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Oil drifting underwater

At today's Department of Homeland Security briefing on the oil spill with the Coast Guard's Thad Allen and NOAA's Jane Lubchenco, subsurface concentrations of oil were confirmed, and found drifting as far as 142 miles away from the site of the explosion.

Allen said that while the term "oil plume" has been used widely for several weeks, he said that is incorrect. "Cloud is a better term," he said.

Lubchenco chimed in, saying that people should think of this like ash from a volcano, the plume takes it up, where it then forms a cloud that drifts about on wind currents.

She added that the underwater measurements show that the oil in this cloud is concentrated in small amounts so far.

"Concentrations of the oil are in the range of 0.5 parts per million," she said.

The test results showed there is oil subsurface, its in the water column, and they are using samples from three different sites to create an MRI-like 3-D underwater image to see where the subsurface oil is and where it is drifting.

Allen also added that one of the four vents on the containment cap is now closed.