啶虫脒和仲丁威在水稻、土壤及田水中的残留消解动态

Residue and degradation of acetamiprid and fenobucarb in rice,soil and field water

在天津、浙江和山东三地开展了两年田间试验研究,建立了一种同时测定水稻、土壤及田水中啶虫脒和仲丁威残留量的分析方法.结果表明,在0.005—0.5 mg.kg-1添加水平范围内,啶虫脒在水稻、土壤和田水中的添加平均回收率为74.21%—106.5%,变异系数为5.6%—14.2%;仲丁威在水稻、土壤和田水中的添加平均回收率为81.12%—108.6%,变异系数为2.31%—10.9%.啶虫脒和仲丁威的最小检出量分别为3.8×10-11g和2.3×10-11g;在稻米、稻壳、植株和土壤中的最低检出浓度为0.01 mg.kg-1,在田水中的最低检出浓度为0.005 mg.kg-1.田间试验结果表明,啶虫脒和仲丁威在水稻植株、土壤和田水中的残留消解动态规律均符合一级动力学反应模型,啶虫脒在水稻植株、土壤和田水中的残留消解半衰期分别为7.0—20.4 d、2.8—7.62d和6.7—15.0 d;仲丁威在水稻植株、土壤和田水中的残留消解半衰期分别为5.7—10.0 d、10.8—15.2 d和2.6—9.5 d.以推荐施药剂量60 g/亩和1.5倍推荐施药剂量90 g/亩,在水稻灌浆期开始第1次施药,最多施药3次,距最后一次施药21 d时,啶虫脒和仲丁威在稻米中的最高残留量分别为0.42 mg.kg-1和0.054 mg.kg-1,低于我国农业行业标准规定的小麦中啶虫脒最大残留限量0.5 mg.kg-1和我国国家标准规定的糙米中仲丁威最大残留限量0.5 mg.kg-1.

A gas chromatography（GC） analytical method was developed for the simultaneous determination of acetamiprid and fenobucarb in rice,soil and field water.Meanwhile,the characteristics of acetamiprid and fenobucarb degradation and residue were investigated by field experiments in Tianjin,Zhejiang,and Shandong province.The results showed that the average recovery rates of acetamiprid in rice field water,soil,plant,rice shell and unpolished rice were in the range of 74.21%—106.5%,with their relative standard deviations of 5.58%—14.2%.The average recovery rates of fenobucarb in rice field water,soil,plant,rice shell and unpolished rice were in the range of 81.12%—108.6%,with their relative standard deviations of 2.31%—10.9%.The minimum detectable limit of acetamiprid was 3.8×10-11 g,and that of fenobucarb was 2.3×10-11 g.The minimum detectable concentrations of acetamiprid in unpolished rice,rice shell,plant and soil were 0.01 mg · kg-1,and in rice field water was 0.005 mg · kg-1.The field experiments revealed that the residual dissipation dynamics of acetamiprid and fenobucarb in plant,soil and water conformed to the first order kinetics reaction model,and they belong to easily degradable pesticide（t1/230 d）.When the recommended dosage and 1.5 times recommended dosages of 22% acetamiprid fenobucarb EC was sprayed for 2—3 times at an interval of 7 d,the maximum residual concentration of acetamiprid and fenobucarb on the 21th d after the last application were 0.419 mg · kg-1 and 0.054 mg · kg-1,respectively.These values are below the Maximum Residue Limits（MRL） for acetamiprid in wheat（0.5 mg · kg-1） by the standards of the Ministry of Agriculture of China,and the MRL for fenobucarb in unpolished rice（0.5 mg · kg-1） by the National Standards of China.