|Seawater covered with thick black oil splashes up in brown-stained whitecaps off the side of the supply vessel Joe Griffin at the site of the Deepwater Horizon oil spill containment efforts in the Gulf of Mexico off the coast of Louisiana Sunday, May 9, 2010. (AP Photo/Gerald Herbert)|
Massive underwater oil plumes found off US Gulf CoastMay 15, 2010
Scientists have found vast underwater plumes of oil, one 10 miles (16km) long and a mile wide, in the Gulf of Mexico following last month's rig explosion.
A Georgia University expert warned oxygen levels had fallen 30% in some areas of the sea, and it could take decades to repair the damage.
BP meanwhile says it has successfully inserted a pipe to siphon oil from the damaged well up to a ship.
The US government has demanded BP make clear its commitment to pay damages.
Researchers from the National Institute for Undersea Science and Technology say they have detected several sprawling oil slicks lurking just beneath the surface of the sea and at depths of 4,000ft (1,200m).
The find suggests the scale of the potential environmental disaster is much worse than previously feared since the Deepwater Horizon drilling rig blew up on 20 April, killing 11 workers.
Samantha Joye, a marine science professor at the University of Georgia, said: "It could take years, possibly decades, for the system to recover from an infusion of this quantity of oil and gas.
"We've never seen anything like this before. It's impossible to fathom the impact."
The experts say the oxygen depletion is likely to continue, endangering sea life and raising the prospect of underwater dead zones.
The scientists said the chemical dispersants BP has been dumping underwater may be preventing the oil from rising to the top of the ocean.
Official estimates doubted
The energy giant has said the chemicals, which it began deploying on Friday, have already resulted in less oil surfacing.
Some scientists cast doubt on official estimates of the oil flow rate, saying the widely repeated figure of 5,000 barrels per day dramatically understates the real amount.
On Sunday, BP said it had successfully inserted a 6in-wide (15cm) tube into the well a mile beneath the surface and diverted some oil and gas to a ship above.
The firm said the test was halted when the tube became dislodged on Saturday night, but the pipe had since been re-inserted.
It could capture more than three-quarters of the leak; BP must also contain a smaller spill on the seabed nearby.
A week ago, BP tried to cap the well with a 100-tonne box, but gave up after it became encrusted with ice crystals.
On Saturday, the Obama administration demanded immediate clarification from BP over its commitment to pay damages for the spill.
Officials said they wanted to be sure BP would honour commitments not to limit costs to a US statutory cap of $75m (£50m).
It is not clear what prompted the letter as BP said last week the cap was irrelevant and it would settle all costs.
Mississippi has become the third US state to have traces of oil wash up on its coast, along with Louisiana and Alabama.
The spill is threatening to eclipse the 1989 Exxon Valdez leak off Alaska as America's worst environmental disaster.