The chemical oil dispersants BP used in its response to the 2010 Deepwater Horizon oil spill did little to mitigate the massive spill and likely did more harm than good, researchers from the University of Miami found.
A study led by a research team from the UM Rosenstiel School of Marine and Atmospheric Science analyzed polycyclic aromatic hydrocarbons (PAHs), the most toxic components of petroleum, from samples taken within a six-mile radius of the Deepwater Horizon blowout site.
Despite 3,000 tons (about 770,000 gallons) of Corexit oil dispersants injected near the well head, substantial amounts of oil continued to surface near the response site. This unprecedented use of the oil dispersants was intended to curb the spread of oil and facilitate its degradation, but the study found the oil dispersants were ineffective in doing either.
Researchers also found that the massive oil plumes that formed deep beneath the surface were not the result of the oil dispersants but the result of energy and pressure at the wellhead nearly a mile deep. These enormous forces forced the oil to break up into micro-droplets – the job that the oil dispersants were supposed to do. Thus, the researchers concluded, the oil dispersants were ineffective and unnecessary.
The oil dispersants also may have worsened the ecological damage caused by BP’s Deepwater Horizon spill by “suppressing the growth of natural oil-degrading bacteria and by increasing the toxicity of the oil itself.”
“There is no real trade-off because there is no upside in using ineffective measures that can worsen environmental disasters,” said Claire Paris, a UM ocean sciences professor and leader of the research team.
The study’s authors said that as the oil industry drills in deeper and deeper water, it must find alternative strategies to manage blowouts. They said that the “capping stack” method BP used to stop the gushing wellhead may be a more effective first-response strategy.
Bio-surfactants, which are less toxic and better at degrading oil, may be a viable alternative for cleaning up oil spills in shallow waters, the researchers noted.