ABSTRACT
Formulations of Corexit®, a family of oil dispersants used in large-scale oil spills, were the primary emulsification agents utilized to enhance the biodegradation of Macondo-252 oil following the Deepwater Horizon spill (DWH) in the Gulf of Mexico (Deepwater Horizon Unified Command [DHUC] 2011). An estimated 6.9 million liters of the dispersant Corexit 9500A was applied in the northern Gulf of Mexico in response to the DWH, with smaller amounts of Corexit 9527 also applied (www.restorethegulf.gov). Although precise formulations are proprietary, Corexit 9527 consists of approximately 48% nonionic surfactants (ethoxylated sorbitan monooleate, ethoxylated sorbitan trioleate, and sorbitan monooleate), 35% of the anionic surfactant, dioctyl sodium sulfosuccinate (DOSS), and 17% hydrocarbon solvents (Wheelock et al. 2002). Although exact percentages are unknown, the primary components of Corexit 9500A as released by the manufacturer (Nalco) include sorbitan,
CONTENTS
Introduction ...................................................................................................................................35 Materials and Methods................................................................................................................. 37
Test Organisms ..................................................................................................................37 Acute Toxicity ....................................................................................................................38 Larval Exposure for Histology and Histological Methods .........................................38 Image Analysis ..................................................................................................................39 Embryo Development ......................................................................................................39 Statistical Analysis ............................................................................................................ 39
Results.......................................................................................................... ...................................40 Toxicity......................................................................................... .......................................40 Physiological Effects .........................................................................................................42 Embryo Development ......................................................................................................42
