title: Effects of oil dispersants on photodegradation of pyrene in marine water.
abstract: 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.
authors: Environmental Engineering Program, Department of Civil Engineering, Auburn University, Auburn, AL 36849, USA; College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China.
authors: Yanyan
authors: Y
authors: Gong
authors: Environmental Engineering Program, Department of Civil Engineering, Auburn University, Auburn, AL 36849, USA.
authors: Jie
authors: J
authors: Fu
authors: U.S. Department of the Interior, Gulf of Mexico OCS, Office of Environment, New Orleans, LA 70123, USA.
authors: S E
authors: SE
authors: O'Reilly
authors: Environmental Engineering Program, Department of Civil Engineering, Auburn University, Auburn, AL 36849, USA. Electronic address: zhaodon@auburn.edu.
authors: Dongye
authors: D
authors: Zhao
mesh_terms: D045424:Complex Mixtures / Q000737:chemistry*; D006812:Humic Substances; D006863:Hydrogen-Ion Concentration; D009994:Osmolar Concentration; D010782:Photolysis / Q000187:drug effects*; D011409:Propylene Glycols / Q000737:chemistry*; D011721:Pyrenes / Q000737:chemistry*; D017382:Reactive Oxygen Species / Q000737:chemistry; D012623:Seawater / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D013451:Sulfonic Acids / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*; D013696:Temperature; D014466:Ultraviolet Rays; D014835:Volatilization / Q000187:drug effects
chemical_list: D045424:Complex Mixtures; D006812:Humic Substances; D011409:Propylene Glycols; D011721:Pyrenes; D017382:Reactive Oxygen Species; D013451:Sulfonic Acids; D013501:Surface-Active Agents; C030984:pyrene
keywords: Marine pollution; Oil dispersant; Oil weathering; PAHs; Photodegradation