An intercomparison of oceanic methane and nitrous oxide measurements

Thumbnail Image
Wilson, Samuel T.
Bange, Hermann W.
Arévalo-Martínez, Damian L.
Barnes, Jonathan
Borges, Alberto V.
Brown, Ian
Bullister, John L.
Burgos, Macarena
Capelle, David W.
Casso, Michael A.
de la Paz, Mercedes
Farías, Laura
Fenwick, Lindsay
Ferrón, Sara
Garcia, Gerardo
Glockzin, Michael
Karl, David M.
Kock, Annette
Laperriere, Sarah
Law, Cliff S.
Manning, Cara C.
Marriner, Andrew
Myllykangas, Jukka-Pekka
Pohlman, John W.
Rees, Andrew P.
Santoro, Alyson E.
Tortell, Philippe D.
Upstill-Goddard, Robert C.
Wisegarver, David P.
Zhang, Gui-Ling
Rehder, Gregor
Alternative Title
As Published
Date Created
Related Materials
Replaced By
Large-scale climatic forcing is impacting oceanic biogeochemical cycles and is expected to influence the water-column distribution of trace gases, including methane and nitrous oxide. Our ability as a scientific community to evaluate changes in the water-column inventories of methane and nitrous oxide depends largely on our capacity to obtain robust and accurate concentration measurements that can be validated across different laboratory groups. This study represents the first formal international intercomparison of oceanic methane and nitrous oxide measurements whereby participating laboratories received batches of seawater samples from the subtropical Pacific Ocean and the Baltic Sea. Additionally, compressed gas standards from the same calibration scale were distributed to the majority of participating laboratories to improve the analytical accuracy of the gas measurements. The computations used by each laboratory to derive the dissolved gas concentrations were also evaluated for inconsistencies (e.g., pressure and temperature corrections, solubility constants). The results from the intercomparison and intercalibration provided invaluable insights into methane and nitrous oxide measurements. It was observed that analyses of seawater samples with the lowest concentrations of methane and nitrous oxide had the lowest precisions. In comparison, while the analytical precision for samples with the highest concentrations of trace gases was better, the variability between the different laboratories was higher: 36% for methane and 27% for nitrous oxide. In addition, the comparison of different batches of seawater samples with methane and nitrous oxide concentrations that ranged over an order of magnitude revealed the ramifications of different calibration procedures for each trace gas. Finally, this study builds upon the intercomparison results to develop recommendations for improving oceanic methane and nitrous oxide measurements, with the aim of precluding future analytical discrepancies between laboratories.
© The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biogeosciences 15 (2018): 5891-5907, doi:10.5194/bg-15-5891-2018.
Embargo Date
Biogeosciences 15 (2018): 5891-5907
Cruise ID
Cruise DOI
Vessel Name
Except where otherwise noted, this item's license is described as Attribution 4.0 International