Spatial and temporal distribution of Fe(II) and H2O2 during EisenEx, an open ocean mesoscale iron enrichment
Measurements of Fe(II) and H2O2 were carried out in the Atlantic sector of the Southern Ocean during EisenEx, an iron enrichment experiment. Iron was added on three separate occasions, approximately every 8 days, as a ferrous sulfate (FeSO4) solution. Vertical profiles of Fe(II) showed maxima consis...
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2005
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Online Access: | https://epic.awi.de/id/eprint/9907/ https://doi.org/10.1016/j.marchem.2004.06.041 https://hdl.handle.net/10013/epic.20402 |
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ftawi:oai:epic.awi.de:9907 2023-09-05T13:23:31+02:00 Spatial and temporal distribution of Fe(II) and H2O2 during EisenEx, an open ocean mesoscale iron enrichment Croot, P. L. Laan, P. Nishioka, J. Strass, Volker Cisewski, Boris Boye, M. Timmermans, K. R. Bellerby, R. G. Goldson, L. Nightingale, P. Baar, H. J. W. de 2005 https://epic.awi.de/id/eprint/9907/ https://doi.org/10.1016/j.marchem.2004.06.041 https://hdl.handle.net/10013/epic.20402 unknown Croot, P. L. , Laan, P. , Nishioka, J. , Strass, V. orcid:0000-0002-7539-1400 , Cisewski, B. , Boye, M. , Timmermans, K. R. , Bellerby, R. G. , Goldson, L. , Nightingale, P. and Baar, H. J. W. d. (2005) Spatial and temporal distribution of Fe(II) and H2O2 during EisenEx, an open ocean mesoscale iron enrichment , Marine chemistry, 95(1/2), 65 . doi:10.1016/j.marchem.2004.06.041 <https://doi.org/10.1016/j.marchem.2004.06.041> , hdl:10013/epic.20402 EPIC3Marine chemistry, 95(1/2), 65 Article isiRev 2005 ftawi https://doi.org/10.1016/j.marchem.2004.06.041 2023-08-22T19:48:19Z Measurements of Fe(II) and H2O2 were carried out in the Atlantic sector of the Southern Ocean during EisenEx, an iron enrichment experiment. Iron was added on three separate occasions, approximately every 8 days, as a ferrous sulfate (FeSO4) solution. Vertical profiles of Fe(II) showed maxima consistent with the plume of the iron infusion. While H2O2 profiles revealed a corresponding minima showing the effect of oxidation of Fe(II) by H2O2, observations showed detectable Fe(II) concentrations existed for up to 8 days after an iron infusion. H2O2 concentrations increased at the depth of the chlorophyll maximum when iron concentrations returned to pre-infusion concentrations (<80 pM) possibly due to biological production related to iron reductase activity.In this work, Fe(II) and dissolved iron were used as tracers themselves for subsequent iron infusions when no further SF6 was added. EisenEx was subject to periods of weak and strong mixing. Slow mixing after the second infusion allowed significant concentrations of Fe(II) and Fe to exist for several days. During this time, dissolved and total iron in the infusion plume behaved almost conservatively as it was trapped between a relict mixed layer and a new rain-induced mixed layer. Using dissolved iron, a value for the vertical diffusion coefficient Kz = 6.7±0.7 cm2 s−1 was obtained for this 2-day period. During a subsequent surface survey of the iron-enriched patch, elevated levels of Fe(II) were found in surface waters presumably from Fe(II) dissolved in the rainwater that was falling at this time.Model results suggest that the reaction between uncomplexed Fe(III) and O2− was a significant source of Fe(II) during EisenEx and helped to maintain high levels of Fe(II) in the water column. This phenomenon may occur in iron enrichment experiments when two conditions are met: (i) When Fe is added to a system already saturated with regard to organic complexation and (ii) when mixing processes are slow, thereby reducing the dispersion of iron into under-saturated ... Article in Journal/Newspaper Southern Ocean Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) Southern Ocean Marine Chemistry 95 1-2 65 88 |
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Open Polar |
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Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) |
op_collection_id |
ftawi |
language |
unknown |
description |
