Biological production in the Bellingshausen Sea from oxygen-to-argon ratios and oxygen triple isotopes
We present estimates of mixed-layer net community oxygen production ( N ) and gross oxygen production ( G ) of the Bellingshausen Sea in March and April 2007. N was derived from oxygen-to-argon (O 2 /Ar) ratios; G was derived using the dual-delta method from triple oxygen isotope measurements. In ad...
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ftcopernicus:oai:publications.copernicus.org:bg17509 2023-05-15T15:41:23+02:00 Biological production in the Bellingshausen Sea from oxygen-to-argon ratios and oxygen triple isotopes Castro-Morales, K. Cassar, N. Shoosmith, D. R. Kaiser, J. 2018-09-27 application/pdf https://doi.org/10.5194/bg-10-2273-2013 https://www.biogeosciences.net/10/2273/2013/ eng eng doi:10.5194/bg-10-2273-2013 https://www.biogeosciences.net/10/2273/2013/ eISSN: 1726-4189 Text 2018 ftcopernicus https://doi.org/10.5194/bg-10-2273-2013 2019-12-24T09:55:27Z We present estimates of mixed-layer net community oxygen production ( N ) and gross oxygen production ( G ) of the Bellingshausen Sea in March and April 2007. N was derived from oxygen-to-argon (O 2 /Ar) ratios; G was derived using the dual-delta method from triple oxygen isotope measurements. In addition, O 2 profiles were collected at 253 CTD stations. N is often approximated by the biological oxygen air–sea exchange flux ( F bio based on the O 2 /Ar supersaturation, assuming that significant horizontal or vertical fluxes are absent. Here we show that the effect of vertical fluxes alone can account for F bio values < 0 in large parts of the Bellingshausen Sea towards the end of the productive season, which could otherwise be mistaken to represent net heterotrophy. Thus, improved estimates of mixed-layer N can be derived from the sum of F bio , F e (entrainment from the upper thermocline during mixed-layer deepening) and F v (diapycnal eddy diffusion across the base of the mixed layer). In the winter sea ice zone (WSIZ), the corresponding correction results in a small change of F bio = (30 ± 17) mmol m −2 d −1 to N = (34 ± 17) mmol m −2 d −1 . However, in the permanent open ocean zone (POOZ), the original F bio value of (−17 ± 10) mmol m −2 d −1 gives a corrected value for N of (−2 ± 18) mmol m −2 d −1 . We hypothesize that in the WSIZ, enhanced water column stability due to the release of freshwater and nutrients from sea ice melt may account for the higher N value. These results stress the importance of accounting for physical biases when estimating mixed-layer marine productivity from in situ O 2 /Ar ratios. Text Bellingshausen Sea Sea ice Copernicus Publications: E-Journals Bellingshausen Sea Biogeosciences 10 4 2273 2291 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
We present estimates of mixed-layer net community oxygen production ( N ) and gross oxygen production ( G ) of the Bellingshausen Sea in March and April 2007. N was derived from oxygen-to-argon (O 2 /Ar) ratios; G was derived using the dual-delta method from triple oxygen isotope measurements. In addition, O 2 profiles were collected at 253 CTD stations. N is often approximated by the biological oxygen air–sea exchange flux ( F bio based on the O 2 /Ar supersaturation, assuming that significant horizontal or vertical fluxes are absent. Here we show that the effect of vertical fluxes alone can account for F bio values < 0 in large parts of the Bellingshausen Sea towards the end of the productive season, which could otherwise be mistaken to represent net heterotrophy. Thus, improved estimates of mixed-layer N can be derived from the sum of F bio , F e (entrainment from the upper thermocline during mixed-layer deepening) and F v (diapycnal eddy diffusion across the base of the mixed layer). In the winter sea ice zone (WSIZ), the corresponding correction results in a small change of F bio = (30 ± 17) mmol m −2 d −1 to N = (34 ± 17) mmol m −2 d −1 . However, in the permanent open ocean zone (POOZ), the original F bio value of (−17 ± 10) mmol m −2 d −1 gives a corrected value for N of (−2 ± 18) mmol m −2 d −1 . We hypothesize that in the WSIZ, enhanced water column stability due to the release of freshwater and nutrients from sea ice melt may account for the higher N value. These results stress the importance of accounting for physical biases when estimating mixed-layer marine productivity from in situ O 2 /Ar ratios. |
format |
Text |
author |
Castro-Morales, K. Cassar, N. Shoosmith, D. R. Kaiser, J. |
spellingShingle |
Castro-Morales, K. Cassar, N. Shoosmith, D. R. Kaiser, J. Biological production in the Bellingshausen Sea from oxygen-to-argon ratios and oxygen triple isotopes |
author_facet |
Castro-Morales, K. Cassar, N. Shoosmith, D. R. Kaiser, J. |
author_sort |
Castro-Morales, K. |
title |
Biological production in the Bellingshausen Sea from oxygen-to-argon ratios and oxygen triple isotopes |
title_short |
Biological production in the Bellingshausen Sea from oxygen-to-argon ratios and oxygen triple isotopes |
title_full |
Biological production in the Bellingshausen Sea from oxygen-to-argon ratios and oxygen triple isotopes |
title_fullStr |
Biological production in the Bellingshausen Sea from oxygen-to-argon ratios and oxygen triple isotopes |
title_full_unstemmed |
Biological production in the Bellingshausen Sea from oxygen-to-argon ratios and oxygen triple isotopes |
title_sort |
biological production in the bellingshausen sea from oxygen-to-argon ratios and oxygen triple isotopes |
publishDate |
2018 |
url |
https://doi.org/10.5194/bg-10-2273-2013 https://www.biogeosciences.net/10/2273/2013/ |
geographic |
Bellingshausen Sea |
geographic_facet |
Bellingshausen Sea |
genre |
Bellingshausen Sea Sea ice |
genre_facet |
Bellingshausen Sea Sea ice |
op_source |
eISSN: 1726-4189 |
op_relation |
doi:10.5194/bg-10-2273-2013 https://www.biogeosciences.net/10/2273/2013/ |
op_doi |
https://doi.org/10.5194/bg-10-2273-2013 |
container_title |
Biogeosciences |
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10 |
container_issue |
4 |
container_start_page |
2273 |
op_container_end_page |
2291 |
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1766374278689718272 |