Marine scientists with the University of South Florida today announced they have proved with scientific evidence what the public has long suspected - that there is a link between the gargantuan BP oil spill and plumes of oil micro-droplets that span for miles beneath the surface in the northern reaches of the Gulf of Mexico.
It is thought to be the first time anyone has established a definitive link connecting the plumes to the oil that spewed for months from the Deepwater Horizon well off the coast of Louisiana.
"Nobody else yet has made that relationship," said USF chemical oceanographer David Hollander, one of several USF oceanographers who have ventured into the Gulf to determine the spill's effects on the environment.
Hollander and his colleagues gathered samples from the northern gulf during a May 22-28 trip aboard the R/V Weatherbird II. They compared those samples with samples of oil provided by BP in late June, weeks after they were requested.
Two massive plumes, or subsurface clouds, have been linked to BP oil through a kind of molecular fingerprinting comparison.
One plume, suspended a quarter-mile beneath the surface, is 22 miles long, 6 miles wide and 100 feet thick, Hollander said. It was observed 45 miles northeast of the Deepwater Horizon well.
The other is deeper, hovering two-thirds to three-quarters of a mile beneath the surface. It is 20 miles long and is roughly 650 feet thick, Hollander said. This cloud was 24 miles east of the Deepwater Horizon site.
Of the two plumes - which are invisible to the naked eye -- the one that is deeper has oil at a concentration of 750 parts per billion. At a concentration of 1,000 parts per billion, oil is thought to be toxic to marine life.
The plume that is closer to the surface has a concentration ranging from 300 to 550 parts per billion, Hollander said.
Researchers homed in on those two areas after a USF ocean circulation expert predicted the oil from the Deepwater Horizon would move in a north-northeast direction. The clouds were found near the DeSoto Canyon, an area critical to Florida's spawning grounds.
The subsurface oil has not degraded nearly at the same rate as the surface oil has, Hollander said, and scientists don't know whether the oil is sinking to the bottom of the gulf or rising to the surface.
Hollander noted that BP once claimed there was no such thing as subsurface oil. The industry is geared to handle oil accidents closer to the surface, such as those stemming from oil tanker accidents or burst pipes.
"What we have learned completely changes the idea of what an oil spill is," Hollander said. The BP spill "has gone from a two-dimensional disaster to a three-dimensional catastrophe."
Getting a molecular fingerprint from the oil in the plumes was a challenge, said Hollander, because, among other things, the oil from the BP well was subjected to severe changes in temperature and pressure, and mixed with sea water, upon its release into the Gulf.
As a result of the researchers' findings, Hollander said, BP now has to take ownership of the subsurface oil and all that entails, including potential damage to marine life. The oil conglomerate has already been forced to take responsibility for the effects of the surface oil washing ashore, dispensing millions of dollars to that end.