Questions about how much oil has been spilled in the last month by the Deepwater Horizon oil rig explosion could be answered if scientists move quickly to measure the plumes of dissolved methane gas drifting around the Gulf of Mexico, a geochemist proposed Sunday.
Writing in an online publication of the journal Nature, David Valentine of the University of California, Santa Barbara, called for "a concerted community effort" by scientists, federal officials and British Petroleum to devote at least two research vessels to the methane measuring mission during the month of June.
The actual amount of oil spilled -- and still spilling -- into the Gulf is one of the central issues surrounding what Valentine describes as likely "the worst oil spill in US history." While federal and British Petroleum officials continue to estimate the rate of leakage at 5,000 barrels a day, some scientists studying video of the leak concluded last week that the volume could be vastly larger.
And while satellite photos and boat measurements are helpful to assess the extent of the surface slick, he said, "these measures are also highly variable with time, place, weather conditions and dispersant application."
Spewing from the ocean floor a mile deep is a mixture that, according to BP, is roughly half methane and other gases by mass and half petroleum compounds, Valentine told Discovery News, and while the oil itself migrates unevenly around the Gulf in ways that are difficult to track, the behavior of methane is more congenial to measurement.
"Although methane from surface-vessel spills or shallow-water blowouts escapes into the air, I expect that the vast majority of methane making the long trip to the sea surface from a deep water spill would dissolve," Valentine wrote. "Unlike oil, methane dissolves uniformly in seawater. And the tools are available to measure it accurately and sensitively."
In June, he said, "we should aim to get to grips with the size and shape of the methane plumes by gracing water flow with 'drifting profiling flats' and through further spot analyses." The method isn't perfect, he said, but "it would at least put a lower bound on the total amount of spilled oil" and provide a good estimate of the rate of the spill.
Writing in an online publication of the journal Nature, David Valentine of the University of California, Santa Barbara, called for "a concerted community effort" by scientists, federal officials and British Petroleum to devote at least two research vessels to the methane measuring mission during the month of June.
The actual amount of oil spilled -- and still spilling -- into the Gulf is one of the central issues surrounding what Valentine describes as likely "the worst oil spill in US history." While federal and British Petroleum officials continue to estimate the rate of leakage at 5,000 barrels a day, some scientists studying video of the leak concluded last week that the volume could be vastly larger.
(This image from BP shows the oil-gas-water mixture spewing May 11 from the main leak site a mile deep on the floor of the gulf.)
And while satellite photos and boat measurements are helpful to assess the extent of the surface slick, he said, "these measures are also highly variable with time, place, weather conditions and dispersant application."
Spewing from the ocean floor a mile deep is a mixture that, according to BP, is roughly half methane and other gases by mass and half petroleum compounds, Valentine told Discovery News, and while the oil itself migrates unevenly around the Gulf in ways that are difficult to track, the behavior of methane is more congenial to measurement.
"Although methane from surface-vessel spills or shallow-water blowouts escapes into the air, I expect that the vast majority of methane making the long trip to the sea surface from a deep water spill would dissolve," Valentine wrote. "Unlike oil, methane dissolves uniformly in seawater. And the tools are available to measure it accurately and sensitively."
In June, he said, "we should aim to get to grips with the size and shape of the methane plumes by gracing water flow with 'drifting profiling flats' and through further spot analyses." The method isn't perfect, he said, but "it would at least put a lower bound on the total amount of spilled oil" and provide a good estimate of the rate of the spill.
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