Th-234-derived particulate organic carbon export from an island-induced phytoplankton bloom in the Southern Ocean
It has long been recognised that some oceanic regions have persistently low-chlorophyll levels, even though there are abundant inorganic nutrients. Studies have shown that these high-nutrient low-chlorophyll (HNLC) areas are depleted in iron, an essential micronutrient. In these regions biological p...
Published in: | Deep Sea Research Part II: Topical Studies in Oceanography |
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Format: | Article in Journal/Newspaper |
Language: | English |
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2007
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Online Access: | https://hdl.handle.net/1983/427429c4-aa9c-4e7e-8161-29cd45e1d9d9 https://research-information.bris.ac.uk/en/publications/427429c4-aa9c-4e7e-8161-29cd45e1d9d9 https://doi.org/10.1016/j.dsr2.2007.06.002 |
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ftubristolcris:oai:research-information.bris.ac.uk:publications/427429c4-aa9c-4e7e-8161-29cd45e1d9d9 2024-01-28T09:59:43+01:00 Th-234-derived particulate organic carbon export from an island-induced phytoplankton bloom in the Southern Ocean Morris, Paul J. Sanders, Richard Turnewitsch, Robert Thomalla, Sandy 2007 https://hdl.handle.net/1983/427429c4-aa9c-4e7e-8161-29cd45e1d9d9 https://research-information.bris.ac.uk/en/publications/427429c4-aa9c-4e7e-8161-29cd45e1d9d9 https://doi.org/10.1016/j.dsr2.2007.06.002 eng eng info:eu-repo/semantics/restrictedAccess Morris , P J , Sanders , R , Turnewitsch , R & Thomalla , S 2007 , ' Th-234-derived particulate organic carbon export from an island-induced phytoplankton bloom in the Southern Ocean ' , Deep Sea Research Part II: Topical Studies in Oceanography , vol. 54 , no. 18-20 , pp. 2208-2232 . https://doi.org/10.1016/j.dsr2.2007.06.002 Southern Ocean IRON FERTILIZATION AQUATIC SYSTEMS ATMOSPHERIC CO2 Th-234 THORIUM ISOTOPES EQUATORIAL ATLANTIC-OCEAN Crozet carbon export PACIFIC-OCEAN POC CROZEX KERGUELEN-ISLANDS WATER COLUMN FRONTAL ZONE article 2007 ftubristolcris https://doi.org/10.1016/j.dsr2.2007.06.002 2024-01-04T23:39:24Z It has long been recognised that some oceanic regions have persistently low-chlorophyll levels, even though there are abundant inorganic nutrients. Studies have shown that these high-nutrient low-chlorophyll (HNLC) areas are depleted in iron, an essential micronutrient. In these regions biological production can be enhanced with artificial mesoscale iron fertilisation. However, the ability of iron-induced blooms to efficiently sequester carbon to mesopelagic depths is still an open question. It is hypothesised that sub-Antarctic islands in the HNLC Southern Ocean are also a source of iron and thus fuel the natural phytoplankton blooms observed in their proximity, thereby enhancing levels of particulate organic carbon (POC) export. To test the third part of this hypothesis, POC export was measured in the Southern Ocean region of the Crozet Islands (52 degrees E, 46 degrees S) during the austral summer of 2004/2005 as part of the CROZEX project. Based on satellite imagery, a high-chlorophyll region (maximum concentration = 4 mu g l(-1)) north and downstream of the islands was distinguished from a low-chlorophyll region (typical concentration = 0.3 mu g l(-1)) south and upstream of the islands. POC export estimates were obtained by using the naturally occurring particle-reactive radionuclide tracer Th-234. POC export was initially 15 mmol C m(-2) d(-1) in the high-chlorophyll bloom region, compared with 5 mmol C m(-2) d(-1) in the low-chlorophyll, non-bloom region. After a moderately small bloom at the southern control stations (max concentration = 0.7 mu g l(-1)) the spatial variability in POC export was lost, resulting in equally high levels of POC export (ca. 20 mmol C m(-2) d(-1)) throughout the study region. Comparison of Th-234-derived POC export with estimates of new production, calculated from nitrate budgets, revealed evidence for a decoupling of new and export production, with this effect most apparent within the northern bloom area. In addition to methodological issues this apparent decoupling of new and ... Article in Journal/Newspaper Antarc* Antarctic Crozet Islands Kerguelen Islands Southern Ocean University of Bristol: Bristol Research Antarctic Austral Kerguelen Kerguelen Islands Pacific Southern Ocean Deep Sea Research Part II: Topical Studies in Oceanography 54 18-20 2208 2232 |
institution |
Open Polar |
collection |
University of Bristol: Bristol Research |
op_collection_id |
ftubristolcris |
language |
English |
topic |
Southern Ocean IRON FERTILIZATION AQUATIC SYSTEMS ATMOSPHERIC CO2 Th-234 THORIUM ISOTOPES EQUATORIAL ATLANTIC-OCEAN Crozet carbon export PACIFIC-OCEAN POC CROZEX KERGUELEN-ISLANDS WATER COLUMN FRONTAL ZONE |
spellingShingle |
