January 7, 2011

Fast-Acting Bacteria Consumed Oil Spill Methane

The nearly 200,000 tons of methane released into the Gulf of Mexico during last year's Deepwater Horizon oil spill were ingested by microbes in just four months, according to a new study published in Thursday's edition of the journal Science.

Methane, which made up one-fifth of the crude oil that was leaked into the Gulf following an explosion on the BP-operated rig in April 2010, sank mostly into the deepest part of the waters. There, according to what researcher David Valentine of the University of California-Santa Barbara told Reuters Environmental Correspondent Deborah Zabarenko, it was assimilated by bacteria.

"The methane was completely consumed by early September," Valentine, a geochemistry professor and one of the study's lead authors, said in a separate interview with AFP, adding that other forms of bacteria also managed to consume ethane and propane released by the explosion. "It happened very quickly and it was a surprise to us."

In the eight weeks following the April 20 blowout onboard the Deepwater Horizon, scientists observed that the methane was not being consumed near the wellhead, Zabarenko said, leading them to speculate that it could eventually dissipate into the air and contribute to global warming by trapping heat in the atmosphere.

"If you have a very large release of methane like this, and it did make it into the atmosphere, that would be a problem," Valentine told the Reuters correspondent. "There have been a number of ... large-scale methane releases in the past that have come from the ocean that have warmed the climate."

However, as Valentine, Texas A&M University oceanographer John Kessler, and their colleagues discovered, not only was that not the case, but the methane disappeared far quicker than they ever could have imagined.

"All of that evidence had pointed to a much longer lifetime of methane in deepwater plumes with a lifespan possibly as long as years," Kessler told Guardian US Environmental Correspondent Suzanne Goldenberg. "It was quite surprising."

"Given observations about how slowly methane is normally consumed, we didn't think the (bacteria) population was up to the challenge at all ... we thought it would be a lot slower," Valentine added during his telephone interview with Zabarenko.


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