Net community production, Thorium-234 activity and particle flux during the Southern Ocean iron fertilization experiment LOHAFEX
A closed eddy core in the Subantarctic Atlantic Ocean was fertilized twice with two tons of iron (as FeSO4), and the 300 km**2 fertilized patch was studied for 39 days to test whether fertilization enhances downward particle flux into the deep ocean. Chlorophyll a and primary productivity doubled af...
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Online Access: | https://doi.pangaea.de/10.1594/PANGAEA.832525 https://doi.org/10.1594/PANGAEA.832525 |
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ftpangaea:oai:pangaea.de:doi:10.1594/PANGAEA.832525 2024-09-09T20:10:10+00:00 Net community production, Thorium-234 activity and particle flux during the Southern Ocean iron fertilization experiment LOHAFEX Martin, Patrick Rutgers van der Loeff, Michiel M Cassar, Nicolas Vandromme, Pieter d'Ovidio, Francesco Stemmann, Lars Rengarajan, Ramabadran Soares, Melena González, Humberto E Ebersbach, Friederike Lampitt, Richard Stephen Sanders, Richard J Barnett, Bruce A Smetacek, Victor Naqvi, Syed Wajih Ahmad MEDIAN LATITUDE: -47.972615 * MEDIAN LONGITUDE: -15.137787 * SOUTH-BOUND LATITUDE: -49.037300 * WEST-BOUND LONGITUDE: -16.097930 * NORTH-BOUND LATITUDE: -44.509310 * EAST-BOUND LONGITUDE: -12.881320 * DATE/TIME START: 2009-01-26T13:04:00 * DATE/TIME END: 2009-03-06T12:31:00 2013 application/zip, 7 datasets https://doi.pangaea.de/10.1594/PANGAEA.832525 https://doi.org/10.1594/PANGAEA.832525 en eng PANGAEA https://doi.pangaea.de/10.1594/PANGAEA.832525 https://doi.org/10.1594/PANGAEA.832525 CC-BY-3.0: Creative Commons Attribution 3.0 Unported Access constraints: unrestricted info:eu-repo/semantics/openAccess Supplement to: Martin, Patrick; Rutgers van der Loeff, Michiel M; Cassar, Nicolas; Vandromme, Pieter; d'Ovidio, Francesco; Stemmann, Lars; Rengarajan, Ramabadran; Soares, Melena; González, Humberto E; Ebersbach, Friederike; Lampitt, Richard Stephen; Sanders, Richard J; Barnett, Bruce A; Smetacek, Victor; Naqvi, Syed Wajih Ahmad (2013): Iron fertilization enhanced net community production but not downward particle flux during the Southern Ocean iron fertilization experiment LOHAFEX. Global Biogeochemical Cycles, 27(3), 871-881, https://doi.org/10.1002/gbc.20077 AWI_MarGeoChem Marine Geochemistry @ AWI dataset publication series 2013 ftpangaea https://doi.org/10.1594/PANGAEA.83252510.1002/gbc.20077 2024-07-24T02:31:21Z A closed eddy core in the Subantarctic Atlantic Ocean was fertilized twice with two tons of iron (as FeSO4), and the 300 km**2 fertilized patch was studied for 39 days to test whether fertilization enhances downward particle flux into the deep ocean. Chlorophyll a and primary productivity doubled after fertilization, and photosynthetic quantum yield (FV/FM) increased from 0.33 to >0.40. Silicic acid (<2 µmol/L) limited diatoms, which contributed <10% of phytoplankton biomass. Copepods exerted high grazing pressure. This is the first study of particle flux out of an artificially fertilized bloom with very low diatom biomass. Net community production (NCP) inside the patch, estimated from O2:Ar ratios, averaged 21 mmol POC/m**2/d, probably ±20%. 234Th profiles implied constant export of ~6.3 mmol POC/m**2/d in the patch, similar to unfertilized waters. The difference between NCP and 234Th-derived export partly accumulated in the mixed layer and was partly remineralized between the mixed layer and 100 m. Neutrally buoyant sediment traps at 200 and 450 m inside and outside the patch caught mostly <1.1 mmol POC/m**2/d, predominantly of fecal origin; flux did not increase upon fertilization. Our data thus indicate intense flux attenuation between 100 and 200 m, and probably between the mixed layer and 100 m. We attribute the lack of fertilization-induced export to silicon limitation of diatoms and reprocessing of sinking particles by detritus feeders. Our data are consistent with the view that nitrate-rich but silicate-deficient waters are not poised for enhanced particle export upon iron addition. Other/Unknown Material Southern Ocean Copepods PANGAEA - Data Publisher for Earth & Environmental Science Southern Ocean ENVELOPE(-16.097930,-12.881320,-44.509310,-49.037300) |
institution |
Open Polar |
collection |
PANGAEA - Data Publisher for Earth & Environmental Science |
op_collection_id |
ftpangaea |
language |
English |
topic |
AWI_MarGeoChem Marine Geochemistry @ AWI |
spellingShingle |
AWI_MarGeoChem Marine Geochemistry @ AWI Martin, Patrick Rutgers van der Loeff, Michiel M Cassar, Nicolas Vandromme, Pieter d'Ovidio, Francesco Stemmann, Lars Rengarajan, Ramabadran Soares, Melena González, Humberto E Ebersbach, Friederike Lampitt, Richard Stephen Sanders, Richard J Barnett, Bruce A Smetacek, Victor Naqvi, Syed Wajih Ahmad Net community production, Thorium-234 activity and particle flux during the Southern Ocean iron fertilization experiment LOHAFEX |
