Oil spill science: Where’s the oil?

cience journalist Mark Schrope is aboard the research vessel Pelican, which is spending the week studying the Deepwater Horizon oil spill in the Gulf of Mexico. Check back to The Great Beyond for daily mission updates.
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This morning, while still several kilometres out from the spill site, we saw the largest concentrations of oil we've yet come across. Most of the water had an oily sheen, and there were large bands of dispersed oil thick enough that you could smell them as we passed through.

We're now just a kilometre or so southeast of the still-gushing well, with the drilling rigs and countless other vessels in plain view. We were shocked on arrival to discover the water here is a beautiful, relatively clear blue. That may sound like a good thing, but it could be a problem.

Last week, this site was covered in oil, and under normal conditions these waters are bluish green because of heavy phytoplankton growth. "The oil might take all the phytoplankton with it to the bottom," says Arnie Diercks, expedition chief scientist for the National Institute for Undersea Science and Technology (NIUST) team, though he cautions this is only a hypothesis. It's impossible to say yet what the impacts might be.

So where is the oil now? That's really the guiding question of the whole expedition. The team will not be able to say for sure this week what's happening. That will take extensive analyses and return trips to get samples later as the oil has even more time to settle. But as of today, there are some intriguing clues.

One piece of equipment the researchers picked up over the weekend is a fluorometer. They attach this to a rosette of water sampling bottles (below) that's lowered to the bottom—1,500 to 2,000 metres deep or so depending on where we are—with bottles triggered to close at various depths to collect samples. The team also attaches the fluorometer to a small glider called the Acrobat, which is programmed to dive down to 54 metres and back up repeatedly for as long as it's in the water. It's running now and will be for the whole night.

The fluorometer sends out a beam of light at a known wavelength and then measures how this light is reemitted at a different wavelength once it hits dissolved material in the water. The instrument is tuned to detect coloured dissolved organic matter (CDOM) fluorescing at the known wavelength for oil.

In the 30 to 50 metre range, the fluorometer is picking up a substantial increase in CDOM that could be the depth to which dissolved oil has made it. "There's something going on down there," says Vernon Asper, a NIUST oceanographer. "That's going to be an extremely interesting signal."

Another instrument on the sampling rosette, called a transmissometer, measures particle concentrations, and readings show a large increase at about 120 metres. High levels of particles at this depth are not surprising, but it could be more concentrated than normal: a zone of oil, aggregated with plankton, other organic material, and possibly even small zooplankton.

Organic aggregates, referred to as marine snow, are common in ocean water columns, but adding huge quantities of dispersed oil to the normal mix is a decidedly new twist that researchers will have to understand in order to gauge the effects of the oil spill. "I did my dissertation on marine snow aggregates and now there's finally a really important application of that knowledge," says Asper with a chuckle, pointing to some aggregates near the surface.

Another potentially telling piece of information comes from the sediment cores, which, to the consternation of those awake, repeatedly failed to trigger properly in the wee hours this morning. Last week at this site they found six or so tiny dead crustaceans, possibly amphipods that normally live up in the water column. Today, once the core finally began working properly again, they found one more. "Fifth times a charm," deadpanned Karl McLetchie, a NIUST engineer and one of those who endured the early morning misfires while a certain reporter allegedly slept.

More: http://blogs.nature.com/news/thegreatbeyond/

just as sure as its spewing out of the ground underneath it. This will have some very long lasting detrimental effects on all life here on earth. They're not talking in terms of hours in stopping this they're talking weeks, months. Another month of this and the gulf is a dead zone for the rest of the lives of anyone alive today. Those bastids at the hearing yesterday should all be strung up with a good strong rope, with preferably the choking kind of knot tied.