"In fact, we observed oxidation of methane by these microbes at the highest rates ever recorded in seawater," Girguis says.
Methane is a greenhouse gas, up to 60 times more potent than carbon dioxide. Gigatons of the volatile gas are produced in seafloor sediments, above and beyond that generated by gas seeps that pockmark the floor of the Gulf of Mexico and other bodies of water. But, Girguis says, somewhere between the seafloor and the sea's surface, much of the methane vanishes.
"We found that concentrations of methane in brine pools are tremendously high: five to six orders of magnitude higher than in the water column above," Girguis says. "Mass spectrometry has given us a window on both the amount of methane diffusing into the water column and how much of this methane is consumed through anaerobic oxidation by microbes within the brine pool. It appears the microbes consume much of the methane, and the rest dissipates over time into the water column."
A study published in the journal Science in August detailed a bacterial species reportedly able to degrade oil anaerobically in the Gulf. But a subsequent Science paper contended that these microbes mainly digested gases like methane, propane, ethane, and butane, not oil. The Deep-Sea Research II paper adds to scientists' growing understanding of these species' ability to degrade the byproducts of the Deepwater Horizon spill.
|Contact: Steve Bradt|