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PLOS ONE doi:10.1371/journal.pone.0050549.g001
Clean seawater, crude oil dispersed by sonication, or crude oil dispersed by
Corexit and sonication were flushed through the sand columns by gravity.
The effluent of the columns was collected as a time series in four vials each.
Their findings: 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. (Did anyone look at this in the BP settlement?)
How does dispersant change oil's behavior in a beach? The authors
write:
The causes of the reduced PAH retention after dispersant application
has several reasons: 1) the dispersant transforms the oil containing the
PAHs into small micelles that can penetrate through the interstitial space
of the sand. 2) the coating of the oil particles produced by the dispersant
reduces the sorption to the sand grains, 3) saline conditions enhance the