Some say effects of Deepwater Horizon spill will be felt for years to come – Dispersants helped bacteria digest oil

By Ben Raines, Press-Register
Sunday, August 01, 2010, 5:24 AM MOBILE, Ala. — Now that BP’s damaged Gulf well appears under control, scientists are struggling to answer two questions: How much oil ended up in the Gulf, and what will be the long-term effects? Federal estimates of the flow rate from the Deepwater Horizon well covered a wide range. But there was one number consistently used by BP and the Coast Guard as they calculated dispersant use. In letters between BP’s Doug Suttles and federal officials, that number was 53,000 barrels per day, or 2,226,000 gallons. That means that over the course of the 87 days that the well was uncontrolled in the Gulf, about 192 million gallons of oil were released. Subtract from that the 45 million gallons BP said it collected with its cap, skimmed off the Gulf’s surface or burned, and that leaves about 147 million gallons of oil. Some of that oil has already washed up on beaches and marshes, but the lion’s share remains unaccounted for. … Ed Overton, a Louisiana State University chemist who has been analyzing oil samples for the federal government and the Press-Register, said the Gulf had done a remarkable job of breaking down the oil. Many of the samples he has been looking at show the oil has almost entirely degraded, he said. “I think the worst is past us,” Overton said. “We’re going to continue seeing oil coming ashore, and there will be impacts, but the bacteria in the Gulf are doing a better job of handling the oil than anybody expected.” Dispersants, he said, “helped put the oil in a form where that bacteria could work on it.” Asked then if underwater dispersant use had been effective, Overton said it appeared that it had, at least by breaking up oil and keeping it from beaches and marshes. But he added that the jury was still out on all of the biological implications of dispersant use. Harriet Perry, who studies crabs at the University of Southern Mississippi, reported a month ago finding crab larvae with globs of oil beneath their shells, one of the first examples of oil moving into the food chain. Perry said she believed the dispersant had broken the oil down into small enough particles that it was able to work its way beneath the larval crabs’ shells. …

Some say effects of Deepwater Horizon spill will be felt for years to come