Microbes Rapidly Consume Methane from Gulf Oil Disaster
The Deepwater Horizon spill was a horrible environmental disaster which caused the release of massive amounts of crude oil into the Gulf of Mexico. Methane, a natural greenhouse gas, was also released during the catastrophe. However, researchers have found that the methane is being consumed by microbes at a rate 10 to 100 times faster than previously believed. These microbes are essential in bringing the Gulf back to a healthier state.
Methane naturally seeps at spots scattered across the sea floor. Special microbes have evolved to digest and thrive off the methane, a carbon-based organic compound. During normal conditions, most of the methane that permeates the sea floor is consumed before it can reach the surface.
The explosion at the Deepwater Horizon rig caused a massive outflow of methane, creating a sort of feeding frenzy for the deep sea microbes. The new methane caused a population explosion, as they constantly ate and multiplied. The researchers' analysis showed that they consumed up to 100 times faster than previously realized.
Peter R. Girguis, associate professor of organismic and evolutionary biology at Harvard University, noted that although the rate of consumption was extremely high, it could not match the rate at which the methane erupted from the damaged well.
The researchers were able to measure the microbial rate of consumption by using a technique called on-site mass spectrometry, which obtained accurate measurements of seafloor methane. For most tools, measuring the deep sea brine pools where methane resides is extremely difficult due to the depth and high pressures.
The new technique allowed the scientists to determine the methane concentrations surrounding the gas seeps as well as the water column above the brine pools. By crunching numbers, they were able to extrapolate how fast the microbes consumed the methane.
"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."
Other bacterial microbes have been discovered that rapidly degrade oil anaerobically in the Gulf, but some researchers have found that the microbes only degrade gases like methane and propane, and not oil. Either way, it will take some time for the Gulf to return to its state pre-Deepwater Horizon incident. Man-made solutions like dispersants are not nearly as efficient as deep sea microbes, Earth's natural water filtration.
This research will be published in the journal, Deep-Sea Research II.