The explosion of the Deepwater Horizon oil well caused nearly 5 million barrels of oil to spew into the Gulf of Mexico. Countermeasures included physical barriers such as booms and the use of chemical dispersants to break up the oil slicks.
Dispersants have been widely tested for their effectiveness but not so much for their toxicity. The dispersant that was used after Deepwater, Corexit 9500, was on a list that the EPA had approved for emergency use. It is estimated that two million gallons of Corexit were sprayed on the Gulf of Mexico.
Recently, scientists at Georgia Tech and in Mexico conducted a toxicity study of Corexit, using tiny marine organisms called rotifers. They exposed rotifers to crude oil, to the dispersant, and to combinations of oil and dispersant. They found that oil mixed with dispersant was 52 times more toxic to the rotifers than oil alone. Not only were adult rotifers killed by the compound, but egg hatch was reduced.
Rotifers are at the base of the Gulf food chain, providing food for crabs, shrimp, and baby fish.
When faced with a disaster such as Deepwater, decisions must be made quickly to avoid catastrophe. It’s obvious that we need a better understanding of the chemical composition and potential toxicity of dispersants before the next disaster strikes.
Web Links
E.O. Wilson—The Bard of Biodiversity
http://discovermagazine.com/2001/dec/breakdialogue#.UNC4arblVGF
The Smaller Majority
http://thesmallermajority.com/
Photo, taken on June 16, 2010, courtesy of Kris Krug via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio. Support for Earth Wise comes from the Cary Institute of Ecosystem Studies in Millbrook, NY, with partial support from the Field Day Foundation.