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LINDA WERTHEIMER, host:
This is MORNING EDITION from NPR News. I'm Linda Wertheimer.
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And I'm Steve Inskeep. Good morning.
We understand, a little better now, where all the oil went after the spill in the Gulf of Mexico. Scientists have mapped out, for the first time, the path that some petrol chemicals took, they traveled underwater.
The so-called plume of oil compound extends for at least 22 miles. And NPR's Dan Charles reports, it's an important new piece of the puzzle.
DAN CHARLES: For several months now, scientists have been reporting that some oil from BP's blown-out well was staying underwater.
Christopher Reddy from the Woods Hole Oceanographic Institution in Massachusetts told a news conference yesterday, this was a big surprise.
Dr. CHRISTOPHER REDDY (Marine chemist, Woods Hole Oceanographic Institution): If you'd asked me - and I've been studying oil spills for 15 years - whether or not you would see oil in the subsurface, I would said, no - doesn't oil float?
CHARLES: That's fascinating, he says, but also troublesome, because if scientists don't know where the oil is, they don't know what harm it might be causing.
In June, Reddy and his colleagues from Woods Hole, took a research boat to the scene of the spill. They lowered a sensor deep into the water and towed it in a large circle around the blown-out well, looking for particular hydrocarbons that are easy to detect. The sensor picked up a signal southwest of the well, in a layer of water 3,000 feet down.
Richard Camilli, another researcher from Woods Hole, says they then sent down a new device, a small unmanned submarine with sensors onboard, called Sentry.
Dr. RICHARD CAMILLI (Researcher, Woods Hole Oceanographic Institution): And we had Sentry fly at a constant depth in kind of a zigzag pattern, moving out from the well site, tracking the plume.
CHARLES: The hydrocarbons were highly diluted in the water. They were coming from the well but they weren't spreading out in all directions. They followed an invisible underwater channel just over a mile wide and 650 feet deep. The researchers tracked that channel southwest for 22 miles, until bad weather forced them to stop.
They thought they might see microorganism feasting on those hydrocarbons and breaking them down. Christopher Reddy says they didn't and he doesn't know why.
Dr. REDDY: Microbes are a lot like teenagers, they work on their own time, their own scale. They do what they want when they want.
CHARLES: There are many other unknowns. Reddy and his colleagues don't yet know how much of the oil that gushed from the well is in this plume, although they hope to, months from now, when they've analyzed all their water samples. They also don't know how toxic it might be to wildlife. Still, this is the best-documented case, so far, of oil flowing underwater. It was released yesterday by the Journal Science.
Dr. STEVEN MURAWSKI (Chief science advisor, National Oceanic and Atmospheric Administration): This report is a big piece of the puzzle.
CHARLES: Steven Murawski is trying to put the whole puzzle together - and figure out where the oil went. He's science advisor for fisheries for the National Oceanic and Atmospheric Administration. Spread across the table in his office, is a map of the Gulf of Mexico.
Dr. MURAWSKI: We've had up to seven vessels at a time, out here, trying to map out the distribution of the underwater feature.
CHARLES: Murawski says more reports are coming, about oil in the deep sea around the well. But he'd like to see more scientists working in other areas, on the continental shelf, for instance, the wide, shallow areas closer to shore.
Dr. MURAWSKI: This is the area where fisheries primarily occur; now we've got a very vigorous fisheries seafood safety monitoring program, but we need to do water chemistry up there as well.
CHARLES: Murawski says he's drafting plans to expand such research, gradually painting a more complete picture of where the spilled oil went.
Dan Charles, NPR News.