As a major sink of atmospheric nitrogen oxides (NOx = NO + NO2), nitrate (NO3−) in polar snow can reflect the long-range transport of NOx and related species (e.g., peroxyacetyl nitrate). On the other hand, because NO3− in snow can be photolyzed, potentially producing gas phase NOx locally, NO3− in snow (and thus, ice) may reflect local processes. Here we investigate the relationship between local atmospheric composition at Summit, Greenland (72°35′N, 38°25′W) and the isotopic composition of NO3− to determine the degree to which local processes influence atmospheric and snow NO3−. Based on snow and atmospheric observations during May–June 2010 and 2011, we find no connection between the local atmospheric concentrations of a suite of gases (BrO, NO, NOy, HNO3, and nitrite (NO2−)) and the NO3− isotopic composition or concentration in snow. This suggests that (1) the snow NO3− at Summit is primarily derived from long-range transport and (2) this NO3− is largely preserved in the snow. Additionally, three isotopically distinct NO3− sources were found to be contributing to the NO3− in the snow at Summit during both 2010 and 2011. Through the complete isotopic composition of NO3−, we suggest that these sources are local anthropogenic particulate NO3− from station activities (δ15N = 16‰, Δ17O = 4‰, and δ18O = 23‰), NO3− formed from midlatitude NOx (δ15N = −10‰, Δ17O = 29‰, δ18O = 78‰) and a NO3− source that is possibly influenced by or derived from stratospheric ozone NO3− (δ15N = 5‰, Δ17O = 39‰, δ18O = 100‰).
Journal of Geophysical Research: Atmospheres
American Geophysical Union (AGU)
Digital Object Identifier (DOI)
Fibiger, D. L., J. E. Dibb, D. Chen, J. L. Thomas, J. F. Burkhart, L. G. Huey, and M. G. Hastings (2016) Analysis of nitrate in the snow and atmosphere at Summit Greenland: Chemistry and Transport, Journal of Geophysical Research, 121, 5010-5030, https://dx.doi.org/10.1002/2015JD024187
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