Use of Ra isotopes to deduce rapid transfer of sediment-derived inputs off Kerguelen
The Southern Ocean is known to be the largest high-nutrient, low-chlorophyll (HNLC) region of the global ocean due to iron limitation. However, a large phytoplankton bloom develops annually downstream of the Kerguelen Islands, a bloom which is sustained partly by iron released from the sediments dep...
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ftdoajarticles:oai:doaj.org/article:dff1b422c72840a9a5df2153ace463f4 2023-05-15T17:02:02+02:00 Use of Ra isotopes to deduce rapid transfer of sediment-derived inputs off Kerguelen V. Sanial P. van Beek B. Lansard M. Souhaut E. Kestenare F. d'Ovidio M. Zhou S. Blain 2015-03-01T00:00:00Z https://doi.org/10.5194/bg-12-1415-2015 https://doaj.org/article/dff1b422c72840a9a5df2153ace463f4 EN eng Copernicus Publications http://www.biogeosciences.net/12/1415/2015/bg-12-1415-2015.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-12-1415-2015 https://doaj.org/article/dff1b422c72840a9a5df2153ace463f4 Biogeosciences, Vol 12, Iss 5, Pp 1415-1430 (2015) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2015 ftdoajarticles https://doi.org/10.5194/bg-12-1415-2015 2022-12-31T02:05:45Z The Southern Ocean is known to be the largest high-nutrient, low-chlorophyll (HNLC) region of the global ocean due to iron limitation. However, a large phytoplankton bloom develops annually downstream of the Kerguelen Islands, a bloom which is sustained partly by iron released from the sediments deposited onto the shelves. In the framework of the KEOPS-2 project, we used radium isotopes ( 224 Ra, T 1/2 = 3.66 d; 223 Ra, T 1/2 = 11.4 d; 228 Ra, T 1/2 = 5.75 yr) to provide information on the origin of iron fertilization and on the timescales of the transfer of sediment-derived inputs (including iron and other micronutrients) towards offshore waters. Significant 224 Ra and 223 Ra activities were found in the near vicinity of the Kerguelen Islands, in agreement with the short half-lives of these isotopes. Significant 224 Ra and 223 Ra activities were also detected up to 200 km downstream of the islands and more unexpectedly in offshore waters south of the polar front. These observations thus clearly indicate (i) that the sediment-derived inputs are rapidly transferred towards offshore waters (on timescales on the order of several days up to several weeks) and (ii) that the polar front is not a physical barrier for the chemical elements released from the sediments of the Kerguelen Plateau. The Ra data set suggests that iron and other micronutrients released by the shelves of the Kerguelen Islands may contribute to fueling the phytoplankton bloom downstream of the islands, despite the presence of the polar front. However, the heterogeneous distribution of the 224 Ra and 223 Ra activities in surface waters suggests that this supply across the front is not a continuous process but rather a process that is highly variable in space and time. Article in Journal/Newspaper Kerguelen Islands Southern Ocean Directory of Open Access Journals: DOAJ Articles Southern Ocean Kerguelen Kerguelen Islands Biogeosciences 12 5 1415 1430 |
institution |
Open Polar |
collection |
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 V. Sanial P. van Beek B. Lansard M. Souhaut E. Kestenare F. d'Ovidio M. Zhou S. Blain Use of Ra isotopes to deduce rapid transfer of sediment-derived inputs off Kerguelen |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
The Southern Ocean is known to be the largest high-nutrient, low-chlorophyll (HNLC) region of the global ocean due to iron limitation. However, a large phytoplankton bloom develops annually downstream of the Kerguelen Islands, a bloom which is sustained partly by iron released from the sediments deposited onto the shelves. In the framework of the KEOPS-2 project, we used radium isotopes ( 224 Ra, T 1/2 = 3.66 d; 223 Ra, T 1/2 = 11.4 d; 228 Ra, T 1/2 = 5.75 yr) to provide information on the origin of iron fertilization and on the timescales of the transfer of sediment-derived inputs (including iron and other micronutrients) towards offshore waters. Significant 224 Ra and 223 Ra activities were found in the near vicinity of the Kerguelen Islands, in agreement with the short half-lives of these isotopes. Significant 224 Ra and 223 Ra activities were also detected up to 200 km downstream of the islands and more unexpectedly in offshore waters south of the polar front. These observations thus clearly indicate (i) that the sediment-derived inputs are rapidly transferred towards offshore waters (on timescales on the order of several days up to several weeks) and (ii) that the polar front is not a physical barrier for the chemical elements released from the sediments of the Kerguelen Plateau. The Ra data set suggests that iron and other micronutrients released by the shelves of the Kerguelen Islands may contribute to fueling the phytoplankton bloom downstream of the islands, despite the presence of the polar front. However, the heterogeneous distribution of the 224 Ra and 223 Ra activities in surface waters suggests that this supply across the front is not a continuous process but rather a process that is highly variable in space and time. |
format |
Article in Journal/Newspaper |
author |
V. Sanial P. van Beek B. Lansard M. Souhaut E. Kestenare F. d'Ovidio M. Zhou S. Blain |
author_facet |
V. Sanial P. van Beek B. Lansard M. Souhaut E. Kestenare F. d'Ovidio M. Zhou S. Blain |
author_sort |
V. Sanial |
title |
Use of Ra isotopes to deduce rapid transfer of sediment-derived inputs off Kerguelen |
title_short |
Use of Ra isotopes to deduce rapid transfer of sediment-derived inputs off Kerguelen |
title_full |
Use of Ra isotopes to deduce rapid transfer of sediment-derived inputs off Kerguelen |
title_fullStr |
Use of Ra isotopes to deduce rapid transfer of sediment-derived inputs off Kerguelen |
title_full_unstemmed |
Use of Ra isotopes to deduce rapid transfer of sediment-derived inputs off Kerguelen |
title_sort |
use of ra isotopes to deduce rapid transfer of sediment-derived inputs off kerguelen |
publisher |
Copernicus Publications |
publishDate |
2015 |
url |
https://doi.org/10.5194/bg-12-1415-2015 https://doaj.org/article/dff1b422c72840a9a5df2153ace463f4 |
geographic |
Southern Ocean Kerguelen Kerguelen Islands |
geographic_facet |
Southern Ocean Kerguelen Kerguelen Islands |
genre |
Kerguelen Islands Southern Ocean |
genre_facet |
Kerguelen Islands Southern Ocean |
op_source |
Biogeosciences, Vol 12, Iss 5, Pp 1415-1430 (2015) |
op_relation |
http://www.biogeosciences.net/12/1415/2015/bg-12-1415-2015.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-12-1415-2015 https://doaj.org/article/dff1b422c72840a9a5df2153ace463f4 |
op_doi |
https://doi.org/10.5194/bg-12-1415-2015 |
container_title |
Biogeosciences |
container_volume |
12 |
container_issue |
5 |
container_start_page |
1415 |
op_container_end_page |
1430 |
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1766055265801601024 |