Researchers have reported that huge plumes of oil remain deep under the surface of the Gulf of Mexico. Samantha Joye, a marine scientist at the University of Georgia who is researching underwater oil plumes, talks to Robert Siegel to discuss her findings.
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ROBERT SIEGEL, host:
To the Gulf of Mexico now, where BP successfully cut a bent riser pipe earlier today - part of the company's latest effort to contain the six-week-old spill. The next step is to lower a containment cap over the leak, though it's unclear just how much of the oil that would capture.
Also unclear is what can or should be done about the hundreds of thousands of barrels that have already fouled the Gulf waters. Much of that oil has begun washing ashore in the form of tar balls.
But last month, at least three groups of researchers reported evidence that some of the oil remains deep under the surface in huge undersea plumes.
One of those researchers joins us now. Professor Samantha Joye is a marine scientist at the University of Georgia. Professor Joye has been working on a research vessel, the Walton Smith in the Gulf, and she joins us now on the water. Thanks for joining us.
Professor SAMANTHA JOYE (Professor of Marine Sciences, University of Georgia): Hi, thanks for having me.
SIEGEL: And first, how would you describe what these plumes are?
Prof. JOYE: Well, basically, these are deepwater features that we see starting at about 200 meters above the bottom, around 1,300 meters water depth. And they're most intense near the spill site, and they decrease in intensity away from the spill site.
SIEGEL: Now, last week, the CEO of BP, Tony Hayward, dismissed reports of plumes. This is what he said.
Mr. TONY HAYWARD (Chief Executive Officer, BP): There's no evidence of oil has a specific gravity that's about half that of water. It's very difficult for oil to stay in the column. It wants to go to the surface because of the difference in specific gravity.
SIEGEL: He's appealing to our memories of middle school science here, saying oil is lighter, it shouldn't be in plumes under the surface. It would naturally be on the surface.
Prof. JOYE: Well, that's true. If you were to take a bottle of oil and release it from a few meters below the surface, a blob of oil, it would float up to the surface. But we're not doing that. What we're doing is we're taking a highly pressurized solution, and we're exploding it out of the sea floor under high pressure and high velocity.
So it's much like putting olive oil in a bottle and then pressurizing it and then spraying it out in an aerosol form.
SIEGEL: Now, do these deepwater plumes pose any different or any greater environmental threat than, say, the tar balls that have been coming ashore?
Prof. JOYE: Well, it's a much different animal because there really is no way to clean these deepwater features up. You can't burn it off. You can't take it off with a skimmer ship. It's not going to wash ashore, where you can clean it up off a beach. So these features are likely to persist in the water for a lot longer and be much more difficult to remediate in the natural processes, natural microbiological processes. Those are the things that are going to take care of the deepwater systems.
SIEGEL: Have you or any of the other researchers been able to actually capture some of a piece of this plume somewhere and analyze it, or are you making these judgments based on sonar or other means?
Prof. JOYE: Well, we actually have a cassette of bottles called niskin samplers, and we lower this cassette of bottles. Then we trigger the bottles and collect water from those specific depths.
And when we do that near the spill site, the water that we retrieve from these plumes smells oily. It has visible oil in it. It has an incredibly high concentration of methane gas. And we have samples that are oily. You can see the oil in the water.
SIEGEL: You've described how deep these plumes would be. How long are they actually? How many miles might a plume stretch from the site of the well off to the east, say?
Prof. JOYE: We're still getting weak to moderate signals as far as 24 kilometers from the spill site. The plume spreads out a lot more as you get far away from it. And when you get more than about (technical difficulty) miles from the leak, you can then no longer smell oil in the water.
SIEGEL: Well, Samantha Joye, thank you very much for talking with us today.
Prof. JOYE: Thanks for having me. Have a good day.
SIEGEL: Professor Samantha Joye is a marine scientist at the University of Georgia. She spoke to us from her research vessel in the Gulf of Mexico. Transcript provided by NPR, Copyright NPR.