Particulate barium tracing of significant mesopelagic carbon remineralisation in the North Atlantic
The remineralisation of sinking particles by prokaryotic heterotrophic activity is important for controlling oceanic carbon sequestration. Here, we report mesopelagic particulate organic carbon (POC) remineralisation fluxes in the North Atlantic along the GEOTRACES-GA01 section (GEOVIDE cruise; May–...
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ftdoajarticles:oai:doaj.org/article:cd86649419a648449a93460b79ab8377 2023-05-15T17:06:14+02:00 Particulate barium tracing of significant mesopelagic carbon remineralisation in the North Atlantic N. Lemaitre H. Planquette F. Planchon G. Sarthou S. Jacquet M. I. García-Ibáñez A. Gourain M. Cheize L. Monin L. André P. Laha H. Terryn F. Dehairs 2018-04-01T00:00:00Z https://doi.org/10.5194/bg-15-2289-2018 https://doaj.org/article/cd86649419a648449a93460b79ab8377 EN eng Copernicus Publications https://www.biogeosciences.net/15/2289/2018/bg-15-2289-2018.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-15-2289-2018 1726-4170 1726-4189 https://doaj.org/article/cd86649419a648449a93460b79ab8377 Biogeosciences, Vol 15, Pp 2289-2307 (2018) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2018 ftdoajarticles https://doi.org/10.5194/bg-15-2289-2018 2022-12-31T14:43:36Z The remineralisation of sinking particles by prokaryotic heterotrophic activity is important for controlling oceanic carbon sequestration. Here, we report mesopelagic particulate organic carbon (POC) remineralisation fluxes in the North Atlantic along the GEOTRACES-GA01 section (GEOVIDE cruise; May–June 2014) using the particulate biogenic barium (excess barium; Ba xs ) proxy. Important mesopelagic (100–1000 m) Ba xs differences were observed along the transect depending on the intensity of past blooms, the phytoplankton community structure, and the physical forcing, including downwelling. The subpolar province was characterized by the highest mesopelagic Ba xs content (up to 727 pmol L −1 ), which was attributed to an intense bloom averaging 6 mg chl a m −3 between January and June 2014 and by an intense 1500 m deep convection in the central Labrador Sea during the winter preceding the sampling. This downwelling could have promoted a deepening of the prokaryotic heterotrophic activity, increasing the Ba xs content. In comparison, the temperate province, characterized by the lowest Ba xs content (391 pmol L −1 ), was sampled during the bloom period and phytoplankton appear to be dominated by small and calcifying species, such as coccolithophorids. The Ba xs content, related to oxygen consumption, was converted into a remineralisation flux using an updated relationship, proposed for the first time in the North Atlantic. The estimated fluxes were of the same order of magnitude as other fluxes obtained using independent methods (moored sediment traps, incubations) in the North Atlantic. Interestingly, in the subpolar and subtropical provinces, mesopelagic POC remineralisation fluxes (up to 13 and 4.6 mmol C m −2 d −1 , respectively) were equalling and occasionally even exceeding upper-ocean POC export fluxes, deduced using the 234 Th method. These results highlight the important impact of the mesopelagic remineralisation on the biological carbon pump of the studied area with a near-zero, deep (> 1000 m) carbon ... Article in Journal/Newspaper Labrador Sea North Atlantic Directory of Open Access Journals: DOAJ Articles Biogeosciences 15 8 2289 2307 |
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Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
spellingShingle |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 N. Lemaitre H. Planquette F. Planchon G. Sarthou S. Jacquet M. I. García-Ibáñez A. Gourain M. Cheize L. Monin L. André P. Laha H. Terryn F. Dehairs Particulate barium tracing of significant mesopelagic carbon remineralisation in the North Atlantic |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
The remineralisation of sinking particles by prokaryotic heterotrophic activity is important for controlling oceanic carbon sequestration. Here, we report mesopelagic particulate organic carbon (POC) remineralisation fluxes in the North Atlantic along the GEOTRACES-GA01 section (GEOVIDE cruise; May–June 2014) using the particulate biogenic barium (excess barium; Ba xs ) proxy. Important mesopelagic (100–1000 m) Ba xs differences were observed along the transect depending on the intensity of past blooms, the phytoplankton community structure, and the physical forcing, including downwelling. The subpolar province was characterized by the highest mesopelagic Ba xs content (up to 727 pmol L −1 ), which was attributed to an intense bloom averaging 6 mg chl a m −3 between January and June 2014 and by an intense 1500 m deep convection in the central Labrador Sea during the winter preceding the sampling. This downwelling could have promoted a deepening of the prokaryotic heterotrophic activity, increasing the Ba xs content. In comparison, the temperate province, characterized by the lowest Ba xs content (391 pmol L −1 ), was sampled during the bloom period and phytoplankton appear to be dominated by small and calcifying species, such as coccolithophorids. The Ba xs content, related to oxygen consumption, was converted into a remineralisation flux using an updated relationship, proposed for the first time in the North Atlantic. The estimated fluxes were of the same order of magnitude as other fluxes obtained using independent methods (moored sediment traps, incubations) in the North Atlantic. Interestingly, in the subpolar and subtropical provinces, mesopelagic POC remineralisation fluxes (up to 13 and 4.6 mmol C m −2 d −1 , respectively) were equalling and occasionally even exceeding upper-ocean POC export fluxes, deduced using the 234 Th method. These results highlight the important impact of the mesopelagic remineralisation on the biological carbon pump of the studied area with a near-zero, deep (> 1000 m) carbon ... |
format |
Article in Journal/Newspaper |
author |
N. Lemaitre H. Planquette F. Planchon G. Sarthou S. Jacquet M. I. García-Ibáñez A. Gourain M. Cheize L. Monin L. André P. Laha H. Terryn F. Dehairs |
author_facet |
N. Lemaitre H. Planquette F. Planchon G. Sarthou S. Jacquet M. I. García-Ibáñez A. Gourain M. Cheize L. Monin L. André P. Laha H. Terryn F. Dehairs |
author_sort |
N. Lemaitre |
title |
Particulate barium tracing of significant mesopelagic carbon remineralisation in the North Atlantic |
title_short |
Particulate barium tracing of significant mesopelagic carbon remineralisation in the North Atlantic |
title_full |
Particulate barium tracing of significant mesopelagic carbon remineralisation in the North Atlantic |
title_fullStr |
Particulate barium tracing of significant mesopelagic carbon remineralisation in the North Atlantic |
title_full_unstemmed |
Particulate barium tracing of significant mesopelagic carbon remineralisation in the North Atlantic |
title_sort |
particulate barium tracing of significant mesopelagic carbon remineralisation in the north atlantic |
publisher |
Copernicus Publications |
publishDate |
2018 |
url |
https://doi.org/10.5194/bg-15-2289-2018 https://doaj.org/article/cd86649419a648449a93460b79ab8377 |
genre |
Labrador Sea North Atlantic |
genre_facet |
Labrador Sea North Atlantic |
op_source |
Biogeosciences, Vol 15, Pp 2289-2307 (2018) |
op_relation |
https://www.biogeosciences.net/15/2289/2018/bg-15-2289-2018.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-15-2289-2018 1726-4170 1726-4189 https://doaj.org/article/cd86649419a648449a93460b79ab8377 |
op_doi |
https://doi.org/10.5194/bg-15-2289-2018 |
container_title |
Biogeosciences |
container_volume |
15 |
container_issue |
8 |
container_start_page |
2289 |
op_container_end_page |
2307 |
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1766061272056463360 |