Stable silicon isotopes uncover a mineralogical control on the benthic silicon cycle in the Arctic Barents Sea
Biogeochemical cycling of silicon (Si) in the Barents Sea is under considerable pressure from physical and chemical changes, including dramatic warming and sea ice retreat, together with a decline in dissolved silicic acid (DSi) concentrations of Atlantic inflow waters since 1990. Associated changes...
Published in: | Geochimica et Cosmochimica Acta |
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Main Authors: | , , , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
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Elsevier
2022
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Online Access: | https://lup.lub.lu.se/record/6f8a482a-dbcd-4dae-b9c3-14554ab5927f https://doi.org/10.1016/j.gca.2022.05.005 |
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ftulundlup:oai:lup.lub.lu.se:6f8a482a-dbcd-4dae-b9c3-14554ab5927f 2023-05-15T15:17:26+02:00 Stable silicon isotopes uncover a mineralogical control on the benthic silicon cycle in the Arctic Barents Sea Ward, James P.J. Hendry, Katharine R. Arndt, Sandra Faust, Johan C. Freitas, Felipe S. Henley, Sian F. Krause, Jeffrey W. März, Christian Ng, Hong Chin Pickering, Rebecca A. Tessin, Allyson C. 2022-07-15 https://lup.lub.lu.se/record/6f8a482a-dbcd-4dae-b9c3-14554ab5927f https://doi.org/10.1016/j.gca.2022.05.005 eng eng Elsevier https://lup.lub.lu.se/record/6f8a482a-dbcd-4dae-b9c3-14554ab5927f http://dx.doi.org/10.1016/j.gca.2022.05.005 scopus:85131807091 Geochimica et Cosmochimica Acta; 329, pp 206-230 (2022) ISSN: 0016-7037 Geochemistry Benthic flux Pore water Reactive pools Sediment nutrient cycling Silicon isotopes contributiontojournal/article info:eu-repo/semantics/article text 2022 ftulundlup https://doi.org/10.1016/j.gca.2022.05.005 2023-02-01T23:39:29Z Biogeochemical cycling of silicon (Si) in the Barents Sea is under considerable pressure from physical and chemical changes, including dramatic warming and sea ice retreat, together with a decline in dissolved silicic acid (DSi) concentrations of Atlantic inflow waters since 1990. Associated changes in the community composition of phytoplankton blooms will alter the material comprising the depositional flux, which will subsequently influence recycling processes at and within the seafloor. In this study we assess the predominant controls on the early diagenetic cycling of Si, a key nutrient in marine ecosystems, by combining stable isotopic analysis (δ30Si) of pore water DSi and of operationally defined reactive pools of the solid phase. We show that low biogenic silica (BSi) contents (0.26–0.52 wt% or 92–185 μmol g dry wt−1) drive correspondingly low asymptotic concentrations of pore water DSi of ∼100 μM, relative to biosiliceous sediments (>20 wt% BSi) wherein DSi can reach ∼900 μM. While Barents Sea surface sediments appear almost devoid of BSi, we present evidence for the rapid recycling of bloom derived BSi that generates striking transient peaks in sediment pore water [DSi] of up to 300 μM, which is a feature that is subject to future shifts in phytoplankton community compositions. Using a simple isotopic mass balance calculation we show that at two of three stations the pore water DSi pool at 0.5 cm below the seafloor (+0.96 to +1.36 ‰) is sourced from the mixing of core top waters (+1.46 to +1.69 ‰) with the dissolution of BSi (+0.82 to +1.50 ‰), supplemented with a lithogenic Si source (LSi) (−0.89 ±0.16‰). Further, our sediment pore water δ30Si profiles uncover a coupling of the Si cycle with the redox cycling of metal oxides associated with isotopically light Si (−2.88 ±0.17‰). We suggest that a high LSi:BSi ratio and apparent metal oxide influence could lead to a degree of stability in the annual background benthic flux of DSi, despite current pressures on pelagic phytoplankton communities. Coupled ... Article in Journal/Newspaper Arctic Barents Sea Phytoplankton Sea ice Lund University Publications (LUP) Arctic Barents Sea Geochimica et Cosmochimica Acta 329 206 230 |
institution |
Open Polar |
collection |
Lund University Publications (LUP) |
op_collection_id |
ftulundlup |
language |
English |
topic |
Geochemistry Benthic flux Pore water Reactive pools Sediment nutrient cycling Silicon isotopes |
spellingShingle |
