Studies of Peroxyacetyl nitrate (PAN) and its interaction with the snowpack at Summit, Greenland

Abstract

[1] Peroxyacetyl nitrate (PAN) was measured in ambient and snowpack interstitial air at Summit, Greenland, in June and July of 1998 and 1999 and at a rural/forest site in the Keewenaw Peninsula of Michigan in January of 1999. At Summit, we found that PAN typically represented between 30 and 60% of NO y . In the summer of 1999, a significant diel variation in both PAN/NO y and NO x /NO y was observed, but this was much less pronounced in 1998. Experiments during SNOW99 near Houghton, Michigan, indicated that PAN undergoes weak uptake onto snow grain surfaces. At Summit, we found that PAN concentrations in the snowpack interstitial air were significantly elevated (by as much as 2 -5 times) relative to ambient levels, implying a flux of PAN out of the snowpack during the study period. We also observed evidence that PAN can be photochemically produced in snow that is exposed to polluted air. These observations indicate that interactions with the snowpack can have a significant impact on PAN concentrations in the boundary layer and point to potential difficulties associated with investigation of long-term changes in PAN uptake into ice cores because of the impact of postdepositional processes.

A thermal dissociation–chemical ionization mass spectrometry (TD‐CIMS) technique for the simultaneous measurement of peroxyacyl nitrates and dinitrogen pentoxide

“…Another area where flux measurements would be useful is over snow‐covered surfaces. There has been recent speculation in the literature that PAN could play a role in NO y transfer between snow and the air above it, potentially influencing ice core nitrate records [ Dibb et al , 1998; Munger et al , 1999; Jacobi et al , 2000; Ford et al , 2002]. PAN has been suggested as a potential source of NO 3 − in surface snow at Summit, Greenland, where low levels of gas phase HNO 3 cannot account for observed enhacements [ Dibb et al , 1998].…”

“…This falls between their measurements of the adsorption enthalpies for HNO 3 (−44 kJ mol −1 ) and NO 2 (−20 kJ mol −1 ), and it indicates that a relatively small fraction of gaseous PAN should partition to the snow at temperatures ≥−27°C (ratio of adsorbed to gas phase PAN at −27°C = 0.08 vs. 0.30 for HONO and 90 for HNO 3 ). The observation of elevated concentrations of PAN in snow at Summit compared to the air above it implies an upward flux out of the snow [ Ford et al , 2002]. An attempt to measure PAN fluxes between snow and the air above it at Neumayer Station, Antarctica, was made by alternating measurements at two different heights, but the difference between the concentrations was frequently below the precision of the measurements and no direction could be determined [ Jacobi et al , 2000].…”

Peroxyacetyl nitrate (PAN) in the urban atmosphere

“…Marley et al (2007); 4,Gaffney et al (1999); 5, Tsani-Bazaca et al (1988); 6, Liu et al (2010); 7, Zhang et al (2009); 8, Roberts et al (2001); 9, Roberts et al (2003); 10, Roberts et al (2002); 11, Grosjean et al (2002); 12, McFadyen and Cape (2005); 13, Watanabe et al (1998); 14, Whalley et al (2004); 15,Zellweger et al (2000); 16,Ford et al (2002); 17,Gaffney et al (1993); 18,Tanimoto et al (2002); 19,Watanabe et al (1998); 20,Rappengluck et al (2003); 21,Jacobi et al (2000); 22,Beine and Krognes (2000).…”

Fluxes of nitrates between snow surfaces and the atmosphere in the European high Arctic

“…2) were too small to be observed with our sampling methods. Additionally, as yet undocumented chemical transformations of NO y reservoir species such as peroxyacetyl nitrate (PAN) or alkyl nitrates to NO − 3 in the snow phase (Ford et al, 2002) may be possible. Beine and Krognes (2000) showed an anticorrelation of PAN mixing ratios with the relative atmospheric humidity at Ny-Ålesund, but no further ev-idence is available that PAN, or alkyl nitrates, lead to a nitrate signal in snow, either directly or indirectly.…”