茚虫威对映体在土壤中的选择性降解

研究了茚虫威在4种不同类型的农田土壤中的降解动态和选择性降解行为.结果表明,添加水平在0.1—5.0 mg.kg-1的条件下,茚虫威对映体在土壤中添加回收率在(78.56±3.16)%—(108.16±5.32)%之间,最低检测限为0.01 mg.kg-1,定量限为0.05 mg.kg-1.茚虫威在土壤中的消解符合一级动力学规律,消解过程受土壤pH值、有机质含量等因素的影响.茚虫威对映体在1#—4#土壤中的降解速率存在明显的差异性,E1的半衰期分别为15.33 d、19.09 d、10.61 d、11.40 d,E2的半衰期分别为15.44 d、15.61 d、8.58 d、11.13 d,降解快慢顺序为:3#>4#>1#>2#,表明茚虫威在偏碱性的土壤中的降解速率要快于在酸性土壤中,且对映体的半衰期差异在有机质含量较高的土壤中表现得更加明显;对映体分数EF值(enantiomer fraction)表明茚虫威对映体在4种供试土壤中除了1#土壤外均存在明显的立体选择性降解.

Enantioselective degradation of indoxacarb enantiomers in soils

The dissipation dynamic and enantioselective degradation of indoxacarb in soils were studied by incubation with racemic indoxacarb in four agricultural soils.When the concentration of indoxacarb was fortified from 0.1 to 5.0 mg · kg-1,the average recoveries varied from(78.56±3.16)% to(108.16±5.32)%,respectively.The limit of detection of indoxacarb in the test soils was 0.01 mg · kg-1,and the limit of quantitation was 0.05 mg · kg-1.The dissipation of indoxacarb enantiomers in the soils followed pseudo-first-order kinetic.The dissipation rate was greatly influenced by pH and organic matter content of each soil.The results showed that the degradation rate of indoxacarb was different in soils 1#—4#.The half-time of the first enantiomer was 15.33 d,19.09 d,10.61 d,11.40 d,and the half-time of the second enantiomer was 15.44 d,15.61 d,8.58 d,11.13 d.The dissipation rate in the descending order was 3#>4#>1#>2#.The results indicated a faster dissipation rate for indoxacarb in alkaline soil than in acidic soil,and there was a bigger difference on half-time period of indoxacarb enantiomers in soil of high organic matter.The EF value indicated that the stereoselective degradation led to significant difference between two enantiomers in the test soils except 1#.