Iron organic speciation during the LOHAFEX experiment: Iron ligands release under biomass control by copepod grazing
The LOHAFEX iron fertilization experiment consisted in the fertilization of the closed core of a cyclonic eddy located south of the Antarctic Polar Front in the Atlantic sector of the Southern Ocean. This eddy was characterized by high nitrate and low silicate concentrations. Despite a 2.5 fold incr...
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Online Access: | http://hdl.handle.net/10261/209694 https://doi.org/10.1016/j.jmarsys.2019.02.002 https://doi.org/10.13039/501100003329 |
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ftcsic:oai:digital.csic.es:10261/209694 2024-02-11T09:56:29+01:00 Iron organic speciation during the LOHAFEX experiment: Iron ligands release under biomass control by copepod grazing Laglera, Luis M. Tovar-Sánchez, Antonio Sukekava, C. F. Naik, H. Naqvi, S. W. A. Wolf-Gladrow, Dieter Ministerio de Economía y Competitividad (España) 2010-07 http://hdl.handle.net/10261/209694 https://doi.org/10.1016/j.jmarsys.2019.02.002 https://doi.org/10.13039/501100003329 unknown Elsevier #PLACEHOLDER_PARENT_METADATA_VALUE# info:eu-repo/grantAgreement/MINECO/Plan Estatal de Investigación Científica y Técnica y de Innovación 2013-2016/CTM2014-59244-C3-3-R http://doi.org/10.1016/j.jmarsys.2019.02.002 Sí doi:10.1016/j.jmarsys.2019.02.002 issn: 0924-7963 Journal of Marine Systems: 103151 (2020) http://hdl.handle.net/10261/209694 http://dx.doi.org/10.13039/501100003329 none LOHAFEX Iron cycling Iron speciation Grazing Southern Ocean Iron fertilization artículo http://purl.org/coar/resource_type/c_6501 2010 ftcsic https://doi.org/10.1016/j.jmarsys.2019.02.00210.13039/501100003329 2024-01-16T10:53:03Z The LOHAFEX iron fertilization experiment consisted in the fertilization of the closed core of a cyclonic eddy located south of the Antarctic Polar Front in the Atlantic sector of the Southern Ocean. This eddy was characterized by high nitrate and low silicate concentrations. Despite a 2.5 fold increase of the chlorophyll-a (Chl-a) concentrations, the composition of the biological community did not change. Phytoplankton biomass was mostly formed by small autotrophic flagellates whereas zooplankton biomass was mostly comprised by the large copepod Calanus simillimus. Efficient recycling of copepod fecal pellets (the main component of the downward flux of organic matter) in the upper 100–150 m of the water column prevented any significant deep export of particulate organic carbon (POC). Before fertilization, dissolved iron (DFe) concentrations in the upper 200 m were low, but not depleted, at ~0.2 nM. High DFe concentrations appeared scattered from day 14 onwards as a result of the grazing activity. A second fertilization on day 21 had no significant effect on the DFe and Chl-a standing stocks. Work with unfiltered samples using different acidification protocols revealed that, by midway of LOHAFEX, rapid recycling of iron-replenished copepod fecal pellets explained the source of bioavailable iron that prolonged the duration of the bloom for many weeks. Here we present the evolution of the organic speciation of iron in the upper 200 m of the water column during LOHAFEX by a Competing Ligand Equilibrium method using voltammetry. During the first 12 days of the experiment, ligands of an affinity for iron similar to the ligands found before fertilization (logK′Fe′L~11.9) accumulated in fertilized waters mostly in the upper 80 m (from ~1 nM to ~2.5 nM). The restriction of ligand accumulation to the depth of Chl-a penetration points to exudation by the growing autotrophic population as the initial source of ligands. From day 5 onwards, we found in many samples a new class of ligands (L1) characterized by a significant ... Article in Journal/Newspaper Antarc* Antarctic Southern Ocean Digital.CSIC (Spanish National Research Council) Antarctic Southern Ocean The Antarctic Journal of Marine Systems 207 103151 |
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Open Polar |
collection |
Digital.CSIC (Spanish National Research Council) |
op_collection_id |
ftcsic |
language |
unknown |
topic |
LOHAFEX Iron cycling Iron speciation Grazing Southern Ocean Iron fertilization |
spellingShingle |