Measurements of Fe(II) and H2O2 were carried out in the Atlantic sector of the Southern Ocean during EisenEx, an iron enrichment experiment. Iron was added on three separate occasions, approximately every 8 days, as a ferrous sulfate (FeSO4) solution. Vertical profiles of Fe(II) showed maxima consistent with the plume of the iron infusion. While H2O2 profiles revealed a corresponding minima showing the effect of oxidation of Fe(II) by H2O2, observations showed detectable Fe(II) concentrations existed for up to 8 days after an iron infusion. H2O2 concentrations increased at the depth of the chlorophyll maximum when iron concentrations returned to pre-infusion concentrations (<80 pM) possibly due to biological production related to iron reductase activity.In this work, Fe(II) and dissolved iron were used as tracers themselves for subsequent iron infusions when no further SF6 was added. EisenEx was subject to periods of weak and strong mixing. Slow mixing after the second infusion allowed significant concentrations of Fe(II) and Fe to exist for several days. During this time, dissolved and total iron in the infusion plume behaved almost conservatively as it was trapped between a relict mixed layer and a new rain-induced mixed layer. Using dissolved iron, a value for the vertical diffusion coefficient Kz = 6.7±0.7 cm2 s−1 was obtained for this 2-day period. During a subsequent surface survey of the iron-enriched patch, elevated levels of Fe(II) were found in surface waters presumably from Fe(II) dissolved in the rainwater that was falling at this time.Model results suggest that the reaction between uncomplexed Fe(III) and O2− was a significant source of Fe(II) during EisenEx and helped to maintain high levels of Fe(II) in the water column. This phenomenon may occur in iron enrichment experiments when two conditions are met: (i) When Fe is added to a system already saturated with regard to organic complexation and (ii) when mixing processes are slow, thereby reducing the dispersion of iron into under-saturated ... |
format |
Article in Journal/Newspaper |
author |
Croot, P. L. Laan, P. Nishioka, J. Strass, Volker Cisewski, Boris Boye, M. Timmermans, K. R. Bellerby, R. G. Goldson, L. Nightingale, P. Baar, H. J. W. de |
spellingShingle |
Croot, P. L. Laan, P. Nishioka, J. Strass, Volker Cisewski, Boris Boye, M. Timmermans, K. R. Bellerby, R. G. Goldson, L. Nightingale, P. Baar, H. J. W. de Spatial and temporal distribution of Fe(II) and H2O2 during EisenEx, an open ocean mesoscale iron enrichment |
author_facet |
Croot, P. L. Laan, P. Nishioka, J. Strass, Volker Cisewski, Boris Boye, M. Timmermans, K. R. Bellerby, R. G. Goldson, L. Nightingale, P. Baar, H. J. W. de |
author_sort |
Croot, P. L. |
title |
Spatial and temporal distribution of Fe(II) and H2O2 during EisenEx, an open ocean mesoscale iron enrichment |
title_short |
Spatial and temporal distribution of Fe(II) and H2O2 during EisenEx, an open ocean mesoscale iron enrichment |
title_full |
Spatial and temporal distribution of Fe(II) and H2O2 during EisenEx, an open ocean mesoscale iron enrichment |
title_fullStr |
Spatial and temporal distribution of Fe(II) and H2O2 during EisenEx, an open ocean mesoscale iron enrichment |
title_full_unstemmed |
Spatial and temporal distribution of Fe(II) and H2O2 during EisenEx, an open ocean mesoscale iron enrichment |
title_sort |
spatial and temporal distribution of fe(ii) and h2o2 during eisenex, an open ocean mesoscale iron enrichment |
publishDate |
2005 |
url |
https://epic.awi.de/id/eprint/9907/ https://doi.org/10.1016/j.marchem.2004.06.041 https://hdl.handle.net/10013/epic.20402 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
EPIC3Marine chemistry, 95(1/2), 65 |
op_relation |
Croot, P. L. , Laan, P. , Nishioka, J. , Strass, V. orcid:0000-0002-7539-1400 , Cisewski, B. , Boye, M. , Timmermans, K. R. , Bellerby, R. G. , Goldson, L. , Nightingale, P. and Baar, H. J. W. d. (2005) Spatial and temporal distribution of Fe(II) and H2O2 during EisenEx, an open ocean mesoscale iron enrichment , Marine chemistry, 95(1/2), 65 . doi:10.1016/j.marchem.2004.06.041 <https://doi.org/10.1016/j.marchem.2004.06.041> , hdl:10013/epic.20402 |
op_doi |
https://doi.org/10.1016/j.marchem.2004.06.041 |
container_title |
Marine Chemistry |
container_volume |
95 |
container_issue |
1-2 |
container_start_page |
65 |
op_container_end_page |
88 |
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1776204120650153984 |