So far the government and BP have conducted several tests a mile deep in the ocean to deploy an oil spill cleanup technique that's never been attempted before: dispersing the oil with a chemical injected into the water at depth. Usually dispersant, which is a detergent that breaks up oil into tiny pieces, is used on the surface of spills. But this unprecedented crisis is calling for an unprecedented solution.
Environmental Protection Agency (EPA) Administrator Lisa Jackson told reporters on a conference call that officials had conducted three tests with robots to determine whether the dispersant, known as Corexit 9500, would work effectively deep underwater. If it didn't, she said, "it doesn't make sense to introduce a new tool to the marine environment." The first two tests didn't work "because of logistics" she said, suggesting that scientists had been unable to get water samples from the right location, though she was vague about the problem. But the third test had been conducted successfully, with scientists at Louisiana State University now analyzing water samples. NOAA Administrator Jane Lubchenco said that the tests were being done to measure chemical makeup of the treated oil at depth.
Jackson said EPA determined that the chemical was between 1/10 and 1/100 "as toxic as oil" and that breaking up the oil in the water column was better than treating it on the surface.
There are several reasons for using dispersant at depth, she said. It works best on fresh oil before it has had a chance to change consistency through
evaporation. And mixing dispersant with the oil at its source may allow the cleanup crews to use less of it than if they used it on the surface.
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