Department of Environmental Sciences, College of the Coast & Environment , Louisiana State University , Baton Rouge , Louisiana 70803 , United States.
Department of Environmental Toxicology , University of California at Davis , Davis , California 95616 , United States.
J Agric Food Chem. 2018 Mar 21;66(11):2654-2659. doi: 10.1021/acs.jafc.8b00211. Epub 2018 Mar 5.
Dicloran appears to be a model pesticide for investigating photodegradation processes in surface waters. Photodegradation processes are particularly relevant to this compound as it is applied to crops grown in proximity to freshwater and marine ecosystems. The photodegradation of dicloran under simulated sunlight was measured in distilled water, artificial seawater, phosphate buffer, and filter-sterilized estuarine water to determine its half-life, degradation rate, and photodegradation products. The half-life was approximately 7.5 h in all media. There was no significant difference in the rate of degradation between distilled water and artificial seawater for dicloran. For the intermediate products, a higher concentration of 2-chloro-1,4-benzoquinone was measured in artificial seawater versus distilled water, while a slightly higher concentration of 1,4-benzoquinone was measured in distilled water versus artificial seawater. The detection of chloride and nitrate ions after 2 h of light exposure suggests photonucleophilic substitution contributes to the degradation process. Differences in product distributions between water types suggest that salinity impacts on chemical degradation may need to be addressed in chemical exposure assessments.
地乐酚似乎是一种用于研究地表水中光降解过程的典型农药。由于该化合物应用于临近淡水和海洋生态系统生长的作物，因此光降解过程对其尤为重要。在模拟阳光下，在蒸馏水、人工海水、磷酸盐缓冲液和过滤消毒的河口水中测量了地乐酚的光降解，以确定其半衰期、降解率和光降解产物。在所有介质中，半衰期约为 7.5 小时。在蒸馏水和人工海水中，地乐酚的降解率没有显著差异。对于中间产物，在人工海水中测量到的 2-氯-1,4-苯醌浓度较高，而在蒸馏水中测量到的 1,4-苯醌浓度略高。在 2 小时的光照暴露后检测到氯离子和硝酸盐离子表明，光亲核取代作用有助于降解过程。水类型之间的产物分布差异表明，在化学暴露评估中可能需要解决盐度对化学降解的影响。
