Nearly three-fourths of oil from the BP spill is gone from the Gulf of Mexico, with 26 percent remaining as a sheen or tarballs, buried in sediment or washed ashore, U.S. scientists said Wednesday.
In a study titled "BP Deepwater Horizon Oil Budget: What Happened to the Oil?," scientists estimated "that burning, skimming and direct recovery from the wellhead removed one quarter (25 percent) of the oil released from the wellhead."
Another 25 percent naturally evaporated or dissolved and 24 percent was dispersed, either naturally or "as the result of operations," into small droplets, the report said.
The rest of the estimated 4.9 million barrels of crude spilled into the Gulf after the April 20 rig explosionthat triggered the leak is either on or just beneath the water's surface as "light sheen or weathered tarballs," has washed ashore where it may have been collected, or is buried in sand and sediments at the sea bottom.
The report found 33 percent of the oilhas been dealt with by the Unified Command, which includes government and private efforts.
"This includes oil that was captured directly from the wellhead by the riser pipe insertion tube and top hat systems (17 percent), burning (5 percent), skimming (3 percent) and chemical dispersion (8 percent)," the report found.
Natural processes broke down the rest of the 74 percent that has been removed from the Gulf.
"The good news is that the vast majority of the oil appears to be gone," Carol Browner, energy and climate change adviser to President Barack Obama, said on ABC's "Good Morning America." "That's what the initial assessment of our scientists is telling us."
"We do feel like this is an important turning point," she said.
The report was released just before officials from the National Oceanic and Atmospheric Administration and the Environmental Protection Agency testified at a U.S. Senate hearing about the use of dispersant chemicals to combat the BP spill.
Paul Anastas, of EPA's office of research and development, acknowledged there are "environmental tradeoffs" to consider when using dispersants.
Anastas told the Senate Environment and Public Works Committee that dispersants are generally less toxic than oil, cut the risk to shorelines and degrade quickly, in days or weeks.
Responding to spill reports Wednesday, President Obama said the battle to stop the devastating spill was finally near an end.
Obama hailed as "welcome news" that BP's efforts to plug the leaking well for good appeared to be working.
"The long battle to stop the leak and contain the oil is finally close to coming to an end," Obama said at the start of a speech to the AFL-CIO union federation in Washington.
But he insisted the government would continue to hold "accountable" those responsible for the worst oil spill in U.S. history, and make sure cleanup and recovery work was carried to fruition. Shares of U.S.-held shares of BP were last fractionally lower in New York trade. London shares , meanwhile, closed up nearly 2 percent.