油分散剂对海洋水中芘光降解的影响。
Effects of oil dispersants on photodegradation of pyrene in marine water.
机构信息
Environmental Engineering Program, Department of Civil Engineering, Auburn University, Auburn, AL 36849, USA; College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China.
Environmental Engineering Program, Department of Civil Engineering, Auburn University, Auburn, AL 36849, USA.
出版信息
J Hazard Mater. 2015 Apr 28;287:142-50. doi: 10.1016/j.jhazmat.2015.01.027. Epub 2015 Jan 12.
This work investigated effects of a popular oil dispersant (Corexit EC9500A) on UV- or sunlight-mediated photodegradation of pyrene (a model polycyclic aromatic hydrocarbon) in seawater. The presence of 18 and 180mg/L of the dispersant increased the first-order photodegradation rate by 5.5% and 16.7%, respectively, and reduced or ceased pyrene volatilization. By combining individual first-order rate laws for volatilization and photodegradation, we proposed an integrated kinetic model that can adequately predict the overall dissipation of pyrene from seawater. Mechanistic studies indicated that superoxide radicals played a predominant role in pyrene photodegradation, and the dispersant enhanced formation of superoxide radicals. 1-Hydroxypyrene was the main intermediate regardless of the dispersant, suggesting that electrons were transferred from excited pyrene to oxygen. In the presence of 18mg/L of the dispersant, the photodegradation rate increased with increasing ionic strength and temperature, but decreased with increasing HA concentration, and remained independent of solution pH. The results are important in understanding roles of oil dispersants on environmental fate of persistent oil components in natural and engineered systems.
本研究考察了一种广受欢迎的油分散剂（Corexit EC9500A）对海水中芘（一种多环芳烃模型化合物）在紫外光或阳光照射下光降解的影响。分散剂浓度分别为 18mg/L 和 180mg/L 时，光降解的一级反应速率常数分别增加了 5.5%和 16.7%，并减少或停止了芘的挥发。通过结合挥发和光降解的个体一级速率定律，我们提出了一个综合的动力学模型，可以充分预测海水中芘的整体耗散。机理研究表明，超氧自由基在芘的光降解中起主要作用，而分散剂增强了超氧自由基的形成。无论是否存在分散剂，1-羟基芘都是主要的中间产物，这表明电子是从激发态的芘转移到氧上的。在 18mg/L 分散剂的存在下，光降解速率随离子强度和温度的增加而增加，但随 HA 浓度的增加而降低，且与溶液 pH 无关。这些结果对于理解油分散剂在自然和工程系统中持久性油成分的环境归宿中的作用非常重要。
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