Scientists find evidence of large underwater oil plume in gulf

Cleanup and containment efforts continue at the Gulf of Mexico site of the oil spill following the Deepwater Horizon explosion.

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By David A. Fahrenthold and Juliet Eilperin
Washington Post Staff Writer
Thursday, May 27, 2010; 4:21 PM

Scientists have found evidence of a large underwater "plume" of oil in the Gulf of Mexico, adding to fears that much of the BP oil spill's impact is hidden beneath the surface.

The scientists, aboard a University of South Florida research vessel, found an area of dissolved oil that is about six miles wide, and extends from the surface down to a depth of about 3,200 feet, said Professor David Hollander.

Hollander said that he believed the plume might have stretched more than 20 miles from the site of a leak on the floor of the Gulf of Mexico, where the Deepwater Horizon drilling rig sank April 22. It has not yet reached Florida.

The plume is clear, with the oil entirely dissolved.

"Here is a situation where, unless you're looking at the chemical fingerprints, [the oil] is absolutely not visible," Hollander said. "It's not some Italian vinaigrette or anything like that. It's absolutely, perfectly clear."

But, Hollander said, even this clear-looking water could contain enough oil to be toxic to small animals at the base of the gulf food chain. He said he was also worried that the oil contains traces of "dispersants," soap-like chemicals sprayed into the oil to break it up.

"You don't want to put soap into a fish tank," Hollander said.

This discovery seems to confirm the fears of some scientists that -- because of the depth of the leak and the heavy use of chemical "dispersants" -- this spill was behaving differently than others. Instead of floating on top of the water, it may be moving beneath it.

That would be troubling because it could mean the oil would slip past coastal defenses such as "containment booms" designed to stop it on the surface. Already, scientists and officials in Louisiana have reported finding thick oil washing ashore despite the presence of floating booms.

It would also be a problem for hidden ecosystems deep under the gulf. There, scientists say, the oil could be absorbed by tiny animals and enter a food chain that builds to large, beloved sport-fish like red snapper. It might also glom on to deep-water coral formations, and cover the small animals that make up each piece of coral.

"It kills them because it prevents them from feeding," said Professor James H. Cowan Jr., of Louisiana State University. "It could essentially starve them to death."

The University of South Florida vessel, the Weatherbird II, used sonar and other devices to sample the water below it. Other scientists have said they have little of the equipment necessary to find oil under the water -- leading to debates about whether the underwater plumes were even there.

This week, Mike Utsler, who helps oversee the spill response off the entire Louisiana coast as BP Houma incident commander, said he's only focused on taking oil off the surface. "We don't know there's oil underwater," he said.

But others had seen worrisome evidence.

Owen Morgan of Amira, a group that specializes in breaking apart spills with oil-eating microbes, found evidence of the oil plume off Venice when his team sampled water 75 feet beneath the service. Morgan -- who said his company is pulling out of Louisiana because of insufficient cooperation from state and federal authorities -- showed a thick, gooey sample consisting of 60 percent crude oil.

"People don't realize how bad it is," Morgan said, dipping a fork in the sample to show the goo that hung in midair without sliding off. "This went on for three miles, of that consistency."

William Hogarth, dean of the USF College of Marine Science, said university researchers have sent samples to federal officials for analysis, but it's clear the oil is new because Stanford scientists had sampled the same area a year ago and found no evidence of oil. The Weatherbird II will conduct another tour next week, he said, with different researchers aboard.

"This is not natural seep," he said, adding that scientists will have to study the region for several years in order to properly gauge its impact. "We're talking about probably a three to five-year monitoring program to see what happens to food chain."


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