Faster degradation of herbicidally-active enantiomer of imidazolinones in soils.
Faster degradation of herbicidally-active enantiomer of imidazolinones in soils.
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DOI：
10.1016/j.chemosphere.2010.03.046
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发表时间：
2010-05
期刊：
影响因子：
8.8
通讯作者：
M. Ramezani;D. Oliver;R. Kookana;W. Lao;Gurjeet Gill;C. Preston
中科院分区：
文献类型：
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作者：
M. Ramezani;D. Oliver;R. Kookana;W. Lao;Gurjeet Gill;C. Preston
咪唑啉酮类除草剂是一类手性除草剂，由两种不同的对映体组成。在这项研究中，三个咪唑啉酮类除草剂，咪唑烟酸，咪唑乙烟酸和灭草喹的对映体的选择性降解，确定在各种土壤中选择覆盖广泛的物理化学特性。所有三种除草剂的R（+）对映体具有更高的除草活性（高达8倍），发现其降解速度比活性较低的S（-）对映体快。对映体分数（EF）被用作咪唑啉酮除草剂的对映体选择性的描述符。EF值随着咪唑啉酮孵育时间的增加而增加，具有快速的初始阶段，然后是较慢的阶段。对映体选择性在酸性土壤（pHw5.02和5.20）中不显著，在碱性土壤（pHw7.6，8.2和8.7）中极显著（P <0.001）。在土壤pH值为5.02~8.7范围内，咪唑烟酸（P <0.001，R2 = 0.41）、咪唑乙烟酸（P <0.002，R2 = 0.47）和咪唑喹（P <0.001，R2 = 0.54）的EF值均呈显著正相关。但与其它土壤性质无相关性。除了显示三种除草剂在所研究的土壤中的对映体选择性降解外，该研究还强调，对于咪唑啉酮，活性更高的对映体可以优选地被微生物降解。
Imidazolinones are chiral herbicides, comprised of two enantiomers with differential herbicidal activity. In this study, the selective degradation of enantiomers of the three imidazolinone herbicides, imazapyr, imazethapyr and imazaquin, was determined in a variety of soils selected to cover a broad range of physico-chemical characteristics. The R(+) enantiomer of all three herbicides, which has greater herbicidal activity (up to eight times), was found to degrade faster than the less active S(−) enantiomer. The enantiomer fraction (EF) was used as a descriptor of enantio-selectivity of the imidazolinone herbicides. The EF values increased with increasing incubation time for imidazolinones with a fast initial phase followed by a slower phase. While the enantio-selectivity was not significant in acidic soils (pHw5.02 and 5.20), it was highly significant (P<0.001) in alkaline soils (pHw7.6, 8.2 and 8.7). Significant positive correlations of EF values of imazapyr (P<0.001, R2=0.41), imazethapyr (P<0.002, R2=0.47) and imazaquin (P<0.001, R2=0.54) were found with the soil pHwranging from 5.02 to 8.7. However, no correlation of EF was found with other soil properties. In addition to showing enantioselective degradation of the three herbicides in the soils studied, the study highlighted that for imidazolinones the herbicidally more active enantiomer can be preferably degraded by microorganisms.