Methane-munching bacteria in the Gulf of Mexico have surprised scientists with their ability to quickly consume the hazardous compound after the record-breaking Deepwater Horizon oil spill that occurred in April 2010.
The explosion on the BP-owned oil rig resulted in the death of 11 workers and the release of approximately 170 million gallons of oil into the Gulf of Mexico.
According to a press release, scientists from UCSB and Texas A&M have reported that methane concentrations present at the spill site have returned to normal levels. Methane, a natural hydrocarbon gas that dissolves in water, was monitored by scientists after the spill in order to quantify the extent of the oil content in the water.
While the original concentration of methane in the water after the spill had been determined to be 100,000 times normal levels, the concentration had returned to normal after 120 days as a result of hydrocarbon oxidizers — organisms that consume oil.
According to David Valentine, a leader of the study and a professor of geochemistry and geomicrobiology at UCSB, the methane has been replaced by a boom of bacteria and a drop in oxygen content.
“What we observed in June was a horizon of deep water laden with methane and other hydrocarbon gases,” Valentine said in a press release. “When we returned in September and October and tracked these waters, we found the gases were gone. In their place were residual methane-eating bacteria, and a one million ton deficit in dissolved oxygen that we attribute to respiration of methane by these bacteria.”
While the consumption of the methane by the hydrocarbon oxidizers was expected, what surprised the scientists was the rate at which the gas was consumed, according to Texas A&M professor and co-leader of the study John Kessler.
“Based on our measurements from earlier in the summer and previous other measurements of methane respiration rates around the world, it appeared that methane [from the Deepwater Horizon spill] would be present in the Gulf for years to come,” Kessler said in a press release. “Instead, the methane respiration rates increased to levels higher than have ever been recorded, ultimately consuming it and prohibiting its release to the atmosphere.”
The consumption of the gas also prevented its entry into the atmosphere, where it could have operated as a greenhouse gas.
“The seafloor stores large quantities of methane, a potent greenhouse gas, which has been suspected to be released naturally, modulating global climate. What the Deepwater Horizon incident has taught us is that releases of methane with similar characteristics will not have the capacity to influence climate.”
While the events surrounding the Deepwater Horizon oil rig were a tragedy, the researchers said they were able to gain a better understanding of the ecology of oil spills in order to prevent or mitigate them in the future.
“We were glad to have the opportunity to lend our expertise to study this oil spill. But also we tried to make a little good come from this disaster and use it to learn something about how the planet functions naturally,” Kessler said in the press release.
“This tragedy enabled an impossible experiment,” Valentine said in a press release. “One that allowed us to track the fate of a massive methane release in the deep ocean, as has occurred naturally throughout Earth’s history.”