Upward nitrate flux and downward particulate organic carbon flux under contrasting situations of stratification and turbulent mixing in an Arctic shelf sea
Increased sea ice melt alters vertical surface-mixing processes in Arctic seas. More melt water strengthens the stratification, but an absent ice cover also exposes the uppermost part of the water column to wind-induced mixing processes. We conducted a field study in the Barents Sea, an Arctic shelf...
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ftdoajarticles:oai:doaj.org/article:a082ce69f6094859a050f7ab817df9d0 2023-05-15T14:46:04+02:00 Upward nitrate flux and downward particulate organic carbon flux under contrasting situations of stratification and turbulent mixing in an Arctic shelf sea Ingrid Wiedmann Jean-Éric Tremblay Arild Sundfjord Marit Reigstad 2017-08-01T00:00:00Z https://doi.org/10.1525/elementa.235 https://doaj.org/article/a082ce69f6094859a050f7ab817df9d0 EN eng BioOne https://www.elementascience.org/articles/235 https://doaj.org/toc/2325-1026 2325-1026 doi:10.1525/elementa.235 https://doaj.org/article/a082ce69f6094859a050f7ab817df9d0 Elementa: Science of the Anthropocene, Vol 5 (2017) nitrate flux POC export sediment trap sedimentation warming Arctic space-for-time substitution Environmental sciences GE1-350 article 2017 ftdoajarticles https://doi.org/10.1525/elementa.235 2022-12-31T10:39:46Z Increased sea ice melt alters vertical surface-mixing processes in Arctic seas. More melt water strengthens the stratification, but an absent ice cover also exposes the uppermost part of the water column to wind-induced mixing processes. We conducted a field study in the Barents Sea, an Arctic shelf sea, to examine the effects of stratification and vertical mixing processes on 1) the upward nitrate flux (into surface layers <65 m) and 2) the downward flux of particulate organic carbon (POC) to ≤200 m. In the Arctic-influenced, drift ice-covered northern Barents Sea, we found a low upward nitrate flux into the surface layers (<0.1 mmol nitrate m–2 d–1) and a moderate downward POC flux (40–200 m: 150–250 mg POC m–2 d–1) during the late phase of a peak bloom. A 1-D residence time calculation indicated that the nitrate concentration in the surface layers constantly declined. In the Atlantic-influenced, ice-free, and weakly stratified southern Barents Sea a high upward nitrate flux was found (into the surface layers ≤25 m: >5 mmol nitrate m–2 d–1) during a post bloom situation which was associated with a high downward POC flux (40–120 m: 260–600 mg POC m–2 d–1). We suggest that strong wind events during our field study induced vertical mixing processes and triggered upwards nitrate flux, while a combination of down-mixed phytoplankton and fast-sinking mesozooplankton fecal pellets enhanced the downward POC flux. The results of this study underscore the need to further investigate the role of strong, episodic wind events on the upward nitrate and downward POC fluxes in weakly stratified regions of the Arctic that may be ice-free in future. Article in Journal/Newspaper Arctic Barents Sea Phytoplankton Sea ice Directory of Open Access Journals: DOAJ Articles Arctic Barents Sea Elem Sci Anth 5 0 43 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
nitrate flux POC export sediment trap sedimentation warming Arctic space-for-time substitution Environmental sciences GE1-350 |
spellingShingle |
nitrate flux POC export sediment trap sedimentation warming Arctic space-for-time substitution Environmental sciences GE1-350 Ingrid Wiedmann Jean-Éric Tremblay Arild Sundfjord Marit Reigstad Upward nitrate flux and downward particulate organic carbon flux under contrasting situations of stratification and turbulent mixing in an Arctic shelf sea |
topic_facet |
nitrate flux POC export sediment trap sedimentation warming Arctic space-for-time substitution Environmental sciences GE1-350 |
description |
Increased sea ice melt alters vertical surface-mixing processes in Arctic seas. More melt water strengthens the stratification, but an absent ice cover also exposes the uppermost part of the water column to wind-induced mixing processes. We conducted a field study in the Barents Sea, an Arctic shelf sea, to examine the effects of stratification and vertical mixing processes on 1) the upward nitrate flux (into surface layers <65 m) and 2) the downward flux of particulate organic carbon (POC) to ≤200 m. In the Arctic-influenced, drift ice-covered northern Barents Sea, we found a low upward nitrate flux into the surface layers (<0.1 mmol nitrate m–2 d–1) and a moderate downward POC flux (40–200 m: 150–250 mg POC m–2 d–1) during the late phase of a peak bloom. A 1-D residence time calculation indicated that the nitrate concentration in the surface layers constantly declined. In the Atlantic-influenced, ice-free, and weakly stratified southern Barents Sea a high upward nitrate flux was found (into the surface layers ≤25 m: >5 mmol nitrate m–2 d–1) during a post bloom situation which was associated with a high downward POC flux (40–120 m: 260–600 mg POC m–2 d–1). We suggest that strong wind events during our field study induced vertical mixing processes and triggered upwards nitrate flux, while a combination of down-mixed phytoplankton and fast-sinking mesozooplankton fecal pellets enhanced the downward POC flux. The results of this study underscore the need to further investigate the role of strong, episodic wind events on the upward nitrate and downward POC fluxes in weakly stratified regions of the Arctic that may be ice-free in future. |
format |
Article in Journal/Newspaper |
author |
Ingrid Wiedmann Jean-Éric Tremblay Arild Sundfjord Marit Reigstad |
author_facet |
Ingrid Wiedmann Jean-Éric Tremblay Arild Sundfjord Marit Reigstad |
author_sort |
Ingrid Wiedmann |
title |
Upward nitrate flux and downward particulate organic carbon flux under contrasting situations of stratification and turbulent mixing in an Arctic shelf sea |
title_short |
Upward nitrate flux and downward particulate organic carbon flux under contrasting situations of stratification and turbulent mixing in an Arctic shelf sea |
title_full |
Upward nitrate flux and downward particulate organic carbon flux under contrasting situations of stratification and turbulent mixing in an Arctic shelf sea |
title_fullStr |
Upward nitrate flux and downward particulate organic carbon flux under contrasting situations of stratification and turbulent mixing in an Arctic shelf sea |
title_full_unstemmed |
Upward nitrate flux and downward particulate organic carbon flux under contrasting situations of stratification and turbulent mixing in an Arctic shelf sea |
title_sort |
upward nitrate flux and downward particulate organic carbon flux under contrasting situations of stratification and turbulent mixing in an arctic shelf sea |
publisher |
BioOne |
publishDate |
2017 |
url |
https://doi.org/10.1525/elementa.235 https://doaj.org/article/a082ce69f6094859a050f7ab817df9d0 |
geographic |
Arctic Barents Sea |
geographic_facet |
Arctic Barents Sea |
genre |
Arctic Barents Sea Phytoplankton Sea ice |
genre_facet |
Arctic Barents Sea Phytoplankton Sea ice |
op_source |
Elementa: Science of the Anthropocene, Vol 5 (2017) |
op_relation |
https://www.elementascience.org/articles/235 https://doaj.org/toc/2325-1026 2325-1026 doi:10.1525/elementa.235 https://doaj.org/article/a082ce69f6094859a050f7ab817df9d0 |
op_doi |
https://doi.org/10.1525/elementa.235 |
container_title |
Elem Sci Anth |
container_volume |
5 |
container_issue |
0 |
container_start_page |
43 |
_version_ |
1766317346780086272 |