Sources and input mechanisms of hafnium and neodymium in surface waters of the Atlantic sector of the Southern Ocean
Radiogenic isotopes of hafnium (Hf) and neodymium (Nd) are powerful tracers for water mass transport and trace metal cycling in the present and past oceans. However, due to the scarcity of available data the processes governing their distribution are not well understood. Here we present the first co...
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ftsouthampton:oai:eprints.soton.ac.uk:368786 2023-07-30T03:58:39+02:00 Sources and input mechanisms of hafnium and neodymium in surface waters of the Atlantic sector of the Southern Ocean Stichel, Torben Frank, Martin Rickli, Jörg Hathorne, Ed C. Haley, Brian A. Jeandel, Catherine Pradoux, Catherine 2012-10-01 https://eprints.soton.ac.uk/368786/ English eng Stichel, Torben, Frank, Martin, Rickli, Jörg, Hathorne, Ed C., Haley, Brian A., Jeandel, Catherine and Pradoux, Catherine (2012) Sources and input mechanisms of hafnium and neodymium in surface waters of the Atlantic sector of the Southern Ocean. Geochimica et Cosmochimica Acta, 94, 22-37. (doi:10.1016/j.gca.2012.07.005 <http://dx.doi.org/10.1016/j.gca.2012.07.005>). Article PeerReviewed 2012 ftsouthampton https://doi.org/10.1016/j.gca.2012.07.005 2023-07-09T21:55:01Z Radiogenic isotopes of hafnium (Hf) and neodymium (Nd) are powerful tracers for water mass transport and trace metal cycling in the present and past oceans. However, due to the scarcity of available data the processes governing their distribution are not well understood. Here we present the first combined dissolved Hf and Nd isotope and concentration data from surface waters of the Atlantic sector of the Southern Ocean. The samples were collected along the Zero Meridian, in the Weddell Sea and in the Drake Passage during RV Polarstern expeditions ANTXXIV/3 and ANTXXIII/3 in the frame of the International Polar Year (IPY) and the GEOTRACES program. The general distribution of Hf and Nd concentrations in the region is similar. However, at the northernmost station located 200 km southwest of Cape Town a pronounced increase of the Nd concentration is observed, whereas the Hf concentration is minimal, suggesting much less Hf than Nd is released by the weathering of the South African Archean cratonic rocks. From the southern part of the Subtropical Front (STF) to the Polar Front (PF) Hf and Nd show the lowest concentrations (<0.12 pmol/kg and 10 pmol/kg, respectively), most probably due to the low terrigenous flux in this area and efficient scavenging of Hf and Nd by biogenic opal. In the vicinity of landmasses the dissolved Hf and Nd isotope compositions are clearly labeled by terrigenous inputs. Near South Africa Nd isotope values as low as ?Nd = ?18.9 indicate unradiogenic inputs supplied via the Agulhas Current. Further south the isotopic data show significant increases to ?Hf = 6.1 and ?Nd = ?4.0 documenting exchange of seawater Nd and Hf with the Antarctic Peninsula. In the open Southern Ocean the Nd isotope compositions are relatively homogeneous (?Nd ? ?8 to ?8.5) towards the STF, within the Antarctic Circumpolar Current, in the Weddell Gyre, and the Drake Passage. The Hf isotope compositions in the entire study area only show a small range between ?Hf = + 6.1 and +2.8 support Hf to be more readily released ... Article in Journal/Newspaper Antarc* Antarctic Antarctic Peninsula Drake Passage International Polar Year IPY Southern Ocean Weddell Sea University of Southampton: e-Prints Soton Antarctic Antarctic Peninsula Drake Passage Southern Ocean The Antarctic Weddell Weddell Sea Geochimica et Cosmochimica Acta 94 22 37 |
institution |
Open Polar |
collection |
University of Southampton: e-Prints Soton |
op_collection_id |
ftsouthampton |
language |
English |
description |
