NPR
Scientists on a research vessel in the Gulf of Mexico are finding a substantial layer of oily sediment stretching for dozens of miles in all directions. Their discovery suggests that a lot of oil from the Deepwater Horizon didn't simply evaporate or dissipate into the water — it has settled to the seafloor.
The Research Vessel Oceanus sailed on Aug. 21 on a mission to figure out what happened to the more than 4 million barrels of oil that gushed into the water. Onboard, Samantha Joye, a professor in the Department of Marine Sciences at the University of Georgia, says she suddenly has a pretty good idea about where a lot of it ended up. It's showing up in samples of the seafloor, between the well site and the coast.
"I've collected literally hundreds of sediment cores from the Gulf of Mexico, including around this area. And I've never seen anything like this," she said in an interview via satellite phone from the boat.
Joye describes seeing layers of oily material — in some places more than 2 inches thick — covering the bottom of the seafloor.
"It's very fluffy and porous. And there are little tar balls in there you can see that look like microscopic cauliflower heads," she says.
It's very clearly a fresh layer. Right below it she finds much more typical seafloor mud. And in that layer, she finds recently dead shrimp, worms and other invertebrates.
'A Slime Highway'
How did the oily sediment get there? Joye says it's possible that chemical dispersants might have sunk some oil, but it's also likely that natural systems are playing an important role.
"The organisms that break down oil excrete mucus — copious amounts of mucus," Joye says. "So it's kind of like a slime highway from the surface to the bottom. Because eventually the slime gets heavy and it sinks."
That sticky material can pick up oil particles as it sinks. Joye can't yet say with certainty that the oily layer is from BP's blown-out well.
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