Sunlight Photolysis of Safener Benoxacor and Herbicide Metolachlor as Mixtures on Simulated Soil Surfaces
Sunlight Photolysis of Safener Benoxacor and Herbicide Metolachlor as Mixtures on Simulated Soil Surfaces
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DOI：
10.1021/acs.est.9b01243
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发表时间：
2019-06-18
影响因子：
11.4
通讯作者：
Dai, Ning
中科院分区：
文献类型：
--
作者：
Su, Lei;Caywood, Leandra M.;Dai, Ning
Benoxacor是一种安全剂，与大量使用的除草剂S-异丙甲草胺配对。含有这两种化合物的商业制剂在出苗前喷洒到土壤上以提高玉米产量。在这项研究中，我们评估了异丙甲草胺和苯恶唑，单独和作为混合物，在三个不同的反应环境：在水中和两个土壤模拟表面（石英和高岭石）的阳光光解。当单独照射时，在每个反应环境中，苯恶唑的降解速度至少比异丙甲草胺快19倍，这与其在太阳光谱内比异丙甲草胺更高的摩尔吸光系数相一致。当异丙甲草胺和解草胺作为混合物进行辐照时，解草胺促进异丙甲草胺在石英上的降解，并在较小程度上促进异丙甲草胺在水中的降解，但不促进高岭石上的降解。在石英上，在解草胺/异丙甲草胺的摩尔比为0.1：1时，异丙甲草胺的降解速度比无解草胺时快1.8倍;随着解草胺/异丙甲草胺比例的增加，异丙甲草胺的降解速率也增加。苯氧草胺的光解速率取决于其初始表面浓度，异丙甲草胺对其光解速率有促进作用。苯草胺的光产物能够吸收太阳光，并作为异丙甲草胺降解的光敏剂。这些结果说明了如何安全剂可以影响其共同配制的除草剂的光化学，并建议这种混合物的影响时，应考虑评估农药的环境命运。
Benoxacor is a safener paired with the high-use herbicide S-metolachlor. Commercial formulations containing both compounds are sprayed onto soil pre-emergence to enhance yields of corn. In this study, we evaluated the sunlight photolysis of metolachlor and benoxacor, individually and as mixtures, in three different reaction environments: in water and on two soil-simulating surfaces (quartz and kaolinite). When irradiated individually, benoxacor degraded at least 19 times faster than metolachlor in each reaction environment, consistent with its higher molar absorptivity within the solar spectrum than metolachlor. When metolachlor and benoxacor were irradiated as mixtures, benoxacor promoted metolachlor degradation on quartz and, to a lesser extent, in water, but not on kaolinite. On quartz, at a benoxacor/metolachlor molar ratio of 0.1:1, metolachlor degraded 1.8 times faster than in the absence of benoxacor; as the benoxacor/metolachlor ratio increased, metolachlor degradation rate also increased. The photolysis rate of benoxacor depended on its initial surface concentration and was promoted by metolachlor. Benoxacor photoproducts were capable of absorbing sunlight and serving as photosensitizers for metolachlor degradation. These results illustrate how a safener can influence the photochemistry of its coformulated herbicide and suggest that such mixture effects should be considered when evaluating the environmental fate of agrochemicals.