Chromium biogeochemistry and stable isotope distribution in the Southern Ocean
Despite the potential of stable chromium (Cr) isotope compositions as a proxy for past changes in oceanic redox condi- tions, a detailed understanding of the processes that govern their spatial distribution in the modern ocean is still lacking. Here, we report seawater Cr isotope compositions and co...
Published in: | Geochimica et Cosmochimica Acta |
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ftunivbern:oai:boris.unibe.ch:132629 2023-08-20T04:00:43+02:00 Chromium biogeochemistry and stable isotope distribution in the Southern Ocean Rickli, Jörg Janssen, David J. Hassler, Christel Ellwood, Michael Jaccard, Samuel L. 2019-07-26 application/pdf https://boris.unibe.ch/132629/1/Rickli%20et%20al.,%2019.pdf https://boris.unibe.ch/132629/ eng eng Elsevier Science https://boris.unibe.ch/132629/ info:eu-repo/semantics/openAccess Rickli, Jörg; Janssen, David J.; Hassler, Christel; Ellwood, Michael; Jaccard, Samuel L. (2019). Chromium biogeochemistry and stable isotope distribution in the Southern Ocean. Geochimica et cosmochimica acta, 262, pp. 188-206. Elsevier Science 10.1016/j.gca.2019.07.033 <http://dx.doi.org/10.1016/j.gca.2019.07.033> 550 Earth sciences & geology info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion PeerReviewed 2019 ftunivbern https://doi.org/10.1016/j.gca.2019.07.033 2023-07-31T21:53:26Z Despite the potential of stable chromium (Cr) isotope compositions as a proxy for past changes in oceanic redox condi- tions, a detailed understanding of the processes that govern their spatial distribution in the modern ocean is still lacking. Here, we report seawater Cr isotope compositions and concentrations from the uppermost 1000 m of the water column in the South- ern Ocean. The survey includes a cross-frontal transect from Tasmania to Antarctica, sites near the Antarctic ice-edge and in the vicinity of the Balleny Islands, as well as sites in the Drake Passage. Although a coastal influence is clearly visible in the silicon-nitrate relationship at the stations neighbouring the Balleny Islands, close to the Mertz Glacier and adjacent to the western Antarctic Peninsula, seawater d53Cr and Cr concentrations remain largely unaffected. As for the coastal sites, Cr depletion and isotopic shifts are also virtually absent in Antarctic and Subantarctic surface waters of the open ocean. Biological uptake of Cr and/or scavenging of Cr onto sinking particles are apparently not strong enough to induce water column variability. Contrasting with the small variations in d53Cr and Cr concentrations at each site, there are, however, systematic meridional changes. The seawater samples show an increase in Cr concentrations and a parallel decrease in d53Cr southwards from the Subantarctic across the Polar Frontal into the Antarctic Zone. Chromium concentrations and d53Cr are, however, uniform at all stations south of the Polar Front. The spa- tial pattern is consistent with the mixing of Southern Ocean sourced Cr with an isotopically heavier Cr pool from northward of the studied area, as evidenced by strong correlations of Cr and d53Cr with salinity at the level of Subantarctic Mode Water and at shallower levels. The heavy d53Cr signature of the northerly Cr pool could either result from Cr cycling in the subtrop- ical gyre or originate in oxygen minimum zones. On a regional scale, d53Cr is strongly correlated with phosphate ... Article in Journal/Newspaper Antarc* Antarctic Antarctic Peninsula Antarctica Balleny Islands Drake Passage Mertz Glacier Southern Ocean BORIS (Bern Open Repository and Information System, University of Bern) Antarctic Antarctic Peninsula Balleny Islands Drake Passage Mertz Glacier ENVELOPE(144.500,144.500,-67.667,-67.667) Southern Ocean The Antarctic Geochimica et Cosmochimica Acta 262 188 206 |
institution |
Open Polar |
collection |
BORIS (Bern Open Repository and Information System, University of Bern) |
op_collection_id |
ftunivbern |
language |
English |
topic |
550 Earth sciences & geology |
spellingShingle |
550 Earth sciences & geology Rickli, Jörg Janssen, David J. Hassler, Christel Ellwood, Michael Jaccard, Samuel L. Chromium biogeochemistry and stable isotope distribution in the Southern Ocean |
