Significant mixed layer nitrification in a natural iron-fertilized bloom of the Southern Ocean
Nitrification, the microbially mediated oxidation of ammonium into nitrate, is generally expected to be low in the Southern Ocean mixed layer. This paradigm assumes that nitrate is mainly provided through vertical mixing and assimilated during the vegetative season, supporting the concept that nitra...
Published in: | Global Biogeochemical Cycles |
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Wiley-Blackwell Publishing, Inc.
2015
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Online Access: | https://doi.org/10.1002/2014GB005051 http://ecite.utas.edu.au/106055 |
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ftunivtasecite:oai:ecite.utas.edu.au:106055 2023-05-15T18:25:01+02:00 Significant mixed layer nitrification in a natural iron-fertilized bloom of the Southern Ocean Fripiat, F Elskens, M Trull, TW Blain, S Cavagna, AJ Fernandez, C Fonseca-Batista, D Planchon, F Raimbault, P Roukaerts, A Dehairs, F 2015 application/pdf https://doi.org/10.1002/2014GB005051 http://ecite.utas.edu.au/106055 en eng Wiley-Blackwell Publishing, Inc. http://ecite.utas.edu.au/106055/1/Fripiat_et_al-2015-Global_Biogeochemical_Cycles (1).pdf http://dx.doi.org/10.1002/2014GB005051 Fripiat, F and Elskens, M and Trull, TW and Blain, S and Cavagna, AJ and Fernandez, C and Fonseca-Batista, D and Planchon, F and Raimbault, P and Roukaerts, A and Dehairs, F, Significant mixed layer nitrification in a natural iron-fertilized bloom of the Southern Ocean, Global Biogeochemical Cycles, 29, (11) pp. 1929-1943. ISSN 0886-6236 (2015) [Refereed Article] http://ecite.utas.edu.au/106055 Earth Sciences Oceanography Chemical Oceanography Refereed Article PeerReviewed 2015 ftunivtasecite https://doi.org/10.1002/2014GB005051 2019-12-13T22:07:13Z Nitrification, the microbially mediated oxidation of ammonium into nitrate, is generally expected to be low in the Southern Ocean mixed layer. This paradigm assumes that nitrate is mainly provided through vertical mixing and assimilated during the vegetative season, supporting the concept that nitrate uptake is equivalent to the new primary production (i.e., primary production which is potentially available for export). Here we show that nitrification is significant (~40-80% of the seasonal nitrate uptake) in the naturally iron-fertilized bloom over the southeast Kerguelen Plateau. Hence, a large fraction of the nitrate-based primary production is regenerated, instead of being exported. It appears that nitrate assimilation (light dependent) and nitrification (partly light inhibited) are spatially separated between the upper and lower parts, respectively, of the deep surface mixed layers. These deep mixed layers, extending well below the euphotic layer, allow nitrifiers to compete with phytoplankton for the assimilation of ammonium. The high contributions of nitrification to nitrate uptake are in agreement with both low export efficiency (i.e., the percentage of primary production that is exported) and low seasonal nitrate drawdown despite high nitrate assimilation. Article in Journal/Newspaper Southern Ocean eCite UTAS (University of Tasmania) Kerguelen Southern Ocean Global Biogeochemical Cycles 29 11 1929 1943 |
institution |
Open Polar |
collection |
eCite UTAS (University of Tasmania) |
op_collection_id |
ftunivtasecite |
language |
English |
topic |
Earth Sciences Oceanography Chemical Oceanography |
spellingShingle |
Earth Sciences Oceanography Chemical Oceanography Fripiat, F Elskens, M Trull, TW Blain, S Cavagna, AJ Fernandez, C Fonseca-Batista, D Planchon, F Raimbault, P Roukaerts, A Dehairs, F Significant mixed layer nitrification in a natural iron-fertilized bloom of the Southern Ocean |
topic_facet |
Earth Sciences Oceanography Chemical Oceanography |
description |
Nitrification, the microbially mediated oxidation of ammonium into nitrate, is generally expected to be low in the Southern Ocean mixed layer. This paradigm assumes that nitrate is mainly provided through vertical mixing and assimilated during the vegetative season, supporting the concept that nitrate uptake is equivalent to the new primary production (i.e., primary production which is potentially available for export). Here we show that nitrification is significant (~40-80% of the seasonal nitrate uptake) in the naturally iron-fertilized bloom over the southeast Kerguelen Plateau. Hence, a large fraction of the nitrate-based primary production is regenerated, instead of being exported. It appears that nitrate assimilation (light dependent) and nitrification (partly light inhibited) are spatially separated between the upper and lower parts, respectively, of the deep surface mixed layers. These deep mixed layers, extending well below the euphotic layer, allow nitrifiers to compete with phytoplankton for the assimilation of ammonium. The high contributions of nitrification to nitrate uptake are in agreement with both low export efficiency (i.e., the percentage of primary production that is exported) and low seasonal nitrate drawdown despite high nitrate assimilation. |
format |
Article in Journal/Newspaper |
author |
Fripiat, F Elskens, M Trull, TW Blain, S Cavagna, AJ Fernandez, C Fonseca-Batista, D Planchon, F Raimbault, P Roukaerts, A Dehairs, F |
author_facet |
Fripiat, F Elskens, M Trull, TW Blain, S Cavagna, AJ Fernandez, C Fonseca-Batista, D Planchon, F Raimbault, P Roukaerts, A Dehairs, F |
author_sort |
Fripiat, F |
title |
Significant mixed layer nitrification in a natural iron-fertilized bloom of the Southern Ocean |
title_short |
Significant mixed layer nitrification in a natural iron-fertilized bloom of the Southern Ocean |
title_full |
Significant mixed layer nitrification in a natural iron-fertilized bloom of the Southern Ocean |
title_fullStr |
Significant mixed layer nitrification in a natural iron-fertilized bloom of the Southern Ocean |
title_full_unstemmed |
Significant mixed layer nitrification in a natural iron-fertilized bloom of the Southern Ocean |
title_sort |
significant mixed layer nitrification in a natural iron-fertilized bloom of the southern ocean |
publisher |
Wiley-Blackwell Publishing, Inc. |
publishDate |
2015 |
url |
https://doi.org/10.1002/2014GB005051 http://ecite.utas.edu.au/106055 |
geographic |
Kerguelen Southern Ocean |
geographic_facet |
Kerguelen Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_relation |
http://ecite.utas.edu.au/106055/1/Fripiat_et_al-2015-Global_Biogeochemical_Cycles (1).pdf http://dx.doi.org/10.1002/2014GB005051 Fripiat, F and Elskens, M and Trull, TW and Blain, S and Cavagna, AJ and Fernandez, C and Fonseca-Batista, D and Planchon, F and Raimbault, P and Roukaerts, A and Dehairs, F, Significant mixed layer nitrification in a natural iron-fertilized bloom of the Southern Ocean, Global Biogeochemical Cycles, 29, (11) pp. 1929-1943. ISSN 0886-6236 (2015) [Refereed Article] http://ecite.utas.edu.au/106055 |
op_doi |
https://doi.org/10.1002/2014GB005051 |
container_title |
Global Biogeochemical Cycles |
container_volume |
29 |
container_issue |
11 |
container_start_page |
1929 |
op_container_end_page |
1943 |
_version_ |
1766206124926697472 |