Levels of carbon, which the team claims is equal to the emissions of the all shipping in the region for the same period, has been discovered through new analysis of air particles around the region during the disaster.

In response to the spill the National Oceanic and Atmospheric Administration (NOAA) redirected its WP-3D research aircraft to survey the atmosphere above the spill site in June.

During the 2010 oil spill an estimated one of every 20 barrels of spilled oil was deliberately burned off to reduce the size of surface slicks to minimise the impact on the shoreline, ecosystems and marine life.

This caused black carbon, the most light-absorbing of airborne particles in the atmosphere, which made the black colour in the smoky plumes rising from the surface oil fires.

Black carbon can also cause warming of the atmosphere by absorbing light and prolonged exposure to breathing it is medically proven to cause human health problems.

“Scientists have wanted to know more about how much black carbon pollution comes from controlled burning and the physical and chemical properties of that pollution. Now we know a lot more,” said lead report author Anne Perring, a scientist with CIRES and the Chemical Sciences Division of NOAA’s Earth System Research Laboratory (ESRL) in Colorado in the United States.

“The study found hot soot plumes from the controlled burns reached much higher into the atmosphere than ship emissions normally rise, potentially prolonging the amount of time the black carbon can remain in the atmosphere, which would affect where the black carbon ends up.

“The researchers also found the average size of the black carbon particles was much larger than that emitted from other sources in the Gulf region, and the emitted particles produced were almost all black carbon, unlike other sources such as forest fires that tend to produce other particles along with black carbon.

Finally, Perring and her colleagues found of the oil burned 4% of the mass was released as black carbon, an important metric rarely observed during clean-up of an oceanic oil spill, which could help guide future decision-making.

The new paper, Characteristics of Black Carbon Aerosol from a Surface Oil Burn During the Deepwater Horizon Oil Spill, has 15 co-authors from NOAA ESRL and CIRES and can be found on Geophysical Research Letters .

Luke Walsh

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