Methane Isotopes in South Pole Firn Air, 2008

Summary

This data set contains depth profiles for delta carbon-13 (δ¹³C) per mil Pee Dee Belemnite (PDB) and delta deuterium (δD) per mil Standard Mean Ocean Water (SMOW) of methane (CH₄) in South Pole firn air. The investigators obtained air samples from two boreholes during December, 2008 and January, 2009, and subsequently determined isotope ratios at 18 depths. The profiles represent a roughly 100-year history of the isotopic composition of CH₄ at South Pole Station (no depth-age model provided).

Data are available via FTP as an ASCII text file (.txt) and a Microsoft Excel file (.xlsx).

Citing These Data

The following example shows how to cite the use of this data set in a publication. For more information, see our Use and Copyright Web page.

The following example shows how to cite this data set in a publication. List the principal investigators, year the data set was released, data set title, publisher: NSIDC, and "Digital media":

Sowers, T. 2011. Methane Isotopes from South Pole Firn Air. Boulder, CO, USA: National Snow and Ice Data Center. http://dx.doi.org/10.7265/N55T3HFP.

Overview Table

Category	Description
Data format	ACSII text file (.txt), Microsoft Excel file (.xlsx)
Spatial coverage and resolution	Southernmost Latitude: 90° S Northernmost Latitude: 90° S Westernmost Longitude: 180° W Easternmost Longitude: 180° E
Temporal coverage and resolution	Samples were obtained during the 2008/2009 field season and represent the period from approximately 1900 to 2009.
File naming convention	2008_S_Pole_Firn_CH4_isotopes.txt; 2008_S_Pole_Firn_CH4_isotopes.xlsx
File size	Files for this data set are less than 51 KB
Parameter(s)	Depth (meters) Delta carbon-13 (‰, PDB) of CH4 Delta deuterium (‰, SMOW) of CH4
Procedures for obtaining data	Available via FTP

Table of Contents

1. Contacts and Acknowledgments
2. Detailed Data Description
3. Data Access and Tools
4. Data Acquisition and Processing
5. References and Related Publications
6. Document Information

1. Contacts and Acknowledgments

Investigator(s)

Dr. Todd Sowers
Earth and Environmental Systems Institute
The Pennsylvania State University
2217 EES Building
University Park, PA 16802

Technical Contact

Acknowledgements

This research was supported by the National Science Foundation (NSF) Office of Polar Programs (OPP) grant ANT 0739491.

2. Detailed Data Description

Format

Data are available as an ASCII text file (.txt) and a Microsoft Excel file (.xlsx).

File and Directory Structure

Data are available on the FTP site in the ftp://sidads.colorado.edu/pub/DATASETS/AGDC/nsidc0502_sowers_v01/ directory.

File Naming Convention

Files are named according to the following convention:

2008_S_Pole_Firn_CH4_isotopes.txt; 2008_S_Pole_Firn_CH4_isotopes.xlsx

File Size

Files for this data set are less than 51 KB.

Spatial Coverage

Data were recovered from two boreholes approximately 20 meters apart at South Pole Station.

Southernmost Latitude: 90° S
Northernmost Latitude: 90° S
Westernmost Longitude: 180° W
Easternmost Longitude: 180° E

Temporal Coverage

The samples, obtained during December 2008 and January 2009, represent 18 measurements of δ¹³C (‰,  PDB) and δD (‰,  SMOW) of methane corresponding to the period from approximately 1900 to 2009.

Parameter or Variable

Parameters are depth (meters below surface) and measurements of δ¹³C (‰,  PDB) and δD (‰,  SMOW) of methane.

Sample Data Record

The following example shows sample data from nsidc0502_sowers_v01.txt:

DEPTH	d13C	d13C STD	dD	dD STD
0.00	-47.09	0.04	-79.6	4.50
19.73	-47.31	0.05	-84.1	3.25
30.04	-47.52	0.11	-81.0	5.61
39.94	-47.59	0.05	-87.5	4.10
60.14	-47.80	0.08	-85.9	2.06

Quality Assessment

The investigator analyzed 156 firn air samples from the 2008-2009 field season and 44 standards for δ¹³C and δD of CH₄. The average standard deviation of replicate samples at each of the 18 depths was ±0.13‰ and ±4.2‰ for δ¹³C and δD, respectively.

3. Data Access and Tools

Data Access

Data are available via FTP

Volume

The total volume of the data set is less than 51 KB

Software and Tools

The data can be accessed using standard spreadsheet software.

Related Data Collections

• Antarctic Glaciological Data Center (AGDC)

4. Data Acquisition and Processing

Theory of Measurements

Changes in δ¹³C and δD of atmospheric CH₄ reflect changes in systems that contribute to the isotopic composition of the gas, such as biomass burning, industrial and agricultural productivity, and biogenic activity in terrestrial, oceanic, and wetland ecosystems.

Sensor or Instrument Description

Isotopic ratios were analyzed with a Finnigan MAT 252 mass spectrometer. Refer to Sowers et al. (2005) for detailed instrument descriptions and processing steps.

Data Acquisition Methods

Firn air samples were recovered from two boreholes approximately 20 meters apart at South Pole Station.

5. References and Related Publications

Battle, M. et al. 1996. Atmospheric Gas Concentrations over the Past Century Measured in Air from Firn at the South Pole. Nature 383, 231-235.

Sowers, T., S. Bernard, O. Aballain, J. Chappellaz, J.M. Barnola, and T. Marik. 2005. Records of the δ¹³C of Atmospheric CH4 over the Last 2 Centuries as Recorded in Antarctic Snow and Ice. Global Biogeochemical Cycles 19, doi:10.1029/2004GB002408.

6. Document Information

The following acronyms are used in this document:

Acronym	Description
δ13C	Delta carbon-13
δD	Delta deuterium
PDB	Pee Dee Belemnite
SMOW	Standard Mean Ocean Water

Document Creation Date

October 2011

Document URL

http://nsidc.org/data/docs/agdc/nsidc0502_sowers/index.html