Gulf oil spill plumes doubled back

UndeUndersea oil plumes doubled back to the 2010 Gulf of Mexico spill site during the disaster, a study released Monday finds. The report explains some of the 'where's the oil' confusion that marked the first months of the tragedy.

The Deepwater Horizon drilling platform disaster began April 20, 2010, with a well blow-out and explosion that killed 11 workers. During the disaster, which lasted three months, observers differed over the location and extent of deep sea plumes of oil released in the tragedy.

Final estimates concluded that the spill released some 4.1 million barrels of crude. Measurements have since shown that layers of crude contaminants pooled at depths of 2,500 feet and 4,225 feet undersea, forming plumes that traveled around the Gulf before finally heading to the southwest in a weak cloud more than 20 miles long.




In the study released Monday by the Proceedings of the National Academy of Sciences journal, and led by David Valentine of the University of California, Santa Barbara, a team recreated the path taken by crude oil constituents spewed from the wellhead some 5,000 feet deep under the Gulf of Mexico. The team combined current, chemistry and biology (an exploding population of hydrocarbon-munching microbes) undersea to recreate the path of the polluted plumes in a simulation.

"This was a complicated environment. There was a lot going on there," Valentine says.

The surprising finding of the analysis is of the "reinoculation" of the plumes, where methane-eating microbe population sizes exploded over the site of the well disaster, and then drifted with currents. Those same currents then circled back to the wellhead, allowing the bug populations to feast on second helpings of the buffet of hydrocarbons.

"That was fortunate," Valentine says, as the bulwarked bugs seem to have made a meal out of much of the methane and crude oil constituents that escaped from the spill. Remarkably, they did so without exhausting the oxygen in the water and creating a dead zone for the microbes, which would have stopped their oil-munching work.

A similar dynamic would be unlikely to play out at other undersea oil drilling sites, Valentine cautions. Currents don't recirculate off the Brazilian coast, for example, just heading out into the Atlantic. In the Caspian Sea, spill plumes would more likely remain stationary until the microbes exhausted the oxygen or other nutrients at the spill site, creating a dead zone.

"The Gulf (of Mexico) is a unique environment, but I think you would see something similar play out there in another spill, as far offshore," (as the Deepwater Horizon spill) Valentine says.

Hopefully, that won't happen anytime soon.