New, giant sea oil plume seen in Gulf

Marine scientists have discovered a massive new plume of what they believe to be oil deep beneath the Gulf of Mexico, stretching 22 miles from the leaking wellhead northeast toward Mobile Bay, Alabama.

The discovery by researchers on the University of South Florida College of Marine Science’s Weatherbird II vessel is the second significant undersea plume recorded since the Deepwater Horizon exploded on April 20.

An untested procedure to plug the blown-out oil well in the Gulf of Mexico seemed to be working, officials said Thursday, but new estimates from scientists showed the spill has already surpassed the Exxon Valdez as the worst in U.S. history.

A team of scientists trying to determine how much oil has been flowing since the offshore rig exploded and sank two days later found the rate was more than twice and possibly up to five times as high as previously thought.

The thick plume was detected just beneath the surface down to about 3,300 feet, and is more than 6 miles wide, said David Hollander, associate professor of chemical oceanography at the school.

Hollander said the team detected the thickest amount of hydrocarbons, likely from the oil spewing from the blown out well, at about 1,300 feet in the same spot on two separate days this week.

The discovery was important, he said, because it confirmed that the substance found in the water was not naturally occurring and that the plume was at its highest concentration in deeper waters.

The researchers will use further testing to determine whether the hydrocarbons they found are the result of dispersants or the emulsification of oil as it traveled away from the well.

The first such plume detected by scientists stretched from the well southwest toward the open sea, but this new undersea oil cloud is headed miles inland into shallower waters where many fish and other species reproduce.

The researchers say they are worried these undersea plumes may are the result of the unprecedented use of chemical dispersants to break up the oil a mile undersea at the site of the leak.

Hollander said the oil they detected has dissolved into the water, and is no longer visible, leading to fears from researchers that the toxicity from the oil and dispersants could pose a big danger to fish larvae and filter feeders such as sperm whales.

"There are two elements to it,” Hollander said. “The plume reaching waters on the continental shelf could have a toxic effect on fish larvae, and we also may see a long term response as it cascades up the food web.”