Newly discovered underwater oil plume paints complex picture of Gulf leak

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Oceanographers announced today the discovery of a wispy oil plume at least 22 miles long and 1.2 miles wide floating beneath the surface of the Gulf of Mexico, a sign that plenty of the oil from BP’s Deepwater Horizon leak remains in the environment. It’s the first conclusive proof that a deep-sea plume from the leak exists, which at least partially explains what happened to the oil in the three months since the Deepwater Horizon rig exploded. It also casts doubt on the federal government’s statement earlier this month that most of the oil has dispersed or disappeared.

But the new study is merely a rough snapshot of what is happening in the depths. Wide disagreement persists among scientists who study the Gulf and oil spills, and they say it could take generations to fully understand the leak’s scope. The best minds in marine science and geology can’t say yet how bad it will be.

Woods Hole Oceanographic Institution researchers Richard Camilli and Chris Reddy followed the plume starting about three miles from the wellhead of the deep-sea Macondo well. Using autonomous submersibles, they took samples for 22 miles, until the approach of Hurricane Alex forced them to turn back.

As of now, they don’t know how much oil (of the estimated 4.9 million gallons leaked) is in the plume, and they can’t be certain how diffuse it is until they analyze more water samples, Reddy said. The researchers say the levels of dissolved oxygen within the plume had not dropped to levels that would suggest bacteria were breaking down the oil in significant volumes.

The report comes two weeks after a government study that most researchers said was widely misinterpreted. Other scientists dismissed the report as inaccurate or incomplete. That report, from the National Incident Command (NIC), said the majority of the oil had evaporated, been recovered or been dispersed — but dispersed does not mean gone.

Rick Steiner, a retired professor at the University of Alaska and marine conservationist who worked on cleaning up the Exxon Valdez oil spill, called that report fatally flawed.

“The estimate that chemical dispersants were successful at dispersing 8 percent of the leaked oil [as stated in the NIC report] is, quite frankly, ludicrous,” he said in an e-mail message.

Many others agree, and at least two studies emerged this week that appear to directly contradict the government’s findings. But none of them proves anything conclusively. Reddy said government scientists, along with those at universities and private institutions, are trying to account for all the oil like balancing a checkbook. But a checkbook is difficult to balance when none of the numbers being used are firmly accurate.

“This data that we’re waiting for, as it becomes available, they will be able to put it into their calculations,” he said. “When we have analyzed those samples, we’ll be able to constrain what the inventory of those compounds was in there. And at that point, we may be able to see whether it’s a penny in a big checking account, or maybe it’s bigger.”

Full story: Newly Discovered Underwater Oil Plume Paints a Complex Picture of Gulf Leak Aftermath | Popular Science