Geochemistry Benthic flux Pore water Reactive pools Sediment nutrient cycling Silicon isotopes Ward, James P.J. Hendry, Katharine R. Arndt, Sandra Faust, Johan C. Freitas, Felipe S. Henley, Sian F. Krause, Jeffrey W. März, Christian Ng, Hong Chin Pickering, Rebecca A. Tessin, Allyson C. Stable silicon isotopes uncover a mineralogical control on the benthic silicon cycle in the Arctic Barents Sea |
topic_facet |
Geochemistry Benthic flux Pore water Reactive pools Sediment nutrient cycling Silicon isotopes |
description |
Biogeochemical cycling of silicon (Si) in the Barents Sea is under considerable pressure from physical and chemical changes, including dramatic warming and sea ice retreat, together with a decline in dissolved silicic acid (DSi) concentrations of Atlantic inflow waters since 1990. Associated changes in the community composition of phytoplankton blooms will alter the material comprising the depositional flux, which will subsequently influence recycling processes at and within the seafloor. In this study we assess the predominant controls on the early diagenetic cycling of Si, a key nutrient in marine ecosystems, by combining stable isotopic analysis (δ30Si) of pore water DSi and of operationally defined reactive pools of the solid phase. We show that low biogenic silica (BSi) contents (0.26–0.52 wt% or 92–185 μmol g dry wt−1) drive correspondingly low asymptotic concentrations of pore water DSi of ∼100 μM, relative to biosiliceous sediments (>20 wt% BSi) wherein DSi can reach ∼900 μM. While Barents Sea surface sediments appear almost devoid of BSi, we present evidence for the rapid recycling of bloom derived BSi that generates striking transient peaks in sediment pore water [DSi] of up to 300 μM, which is a feature that is subject to future shifts in phytoplankton community compositions. Using a simple isotopic mass balance calculation we show that at two of three stations the pore water DSi pool at 0.5 cm below the seafloor (+0.96 to +1.36 ‰) is sourced from the mixing of core top waters (+1.46 to +1.69 ‰) with the dissolution of BSi (+0.82 to +1.50 ‰), supplemented with a lithogenic Si source (LSi) (−0.89 ±0.16‰). Further, our sediment pore water δ30Si profiles uncover a coupling of the Si cycle with the redox cycling of metal oxides associated with isotopically light Si (−2.88 ±0.17‰). We suggest that a high LSi:BSi ratio and apparent metal oxide influence could lead to a degree of stability in the annual background benthic flux of DSi, despite current pressures on pelagic phytoplankton communities. Coupled ... |
format |
Article in Journal/Newspaper |
author |
Ward, James P.J. Hendry, Katharine R. Arndt, Sandra Faust, Johan C. Freitas, Felipe S. Henley, Sian F. Krause, Jeffrey W. März, Christian Ng, Hong Chin Pickering, Rebecca A. Tessin, Allyson C. |
author_facet |
Ward, James P.J. Hendry, Katharine R. Arndt, Sandra Faust, Johan C. Freitas, Felipe S. Henley, Sian F. Krause, Jeffrey W. März, Christian Ng, Hong Chin Pickering, Rebecca A. Tessin, Allyson C. |
author_sort |
Ward, James P.J. |
title |
Stable silicon isotopes uncover a mineralogical control on the benthic silicon cycle in the Arctic Barents Sea |
title_short |
Stable silicon isotopes uncover a mineralogical control on the benthic silicon cycle in the Arctic Barents Sea |
title_full |
Stable silicon isotopes uncover a mineralogical control on the benthic silicon cycle in the Arctic Barents Sea |
title_fullStr |
Stable silicon isotopes uncover a mineralogical control on the benthic silicon cycle in the Arctic Barents Sea |
title_full_unstemmed |
Stable silicon isotopes uncover a mineralogical control on the benthic silicon cycle in the Arctic Barents Sea |
title_sort |
stable silicon isotopes uncover a mineralogical control on the benthic silicon cycle in the arctic barents sea |
publisher |
Elsevier |
publishDate |
2022 |
url |
https://lup.lub.lu.se/record/6f8a482a-dbcd-4dae-b9c3-14554ab5927f https://doi.org/10.1016/j.gca.2022.05.005 |
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 |
Geochimica et Cosmochimica Acta; 329, pp 206-230 (2022) ISSN: 0016-7037 |
op_relation |
https://lup.lub.lu.se/record/6f8a482a-dbcd-4dae-b9c3-14554ab5927f http://dx.doi.org/10.1016/j.gca.2022.05.005 scopus:85131807091 |
op_doi |
https://doi.org/10.1016/j.gca.2022.05.005 |
container_title |
Geochimica et Cosmochimica Acta |
container_volume |
329 |
container_start_page |
206 |
op_container_end_page |
230 |
_version_ |
1766347678528045056 |