Fe(II) stability in coastal seawater during experiments in Patagonia, Svalbard, and Gran Canaria
The speciation of dissolved iron (DFe) in the ocean is widely assumed to consist almost exclusively of Fe(III)-ligand complexes. Yet in most aqueous environments a poorly defined fraction of DFe also exists as Fe(II), the speciation of which is uncertain. Here we deploy flow injection analysis to me...
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Copernicus Publications
2020
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ftdoajarticles:oai:doaj.org/article:6a42d39fde6f4c12a9060a0df8d8f0af 2023-05-15T18:29:40+02:00 Fe(II) stability in coastal seawater during experiments in Patagonia, Svalbard, and Gran Canaria M. J. Hopwood C. Santana-González J. Gallego-Urrea N. Sanchez E. P. Achterberg M. V. Ardelan M. Gledhill M. González-Dávila L. Hoffmann Ø. Leiknes J. M. Santana-Casiano T. M. Tsagaraki D. Turner 2020-03-01T00:00:00Z https://doi.org/10.5194/bg-17-1327-2020 https://doaj.org/article/6a42d39fde6f4c12a9060a0df8d8f0af EN eng Copernicus Publications https://www.biogeosciences.net/17/1327/2020/bg-17-1327-2020.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-17-1327-2020 1726-4170 1726-4189 https://doaj.org/article/6a42d39fde6f4c12a9060a0df8d8f0af Biogeosciences, Vol 17, Pp 1327-1342 (2020) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2020 ftdoajarticles https://doi.org/10.5194/bg-17-1327-2020 2022-12-31T14:23:01Z The speciation of dissolved iron (DFe) in the ocean is widely assumed to consist almost exclusively of Fe(III)-ligand complexes. Yet in most aqueous environments a poorly defined fraction of DFe also exists as Fe(II), the speciation of which is uncertain. Here we deploy flow injection analysis to measure in situ Fe(II) concentrations during a series of mesocosm/microcosm/multistressor experiments in coastal environments in addition to the decay rate of this Fe(II) when moved into the dark. During five mesocosm/microcosm/multistressor experiments in Svalbard and Patagonia, where dissolved (0.2 µ m) Fe and Fe(II) were quantified simultaneously, Fe(II) constituted 24 %–65 % of DFe, suggesting that Fe(II) was a large fraction of the DFe pool. When this Fe(II) was allowed to decay in the dark, the vast majority of measured oxidation rate constants were less than calculated constants derived from ambient temperature, salinity, pH, and dissolved O 2 . The oxidation rates of Fe(II) spikes added to Atlantic seawater more closely matched calculated rate constants. The difference between observed and theoretical decay rates in Svalbard and Patagonia was most pronounced at Fe(II) concentrations <2 nM, suggesting that the effect may have arisen from organic Fe(II) ligands. This apparent enhancement of Fe(II) stability under post-bloom conditions and the existence of such a high fraction of DFe as Fe(II) challenge the assumption that DFe speciation in coastal seawater is dominated by ligand bound-Fe(III) species. Article in Journal/Newspaper Svalbard Directory of Open Access Journals: DOAJ Articles Svalbard Patagonia Biogeosciences 17 5 1327 1342 |
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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 M. J. Hopwood C. Santana-González J. Gallego-Urrea N. Sanchez E. P. Achterberg M. V. Ardelan M. Gledhill M. González-Dávila L. Hoffmann Ø. Leiknes J. M. Santana-Casiano T. M. Tsagaraki D. Turner Fe(II) stability in coastal seawater during experiments in Patagonia, Svalbard, and Gran Canaria |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
The speciation of dissolved iron (DFe) in the ocean is widely assumed to consist almost exclusively of Fe(III)-ligand complexes. Yet in most aqueous environments a poorly defined fraction of DFe also exists as Fe(II), the speciation of which is uncertain. Here we deploy flow injection analysis to measure in situ Fe(II) concentrations during a series of mesocosm/microcosm/multistressor experiments in coastal environments in addition to the decay rate of this Fe(II) when moved into the dark. During five mesocosm/microcosm/multistressor experiments in Svalbard and Patagonia, where dissolved (0.2 µ m) Fe and Fe(II) were quantified simultaneously, Fe(II) constituted 24 %–65 % of DFe, suggesting that Fe(II) was a large fraction of the DFe pool. When this Fe(II) was allowed to decay in the dark, the vast majority of measured oxidation rate constants were less than calculated constants derived from ambient temperature, salinity, pH, and dissolved O 2 . The oxidation rates of Fe(II) spikes added to Atlantic seawater more closely matched calculated rate constants. The difference between observed and theoretical decay rates in Svalbard and Patagonia was most pronounced at Fe(II) concentrations <2 nM, suggesting that the effect may have arisen from organic Fe(II) ligands. This apparent enhancement of Fe(II) stability under post-bloom conditions and the existence of such a high fraction of DFe as Fe(II) challenge the assumption that DFe speciation in coastal seawater is dominated by ligand bound-Fe(III) species. |
format |
Article in Journal/Newspaper |
author |
M. J. Hopwood C. Santana-González J. Gallego-Urrea N. Sanchez E. P. Achterberg M. V. Ardelan M. Gledhill M. González-Dávila L. Hoffmann Ø. Leiknes J. M. Santana-Casiano T. M. Tsagaraki D. Turner |
author_facet |
M. J. Hopwood C. Santana-González J. Gallego-Urrea N. Sanchez E. P. Achterberg M. V. Ardelan M. Gledhill M. González-Dávila L. Hoffmann Ø. Leiknes J. M. Santana-Casiano T. M. Tsagaraki D. Turner |
author_sort |
M. J. Hopwood |
title |
Fe(II) stability in coastal seawater during experiments in Patagonia, Svalbard, and Gran Canaria |
title_short |
Fe(II) stability in coastal seawater during experiments in Patagonia, Svalbard, and Gran Canaria |
title_full |
Fe(II) stability in coastal seawater during experiments in Patagonia, Svalbard, and Gran Canaria |
title_fullStr |
Fe(II) stability in coastal seawater during experiments in Patagonia, Svalbard, and Gran Canaria |
title_full_unstemmed |
Fe(II) stability in coastal seawater during experiments in Patagonia, Svalbard, and Gran Canaria |
title_sort |
fe(ii) stability in coastal seawater during experiments in patagonia, svalbard, and gran canaria |
publisher |
Copernicus Publications |
publishDate |
2020 |
url |
https://doi.org/10.5194/bg-17-1327-2020 https://doaj.org/article/6a42d39fde6f4c12a9060a0df8d8f0af |
geographic |
Svalbard Patagonia |
geographic_facet |
Svalbard Patagonia |
genre |
Svalbard |
genre_facet |
Svalbard |
op_source |
Biogeosciences, Vol 17, Pp 1327-1342 (2020) |
op_relation |
https://www.biogeosciences.net/17/1327/2020/bg-17-1327-2020.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-17-1327-2020 1726-4170 1726-4189 https://doaj.org/article/6a42d39fde6f4c12a9060a0df8d8f0af |
op_doi |
https://doi.org/10.5194/bg-17-1327-2020 |
container_title |
Biogeosciences |
container_volume |
17 |
container_issue |
5 |
container_start_page |
1327 |
op_container_end_page |
1342 |
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1766212932562059264 |