Geographic variability of nitrate deposition and preservation over the Greenland ice sheet

An analysis of 96 snow pit and ice cores distributed over the Greenland ice sheet is used to determine the main drivers of variability in the preserved records of nitrate concentration. The data set provides samples from spatially distributed locations, allowing us to investigate the effect of snow...

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Main Authors: Burkhart, JF, Bales, RC, McConnell, JR, Hutterli, MA, Frey, MM
Format: Article in Journal/Newspaper
Language:unknown
Published: eScholarship, University of California 2009
Subjects:
Online Access:https://escholarship.org/uc/item/4jf45773
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spelling ftcdlib:oai:escholarship.org/ark:/13030/qt4jf45773 2023-05-15T16:28:56+02:00 Geographic variability of nitrate deposition and preservation over the Greenland ice sheet Burkhart, JF Bales, RC McConnell, JR Hutterli, MA Frey, MM 2009-03-27 https://escholarship.org/uc/item/4jf45773 unknown eScholarship, University of California qt4jf45773 https://escholarship.org/uc/item/4jf45773 public Journal of Geophysical Research Atmospheres, vol 114, iss 6 Meteorology & Atmospheric Sciences article 2009 ftcdlib 2021-06-28T17:06:43Z An analysis of 96 snow pit and ice cores distributed over the Greenland ice sheet is used to determine the main drivers of variability in the preserved records of nitrate concentration. The data set provides samples from spatially distributed locations, allowing us to investigate the effect of snow accumulation rate, temperature, and sublimation on nitrate concentration. The mean ice sheet concentration in the dry snow zone (2000 ≥ mean annual sea level (masl)) is 132 ng g-1, ranging between 47 and 265 ng g -1 with a standard deviation of ±37 ng g-1. Nitrate flux varies between 1.1 and 14.7 μg cm-2 a-1 with a mean of 4 ± 2 μg cm-2 a-1. Large-scale spatial variability exists as a result of accumulation gradients, with concentration 5% greater in the northern plateau, yet flux over the northern plateau is 30% lower than the dry snow zone as a whole. While spatially, flux appears to be more dependent on accumulation, preservation of flux shows increasing dependence on concentration with increasing accumulation. The relationship between concentration and accumulation is nonlinear, showing less dependence in the low-accumulation regions versus high-accumulation regions. Accumulation alone is insufficient to account for the observed variability in nitrate flux in the low-accumulation regions, and evidence supports the need for additional components to a transfer function model for nitrate that includes photochemistry, temperature, and sublimation. Spatial variability across the ice sheet is nonuniform, and changes in nitrate concentration have occurred in some regions at a greater rate than others. While the data support that overall the ice sheet acts as an archive of paleoatmospheric concentration despite the effects of postdepositional processing, one needs to consider spatial variables to properly account for trends and variability in the records. This is tested by evaluating past spatial relationships and yields the result that the significant geographic shifts with respect to reactive N concentrations have occurred over the ice sheet in the past century. Copyright 2009 by the American Geophysical Union. Article in Journal/Newspaper Greenland Ice Sheet University of California: eScholarship Greenland
institution Open Polar
collection University of California: eScholarship
op_collection_id ftcdlib
language unknown
topic Meteorology & Atmospheric Sciences
spellingShingle Meteorology & Atmospheric Sciences
Burkhart, JF
Bales, RC
McConnell, JR
Hutterli, MA
Frey, MM
Geographic variability of nitrate deposition and preservation over the Greenland ice sheet
topic_facet Meteorology & Atmospheric Sciences
description An analysis of 96 snow pit and ice cores distributed over the Greenland ice sheet is used to determine the main drivers of variability in the preserved records of nitrate concentration. The data set provides samples from spatially distributed locations, allowing us to investigate the effect of snow accumulation rate, temperature, and sublimation on nitrate concentration. The mean ice sheet concentration in the dry snow zone (2000 ≥ mean annual sea level (masl)) is 132 ng g-1, ranging between 47 and 265 ng g -1 with a standard deviation of ±37 ng g-1. Nitrate flux varies between 1.1 and 14.7 μg cm-2 a-1 with a mean of 4 ± 2 μg cm-2 a-1. Large-scale spatial variability exists as a result of accumulation gradients, with concentration 5% greater in the northern plateau, yet flux over the northern plateau is 30% lower than the dry snow zone as a whole. While spatially, flux appears to be more dependent on accumulation, preservation of flux shows increasing dependence on concentration with increasing accumulation. The relationship between concentration and accumulation is nonlinear, showing less dependence in the low-accumulation regions versus high-accumulation regions. Accumulation alone is insufficient to account for the observed variability in nitrate flux in the low-accumulation regions, and evidence supports the need for additional components to a transfer function model for nitrate that includes photochemistry, temperature, and sublimation. Spatial variability across the ice sheet is nonuniform, and changes in nitrate concentration have occurred in some regions at a greater rate than others. While the data support that overall the ice sheet acts as an archive of paleoatmospheric concentration despite the effects of postdepositional processing, one needs to consider spatial variables to properly account for trends and variability in the records. This is tested by evaluating past spatial relationships and yields the result that the significant geographic shifts with respect to reactive N concentrations have occurred over the ice sheet in the past century. Copyright 2009 by the American Geophysical Union.
format Article in Journal/Newspaper
author Burkhart, JF
Bales, RC
McConnell, JR
Hutterli, MA
Frey, MM
author_facet Burkhart, JF
Bales, RC
McConnell, JR
Hutterli, MA
Frey, MM
author_sort Burkhart, JF
title Geographic variability of nitrate deposition and preservation over the Greenland ice sheet
title_short Geographic variability of nitrate deposition and preservation over the Greenland ice sheet
title_full Geographic variability of nitrate deposition and preservation over the Greenland ice sheet
title_fullStr Geographic variability of nitrate deposition and preservation over the Greenland ice sheet
title_full_unstemmed Geographic variability of nitrate deposition and preservation over the Greenland ice sheet
title_sort geographic variability of nitrate deposition and preservation over the greenland ice sheet
publisher eScholarship, University of California
publishDate 2009
url https://escholarship.org/uc/item/4jf45773
geographic Greenland
geographic_facet Greenland
genre Greenland
Ice Sheet
genre_facet Greenland
Ice Sheet
op_source Journal of Geophysical Research Atmospheres, vol 114, iss 6
op_relation qt4jf45773
https://escholarship.org/uc/item/4jf45773
op_rights public
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