According to a study released today by the National Oceanic and Atmospheric Administration (NOAA) and published in the Proceedings of the National Academy of Sciences, the massive plume from the Deepwater Horizon oil spill in the Gulf of Mexico had an additional airborne component – about 8% of the oil from the spill evaporated and formed a cloud of pollution 18.5 miles wide – the size of a large urban area. The amount of airborne organic particles resulting from the evaporated oil was ten times more than what resulted from all surface burning of oil in the wake of the disaster.
“We could see the sooty black clouds from the burning oil, but there’s more to this than meets the eye. Our instruments detected a much more massive atmospheric plume of almost invisible small organic particles and pollutant gases downwind of the oil spill site,” said Ann M. Middlebrook, scientist at NOAA Earth System Research Laboratory‘s (ESRL) Chemical Sciences Division (CSD) and lead author of the study. When oil started leaking from the damaged Deepwater Horizon oil rig in the Gulf of Mexico in April of 2010 it rose to the surface of the Gulf where some of it burned, but a lot of it simply evaporated — according to the study.
Some of the evaporated oil — about 8% — became airborne organic particles small enough to be breathed by human lungs, formed a giant plume of pollution and headed toward the coastline with the prevailing winds. NOAA’s ESRL researchers made a computer model of the plume and discovered that their predictions of when the plume would have reached the shoreline matched up perfectly with a rise in particle pollution from local onshore air monitoring systems.
When the particle pollution entered the atmosphere it reacted with the small amount of nitrogen oxides in the oil spill’s vicinity — which existed in part due to cleanup and recovery efforts — and formed ozone pollution. “The levels of ozone were similar to what occurs in large urban areas. During the oil spill, it was like having a large city’s worth of pollution appear out in the middle of the Gulf of Mexico,” said Daniel M. Murphy, NOAA scientist at ESRL/CSD and a co-author of the study. The NOAA gathered information for this study on two of their WP-3D research aircraft and from local monitoring systems on rigs, local ships and on land in the gulf.