• by Matthew O. Berger (washington)
• Friday, August 20, 2010
• Inter Press Service

Between April and August this year, 4.9 million barrels of oil were spilled into the Gulf of Mexico. How much remains today is not yet clear and is a hot topic of debate among academic and government scientists.

The largest accidental oil spill in history began four months ago Friday following an explosion on the BP-leased Deepwater Horizon drilling rig off the Louisiana coast. Since the capping of the gushing well on Jul. 15, there have been a flurry of efforts to put a number on the quantity of oil remaining — and its potential impacts.

Sparking the debate over this number was a U.S. government report released Aug. 4 that estimated 74 percent of the leaked oil had been captured, burned, evaporated or dissolved.

Marine scientists at the University of Georgia challenged those estimates earlier this week, saying that based on their studies as much as 79 percent of the oil still remains.

Neither study has been peer-reviewed or published in a scientific journal, leading many to treat them simply as competing estimates.

But they do point to the range of possible estimates in the wake of the massive oil spill and the questionable accuracy of government reports on the extent of the spill and its damages.

If you add up what was pumped to tankers at the surface, the effects of the dispersants in encouraging digestion by bacteria over evaporation, and what was burned off, you can get a number, incident commander for the gulf oil disaster Thad Allen said Friday in Washington. 'If you add all that up and solve for X, you get 26 percent' as the amount of the 4.9 million barrels that remains in the Gulf.

Realising that this number is only one estimate of many is important, though, he said. 'Is it completely accurate? No. It's based on certain assumptions,' Allen said.

The government numbers were cast into even deeper doubt by a study published in Friday's issue of the journal Science.

Highlighting the study was data from June on the size of a plume of oil compounds near the ruptured well — at least 22 miles long and 1.2 miles wide, 650 feet high and over 3,000 feet below the surface of the Gulf — and the finding that this plume would likely persist for some time.

Despite speculations that droplets of oil below the surface were being easily biodegraded, the plume shows that oil 'is persisting for longer periods than we would have expected,' said Richard Camilli, of the Wood's Hole Oceanographic Institution and the paper's lead author.

Analyzing the quantity and the toxicity of the oil in that plume and will still take some time, Camilli and his colleagues said Thursday in Washington, and the fact that their samples were taken in June likely means the plume has changed in size and composition since then.

Yet the study does show that there is likely a much more complicated answer to the question of what happened to all that oil then Washington has so far let on.

Following the questions raised about the government's findings on the amount of oil left in the Gulf, government findings over the safety of seafood from the region have also come under scrutiny.

Senator Ed Markey held a hearing on Capitol Hill Thursday to look deeper into the matter. His and others' main concern is that while satisfactory testing may be done to determine the presence of oil in seafood, the dispersants that were used in the gulf may not all show up in those tests.

Most likely, the amount of chemicals in organisms varies from species to species, with oysters the most likely to remain contaminated, scientists have said.

The National Oceanic and Atmospheric Administration says it is continuing to monitor the level of contaminants in gulf seafood, but 54 percent of U.S. respondents to a poll taken Aug. 11 to 16 by the Associated Press remain unconvinced about the food's safety.

An end in sight

Allen said he understood the frustration caused by the inability of the government and BP to guarantee when the final operation to shut off the well completely and permanently would take place, but that the preparations for this 'bottom kill' are underway.

'Sometime in the week after Labour Day we will be in a position to execute the bottom kill,' he said. 'We are down to the very end of this process but we are moving cautiously.'

'We are not done. Nobody has declared mission accomplished,' he added.

In the weeks and months to come, several criminal investigations will look into the causes and handling of the blowout and the clean-up work will continue, with a greater focus on the coasts and marshes that have been affected.

We are in the 'process of transitioning to a lot of work that's inshore,' said Allen. He said he and others and had been having discussions with local officials to determine 'how clean is clean'.

'BP will not be involved in that' inshore work, he said.

© Inter Press Service (2010) — All Rights Reserved. Original source: Inter Press Service

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