Oil plume lingering in Gulf, study confirms

Patrick Semansky /ASSOCIATED PRESS

THE NEW YORK TIMES

Published: 8:19 p.m. Thursday, Aug. 19, 2010

New research confirms the existence of a huge plume of dispersed oil deep in the Gulf of Mexico and suggests that it has not broken down rapidly, raising the possibility that it might pose a threat to wildlife for months or even years.

The study, the most ambitious scientific paper to emerge so far from the Deepwater Horizon spill, casts some doubt on recent statements by the federal government that oil in the Gulf appears to be dissipating at a brisk clip. However, the lead scientist in the research, Richard Camilli, cautioned that the samples were taken in June and circumstances could have changed in the past two months.

The paper, which will appear in today's issue of the journal Science, adds to a welter of recent, and to some extent conflicting, scientific claims about the status of the Gulf. Although scientists generally agree that the risk of additional harm at the surface and near the shore has diminished since the well was capped a month ago, a sharp debate has arisen about the continuing risk from oil in the deep waters.

So far, scientific information about the Gulf has emerged largely from government reports and statements issued by scientists. Many additional research papers are in the works, and it could be months before a clear scientific picture emerges.

The slow breakdown of deep oil that Camilli's group found had a silver lining: It meant that the bacteria trying to eat the oil did not appear to have consumed an excessive amount of oxygen in the vicinity of the spill, alleviating concerns that the oxygen might have declined so much that it threatened sea life. On this point, Camilli's research backs statements that the government has been making for weeks.

Concentrations of hydrocarbons in the plume were generally low and declined gradually as the plume traveled through the Gulf, although Camilli's team has not completed tests on how toxic the chemicals might be to sea life.

For weeks, BP, the company that owned the out-of-control well, disputed claims from scientists that a huge plume of dispersed oil droplets had formed in the Gulf, with its chief executive at the time, Tony Hayward, saying at one point, "There aren't any plumes."

The National Oceanic and Atmospheric Administration, though initially skeptical, ultimately confirmed the existence of such plumes in two reports. The new paper appears to dispel any lingering doubt, providing detailed evidence that one major plume and at least one minor plume existed and that they contained large quantities of hydrocarbons, albeit dispersed into tiny droplets.

Final ‘kill' to be delayed

The final sealing of BP's stricken well in the Gulf will be delayed until after Labor Day, officials said Thursday, so that the company can replace equipment that contributed to the well's failure.

Thad Allen, the retired Coast Guard admiral who is leading the federal response to the spill, said at a briefing in Washington that after discussions between BP engineers and government scientists, BP had agreed to remove the damaged blowout preventer — the device that failed when the drill rig exploded in April — and the new cap that was installed atop it last month.

They will be replaced by another blowout preventer that Allen said would be better able to handle any pressure changes that might occur when a relief well intercepts the stricken well and pumps mud and cement into it in a final "bottom kill" operation.

One concern is that about 1,000 barrels of oil are trapped in the outer portion of the well. If more mud is pumped in, the pressure in the well could rise and the top seals or cement might be damaged, allowing oil and gas to travel up into the damaged blowout preventer and, potentially, into the Gulf.