Radium-228-derived ocean mixing and trace element inputs in the South Atlantic
Trace elements 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, th...
Published in: | Biogeosciences |
---|---|
Main Authors: | , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Copernicus Publications (EGU)
2021
|
Subjects: | |
Online Access: | https://oceanrep.geomar.de/id/eprint/51385/ https://oceanrep.geomar.de/id/eprint/51385/7/bg-18-1645-2021.pdf https://doi.org/10.5194/bg-18-1645-2021 |
id |
ftoceanrep:oai:oceanrep.geomar.de:51385 |
---|---|
record_format |
openpolar |
spelling |
ftoceanrep:oai:oceanrep.geomar.de:51385 2024-02-11T10:08:54+01:00 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. 2021-03-09 text https://oceanrep.geomar.de/id/eprint/51385/ https://oceanrep.geomar.de/id/eprint/51385/7/bg-18-1645-2021.pdf https://doi.org/10.5194/bg-18-1645-2021 en eng Copernicus Publications (EGU) https://oceanrep.geomar.de/id/eprint/51385/7/bg-18-1645-2021.pdf Hsieh, Y. T., Geibert, W., 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. Open Access Biogeosciences (BG), 18 (5). pp. 1645-1671. DOI 10.5194/bg-18-1645-2021 <https://doi.org/10.5194/bg-18-1645-2021>. doi:10.5194/bg-18-1645-2021 cc_by_4.0 info:eu-repo/semantics/openAccess Article PeerReviewed 2021 ftoceanrep https://doi.org/10.5194/bg-18-1645-2021 2024-01-15T00:22:57Z Trace elements 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 = 1.7 ± 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 = 1.0–1.5 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 shelf to open ocean. These approaches bracket the possible range of off-shelf fluxes from the Argentine margin to be: 3.8–22 (× 103) nmol Co m−2 d−1, 7.9–20 (× 104) nmol Fe m−2 d−1 and 2.7–6.5 (× 104) nmol Zn m−2 d−1. Off-shelf fluxes from the Cape 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 0.4–1.2 nmol Co m−2 d−1, 3.6–11 nmol Fe m−2 d−1, and 13–16 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. It is insufficient, however, to provide the trace elements removed by biological uptake. Other ... Article in Journal/Newspaper Southern Ocean OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) Southern Ocean Argentine Biogeosciences 18 5 1645 1671 |
institution |
Open Polar |
collection |
OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) |
op_collection_id |
ftoceanrep |
language |
English |
description |
Trace elements 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 = 1.7 ± 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 = 1.0–1.5 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 shelf to open ocean. These approaches bracket the possible range of off-shelf fluxes from the Argentine margin to be: 3.8–22 (× 103) nmol Co m−2 d−1, 7.9–20 (× 104) nmol Fe m−2 d−1 and 2.7–6.5 (× 104) nmol Zn m−2 d−1. Off-shelf fluxes from the Cape 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 0.4–1.2 nmol Co m−2 d−1, 3.6–11 nmol Fe m−2 d−1, and 13–16 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. It is insufficient, however, to provide the trace elements removed by biological uptake. Other ... |
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 |
publisher |
Copernicus Publications (EGU) |
publishDate |
2021 |
url |
https://oceanrep.geomar.de/id/eprint/51385/ https://oceanrep.geomar.de/id/eprint/51385/7/bg-18-1645-2021.pdf https://doi.org/10.5194/bg-18-1645-2021 |
geographic |
Southern Ocean Argentine |
geographic_facet |
Southern Ocean Argentine |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_relation |
https://oceanrep.geomar.de/id/eprint/51385/7/bg-18-1645-2021.pdf Hsieh, Y. T., Geibert, W., 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. Open Access Biogeosciences (BG), 18 (5). pp. 1645-1671. DOI 10.5194/bg-18-1645-2021 <https://doi.org/10.5194/bg-18-1645-2021>. doi:10.5194/bg-18-1645-2021 |
op_rights |
cc_by_4.0 info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/bg-18-1645-2021 |
container_title |
Biogeosciences |
container_volume |
18 |
container_issue |
5 |
container_start_page |
1645 |
op_container_end_page |
1671 |
_version_ |
1790608547378102272 |