Measurements of changes in the atmospheric O2/N2 ratio have typically relied on compressed air derived from highpressure tanks as the reference material against which atmospheric changes are assessed. The validity of this procedure is examined here in the context of the history of 18 O2/N2 reference tanks compared over a 12-yr time-frame. By considering differences in tank sizes, material types, and by performing additional tests, the long-term stability of the delivered gas is evaluated with respect to surface reactions, leakage, regulator effects, and thermal diffusion and gravimetric fractionation. Results are also reported for the stability of CO2 in these tanks. The results emphasize the importance of orienting tanks horizontally within a thermally insulated enclosure to reduce thermal and gravimetric fractionation of both O2/N2 and CO2 concentrations, and they emphasize the importance of avoiding elastomeric Orings at the head-valve base. With the procedures documented here, the long-term drift in O2/N2 appears to be zero to within approximately ±0.4 per meg yr-1, which projects to an uncertainty of ±0.16 Pg C yr-1 (1ó) in O2-based global carbon budgets.
Submitted on Mar 29, 2006
Accepted on Jul 27, 2006
Published on Jan 1, 2007
ReferencesBalkanski , Y. , Monfray , P. , Battle , M. and Heimann , M . 1999 . Ocean primary production derived from satellite data: An evaluation with at-mospheric oxygen measurements . Glob. Biogeochem. Cycle 13 , 257 – 271 .
Battle , M. , Bender , M. L. , Tans , P. P. , White , J. W. C. , Ellis , J. T. and co-authors. 2000. Global carbon sinks and their variability inferred from atmospheric 02 and 313C. Science 287, 2467 – 2470 .
Bender , M. L. , Tans , P. P. , Ellis , J. T. , Orchardo , J. and Habfast , K . 1994 . A high-precision isotope ratio mass-spectrometry method for measuring the 02/N2 ratio of air . Geochim. Cosmochim. Acta 58 , 4751 – 4758 .
Bender , M. L. , Ho , D. T. , Hendricks , M. B. , Mika , R. , Battle , M . 0. and co-authors. 2005. Atmospheric 02/N2 changes, 1993-2002: Im-plications for the partitioning of fossil fuel CO2 sequestration. Glob. Biogeochem. Cycle 19(GB4017),4011-4015.
Broecker , W. S . 1970 . Mans oxygen reserves. Science 168 , 1537 – 1538. Keeling, R. E 1988a. Measuring correlations between atmospheric oxy-gen and carbon-dioxide mole fractions - a preliminary-study in urban air . J. Atmos. Chem . 7 , 153 – 176 .
Keeling , R. E 1988b. Development of an Interferometric Oxygen Ana-lyzer for Precise Measurement of the Atmospheric 02 Mole Fraction. Harvard University, 178.
Keeling , R. E and Shertz , S. R . 1992 . Seasonal and interarmual variations in atmospheric oxygen and implications for the global cabon-cycle . Nature 358 , 723 – 727 .
Keeling , R. E , Najjar , R. P. , Bender , M. L. and Tans , P. P . 1993 . What atmospheric oxygen measurements can tell us about the global carbon-cycle . Glob. Biogeochem. Cycle 7 , 37 – 67 .
Keeling , R. E , Piper , S. C. and Heimann , M . 1996 . Global and hemi-spheric CO2 sinks deduced from changes in atmospheric 02 concen-tration . Nature 381 , 218 – 221 .
Keeling , R. E , Manning , A. C. , McEvoy , E. M. and Shertz , S. R . 1998a . Methods for measuring changes in atmospheric 02 concentration and their application in southern hemisphere air . J. Geophys. Res.-Atmos . 103 , 3381 – 3397 .
Keeling , R. F , Stephens , B. B. , Najjar , R. G. , Doney , S. C. , Archer , D. and co-authors.1998b. Seasonal variations in the atmospheric 02/N2 ratio in relation to the kinetics of air-sea gas exchange. Glob. Biogeochem. Cycle 12, 141 – 163.
Keeling , R. E , Blaine , T. , Paplawsky , B. , Katz , L. , Atwood , C. and co-authors. 2004. Measurement of changes in atmospheric Ar/N2 ratio using a rapid-switching, single-capillary mass spectrometer system. Tellus 56B, 322 – 338.
Langenfelds , R. L . 2002 . Studies of the carbon cycle using atmospheric oxygen and associated tracers . University of Tasmania , 338 .
Machta , L. and Hughes , E . 1970 . Atmospheric Oxygen in 1967 to 1970 . Science 168 , 1582 – 1584 .
Manning , A. C. , Keeling , R. E and Severinghaus , J. P . 1999 . Precise atmospheric oxygen measurements with a paramagnetic oxygen ana-lyzer . Glob. Biogeochem. Cycle 13 , 1107 – 1115 .
Manning , A. C. and Keeling , R. E 2006 . Global oceanic and land biotic carbon sinks from the Scripps atmospheric oxygen flask sampling network . Tellus 58B , 95 – 116 .
Najjar , R. G. and Keeling , R. E 2000 . Mean annual cycle of the air-sea oxygen flux: A global view . Glob. Biogeochem. Cycle 14 , 573 – 584 .
Reid , R. C. , Prausnitz , J. M. and Poling , B. E . 1987 . The Properties of Gases and Liquids 4th Edition . McGraw-Hill , New York .
Stephens , B. B. , Keeling , R. E , Heimann , M. , Six , K. D. , Mumane , R. and co-authors. 1998. Testing global ocean carbon cycle models using measurements of atmospheric 02 and CO2 concentration. Glob. Biogeochem. Cycle 12, 213 – 230.
Stephens , B. B. , Keeling , R. E and Paplawsky , W . 2003 . Shipboard measurements of atmospheric oxygen using a vacuum-ultraviolet ab-sorption technique . Tellus 55B , 857 – 878 .
Stephens , B. B. , Bakwin , P. , Tans , P. P. , Teclaw , R. and Baumann , D . 2006. Application of a differential fuel-cell analyzer for measuring atmospheric oxygen variations. Journal of atmospheric and oceanic technology in press.
Sturm , P. , Leuenberger , M. , Sirignano , C. , Neubert , R. E. M. , Meijer , H. A. J. and co-authors. 2004. Permeation of atmospheric gases through polymer 0-rings used in flasks for air sampling./. Geophys. Res.-Atmos. 109, D04309.
Tohjima , Y . 2000 . Method for measuring changes in the atmospheric 02/N2 ratio by a gas chromatograph equipped with a thermal conduc-tivity detector . J. Geophys. Res.-Atmos . 105 , 14575 – 14584 .
Tohjima , Y. , Machida , T. , Watai , T. , Akama , I. , Amari , T. and co-authors. 2005. Preparation of gravimetric standards for measurements of atmo-spheric oxygen and reevaluation of atmospheric oxygen concentration. J. Geophys. Res.-Atmos. 110, D11302.
RetroSearch is an open source project built by @garambo | Open a GitHub Issue
Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo
HTML:
3.2
| Encoding:
UTF-8
| Version:
0.7.3