LOHAFEX Iron cycling Iron speciation Grazing Southern Ocean Iron fertilization Laglera, Luis M. Tovar-Sánchez, Antonio Sukekava, C. F. Naik, H. Naqvi, S. W. A. Wolf-Gladrow, Dieter Iron organic speciation during the LOHAFEX experiment: Iron ligands release under biomass control by copepod grazing |
topic_facet |
LOHAFEX Iron cycling Iron speciation Grazing Southern Ocean Iron fertilization |
description |
The LOHAFEX iron fertilization experiment consisted in the fertilization of the closed core of a cyclonic eddy located south of the Antarctic Polar Front in the Atlantic sector of the Southern Ocean. This eddy was characterized by high nitrate and low silicate concentrations. Despite a 2.5 fold increase of the chlorophyll-a (Chl-a) concentrations, the composition of the biological community did not change. Phytoplankton biomass was mostly formed by small autotrophic flagellates whereas zooplankton biomass was mostly comprised by the large copepod Calanus simillimus. Efficient recycling of copepod fecal pellets (the main component of the downward flux of organic matter) in the upper 100–150 m of the water column prevented any significant deep export of particulate organic carbon (POC). Before fertilization, dissolved iron (DFe) concentrations in the upper 200 m were low, but not depleted, at ~0.2 nM. High DFe concentrations appeared scattered from day 14 onwards as a result of the grazing activity. A second fertilization on day 21 had no significant effect on the DFe and Chl-a standing stocks. Work with unfiltered samples using different acidification protocols revealed that, by midway of LOHAFEX, rapid recycling of iron-replenished copepod fecal pellets explained the source of bioavailable iron that prolonged the duration of the bloom for many weeks. Here we present the evolution of the organic speciation of iron in the upper 200 m of the water column during LOHAFEX by a Competing Ligand Equilibrium method using voltammetry. During the first 12 days of the experiment, ligands of an affinity for iron similar to the ligands found before fertilization (logK′Fe′L~11.9) accumulated in fertilized waters mostly in the upper 80 m (from ~1 nM to ~2.5 nM). The restriction of ligand accumulation to the depth of Chl-a penetration points to exudation by the growing autotrophic population as the initial source of ligands. From day 5 onwards, we found in many samples a new class of ligands (L1) characterized by a significant ... |
author2 |
Ministerio de Economía y Competitividad (España) |
format |
Article in Journal/Newspaper |
author |
Laglera, Luis M. Tovar-Sánchez, Antonio Sukekava, C. F. Naik, H. Naqvi, S. W. A. Wolf-Gladrow, Dieter |
author_facet |
Laglera, Luis M. Tovar-Sánchez, Antonio Sukekava, C. F. Naik, H. Naqvi, S. W. A. Wolf-Gladrow, Dieter |
author_sort |
Laglera, Luis M. |
title |
Iron organic speciation during the LOHAFEX experiment: Iron ligands release under biomass control by copepod grazing |
title_short |
Iron organic speciation during the LOHAFEX experiment: Iron ligands release under biomass control by copepod grazing |
title_full |
Iron organic speciation during the LOHAFEX experiment: Iron ligands release under biomass control by copepod grazing |
title_fullStr |
Iron organic speciation during the LOHAFEX experiment: Iron ligands release under biomass control by copepod grazing |
title_full_unstemmed |
Iron organic speciation during the LOHAFEX experiment: Iron ligands release under biomass control by copepod grazing |
title_sort |
iron organic speciation during the lohafex experiment: iron ligands release under biomass control by copepod grazing |
publisher |
Elsevier |
publishDate |
2010 |
url |
http://hdl.handle.net/10261/209694 https://doi.org/10.1016/j.jmarsys.2019.02.002 https://doi.org/10.13039/501100003329 |
geographic |
Antarctic Southern Ocean The Antarctic |
geographic_facet |
Antarctic Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_relation |
#PLACEHOLDER_PARENT_METADATA_VALUE# info:eu-repo/grantAgreement/MINECO/Plan Estatal de Investigación Científica y Técnica y de Innovación 2013-2016/CTM2014-59244-C3-3-R http://doi.org/10.1016/j.jmarsys.2019.02.002 Sí doi:10.1016/j.jmarsys.2019.02.002 issn: 0924-7963 Journal of Marine Systems: 103151 (2020) http://hdl.handle.net/10261/209694 http://dx.doi.org/10.13039/501100003329 |
op_rights |
none |
op_doi |
https://doi.org/10.1016/j.jmarsys.2019.02.00210.13039/501100003329 |
container_title |
Journal of Marine Systems |
container_volume |
207 |
container_start_page |
103151 |
_version_ |
1790603471262580736 |