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Data Set ID:
NSIDC-0107

Concentration and Isotopic Composition of O2 and N2 in Trapped Gases of the Vostok Ice Core, Version 1

These data describe the d18O of O2, d15N of N2, d18Oatm, and O2/N2 ratios of trapped gases in the Vostok ice core from East Antarctica. The investigator used a mass spectrometer to measure gas concentrations and isotopic compositions. Data extend to approximately 420,000 years ago. Two different age models are included.

Data are available in tab-delimited ASCII format via ftp.

Geographic Coverage

Spatial Coverage:
  • N: -72.28, S: -72.28, E: 106.48, W: 106.48

Spatial Resolution: Not Specified
Temporal Coverage: Not specified
Temporal Resolution: Not specified
Parameter(s):
  • Glaciers/Ice Sheets > Ice Sheets
  • Ice Core Records > Isotopes
  • Snow/Ice > Snow/Ice Chemistry
Platform(s) GROUND STATIONS
Sensor(s): MASS SPECTROMETERS
Data Format(s):
  • ASCII Text
Version: V1
Data Contributor(s): Michael Bender

Data Citation

As a condition of using these data, you must cite the use of this data set using the following citation. For more information, see our Use and Copyright Web page.

Bender, M. 2002. Concentration and Isotopic Composition of O2 and N2 in Trapped Gases of the Vostok Ice Core, Version 1. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: http://dx.doi.org/10.7265/N5862DCW. [Date Accessed].

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Detailed Data Description

Format

Data consist of four tab-delimited ASCII files. For a description of these files, see Sample Data Records.

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File Size

File sizes range from 9 KB to 132 KB.

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Sample Data Record

"Vos_O2-N2_isotope_data_all" contains all data for the 4G, 3G, and 5G cores:

Core  Depth     del 15N     del 18O  del 18Oatm   del O2/N2
					
5G    174.5     0.49	     1.09      0.11         -28.2
5G    174.5     0.56	     1.14      0.01         -35.2
5G    185.2     0.58	     0.97     -0.19         -26.4
5G    185.2     0.58	     0.99     -0.18         -30.5

Vos_O2-N2_isotope_data_avg contains average values of the properties at given depths:

Core  Depth     del 15N     del 18O  del 18Oatm   del O2/N2
					
5G    174.5     0.53         1.11      0.06         -31.7
5G    185.2     0.58         0.98     -0.19         -28.4
5G    205.7     0.56         0.94     -0.18         -34.0

Vostok_EGT20_chronology contains gas ages and ice ages assigned to each depth according to the EGT20 chronology. Gas age-ice age differences are included under the header EGT20 *age. Refer to the Temporal Coverage section.

Depth   EGT20 ice age   EGT20 *age   EGT20 gas age
			
150     5.721           3.319        2.402
151     5.769           3.307        2.462
152     5.816           3.306        2.51
153     5.863           3.315        2.548

Vostok_d18Oatm_chronology contains gas ages and ice ages assigned to each depth according to the δ18Oatm chronology. Gas age-ice age differences are included under the header EGT20 *age. Refer to the Temporal Coverage section.

Depth   18Oatm ice age   EGT20 *age   18Oatm gas age
			
150     5.68             3.32         2.36
151     5.72             3.31         2.42
152     5.77             3.31         2.47
153     5.82             3.32         2.50
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Spatial Coverage

Sampled ice cores came from Russia's Vostok Station in East Antarctica, located at 72.28 degrees south latitude, 106.48 degrees east longitude.

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Study Area Location Map

Vostok Station is indicated on the map below by the letter V. Crosshairs mark the position of the south pole.

Map: Location of study site

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Temporal Coverage

Data extend to 3623 meters depth, or approximately 420,000 years ago (i.e., 420 ka).

Isotopic data are presented along with two proposed chronologies. The first is the Extended Glaciological Timescale (EGT20), a minimally tuned glaciological chronology utilized by Petit et al. (1999). The second is an orbitally tuned chronology that exploits the strong relationship between δ18Oatm and insolation changes. This chronology, described by Petit et al. (1999), is enhanced by control points that assume correspondence between insolation maxima and the midpoints of decreases in δ18Oatm. An additional control point at 385 ka gas age has been added here. Theδ18Oatm chronology utilizes gas age-ice age differences from the EGT20 timescale.

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Parameter or Variable

Data describe the δ18O of O2, δ15N of N2, δ18Oatm, and O2/N2 ratios of trapped gas samples from the Vostok ice cores. All results are reported with respect to the standard of late twentieth-century air.

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Software and Tools

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Data Acquisition and Processing

Theory of Measurements:

δ18Oatm is a useful variable for correlating ice cores, and for inferring information about past climate and ice extent. At any given time, δ18O is approximately constant throughout the atmosphere, but this value varies over time due to changes in the hydrologic cycle, ice sheet volume, and worldwide patterns of plant growth. The δ18O of O2 in the past atmosphere (δ18Oatm) is calculated by subtracting 2xδ15N from δ18O, thus correcting for gravitational fractionation, a process that occurs while air is trapped within the firn prior to being isolated from the atmosphere.

Another effect results from how gases are retained within an ice core. The ratio of O2 to N2 trapped within the core is typically less than the original ratio of the trapped air because O2 is a smaller molecule than N2, and thus escapes more readily from the core as bubbles form and during core storage. δ15N of N2 has a constant value of zero in the atmosphere, but is greater than zero in firn air due to gravitational fractionation. δ18O of O2 is also enriched by gravitational fractionation.

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Data Acquisition Methods:

The investigator collected trapped gases by melting ice samples in a vacuum, refreezing them, and condensing the headspace gases into a stainless steel tube immersed in liquid helium. Trapped gases were admitted to the mass spectrometer and analyzed versus a dry air standard to determine the isotopic composition of N2, the isotopic composition of O2, and the O2/N2 ratio. Methodology followed that of Sowers et al. (1989), except that the investigator did not remelt and refreeze samples after the initial collection. This change in methodology caused loss of O2, which is more soluble than N2, and thus lowered the measured O2/N2 ratios slightly

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References and Related Publications

Contacts and Acknowledgments

Dr. Michael Bender
Department of Geosciences
Princeton University
Princeton, NJ     USA

Acknowledgements: 

Todd Sowers, Joseph Orchardo, Bruno Malaize, and Mary-Lynn Dickson helped with sample analysis.

Document Information

Document Creation Date:

30 January 2002

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