Corexit 9500A allows crude oil components to penetrate faster and deeper into permeable saturated sands where the absence of oxygen may slow degradation and extend the lifespan of potentially harmful polycyclic aromatic hydrocarbons (PAHs), a.k.a. organic pollutants—a.k.a. persistently abominable hork—in the marine environment.
"The oil concentrations used in our experiments are at the lower end of those reported for coastal waters after the Deepwater Horizon accident, and the Gulf of Mexico beaches were flooded with consecutive surges of oil."
Furthermore, the authors warn, dispersants used in nearshore oil spills might penetrate deeply enough into saturated sands to threaten groundwater supplies.