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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ftdoajarticles:oai:doaj.org/article:da489d069c5c4a6ba240472f94e8ee71 2023-05-15T18:25:59+02:00 Equilibrator-based measurements of dissolved nitrous oxide in the surface ocean using an integrated cavity output laser absorption spectrometer I. Grefe J. Kaiser 2014-06-01T00:00:00Z https://doi.org/10.5194/os-10-501-2014 https://doaj.org/article/da489d069c5c4a6ba240472f94e8ee71 EN eng Copernicus Publications http://www.ocean-sci.net/10/501/2014/os-10-501-2014.pdf https://doaj.org/toc/1812-0784 https://doaj.org/toc/1812-0792 1812-0784 1812-0792 doi:10.5194/os-10-501-2014 https://doaj.org/article/da489d069c5c4a6ba240472f94e8ee71 Ocean Science, Vol 10, Iss 3, Pp 501-512 (2014) Geography. Anthropology. Recreation G Environmental sciences GE1-350 article 2014 ftdoajarticles https://doi.org/10.5194/os-10-501-2014 2022-12-31T08:41:49Z 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 ... Article in Journal/Newspaper Southern Ocean Directory of Open Access Journals: DOAJ Articles Southern Ocean Ocean Science 10 3 501 512 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 |
spellingShingle |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 I. Grefe J. Kaiser Equilibrator-based measurements of dissolved nitrous oxide in the surface ocean using an integrated cavity output laser absorption spectrometer |
topic_facet |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 |
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 ... |
format |
Article in Journal/Newspaper |
author |
I. Grefe J. Kaiser |
author_facet |
I. Grefe J. Kaiser |
author_sort |
I. Grefe |
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 |
publisher |
Copernicus Publications |
publishDate |
2014 |
url |
https://doi.org/10.5194/os-10-501-2014 https://doaj.org/article/da489d069c5c4a6ba240472f94e8ee71 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Ocean Science, Vol 10, Iss 3, Pp 501-512 (2014) |
op_relation |
http://www.ocean-sci.net/10/501/2014/os-10-501-2014.pdf https://doaj.org/toc/1812-0784 https://doaj.org/toc/1812-0792 1812-0784 1812-0792 doi:10.5194/os-10-501-2014 https://doaj.org/article/da489d069c5c4a6ba240472f94e8ee71 |
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_ |
1766207744265682944 |