Gulf oil spill: Oil concentrations in gulf waters are decreasing

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Federal scientists say the concentrations of oil they are finding in Gulf of Mexico waters are continuing to decline.

‘We’ve been seeing a very clear trend of diminished concentrations,’ said Sam Walker, a chief science advisor with the National Oceanic and Atmospheric Administration. ‘Particularly in the water column, we’re down into the parts per billion range now.’

BP’s blown-out well, which was fully plugged over the weekend, has not leaked since mid-July. As a result, hydrocarbon levels are now much lower than early in the summer, when university cruises detected large plumes of tiny oil droplets floating in deep waters.

Speaking at a Tuesday news briefing, Walker said that NOAA was continuing extensive sampling, both of seafloor sediments and the water column.’There are in fact places where oil still resides,’ he said. ‘Particularly in the near-shore area, it’s been entrained in sediments.’

Although some 23,000 cleanup workers remain on duty, their numbers are falling and the response effort is being consolidated under the command of the New Orleans headquarters.

Crews are still skimming residual oil from Louisiana marshes and scouring pockets of oil along 600 miles of shoreline from Louisiana to Florida, Rear Adm. Paul Zukunft said.

The federal government is also mapping and testing natural oil seeps to help scientists distinguish them from the BP spill.

-- Bettina Boxall

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