Deepwater Horizon’s Oil-Eating Microbes May Have Eaten Less Oil Than We Expected
The April 20, 2010, the Deep Water Horizon oil drilling rig started leaking oil into the Gulf Of Mexico. Over the course of 84 days, it would eventually become the largest accidental marine oil spill in the history of the petroleum industry. About five million gallons of oil and up to 500,000 tons of natural gas have been discharged into the Gulf of Mexico so far, and despite massive cleanup efforts, the damage could not be contained. It came as some relief to researchers that oil-eating microbes might be able to breakdown the oil before affecting nearby aquatic life, but new research shows that the claim may have been exaggerated.
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The research questions the microbes' effectiveness in completely and consistently removing oil. Led by Samantha Joye, a professor of marine science at the University of Georgia's Franklin College of Arts and Sciences, she said in a press release that "most of the gas injected into the Gulf was methane, a potent greenhouse gas that contributes to global climate change. So we were naturally concerned that this potent greenhouse gas could escape into the atmosphere. Many assumed that methane-oxidizing microbes would simply consume the methane efficiently, but our data suggests that this isn't what happened."
The researchers measured methane concentrations and the activity of methane-consuming bacteria over the course of 10 months, with the most important samples being taken in March 2010, before the rig's explosion. Although they saw that the microbes were consuming methane rather quickly during the first couple of months, later measurements indicated slower rates of consumption or biodegradation, even though methane was still being discharged from the wellhead.
The scientists realized that it was the absence of other environmental, physiological, and physical components, and not a lack of methane that was hindering the microbes' ability to consume the gas. "For these bacteria to work efficiently, they need unlimited access to nutrients like inorganic nitrogen and trace metals, but they also need elevated methane levels to persist long enough to support high rates of consumption," Joye said in the release. "The bacteria in the Gulf were probably able to consume about half of the methane released, but we hypothesize that an absence of essential nutrients and the dispersal of gas throughout the water column prevented complete consumption of the discharged methane."
Her research corroborates with previous findings, but, as she points out, her team focused on a long-term analysis. "The issue here was short-term sampling versus long-term time series sampling," she said. "I hope our paper clearly relays the message that long-term sampling is the only way to capture the evolution of a natural system as it responds to large perturbations like oil well blowouts or any other abrupt methane release."
The need of the hour according to her is to better understand these oil-eating microbes so that they can be effectively utilized to contain methane releases in the future.
It's necessary, she said, to better understand these oil-eating microbes so that they can be utilized more effectively in the future. "It's only a matter of time before we face another serious incident like Deepwater Horizon," she said. "The key is understanding the things that regulate how fast bacteria can consume methane, and that will give us insight into the ultimate fate of this potent greenhouse gas in our oceans."
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