Journal ArticleDOI
Application of a Differential Fuel-Cell Analyzer for Measuring Atmospheric Oxygen Variations
TLDR
In this article, a commercial differential fuel-cell analyzer has been adapted to make field-based ppm-level measurements of atmospheric O2 variations, achieving a 1σ precision of ±2.5 per meg (≈0.5 ppm) for a 2-min measurement.Abstract:
A commercially available differential fuel-cell analyzer has been adapted to make field-based ppm-level measurements of atmospheric O2 variations. With the implementation of rapid calibrations and active pressure and flow control, the analysis system described here has a 1σ precision of ±2.5 per meg (≈0.5 ppm) for a 2-min measurement. Allowing for system stabilization after switching inlet lines, a 6-min measurement with a precision of ±1.4 per meg (≈0.3 ppm) every 20 min is obtained. The elimination of biases in any atmospheric O2 measurement depends critically on careful gas-handling procedures, and after screening for known sources of bias a comparability of ±10 per meg (≈2 ppm) with the present setup is estimated. In comparison to existing techniques, the relatively small size, low cost, fast response, motion insensitivity, and ease of implementation of the fuel-cell analyzer make it particularly useful for a wide range of unattended field applications. This system has been used to measure at...read more
Citations
More filters
Journal ArticleDOI
Evaluating two experimental approaches for measuring ecosystem carbon oxidation state and oxidative ratio
TL;DR: In this paper, the authors compare two methods for measuring the degree of oxidation of organic carbon (Cox) and ecosystem oxidative ratio (OR), the molar ratio of O2 to CO2 fluxes associated with net ecosystem exchange.
Book ChapterDOI
Studies of recent changes in atmospheric O2 content
TL;DR: In this paper, a very close coupling exists between changes in atmospheric O2 and CO2 concentrations, owing to the chemistry of photosynthesis, respiration, and combustion, and various applications of the observations are discussed, including quantifying the magnitude of the global land and ocean carbon sinks and testing ocean biogeochemical models.
Journal ArticleDOI
In-situ measurements of oxygen, carbon monoxide and greenhouse gases from Ochsenkopf tall tower in Germany
Rona Thompson,Andrew C. Manning,E. Gloor,U. Schultz,Thomas Seifert,F. Hänsel,Armin Jordan,Martin Heimann +7 more
TL;DR: In this article, in-situ measurements of CO2, O2, CH4, CO, N2O and SF6 were collected from 23, 90 and 163 m above ground on the Ochsenkopf tower in the Fichtelgebirge range, Germany.
Journal ArticleDOI
A new approach for flow-through respirometry measurements in humans.
Edward L. Melanson,Jan P. Ingebrigtsen,Audrey Bergouignan,Kazunori Ohkawara,Wendy M. Kohrt,John R. B. Lighton +5 more
TL;DR: A novel approach to measuring gas exchange using a pull-type whole room indirect calorimeter is described, and a novel switching approach is used that permits constant, uninterrupted measurement of the excurrent airstream while allowing frequent measurements of the incurrent airstREAM.
Journal ArticleDOI
Measurement of soil carbon oxidation state and oxidative ratio by 13 C nuclear magnetic resonance
William C. Hockaday,Caroline A. Masiello,James T. Randerson,Ronald J. Smernik,Jeff Baldock,Oliver A. Chadwick,Jennifer W. Harden +6 more
TL;DR: In this article, direct polarization solid-state 13 C NMR with the molecular mixing model was used to estimate the OR of carbon flux from a boreal forest fire and showed a large natural variability in soil Cox and OR values.
References
More filters
Journal ArticleDOI
Climate change 2001: the scientific basis
John Theodore Houghton,Y. Ding,David John Griggs,M. Noguer,P. J. van der Linden,X. Dai,K. Maskell,C. A. Johnson +7 more
TL;DR: In this article, the authors present an overview of the climate system and its dynamics, including observed climate variability and change, the carbon cycle, atmospheric chemistry and greenhouse gases, and their direct and indirect effects.
Journal ArticleDOI
Towards robust regional estimates of CO2 sources and sinks using atmospheric transport models.
Kevin R. Gurney,Rachel M. Law,A. S. Denning,Peter Rayner,David Baker,Philippe Bousquet,Lori Bruhwiler,Yu-Hsin Chen,Philippe Ciais,Song-Miao Fan,Inez Fung,Manuel Gloor,Martin Heimann,Kaz Higuchi,Jasmin John,Takashi Maki,Shamil Maksyutov,Kenneth A. Masarie,Philippe Peylin,Michael J. Prather,Bernard Pak,James T. Randerson,Jorge L. Sarmiento,S. Taguchi,Taro Takahashi,C.-W. Yuen +25 more
TL;DR: An uptake of CO2 in the southern extratropical ocean less than that estimated from ocean measurements is found, a result that is not sensitive to transport models or methodological approaches, and carbon fluxes integrated over latitudinal zones are strongly constrained by observations in the middle to high latitudes.
Journal ArticleDOI
Global and hemispheric CO2 sinks deduced from changes in atmospheric O2 concentration
TL;DR: In this paper, the authors present an extensive O2/N2 data set which shows simultaneous trends in O 2 /N 2 in both northern and southern hemispheres and allows the O 2/N 2 gradient between the two hemisphere to be quantified, consistent with a budget in which, for the 1991-94 period, the global oceans and the northern land biota each removed the equivalent of approximately 30% of fossil-fuel CO2 emissions, while the tropical land biome as a whole were not a strong source or sink.
Journal ArticleDOI
Global Carbon Sinks and Their Variability Inferred from Atmospheric O2 and δ13C
M. O. Battle,Michael L. Bender,P. P. Tans,James W. C. White,J. T. Ellis,Thomas J. Conway,Roger J. Francey +6 more
TL;DR: In this paper, time series measurements of atmospheric O2 show that the land biosphere and world oceans annually sequestered 1.4 ± 0.8 and 2.0 ± 1.6 gigatons of carbon, respectively, between mid-1991 and mid-1997.
Journal ArticleDOI
Root Respiration Associated with Ammonium and Nitrate Absorption and Assimilation by Barley
TL;DR: Estimates of in vivo nitrate assimilation from excised roots and whole plants indicated that the nar1a mutation influences assimilation only in the shoot and that exposure to NO(3) (-) induced shoot nitrate reduction more slowly than root nitrates reduction in all three genotypes.
Related Papers (5)
Seasonal and interannual variations in atmospheric oxygen and implications for the global carbon cycle
Ralph F. Keeling,S. Shertz +1 more