topic_facet |
AWI_MarGeoChem Marine Geochemistry @ AWI |
description |
A closed eddy core in the Subantarctic Atlantic Ocean was fertilized twice with two tons of iron (as FeSO4), and the 300 km**2 fertilized patch was studied for 39 days to test whether fertilization enhances downward particle flux into the deep ocean. Chlorophyll a and primary productivity doubled after fertilization, and photosynthetic quantum yield (FV/FM) increased from 0.33 to >0.40. Silicic acid (<2 µmol/L) limited diatoms, which contributed <10% of phytoplankton biomass. Copepods exerted high grazing pressure. This is the first study of particle flux out of an artificially fertilized bloom with very low diatom biomass. Net community production (NCP) inside the patch, estimated from O2:Ar ratios, averaged 21 mmol POC/m**2/d, probably ±20%. 234Th profiles implied constant export of ~6.3 mmol POC/m**2/d in the patch, similar to unfertilized waters. The difference between NCP and 234Th-derived export partly accumulated in the mixed layer and was partly remineralized between the mixed layer and 100 m. Neutrally buoyant sediment traps at 200 and 450 m inside and outside the patch caught mostly <1.1 mmol POC/m**2/d, predominantly of fecal origin; flux did not increase upon fertilization. Our data thus indicate intense flux attenuation between 100 and 200 m, and probably between the mixed layer and 100 m. We attribute the lack of fertilization-induced export to silicon limitation of diatoms and reprocessing of sinking particles by detritus feeders. Our data are consistent with the view that nitrate-rich but silicate-deficient waters are not poised for enhanced particle export upon iron addition. |
format |
Other/Unknown Material |
author |
Martin, Patrick Rutgers van der Loeff, Michiel M Cassar, Nicolas Vandromme, Pieter d'Ovidio, Francesco Stemmann, Lars Rengarajan, Ramabadran Soares, Melena González, Humberto E Ebersbach, Friederike Lampitt, Richard Stephen Sanders, Richard J Barnett, Bruce A Smetacek, Victor Naqvi, Syed Wajih Ahmad |
author_facet |
Martin, Patrick Rutgers van der Loeff, Michiel M Cassar, Nicolas Vandromme, Pieter d'Ovidio, Francesco Stemmann, Lars Rengarajan, Ramabadran Soares, Melena González, Humberto E Ebersbach, Friederike Lampitt, Richard Stephen Sanders, Richard J Barnett, Bruce A Smetacek, Victor Naqvi, Syed Wajih Ahmad |
author_sort |
Martin, Patrick |
title |
Net community production, Thorium-234 activity and particle flux during the Southern Ocean iron fertilization experiment LOHAFEX |
title_short |
Net community production, Thorium-234 activity and particle flux during the Southern Ocean iron fertilization experiment LOHAFEX |
title_full |
Net community production, Thorium-234 activity and particle flux during the Southern Ocean iron fertilization experiment LOHAFEX |
title_fullStr |
Net community production, Thorium-234 activity and particle flux during the Southern Ocean iron fertilization experiment LOHAFEX |
title_full_unstemmed |
Net community production, Thorium-234 activity and particle flux during the Southern Ocean iron fertilization experiment LOHAFEX |
title_sort |
net community production, thorium-234 activity and particle flux during the southern ocean iron fertilization experiment lohafex |
publisher |
PANGAEA |
publishDate |
2013 |
url |
https://doi.pangaea.de/10.1594/PANGAEA.832525 https://doi.org/10.1594/PANGAEA.832525 |
op_coverage |
MEDIAN LATITUDE: -47.972615 * MEDIAN LONGITUDE: -15.137787 * SOUTH-BOUND LATITUDE: -49.037300 * WEST-BOUND LONGITUDE: -16.097930 * NORTH-BOUND LATITUDE: -44.509310 * EAST-BOUND LONGITUDE: -12.881320 * DATE/TIME START: 2009-01-26T13:04:00 * DATE/TIME END: 2009-03-06T12:31:00 |
long_lat |
ENVELOPE(-16.097930,-12.881320,-44.509310,-49.037300) |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean Copepods |
genre_facet |
Southern Ocean Copepods |
op_source |
Supplement to: Martin, Patrick; Rutgers van der Loeff, Michiel M; Cassar, Nicolas; Vandromme, Pieter; d'Ovidio, Francesco; Stemmann, Lars; Rengarajan, Ramabadran; Soares, Melena; González, Humberto E; Ebersbach, Friederike; Lampitt, Richard Stephen; Sanders, Richard J; Barnett, Bruce A; Smetacek, Victor; Naqvi, Syed Wajih Ahmad (2013): Iron fertilization enhanced net community production but not downward particle flux during the Southern Ocean iron fertilization experiment LOHAFEX. Global Biogeochemical Cycles, 27(3), 871-881, https://doi.org/10.1002/gbc.20077 |
op_relation |
https://doi.pangaea.de/10.1594/PANGAEA.832525 https://doi.org/10.1594/PANGAEA.832525 |
op_rights |
CC-BY-3.0: Creative Commons Attribution 3.0 Unported Access constraints: unrestricted info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1594/PANGAEA.83252510.1002/gbc.20077 |
_version_ |
1809944550042501120 |