April 20, 2010BP’s oil rig exploded in the Gulf of Mexico. Since then the oil slick has been expanding in the ocean. American scientists now present in the magazineScience thefirst independent measurement on the volume of the spill. In total, as of July 15, 56,000 to 68,000 barrels of oil have been spilled daily (each barrel contains 158 liters). The total estimate of the oil spilled is about4.4 million barrels.
“We wanted to do an independent estimate since there was a feeling that the figures that were circulating did not have to be precise,” says Timothy Crone, lead author and marine geophysicist at the Lamont-Doherty Earth Observatory at Columbia University. ). According to the research team, the information was necessary to determine long-term and short-term reactions.
The new study divides the flow rate intoof the periods: from April 22 to June 3 -when oil spurted out of an irregular crack in the elevator-, and from June 3 -when the elevator was cut off and the oil was temporarily released into the ocean without obstructions.
Together with Maya Tolstoy, Lamont’s co-author and marine geophysicist, Crone used a technique of visual analysis, developed by himself and called“optical pen velocimetry”. Video from the first period indicated a flow of about 56,000 barrels a day. After the pipe was cut, the rate increased to about 68,000 barrels. After counting the elapsed time, the scientists subtracted the 804,877 barrels collected by BP in that place, until reaching the4.4 million barrels spilled.
Volcano technique to study spills
Optical plume velocimetry began to be developed by Crone in 2006 to study natural hydrothermal vents, cracks and holes created by volcanic activity at the bottom of the ocean that spew jets of superheated, mineral-laden water, similar to those of the jet of a pipe that is leaking oil. The technique uses ahigh resolution video taken by underwater camerasto track wave motion and turbulent flows in the water, and breaks down motion pixel by pixel. Crone tested it first in the laboratory, then with deep ocean sources in the eastern Pacific and on the Juan de Fuca ridge off the northeastern Pacific coast of the United States.
But this study is, according to its authors, “just a beginning.” The scientists report that the leaks could have varied from day to day and that the analysis did not include videos of other small leaks from smaller holes higher in the pipe, which are believed to have grown over time. Therefore, “the actual numbers may be higher in any case,” explains Crone.
On September 19, the United States authorities definitively sealed the oil well that caused what is already considered the worst ecological catastrophe in the country’s history. However, stillmonths to complete the cleanup of the spill.
