Researchers confirmed Tuesday that oil is floating as deep as 3,300 feet below the surface of the Gulf of Mexico in layers that may pose unprecedented challenges to efforts to clean up the effects of the spewing BP Deepwater Horizon well.
Jane Lubchenco, the head of the National Oceanic and Atmospheric Administration, said oil in "very low concentrations" was found at varying depths 40 miles and 42 nautical miles northeast of the well and also 142 nautical miles southeast of the well.
Only the oil found on the surface 40 miles from the well could be confirmed as having come from the BP spill. The oil found 142 miles from the site was unlike the BP oil, Lubchenco said, while other samples were in concentrations too low to determine their origins.
Scientists don't yet know what the impact the subsurface oil might have on sea life, Lubchenco said.
"It's in low concentration," she said. "That does not mean it doesn't have significant impact. The impact that it has we remain to understand."
The subsurface oil could prove to be a challenge to clean up efforts. Coast Guard Adm. Thad Allen, the Obama administration's point man on the spill, said the Coast Guard has little experience in cleaning up oil suspended in water.
"We have not generally done subsurface response" to an oil spill, Allen said, except in instances where heavy oil has sunk to the seafloor. "In my on personal experience, I have not dealt with it."
Allen said the Coast Guard would have to do research to know what could be done to respond to the subsurface oil.
Dispersed oil "is not in a form that's easily removed," said Samantha Joye, a professor of marine sciences at the University of Georgia at Athens during a briefing she held on Tuesday about her latest research cruise in search of submerged oil.
Joye was one of the first scientists to discover submerged layers of oil, reports of which Lubchenco attacked in mid May as "misleading, premature and, in some cases, inaccurate."
On Tuesday, however, that dispute appeared to have been forgotten.
"We have always known that there is oil under the surface," Lubchenco said. "The questions that NOAA and many of its academic partners are pursuing are, where is that oil, in what concentrations and what impact is this having on the ecosystems."
Ernst Peebles, a University of South Florida scientist who was aboard NOAA's R/V Weatherbird II when it took 25 samples from the Gulf waters May 23-26, said what was clear was that there was oil at various depths in layers.
"We don't know its origin, its extent. The layers are definitely oil. The origins are less clear," he said.
Scientists aboard the Weatherbird II found oil "mousse," the now infamous brown or orange substance seen primarily along the surface of the Gulf from Louisiana to Florida, as deep as 10 feet below the surface, Ernst and NOAA scientist Steven Murawski told reporters in St. Petersburg, Fla.
In her separate conference call with reporters, Joye said that on her most recent research mission, a two-week cruise on the vessel F.G. Walton Smith that ended on Sunday, her team found a plume of oil from the leaking well that was about 15 miles long and three miles wide. Its thickness ranged from 600 feet close to the well to 1,600 feet farther out.
Joye said the researchers found unusually high levels of methane in the water. The Deepwater Horizon drilling rig burst into flame on April 20 when a jet of methane exploded up the well's pipe and enveloped the rig.
Joye said the presence of so much oil and methane is depleting oxygen in the water, and that the amount of methane in the water increased after BP engineers severed the well's twisted riser pipe last week to fit a "top hat" containment device over it.
She said she and her crew members could hear from three-quarters of a mile away the roar as BP crews on the surface burned the gas they were recovering.
Joye also said that the widespread use of chemical dispersants to break up the oil was likely to have consequences that may not be known for years.
"We have no clue what these dispersants do to phytoplankton, to microorganisms," Joye said. "We know that they are toxic to many larvae. It's impossible I think to know what the impacts are going to be and what the repercussions for various fisheries are going to be."
However, she said it was clear that there'd be changes.
"When you interfere with the natural processes in a system, when you alter the carbon cycle and the oxygen cycle, it's very likely that impacts will cascade up the food web to the top predators. The primary producers, the base of the food web in the ocean is going to be altered by this spill. There's no doubt about that."
The reports about underwater oil came as Allen said he had renewed efforts to get a better handle on how much oil is spewing from the wellhead. On Monday, a member of the government's Flow Rate Technical Group told McClatchy he thought the well now may be gushing 100,000 barrels a day into the Gulf after the riser pipe was cut.
Allen said he'd asked the flow rate panel, which includes both academic and government experts, to re-examine the question of how much oil is flowing from the pipe and "give us a revised total flow rate pre-riser cut, post riser cut."
Allen also said he'd look into complaints from some members of the panel that BP hadn't provided video and other data they feel is needed to accurately assess the oil well's flow.
Allen said the "top hat," put in place last week, captured 14,842 barrels in a 24-hour period, an amount just below the 15,000-barrel capacity of the ship processing the oil at the surface. A second ship should be at the site in the "next two to three days" that will raise the capacity to 20,000 barrels a day, and BP is in the process of installing a larger production facility to handle the spill.
Allen also bristled at the suggestion of a reporter that he and other Obama administration officials have implied that the response is going well, despite the lack of enough ships to collect the oil and their lack of knowledge of how much oil is being spilled.
"I have never said this is going well," Allen said. "We're throwing everything we've got. This is the largest oil spill response in the history of this country. . . . We're making no illusions that this is anything other than a catastrophe and we're addressing it as such and we'll continue to do that."
(Lebovich, of the Miami Herald, reported from Miami. Jones, of the Bradenton Herald, reported from Bradenton, Fla. Renee Schoof in Washington contributed to this article.)
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