topic_facet |
550 Earth sciences & geology |
description |
Despite the potential of stable chromium (Cr) isotope compositions as a proxy for past changes in oceanic redox condi- tions, a detailed understanding of the processes that govern their spatial distribution in the modern ocean is still lacking. Here, we report seawater Cr isotope compositions and concentrations from the uppermost 1000 m of the water column in the South- ern Ocean. The survey includes a cross-frontal transect from Tasmania to Antarctica, sites near the Antarctic ice-edge and in the vicinity of the Balleny Islands, as well as sites in the Drake Passage. Although a coastal influence is clearly visible in the silicon-nitrate relationship at the stations neighbouring the Balleny Islands, close to the Mertz Glacier and adjacent to the western Antarctic Peninsula, seawater d53Cr and Cr concentrations remain largely unaffected. As for the coastal sites, Cr depletion and isotopic shifts are also virtually absent in Antarctic and Subantarctic surface waters of the open ocean. Biological uptake of Cr and/or scavenging of Cr onto sinking particles are apparently not strong enough to induce water column variability. Contrasting with the small variations in d53Cr and Cr concentrations at each site, there are, however, systematic meridional changes. The seawater samples show an increase in Cr concentrations and a parallel decrease in d53Cr southwards from the Subantarctic across the Polar Frontal into the Antarctic Zone. Chromium concentrations and d53Cr are, however, uniform at all stations south of the Polar Front. The spa- tial pattern is consistent with the mixing of Southern Ocean sourced Cr with an isotopically heavier Cr pool from northward of the studied area, as evidenced by strong correlations of Cr and d53Cr with salinity at the level of Subantarctic Mode Water and at shallower levels. The heavy d53Cr signature of the northerly Cr pool could either result from Cr cycling in the subtrop- ical gyre or originate in oxygen minimum zones. On a regional scale, d53Cr is strongly correlated with phosphate ... |
format |
Article in Journal/Newspaper |
author |
Rickli, Jörg Janssen, David J. Hassler, Christel Ellwood, Michael Jaccard, Samuel L. |
author_facet |
Rickli, Jörg Janssen, David J. Hassler, Christel Ellwood, Michael Jaccard, Samuel L. |
author_sort |
Rickli, Jörg |
title |
Chromium biogeochemistry and stable isotope distribution in the Southern Ocean |
title_short |
Chromium biogeochemistry and stable isotope distribution in the Southern Ocean |
title_full |
Chromium biogeochemistry and stable isotope distribution in the Southern Ocean |
title_fullStr |
Chromium biogeochemistry and stable isotope distribution in the Southern Ocean |
title_full_unstemmed |
Chromium biogeochemistry and stable isotope distribution in the Southern Ocean |
title_sort |
chromium biogeochemistry and stable isotope distribution in the southern ocean |
publisher |
Elsevier Science |
publishDate |
2019 |
url |
https://boris.unibe.ch/132629/1/Rickli%20et%20al.,%2019.pdf https://boris.unibe.ch/132629/ |
long_lat |
ENVELOPE(144.500,144.500,-67.667,-67.667) |
geographic |
Antarctic Antarctic Peninsula Balleny Islands Drake Passage Mertz Glacier Southern Ocean The Antarctic |
geographic_facet |
Antarctic Antarctic Peninsula Balleny Islands Drake Passage Mertz Glacier Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Antarctic Peninsula Antarctica Balleny Islands Drake Passage Mertz Glacier Southern Ocean |
genre_facet |
Antarc* Antarctic Antarctic Peninsula Antarctica Balleny Islands Drake Passage Mertz Glacier Southern Ocean |
op_source |
Rickli, Jörg; Janssen, David J.; Hassler, Christel; Ellwood, Michael; Jaccard, Samuel L. (2019). Chromium biogeochemistry and stable isotope distribution in the Southern Ocean. Geochimica et cosmochimica acta, 262, pp. 188-206. Elsevier Science 10.1016/j.gca.2019.07.033 <http://dx.doi.org/10.1016/j.gca.2019.07.033> |
op_relation |
https://boris.unibe.ch/132629/ |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1016/j.gca.2019.07.033 |
container_title |
Geochimica et Cosmochimica Acta |
container_volume |
262 |
container_start_page |
188 |
op_container_end_page |
206 |
_version_ |
1774719918861713408 |