Open AccessSeasonal accumulation timing and preservation of nitrate in firn at Summit, Greenland
Author(s) -
Burkhart John F.,
Hutterli Manuel,
Bales Roger C.,
McConnell Joseph R.
Publication year - 2004
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2004jd004658
Subject(s) - firn , snow , nitrate , meltwater , environmental science , atmospheric sciences , geology , climatology , physical geography , geomorphology , chemistry , geography , organic chemistry
In a yearlong investigation of the air‐snow transfer function for nitrate (NO 3 − ) at the Greenland Environmental Observatory, Summit (3203 m above sea level), surface snow concentrations measured every other day were compared with levels measured in 10 snow pits dug adjacent to accumulation stakes. Concentrations in the surface snow ranged from 0.4 to 34 μ M with a mean of 2.9 ± 1.9 μ M . Measured firn profiles in the snow pits had a maximum NO 3 − concentration of 12 μ M and a mean of 2.7 ± 0.5 μ M . Reconstructed profiles from surface snow observations and accumulation data closely matched the observed profiles. The small difference in preserved concentrations from observed surface snow concentrations gives evidence of only 7% postdepositional loss at this site (mean annual accumulation ∼23 g cm −2 yr −1 ). Removing the three highest outliers (which may originate from local sources) of surface snow concentration drops the mean to 2.7 μ M , further demonstrating preservation. Results indicate that at this site accumulation is the most significant process affecting preservation of nitrate in the firn. Other rapid postdepositional processes may impact surface snow concentrations, but do not appear to significantly change the preserved record. The inverse analysis of converting preserved records to surface snow concentrations provides equivalent evidence of the same preservation.