Southern Ocean IRON FERTILIZATION AQUATIC SYSTEMS ATMOSPHERIC CO2 Th-234 THORIUM ISOTOPES EQUATORIAL ATLANTIC-OCEAN Crozet carbon export PACIFIC-OCEAN POC CROZEX KERGUELEN-ISLANDS WATER COLUMN FRONTAL ZONE Morris, Paul J. Sanders, Richard Turnewitsch, Robert Thomalla, Sandy Th-234-derived particulate organic carbon export from an island-induced phytoplankton bloom in the Southern Ocean |
topic_facet |
Southern Ocean IRON FERTILIZATION AQUATIC SYSTEMS ATMOSPHERIC CO2 Th-234 THORIUM ISOTOPES EQUATORIAL ATLANTIC-OCEAN Crozet carbon export PACIFIC-OCEAN POC CROZEX KERGUELEN-ISLANDS WATER COLUMN FRONTAL ZONE |
description |
It has long been recognised that some oceanic regions have persistently low-chlorophyll levels, even though there are abundant inorganic nutrients. Studies have shown that these high-nutrient low-chlorophyll (HNLC) areas are depleted in iron, an essential micronutrient. In these regions biological production can be enhanced with artificial mesoscale iron fertilisation. However, the ability of iron-induced blooms to efficiently sequester carbon to mesopelagic depths is still an open question. It is hypothesised that sub-Antarctic islands in the HNLC Southern Ocean are also a source of iron and thus fuel the natural phytoplankton blooms observed in their proximity, thereby enhancing levels of particulate organic carbon (POC) export. To test the third part of this hypothesis, POC export was measured in the Southern Ocean region of the Crozet Islands (52 degrees E, 46 degrees S) during the austral summer of 2004/2005 as part of the CROZEX project. Based on satellite imagery, a high-chlorophyll region (maximum concentration = 4 mu g l(-1)) north and downstream of the islands was distinguished from a low-chlorophyll region (typical concentration = 0.3 mu g l(-1)) south and upstream of the islands. POC export estimates were obtained by using the naturally occurring particle-reactive radionuclide tracer Th-234. POC export was initially 15 mmol C m(-2) d(-1) in the high-chlorophyll bloom region, compared with 5 mmol C m(-2) d(-1) in the low-chlorophyll, non-bloom region. After a moderately small bloom at the southern control stations (max concentration = 0.7 mu g l(-1)) the spatial variability in POC export was lost, resulting in equally high levels of POC export (ca. 20 mmol C m(-2) d(-1)) throughout the study region. Comparison of Th-234-derived POC export with estimates of new production, calculated from nitrate budgets, revealed evidence for a decoupling of new and export production, with this effect most apparent within the northern bloom area. In addition to methodological issues this apparent decoupling of new and ... |
format |
Article in Journal/Newspaper |
author |
Morris, Paul J. Sanders, Richard Turnewitsch, Robert Thomalla, Sandy |
author_facet |
Morris, Paul J. Sanders, Richard Turnewitsch, Robert Thomalla, Sandy |
author_sort |
Morris, Paul J. |
title |
Th-234-derived particulate organic carbon export from an island-induced phytoplankton bloom in the Southern Ocean |
title_short |
Th-234-derived particulate organic carbon export from an island-induced phytoplankton bloom in the Southern Ocean |
title_full |
Th-234-derived particulate organic carbon export from an island-induced phytoplankton bloom in the Southern Ocean |
title_fullStr |
Th-234-derived particulate organic carbon export from an island-induced phytoplankton bloom in the Southern Ocean |
title_full_unstemmed |
Th-234-derived particulate organic carbon export from an island-induced phytoplankton bloom in the Southern Ocean |
title_sort |
th-234-derived particulate organic carbon export from an island-induced phytoplankton bloom in the southern ocean |
publishDate |
2007 |
url |
https://hdl.handle.net/1983/427429c4-aa9c-4e7e-8161-29cd45e1d9d9 https://research-information.bris.ac.uk/en/publications/427429c4-aa9c-4e7e-8161-29cd45e1d9d9 https://doi.org/10.1016/j.dsr2.2007.06.002 |
geographic |
Antarctic Austral Kerguelen Kerguelen Islands Pacific Southern Ocean |
geographic_facet |
Antarctic Austral Kerguelen Kerguelen Islands Pacific Southern Ocean |
genre |
Antarc* Antarctic Crozet Islands Kerguelen Islands Southern Ocean |
genre_facet |
Antarc* Antarctic Crozet Islands Kerguelen Islands Southern Ocean |
op_source |
Morris , P J , Sanders , R , Turnewitsch , R & Thomalla , S 2007 , ' Th-234-derived particulate organic carbon export from an island-induced phytoplankton bloom in the Southern Ocean ' , Deep Sea Research Part II: Topical Studies in Oceanography , vol. 54 , no. 18-20 , pp. 2208-2232 . https://doi.org/10.1016/j.dsr2.2007.06.002 |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1016/j.dsr2.2007.06.002 |
container_title |
Deep Sea Research Part II: Topical Studies in Oceanography |
container_volume |
54 |
container_issue |
18-20 |
container_start_page |
2208 |
op_container_end_page |
2232 |
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1789338297149947904 |