Radiogenic isotopes of hafnium (Hf) and neodymium (Nd) are powerful tracers for water mass transport and trace metal cycling in the present and past oceans. However, due to the scarcity of available data the processes governing their distribution are not well understood. Here we present the first combined dissolved Hf and Nd isotope and concentration data from surface waters of the Atlantic sector of the Southern Ocean. The samples were collected along the Zero Meridian, in the Weddell Sea and in the Drake Passage during RV Polarstern expeditions ANTXXIV/3 and ANTXXIII/3 in the frame of the International Polar Year (IPY) and the GEOTRACES program. The general distribution of Hf and Nd concentrations in the region is similar. However, at the northernmost station located 200 km southwest of Cape Town a pronounced increase of the Nd concentration is observed, whereas the Hf concentration is minimal, suggesting much less Hf than Nd is released by the weathering of the South African Archean cratonic rocks. From the southern part of the Subtropical Front (STF) to the Polar Front (PF) Hf and Nd show the lowest concentrations (<0.12 pmol/kg and 10 pmol/kg, respectively), most probably due to the low terrigenous flux in this area and efficient scavenging of Hf and Nd by biogenic opal. In the vicinity of landmasses the dissolved Hf and Nd isotope compositions are clearly labeled by terrigenous inputs. Near South Africa Nd isotope values as low as ?Nd = ?18.9 indicate unradiogenic inputs supplied via the Agulhas Current. Further south the isotopic data show significant increases to ?Hf = 6.1 and ?Nd = ?4.0 documenting exchange of seawater Nd and Hf with the Antarctic Peninsula. In the open Southern Ocean the Nd isotope compositions are relatively homogeneous (?Nd ? ?8 to ?8.5) towards the STF, within the Antarctic Circumpolar Current, in the Weddell Gyre, and the Drake Passage. The Hf isotope compositions in the entire study area only show a small range between ?Hf = + 6.1 and +2.8 support Hf to be more readily released ... |
format |
Article in Journal/Newspaper |
author |
Stichel, Torben Frank, Martin Rickli, Jörg Hathorne, Ed C. Haley, Brian A. Jeandel, Catherine Pradoux, Catherine |
spellingShingle |
Stichel, Torben Frank, Martin Rickli, Jörg Hathorne, Ed C. Haley, Brian A. Jeandel, Catherine Pradoux, Catherine Sources and input mechanisms of hafnium and neodymium in surface waters of the Atlantic sector of the Southern Ocean |
author_facet |
Stichel, Torben Frank, Martin Rickli, Jörg Hathorne, Ed C. Haley, Brian A. Jeandel, Catherine Pradoux, Catherine |
author_sort |
Stichel, Torben |
title |
Sources and input mechanisms of hafnium and neodymium in surface waters of the Atlantic sector of the Southern Ocean |
title_short |
Sources and input mechanisms of hafnium and neodymium in surface waters of the Atlantic sector of the Southern Ocean |
title_full |
Sources and input mechanisms of hafnium and neodymium in surface waters of the Atlantic sector of the Southern Ocean |
title_fullStr |
Sources and input mechanisms of hafnium and neodymium in surface waters of the Atlantic sector of the Southern Ocean |
title_full_unstemmed |
Sources and input mechanisms of hafnium and neodymium in surface waters of the Atlantic sector of the Southern Ocean |
title_sort |
sources and input mechanisms of hafnium and neodymium in surface waters of the atlantic sector of the southern ocean |
publishDate |
2012 |
url |
https://eprints.soton.ac.uk/368786/ |
geographic |
Antarctic Antarctic Peninsula Drake Passage Southern Ocean The Antarctic Weddell Weddell Sea |
geographic_facet |
Antarctic Antarctic Peninsula Drake Passage Southern Ocean The Antarctic Weddell Weddell Sea |
genre |
Antarc* Antarctic Antarctic Peninsula Drake Passage International Polar Year IPY Southern Ocean Weddell Sea |
genre_facet |
Antarc* Antarctic Antarctic Peninsula Drake Passage International Polar Year IPY Southern Ocean Weddell Sea |
op_relation |
Stichel, Torben, Frank, Martin, Rickli, Jörg, Hathorne, Ed C., Haley, Brian A., Jeandel, Catherine and Pradoux, Catherine (2012) Sources and input mechanisms of hafnium and neodymium in surface waters of the Atlantic sector of the Southern Ocean. Geochimica et Cosmochimica Acta, 94, 22-37. (doi:10.1016/j.gca.2012.07.005 <http://dx.doi.org/10.1016/j.gca.2012.07.005>). |
op_doi |
https://doi.org/10.1016/j.gca.2012.07.005 |
container_title |
Geochimica et Cosmochimica Acta |
container_volume |
94 |
container_start_page |
22 |
op_container_end_page |
37 |
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1772821408456376320 |