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Scientists Find Evidence That Oil And Dispersant Mix Is Making Its Way Into The Foodchain

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The effects of the oil spill continue. Dan Froomkin reports in the Huffington Post:

Scientists have found signs of an oil-and-dispersant mix under the shells of tiny blue crab larvae in the Gulf of Mexico, the first clear indication that the unprecedented use of dispersants in the BP oil spill has broken up the oil into toxic droplets so tiny that they can easily enter the foodchain.

Marine biologists started finding orange blobs under the translucent shells of crab larvae in May, and have continued to find them "in almost all" of the larvae they collect, all the way from Grand Isle, Louisiana, to Pensacola, Fla. — more than 300 miles of coastline — said Harriet Perry, a biologist with the University of Southern Mississippi’s Gulf Coast Research Laboratory.

And now, a team of researchers from Tulane University using infrared spectrometry to determine the chemical makeup of the blobs has detected the signature for Corexit, the dispersant BP used so widely in the Deepwater Horizon

"It does appear that there is a Corexit sort of fingerprint in the blob samples that we ran," Erin Gray, a Tulane biologist, told the Huffington Post Thursday. Two independent tests are being run to confirm those findings, "so don’t say that we’re 100 percent sure yet," Gray said.

"The chemistry test is still not completely conclusive," said Tulane biology professor Caz Taylor, the team’s leader. "But that seems the most likely thing."

With BP’s well possibly capped for good, and the surface slick shrinking, some observers of the Gulf disaster are starting to let down their guard, with some journalists even asking: Where is the oil?

But the answer is clear: In part due to the1.8 million gallons of dispersant that BP used, a lot of the estimated 200 million or more gallons of oil that spewed out of the blown well remains under the surface of the Gulf in plumes of tiny toxic droplets. And it’s short- and long-term effects could be profound.

BP sprayed dispersant onto the surface of the slick and into the jet of oil and gas as it erupted out of the wellhead a mile beneath the surface. As a result, less oil reached the surface and the Gulf’s fragile coastline. But more remained under the surface.

Fish, shrimp and crab larvae, which float around in the open seas, are considered the most likely to die on account of exposure to the subsea oil plumes. There are fears, for instance, that an entire year’s worth of bluefin tuna larvae may have perished.

But this latest discovery suggests that it’s not just larvae at risk from the subsurface droplets. It’s also the animals that feed on them.

"There are so many animals that eat those little larvae," said Robert J. Diaz, a marine scientist at the College of William and Mary.

Oil itself is of course toxic, especially over long exposure. But some scientists worry that the mixture of oil with dispersants will actually prove more toxic, in part because of the still not entirely understood ingredients of Corexit, and in part because of the reduction in droplet size.

"Corexit is in the water column, just as we thought, and it is entering the bodies of animals. And it’s probably having a lethal impact there," said Susan Shaw, director of the Marine Environmental Research Institute. The dispersant, she said, is like " a delivery system" for the oil.

Although a large group of marine scientists meeting in late May reached a consensus that the application of dispersants was a legitimate element of the spill response, another group, organized by Shaw, more recently concluded "that Corexit dispersants, in combination with crude oil, pose grave health risks to marine life and human health and threaten to deplete critical niches in the Gulf food web that may never recover."

One particular concern: . . .

Continue reading.

Written by Leisureguy

30 July 2010 at 11:58 am

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