2.05~2.98 d。毒死蜱在稻田土壤、糙米、谷壳和植株中的最终残留量随施药剂量、次数的增加而增加,随采样时间延长而降低。按推荐剂量1 800 g/hm~2和1.5倍推荐剂量2 700 g/hm~2各施25%异丙威·毒死蜱乳油3~4次,距末次施药33 d,土壤中毒死蜱的最大残留量分别为0.044 7 mg/kg和0.081 2 mg/kg,植株中毒死蜱的最大残留量分别为0.047 9 mg/kg和0.063 2 mg/kg,收获的糙米中毒死蜱的最大残留量分别为0.045 4 mg/kg和0.076 5 mg/kg,谷壳中毒死蜱的最大残留量分别为0.084 3 mg/kg和0.093 6 mg/kg,均低于我国规定的毒死蜱在稻谷中的最大残留限量(0.5 mg/kg),此时收获的稻谷食用安全。

Residue and Degradation Dynamics of Chlorpyrifos in Mixed Agent in Rice and Paddy Field

In order to discuss the residue and degradation dynamics of 25% isoprocarb and chlorpyrifos EC in rice and paddy filed,this study had used the measurement technique of GC-NPD to determine the residues of chlorpyrifos in rice and paddy field,so as to provide scientific basis for the reasonable usage of this agent in rice and paddy.The results showed that the curve of residue dynamics of chlorpyrifos in water,soil and plants accorded with the first-order kinetics equation,and the half-lives of chlorpyrifos were 1.45-3.48 d in water,3.16-6.36 d in soil,2.05-2.98 d in plants,respectively.The final residues of chlorpyrifos in soil,brown rice,husk and plants,increased correspondingly with the increase of spraying dosage and times,and decreased accordingly with the prolonging of sampling time.When 25% isoprocard and chlorpyrifos EC was applied 3 or 4 times at recommended dosage and 1.5 times recommended dosage in rice field,over 33 days after the last application,the final residues maximum of chlorpyrifos were 0.044 7 mg/kg and 0.081 2 mg/kg in soil,0.045 4 mg/kg and 0.076 5 mg/kg in brown rice,0.084 3 mg/kg and 0.093 6 mg/kg in husk,0.047 9 mg/kg and 0.063 2 mg/kg in plants,respectively,which all were below the maximum residue limit(MRL) 0.5 mg/kg of rice in China,and the rice harvested at this time was safe for human consumption.