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Gulf Cruise Raises Questions on Methane, But Much Data Still to Analyze
23 June 2010 2:21 pm
Preliminary results from a research cruise measuring methane in deep water near the gushing BP well point to large concentrations of the gas, but what that means for the environment is far from clear.
A crew led by John Kessler, a chemical oceanographer at Texas A&M University, College Station, returned late on Monday from a 10-day cruise on the R/V Cape Hatteras. His team sampled methane in 35 places at depths from 1200 to 1700 meters and at distances from the well head ranging from 7 miles to as close as 500 meters.
Although the crew's water samples have yet to be analyzed, shipboard measurements showed that "concentrations of methane and some of the other components of natural gas, namely, ethane and propane, in the deep waters of the Gulf of Mexico are astonishingly high," Kessler announced at a press conference yesterday afternoon.
Methane concentrations ranged from 10,000 to nearly 1 million times higher in some spots than the normal concentration, which is about 20 nanomoles per liter, Kessler said. These measurements agree with those from a 2-week cruise on the Walton Smith that returned 6 June.
Scientists worry that methane-eating microbes could deplete oxygen in these waters. Kessler said the crew measured oxygen reductions of about 30% at some deep sites but saw no oxygen depletion in others. "It's certainly something where we need to go through our data with a more fine-toothed comb and determine why that is," he said.
The cruise had another purpose-to better quantify how much oil has gushed out of BP's blown well. About 40% of the material flowing out is methane gas, according to measurements by BP engineers, and Kessler's colleague David Valentine, an oceanographer at the University of California, Santa Barbara, proposed measuring methane as a way of quantifying the spilled oil. Kessler said he and Valentine hope to make preliminary estimates in the next week.