More evidence of deep clouds of oil drifting in the Gulf of Mexico emerged Tuesday as scientists warned that changes in the powerful loop current could bring trouble to Florida.
And though BP is promising millions in aid, the company has refused to offer a sample of its oil to University of South Florida scientists who are working to confirm the source of the oil clouds, said the study's chief investigator, David Hollander.
"I was just taken aback by it," Hollander said. "It was a little unsettling."
On Tuesday, USF scientists announced they had found concentrations of oil-related chemicals 42 miles northeast of the Deepwater Horizon rig and 142 miles to the southeast. Some of the substance was found two-thirds of a mile below the surface.
Scientists will try to confirm its origin by "fingerprinting" the oil, or chemically matching it to BP's oil. That task has been hampered by a BP official's refusal to provide scientists with a sample of its oil, Hollander said.
A BP spokesman said he wasn't able to comment on that exchange but that "BP is cooperating fully with NOAA's research into the subsurface impacts of the oil spill."
While local scientists would not definitively link the Deepwater Horizon site with the far-reaching oil in the gulf, not all scientists tiptoed around the issue.
Samantha Joye of the University of Georgia, who recently returned from a two-week expedition in the gulf, was quoted in the Washington Post: "There is strong evidence that the plume does derive from the Deepwater Horizon."
She said she has "never seen concentrations of methane this high anywhere" in the 15 years she has worked in the gulf, suggesting that natural seepage is not a factor.
The University of Georgia-led team tracked the plume from three-quarters of a mile to nearly 14 miles from the BP wellhead.
Also Tuesday, a National Oceanic and Atmospheric Administration survey vessel, Thomas Jefferson, found clouds of hydrocarbons less than 8 nautical miles from the site of the BP oil spill. The clouds, at depths of more than 3,600 feet, are about 330 feet in height.
Meanwhile, the USF scientists had more bad news:
They've confirmed a low concentration of oil off the southern tip of Florida, in the gulf stream. That oil is projected to flow north, off Florida's east coast, but is unlikely to reach shore.
They also had troubling news about the loop current, the warm river of water that enters the gulf from the Yucatán Peninsula and surges north into the central gulf before looping south and around the tip of Florida.
Last week, they said it appeared to be reshaping, meaning it would be less likely to carry oil from the spill toward Florida and the East Coast.
That respite may be over, said USF Ocean Circulation Group director Robert Weisberg.
"Over time, there will be more oil getting into the loop current and the Florida Straits," he said. "We just have to watch."
News of the oil clouds emerged Tuesday at a news conference at USF St. Petersburg. Scientists said they hope to confirm the origin of the subsurface oil within two weeks.
"We're trying to do it right as opposed to trying to do it quick," Hollander said.
The gulf water samples were taken by scientists aboard the Weatherbird II, a USF research vessel deployed May 23-26.
Initial tests done almost two weeks ago showed that oil had sunk a half-mile below the surface in a 6-mile-wide portion of the plume, about 20 miles northeast of the collapsed rig.
BP CEO Tony Hayward has said that the oil spewing from the Deepwater Horizon was staying on the surface.
When asked about Hayward's comments, Steven Murawski of NOAA said, "The data speaks for itself."
Times staff writer Katie Sanders contributed to this report.