Drop in methane levels reported in Gulf oil spill region

The study into the methane concentrations was led by oceanographers John Kessler of Texas A&M and David Valentine of UCSB. The findings show that more than 200,000 metric tons of dissolved methane were removed through the action of bacteria blooms that completely consumed the immense gas plumes the team had identified in mid-June.

At that time, the team reported finding methane gas in amounts 100,000 times above normal levels. But, about 120 days after the initial spill, they could only find normal concentrations of methane.

’What we observed in June was a horizon of deep water laden with methane and other hydrocarbon gases,’ Valentine said. ’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.’

Kessler added: ’Based on our measurements from earlier in the summer and previous measurements of methane respiration rates around the world, it appeared that [Deepwater Horizon] methane would be present in the Gulf for years to come. Instead, the methane respiration rates increased to levels higher than have ever been recorded, ultimately consuming it and prohibiting its release to the atmosphere.’