Corexit, oil and marine microgels

Corexit, an EPA-approved chemical dispersant, was intensively used during the 2010 Deepwater Horizon Oil Spill in the Gulf of Mexico. Current studies surrounding Corexit have mainly focused on its toxicity and oil removal capacity. The potential impact of Corexit on the surface ocean carbon dynamics has remained largely unknown. The spontaneous assembly of DOM (dissolved organic matter) polymers into microgels (POM, particulate organic matter) was demonstrated previously that it can influence various critical processes, such as colloidal pump, microbial loops, and nutrition availability in the surface ocean. Here, we report that Corexit alone can significantly inhibit DOM microgel formation and reduce the stability of pre-existing microgels. However, Corexit and oil, Chemically Enhanced Water Accommodated Fraction (CEWAF), could effectively facilitate DOM microgel formation. The unanticipated disturbance of Corexit and oil spills on the critical DOM-POM continuum warrant particular caution and thus should be considered for future application of Corexit during oil spills.