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Oil Spill's Size Swells

Deepwater Horizon: Magnitude of gulf accident is far larger than previous estimates

by Elizabeth K. Wilson
September 27, 2010 | A version of this story appeared in Volume 88, Issue 39

Credit: Senate Committee on Environment & Public Works

Nearly 185 million gal of oil gushed into the Gulf of Mexico during BP’s Deepwater Horizon spill, a number that’s at least an order of magnitude higher than previous estimates, scientists report in Science
(DOI: 10.1126/science.1195840). This is the first independent, peer-reviewed paper to assess the spill’s magnitude.

The report comes on the heels of BP’s Sept. 18 announcement that it had finally installed a permanent concrete plug on the damaged well more than five months after an explosion tore a hole in the well and killed 11 workers.

To estimate the spill’s size, marine geophysicists Timothy J. Crone and Maya Tolstoy of the Lamont-Doherty Earth Observatory at Columbia University studied high-resolution videos of the fountain of oil pouring into the ocean and used fluid dynamics to estimate the flow rates. Their estimate, they caution, is still a ballpark figure, with an error margin of 20%.

The work “finally gives us a reading on what the magnitude of the disaster was,” Florida State University oceanography professor Ian MacDonald tells C&EN. Until now, “we haven’t had that.”

The Flow Rate Technical Group, a consortium of federal and academic scientists assembled by the government and led by U.S. Geological Survey Director Marcia McNutt, has released four reports estimating the spill magnitude. On Aug. 2, the group issued a press release reporting flow rates similar to those from Crone and Tolstoy. The consortium’s final report has not yet been disclosed.

MacDonald adds that the technical group’s agreement with the published work is “heartening.”

The spill’s magnitude has been hotly debated, with ever more detailed studies resulting in increasing estimates. Early estimates of about 42,000 gal per day were soon eclipsed by new reports. A report released by the Flow Rate Technical Group on May 27 estimated the flow rate at between 50,000 and 80,000 gal per day. In comparison, Crone and Tolstoy estimate that during times of greatest flow, more than 2.5 million gal per day was escaping into the ocean.

Meanwhile, the White House has commissioned a research effort to study the effects of the spill on the environment. It will be headed by noted marine biologist Jane Lubchenco, the administrator of the National Oceanic & Atmospheric Administration.

Lubchenco tells C&EN that the agreement between the work of the Flow Rate Technical Group, which includes NOAA scientists, and the published research, "is valuable information for the public, and adds confidence in our collective efforts."

Using this and other videos of oil gushing out of the Deepwater Horizon well, scientists estimated the magnitude of the spill.



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