Radium-228-derived ocean mixing and trace element inputs in the South Atlantic
Trace elements (TEs) play important roles as micronutrients in modulating marine productivity in the global ocean. The South Atlantic around 40∘ S is a prominent region of high productivity and a transition zone between the nitrate-depleted subtropical gyre and the iron-limited Southern Ocean. Howev...
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2021
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Online Access: | https://epic.awi.de/id/eprint/53838/ https://epic.awi.de/id/eprint/53838/1/bg-18-1645-2021_228Ra_South_Atlantic.pdf https://doi.org/10.5194/bg-18-1645-2021 https://hdl.handle.net/10013/epic.9dd30ca7-d395-4584-970c-2505f8eb33bf |
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ftawi:oai:epic.awi.de:53838 2024-09-15T18:37:25+00:00 Radium-228-derived ocean mixing and trace element inputs in the South Atlantic Hsieh, Yu-Te Geibert, Walter Woodward, E. Malcolm S. Wyatt, Neil J. Lohan, Maeve C. Achterberg, Eric P. Henderson, Gideon M. 2021 application/pdf https://epic.awi.de/id/eprint/53838/ https://epic.awi.de/id/eprint/53838/1/bg-18-1645-2021_228Ra_South_Atlantic.pdf https://doi.org/10.5194/bg-18-1645-2021 https://hdl.handle.net/10013/epic.9dd30ca7-d395-4584-970c-2505f8eb33bf unknown https://epic.awi.de/id/eprint/53838/1/bg-18-1645-2021_228Ra_South_Atlantic.pdf Hsieh, Y. T. , Geibert, W. orcid:0000-0001-8646-2334 , Woodward, E. M. S. , Wyatt, N. J. , Lohan, M. C. , Achterberg, E. P. and Henderson, G. M. (2021) Radium-228-derived ocean mixing and trace element inputs in the South Atlantic , Biogeosciences, 18 (5), pp. 1645-1671 . doi:10.5194/bg-18-1645-2021 <https://doi.org/10.5194/bg-18-1645-2021> , hdl:10013/epic.9dd30ca7-d395-4584-970c-2505f8eb33bf EPIC3Biogeosciences, 18(5), pp. 1645-1671, ISSN: 1726-4189 Article isiRev 2021 ftawi https://doi.org/10.5194/bg-18-1645-2021 2024-06-24T04:26:11Z Trace elements (TEs) play important roles as micronutrients in modulating marine productivity in the global ocean. The South Atlantic around 40∘ S is a prominent region of high productivity and a transition zone between the nitrate-depleted subtropical gyre and the iron-limited Southern Ocean. However, the sources and fluxes of trace elements to this region remain unclear. In this study, the distribution of the naturally occurring radioisotope 228Ra in the water column of the South Atlantic (Cape Basin and Argentine Basin) has been investigated along a 40∘ S zonal transect to estimate ocean mixing and trace element supply to the surface ocean. Ra-228 profiles have been used to determine the horizontal and vertical mixing rates in the near-surface open ocean. In the Argentine Basin, horizontal mixing from the continental shelf to the open ocean shows an eddy diffusion of Kx=1.8±1.4 (106 cm2 s−1) and an integrated advection velocity w=0.6±0.3 cm s−1. In the Cape Basin, horizontal mixing is Kx=2.7±0.8 (107 cm2 s−1) and vertical mixing Kz = 1.0–1.7 cm2 s−1 in the upper 600 m layer. Three different approaches (228Ra diffusion, 228Ra advection, and 228Ra/TE ratio) have been applied to estimate the dissolved trace element fluxes from the shelf to the open ocean. These approaches bracket the possible range of off-shelf fluxes from the Argentine Basin margin to be 4–21 (×103) nmol Co m−2 d−1, 8–19 (×104) nmol Fe m−2 d−1 and 2.7–6.3 (×104) nmol Zn m−2 d−1. Off-shelf fluxes from the Cape Basin margin are 4.3–6.2 (×103) nmol Co m−2 d−1, 1.2–3.1 (×104) nmol Fe m−2 d−1, and 0.9–1.2 (×104) nmol Zn m−2 d−1. On average, at 40∘ S in the Atlantic, vertical mixing supplies 0.1–1.2 nmol Co m−2 d−1, 6–9 nmol Fe m−2 d−1, and 5–7 nmol Zn m−2 d−1 to the euphotic zone. Compared with atmospheric dust and continental shelf inputs, vertical mixing is a more important source for supplying dissolved trace elements to the surface 40∘ S Atlantic transect. It is insufficient, however, to provide the trace elements removed by biological uptake, ... Article in Journal/Newspaper Southern Ocean Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) Biogeosciences 18 5 1645 1671 |
institution |
Open Polar |
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Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) |
op_collection_id |
ftawi |
language |
unknown |
description |
