Reply #34: I don't know. Even scientists aren't in agreement on this yet.

[Forkboy]

Some scientists doubt data on dissipation of oil from gulf

But, in interviews, scientists who worked on the report said the figures were based in large part on assumptions and estimates, educated guesses with a significant margin of error.

Some outside scientists went further: In a situation in which many facts remain murky, they said, the government seemed to have used interpretations that made the gulf — and the federal efforts to save it — look as good as possible.

“There’s a lot of . . . smoke and mirrors in this report, I’m afraid,’’ said Ian MacDonald, a professor of biological oceanography at Florida State University. “It seems very reassuring, but the data aren’t there to actually bear out the assurances.’’
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But scientists who worked on the report said many of the numbers on the White House’s pie chart had significant margins of error. The estimate of how much oil evaporated was calculated using a formula designed for spills near the surface, not 5,000 feet underwater. The calculation of how much oil would be “dispersed’’ as it flowed from the well was a new one, extrapolated from data about the way oil is broken by waves.
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The situation is “being portrayed as `the oil is out of the environment; it’s gone,’ ’’ said Michael Blum, a professor of earth and ecological science at Tulane University in New Orleans. But, he said, all that is certain is that “the form of the oil has shifted. Dispersed oil is still oil. It’s just in a different form.’’

Even if the government is right and only 26 percent of the oil is left, that would still be 1.3 million barrels, five times the oil spilled from the Exxon Valdez in 1989.

“In terms of the environmental impacts, the story is really not written yet,’’ despite the numbers released, said Steve Murawski, a NOAA senior scientist.

http://www.boston.com/news/science/articles/2010/08/05/some_scientists_doubt_data_on_dissipation_of_oil_from_gulf/