Particle and gas emissions from an in situ burn of crude oil on the ocean

Burning is a very effective way of removing oil spills from the ocean; the tradeoff is the potential for significant air pollution. Airborne measurements are described for particles and gases from two test burns of crude oil offshore of St. Johns, Newfoundland during the Newfoundland Offshore Burn Experiment (NOBE). The smoke plumes from the burns initially rose 200-400 m into the air and then continued to rise and disperse laterally downwind. The concentrations of accumulation-mode particles in the smoke were similar to 45,000 cm(-3) at 1.5 km from the fires, and they remained as high as similar to 4,000 cm(-3) after an hour or more of travel time downwind. Total particle mass loadings in the plumes were over 1000 mu g m(-3) near the fires, but decreased to similar to 100 mu g m(-3) at 25 km downwind. For each kilogram of fuel consumed, similar to 770 g of carbon was released in the form of CO2, similar to 13 g of carbon as CO, similar to 5 g as volatile organic compounds (VOCs), and similar to 87 g as particles with diameters <3.5 mu m, of which similar to 66 g was elemental carbon and similar to 7 g condensed organic carbon. Also, similar to 3 g of SO2 was released per kilogram of fuel burned. A relatively low combustion efficiency was indicated by the average molar ratio of the concentration of CO to excess CO2 of 0.017. The molar ratio of NOx to excess CO2 typically varied from 0.3 x 10(-3) to 0.4 x 10(-3), implying little fixation of atmospheric nitrogen and low concentrations of NOx. For comparison, the total smoke particle production rate in the NOBE burns was about the same as that for a nine-acre slash burn.