Equilibrator-based measurements of dissolved nitrous oxide in the surface ocean using an integrated cavity output laser absorption spectrometer
Dissolved nitrous oxide (N 2 O) concentrations are usually determined by gas chromatography (GC). Here we present laboratory tests and initial field measurements using a novel setup comprising a commercially available laser-based analyser for N 2 O, carbon monoxide and water vapour coupled to a glas...
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Online Access: | https://doi.org/10.5194/os-10-501-2014 https://os.copernicus.org/articles/10/501/2014/ |
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ftcopernicus:oai:publications.copernicus.org:os20639 2023-05-15T18:25:58+02:00 Equilibrator-based measurements of dissolved nitrous oxide in the surface ocean using an integrated cavity output laser absorption spectrometer Grefe, I. Kaiser, J. 2018-01-15 info:eu-repo/semantics/application/pdf https://doi.org/10.5194/os-10-501-2014 https://os.copernicus.org/articles/10/501/2014/ eng eng info:eu-repo/grantAgreement/EC/FP7/237890 doi:10.5194/os-10-501-2014 https://os.copernicus.org/articles/10/501/2014/ info:eu-repo/semantics/openAccess eISSN: 1812-0792 info:eu-repo/semantics/Text 2018 ftcopernicus https://doi.org/10.5194/os-10-501-2014 2020-07-20T16:25:02Z Dissolved nitrous oxide (N 2 O) concentrations are usually determined by gas chromatography (GC). Here we present laboratory tests and initial field measurements using a novel setup comprising a commercially available laser-based analyser for N 2 O, carbon monoxide and water vapour coupled to a glass-bed equilibrator. This approach is less labour-intensive and provides higher temporal and spatial resolution than the conventional GC technique. The standard deviation of continuous equilibrator or atmospheric air measurements was 0.2 nmol mol −1 (averaged over 5 min). The short-term repeatability for reference gas measurements within 1 h of each other was 0.2 nmol mol −1 or better. Another indicator of the long-term stability of the analyser is the standard deviation of the calibrated N 2 O mole fraction in marine air, which was between 0.5 and 0.7 nmol mol −1 . The equilibrator measurements were compared with purge-and-trap gas chromatography–mass spectrometry (GC-MS) analyses of N 2 O concentrations in discrete samples from the Southern Ocean and showed agreement to within the 2% measurement uncertainty of the GC-MS method. The equilibrator response time to concentration changes in water was from 142 to 203 s, depending on the headspace flow rate. The system was tested at sea during a north-to-south transect of the Atlantic Ocean. While the subtropical gyres were slightly undersaturated, the equatorial region was a source of nitrous oxide to the atmosphere, confirming previous findings (Forster et al., 2009). The ability to measure at high temporal and spatial resolution revealed submesoscale variability in dissolved N 2 O concentrations. Mean sea-to-air fluxes in the tropical and subtropical Atlantic ranged between −1.6 and 0.11 μmol m −2 d −1 and confirm that the subtropical Atlantic is not an important source region for N 2 O to the atmosphere, compared to global average fluxes of 0.6–2.4 μmol m −2 d −1 . The system can be easily modified for autonomous operation on voluntary observing ships (VOS). Future work should include an interlaboratory comparison exercise with other methods of dissolved N 2 O analyses. Other/Unknown Material Southern Ocean Copernicus Publications: E-Journals Southern Ocean Ocean Science 10 3 501 512 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
Dissolved nitrous oxide (N 2 O) concentrations are usually determined by gas chromatography (GC). Here we present laboratory tests and initial field measurements using a novel setup comprising a commercially available laser-based analyser for N 2 O, carbon monoxide and water vapour coupled to a glass-bed equilibrator. This approach is less labour-intensive and provides higher temporal and spatial resolution than the conventional GC technique. The standard deviation of continuous equilibrator or atmospheric air measurements was 0.2 nmol mol −1 (averaged over 5 min). The short-term repeatability for reference gas measurements within 1 h of each other was 0.2 nmol mol −1 or better. Another indicator of the long-term stability of the analyser is the standard deviation of the calibrated N 2 O mole fraction in marine air, which was between 0.5 and 0.7 nmol mol −1 . The equilibrator measurements were compared with purge-and-trap gas chromatography–mass spectrometry (GC-MS) analyses of N 2 O concentrations in discrete samples from the Southern Ocean and showed agreement to within the 2% measurement uncertainty of the GC-MS method. The equilibrator response time to concentration changes in water was from 142 to 203 s, depending on the headspace flow rate. The system was tested at sea during a north-to-south transect of the Atlantic Ocean. While the subtropical gyres were slightly undersaturated, the equatorial region was a source of nitrous oxide to the atmosphere, confirming previous findings (Forster et al., 2009). The ability to measure at high temporal and spatial resolution revealed submesoscale variability in dissolved N 2 O concentrations. Mean sea-to-air fluxes in the tropical and subtropical Atlantic ranged between −1.6 and 0.11 μmol m −2 d −1 and confirm that the subtropical Atlantic is not an important source region for N 2 O to the atmosphere, compared to global average fluxes of 0.6–2.4 μmol m −2 d −1 . The system can be easily modified for autonomous operation on voluntary observing ships (VOS). Future work should include an interlaboratory comparison exercise with other methods of dissolved N 2 O analyses. |
format |
Other/Unknown Material |
author |
Grefe, I. Kaiser, J. |
spellingShingle |
Grefe, I. Kaiser, J. Equilibrator-based measurements of dissolved nitrous oxide in the surface ocean using an integrated cavity output laser absorption spectrometer |
author_facet |
Grefe, I. Kaiser, J. |
author_sort |
Grefe, I. |
title |
Equilibrator-based measurements of dissolved nitrous oxide in the surface ocean using an integrated cavity output laser absorption spectrometer |
title_short |
Equilibrator-based measurements of dissolved nitrous oxide in the surface ocean using an integrated cavity output laser absorption spectrometer |
title_full |
Equilibrator-based measurements of dissolved nitrous oxide in the surface ocean using an integrated cavity output laser absorption spectrometer |
title_fullStr |
Equilibrator-based measurements of dissolved nitrous oxide in the surface ocean using an integrated cavity output laser absorption spectrometer |
title_full_unstemmed |
Equilibrator-based measurements of dissolved nitrous oxide in the surface ocean using an integrated cavity output laser absorption spectrometer |
title_sort |
equilibrator-based measurements of dissolved nitrous oxide in the surface ocean using an integrated cavity output laser absorption spectrometer |
publishDate |
2018 |
url |
https://doi.org/10.5194/os-10-501-2014 https://os.copernicus.org/articles/10/501/2014/ |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
eISSN: 1812-0792 |
op_relation |
info:eu-repo/grantAgreement/EC/FP7/237890 doi:10.5194/os-10-501-2014 https://os.copernicus.org/articles/10/501/2014/ |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/os-10-501-2014 |
container_title |
Ocean Science |
container_volume |
10 |
container_issue |
3 |
container_start_page |
501 |
op_container_end_page |
512 |
_version_ |
1766207725185794048 |