Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS), CSIC, Avenida Reina Mercedes 10, P.O. Box 1052, 41080 Sevilla, Spain.
J Environ Manage. 2013 Oct 15;128:92-9. doi: 10.1016/j.jenvman.2013.04.055. Epub 2013 May 27.
Certain soil management practices can affect the enantioselective behavior of chiral pesticide enantiomers in agricultural soils. In this work, laboratory experiments were conducted to study the effects of olive-mill waste (OMW) addition to a Mediterranean agricultural soil on the enantioselectivity of sorption, degradation, and leaching processes of the chiral fungicide metalaxyl. Sorption-desorption isotherms indicated that the sorption of metalaxyl enantiomers by unamended and OMW-amended soil (2% w/w) was non-enantioselective and that OMW addition had little effect on the extent of sorption of metalaxyl enantiomers by the soil. Soil incubation experiments revealed that the degradation of metalaxyl in unamended soil was highly enantioselective, with R-metalaxyl being degraded faster (t1/2 = 12 days) than S-metalaxyl (t1/2 = 39 days). OMW addition to the soil increased the half-life of the biologically-active R-metalaxyl enantiomer from 12 to 28 days, and decreased the half-life of the non-active S-metalaxyl enantiomer from 39 to 33 days. Consequently, the enantioselectivity of metalaxyl degradation in the soil was greatly reduced upon OMW addition. Column leaching data were consistent with batch sorption and incubation results, showing similar retardation of S- and R-metalaxyl in unamended and OMW-amended soil and enantioselective leaching of the fungicide only in unamended soil. The results have important implications regarding the biological efficacy and environmental impact of the fungicide when applied as a mixture of enantiomers or racemate to OMW-treated soils.
某些土壤管理措施会影响手性农药对映体在农业土壤中的对映体选择性行为。在这项工作中，进行了实验室实验，以研究橄榄渣（OMW）添加到地中海农业土壤中对拟除虫菊酯杀菌剂金属axyl 的吸附、降解和淋溶过程的对映体选择性的影响。吸附-解吸等温线表明，未添加和添加 OMW（2%w/w）的土壤对金属axyl 对映体的吸附是非对映选择性的，并且 OMW 添加对土壤对金属axyl 对映体的吸附程度影响不大。土壤培养实验表明，未添加土壤中金属axyl 的降解具有高度的对映体选择性，R-金属axyl 的降解速度（t1/2=12 天）快于 S-金属axyl（t1/2=39 天）。OMW 添加到土壤中增加了生物活性 R-金属axyl 对映体的半衰期从 12 天增加到 28 天，同时减少了非活性 S-金属axyl 对映体的半衰期从 39 天减少到 33 天。因此，OMW 添加大大降低了土壤中金属axyl 降解的对映体选择性。柱淋滤数据与批量吸附和培养结果一致，表明未添加和添加 OMW 的土壤中 S-和 R-金属axyl 的类似延迟以及仅在未添加土壤中对杀菌剂的对映体淋滤。这些结果在手性农药作为混合物或外消旋体施用于经 OMW 处理的土壤时，对其生物功效和环境影响具有重要意义。