Trace elements (TEs) play important roles as micronutrients in modulating marine productivity in the global ocean. The South Atlantic around 40∘ S is a prominent region of high productivity and a transition zone between the nitrate-depleted subtropical gyre and the iron-limited Southern Ocean. However, the sources and fluxes of trace elements to this region remain unclear. In this study, the distribution of the naturally occurring radioisotope 228Ra in the water column of the South Atlantic (Cape Basin and Argentine Basin) has been investigated along a 40∘ S zonal transect to estimate ocean mixing and trace element supply to the surface ocean. Ra-228 profiles have been used to determine the horizontal and vertical mixing rates in the near-surface open ocean. In the Argentine Basin, horizontal mixing from the continental shelf to the open ocean shows an eddy diffusion of Kx=1.8±1.4 (106 cm2 s−1) and an integrated advection velocity w=0.6±0.3 cm s−1. In the Cape Basin, horizontal mixing is Kx=2.7±0.8 (107 cm2 s−1) and vertical mixing Kz = 1.0–1.7 cm2 s−1 in the upper 600 m layer. Three different approaches (228Ra diffusion, 228Ra advection, and 228Ra/TE ratio) have been applied to estimate the dissolved trace element fluxes from the shelf to the open ocean. These approaches bracket the possible range of off-shelf fluxes from the Argentine Basin margin to be 4–21 (×103) nmol Co m−2 d−1, 8–19 (×104) nmol Fe m−2 d−1 and 2.7–6.3 (×104) nmol Zn m−2 d−1. Off-shelf fluxes from the Cape Basin margin are 4.3–6.2 (×103) nmol Co m−2 d−1, 1.2–3.1 (×104) nmol Fe m−2 d−1, and 0.9–1.2 (×104) nmol Zn m−2 d−1. On average, at 40∘ S in the Atlantic, vertical mixing supplies 0.1–1.2 nmol Co m−2 d−1, 6–9 nmol Fe m−2 d−1, and 5–7 nmol Zn m−2 d−1 to the euphotic zone. Compared with atmospheric dust and continental shelf inputs, vertical mixing is a more important source for supplying dissolved trace elements to the surface 40∘ S Atlantic transect. It is insufficient, however, to provide the trace elements removed by biological uptake, ... |
format |
Article in Journal/Newspaper |
author |
Hsieh, Yu-Te Geibert, Walter Woodward, E. Malcolm S. Wyatt, Neil J. Lohan, Maeve C. Achterberg, Eric P. Henderson, Gideon M. |
spellingShingle |
Hsieh, Yu-Te Geibert, Walter Woodward, E. Malcolm S. Wyatt, Neil J. Lohan, Maeve C. Achterberg, Eric P. Henderson, Gideon M. Radium-228-derived ocean mixing and trace element inputs in the South Atlantic |
author_facet |
Hsieh, Yu-Te Geibert, Walter Woodward, E. Malcolm S. Wyatt, Neil J. Lohan, Maeve C. Achterberg, Eric P. Henderson, Gideon M. |
author_sort |
Hsieh, Yu-Te |
title |
Radium-228-derived ocean mixing and trace element inputs in the South Atlantic |
title_short |
Radium-228-derived ocean mixing and trace element inputs in the South Atlantic |
title_full |
Radium-228-derived ocean mixing and trace element inputs in the South Atlantic |
title_fullStr |
Radium-228-derived ocean mixing and trace element inputs in the South Atlantic |
title_full_unstemmed |
Radium-228-derived ocean mixing and trace element inputs in the South Atlantic |
title_sort |
radium-228-derived ocean mixing and trace element inputs in the south atlantic |
publishDate |
2021 |
url |
https://epic.awi.de/id/eprint/53838/ https://epic.awi.de/id/eprint/53838/1/bg-18-1645-2021_228Ra_South_Atlantic.pdf https://doi.org/10.5194/bg-18-1645-2021 https://hdl.handle.net/10013/epic.9dd30ca7-d395-4584-970c-2505f8eb33bf |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
EPIC3Biogeosciences, 18(5), pp. 1645-1671, ISSN: 1726-4189 |
op_relation |
https://epic.awi.de/id/eprint/53838/1/bg-18-1645-2021_228Ra_South_Atlantic.pdf Hsieh, Y. T. , Geibert, W. orcid:0000-0001-8646-2334 , Woodward, E. M. S. , Wyatt, N. J. , Lohan, M. C. , Achterberg, E. P. and Henderson, G. M. (2021) Radium-228-derived ocean mixing and trace element inputs in the South Atlantic , Biogeosciences, 18 (5), pp. 1645-1671 . doi:10.5194/bg-18-1645-2021 <https://doi.org/10.5194/bg-18-1645-2021> , hdl:10013/epic.9dd30ca7-d395-4584-970c-2505f8eb33bf |
op_doi |
https://doi.org/10.5194/bg-18-1645-2021 |
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Biogeosciences |
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18 |
container_issue |
5 |
container_start_page |
1645 |
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1671 |
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1810481792354877440 |