Surprisingly small HONO emissions from snow surfaces at Browning Pass, Antarctica

• Published in: Atmospheric chemistry and physics Vol. 6; no. 9; pp. 2569 - 2580
• Main Authors: Beine, H. J., Amoroso, A., Dominé, F., King, M. D., Nardino, M., Ianniello, A., France, J. L.
• Format: Journal Article
• Language: English
• Published: European Geosciences Union 03-07-2006; Copernicus Publications
• Subjects: Ocean, Atmosphere; Sciences of the Universe; Antarctica
• ISSN: 1680-7324; 1680-7316; 1680-7324
• DOI: 10.5194/acp-6-2569-2006

Measured Fluxes of nitrous acid at Browning Pass, Antarctica were very low, despite conditions that are generally understood as favorable for HONO emissions, including: acidic snow surfaces, an abundance of NO3- anions in the snow surface, and abundant UV light for NO3- photolysis. Photochemical modeling suggests noon time HONO fluxes of 5–10 nmol m-2 h-1; the measured fluxes, however, were close to zero throughout the campaign. The location and state of NO3- in snow is crucial to its reactivity. The analysis of soluble mineral ions in snow reveals that the NO3- ion is probably present in aged snows as NaNO3. This is peculiar to our study site, and we suggest that this may affect the photochemical reactivity of NO3-, by preventing the release of products, or providing a reactive medium for newly formed HONO. In fresh snow, the NO3- ion is probably present as dissolved or adsorbed HNO3 and yet, no HONO emissions were observed. We speculate that HONO formation from NO3- photolysis may involve electron transfer reactions of NO2 from photosensitized organics and that fresh snows at our site had insufficient concentrations of adequate organic compounds to favor this reaction.