Mt. Erebus, the Largest Point Source of NO sub(2) in Antarctica

Concentrations of sulfur dioxide and nitrogen dioxide were measured simultaneously in the plume emitted by Mt. Erebus, Antarctica, using ground-based UV differential optical absorption spectroscopy. The correlation between SO sub(2) and NO sub(2) indicated a molar SO sub(2)/NO sub(2) ratio ranging from approximately 7 to 12 in the plume. Because NO sub(2) is not a direct volcanic gas emission, the origin was attributed to thermal fixation of atmospheric and/or magmatic nitrogen at the lava lake surface. The estimated NO sub(2) flux from the summit crater was found to be modest compared to some sources, but in the context of the Antarctic free troposphere, the flux appeared to be significant.