Dissolved iron and iron isotopes in the southeastern Pacific Ocean
The Southeast Pacific Ocean is a severely understudied yet dynamic region for trace metals such as iron, since it experiences steep redox and productivity gradients in upper waters and strong hydrothermal iron inputs to deep waters. In this study, we report the dissolved iron (dFe) distribution from...
Published in: | Global Biogeochemical Cycles |
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ftmit:oai:dspace.mit.edu:1721.1/110777 2023-06-11T04:05:32+02:00 Dissolved iron and iron isotopes in the southeastern Pacific Ocean Conway, Tim M. Thyng, Kristen M. John, Seth G. Fitzsimmons, Jessica Nicole Lee, Jong-Mi Kayser, Richard A Boyle, Edward A Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Boyle, Edward Fitzsimmons, Jessica Nicole Lee, Jong-Mi Kayser, Richard A Boyle, Edward A 2016-10 application/pdf http://hdl.handle.net/1721.1/110777 en_US eng American Geophysical Union (AGU) http://dx.doi.org/10.1002/2015GB005357 Global Biogeochemical Cycles 0886-6236 http://hdl.handle.net/1721.1/110777 Fitzsimmons, Jessica N.; Conway, Tim M.; Lee, Jong-Mi et al. “Dissolved Iron and Iron Isotopes in the Southeastern Pacific Ocean.” Global Biogeochemical Cycles 30, 10 (October 2016): 1372–1395 © 2016 American Geophysical Union orcid:0000-0002-6394-1866 Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. Prof. Boyle via Chris Sherratt Article http://purl.org/eprint/type/JournalArticle 2016 ftmit https://doi.org/10.1002/2015GB005357 2023-05-29T08:46:01Z The Southeast Pacific Ocean is a severely understudied yet dynamic region for trace metals such as iron, since it experiences steep redox and productivity gradients in upper waters and strong hydrothermal iron inputs to deep waters. In this study, we report the dissolved iron (dFe) distribution from seven stations and Fe isotope ratios (δ⁵⁶Fe) from three of these stations across a near-zonal transect from 20 to 27°S. We found elevated dFe concentrations associated with the oxygen-deficient zone (ODZ), with light δ⁵⁶Fe implicating porewater fluxes of reduced Fe. However, temporal dFe variability and rapid δ⁵⁶Fe shifts with depth suggest gradients in ODZ Fe source and/or redox processes vary over short-depth/spatial scales. The dFe concentrations decreased rapidly offshore, and in the upper ocean dFe was controlled by biological processes, resulting in an Fe:C ratio of 4.2 µmol/mol. Calculated vertical diffusive Fe fluxes were greater than published dust inputs to surface waters, but both were orders of magnitude lower than horizontal diffusive fluxes, which dominate dFe delivery to the gyre. The δ⁵⁶Fe data in the deep sea showed evidence for a −0.2‰ Antarctic Intermediate Water end-member and a heavy δ⁵⁶Fe of +0.55‰ for distally transported hydrothermal dissolved Fe from the East Pacific Rise. These heavy δ⁵⁶Fe values were contrasted with the near-crustal δ56Fe recorded in the hydrothermal plume reaching Station ALOHA in the North Pacific. The heavy hydrothermal δ⁵⁶Fe precludes a nanopyrite composition of hydrothermal dFe and instead suggests the presence of oxides or, more likely, binding of hydrothermal dFe by organic ligands in the distal plume. National Science Foundation (U.S.) (NSF Award 0645960) National Science Foundation (U.S.) (NSF-OIA Award EF-0424599) Article in Journal/Newspaper Antarc* Antarctic DSpace@MIT (Massachusetts Institute of Technology) Antarctic Pacific Global Biogeochemical Cycles 30 10 1372 1395 |
institution |
Open Polar |
collection |
DSpace@MIT (Massachusetts Institute of Technology) |
op_collection_id |
ftmit |
language |
English |
description |
The Southeast Pacific Ocean is a severely understudied yet dynamic region for trace metals such as iron, since it experiences steep redox and productivity gradients in upper waters and strong hydrothermal iron inputs to deep waters. In this study, we report the dissolved iron (dFe) distribution from seven stations and Fe isotope ratios (δ⁵⁶Fe) from three of these stations across a near-zonal transect from 20 to 27°S. We found elevated dFe concentrations associated with the oxygen-deficient zone (ODZ), with light δ⁵⁶Fe implicating porewater fluxes of reduced Fe. However, temporal dFe variability and rapid δ⁵⁶Fe shifts with depth suggest gradients in ODZ Fe source and/or redox processes vary over short-depth/spatial scales. The dFe concentrations decreased rapidly offshore, and in the upper ocean dFe was controlled by biological processes, resulting in an Fe:C ratio of 4.2 µmol/mol. Calculated vertical diffusive Fe fluxes were greater than published dust inputs to surface waters, but both were orders of magnitude lower than horizontal diffusive fluxes, which dominate dFe delivery to the gyre. The δ⁵⁶Fe data in the deep sea showed evidence for a −0.2‰ Antarctic Intermediate Water end-member and a heavy δ⁵⁶Fe of +0.55‰ for distally transported hydrothermal dissolved Fe from the East Pacific Rise. These heavy δ⁵⁶Fe values were contrasted with the near-crustal δ56Fe recorded in the hydrothermal plume reaching Station ALOHA in the North Pacific. The heavy hydrothermal δ⁵⁶Fe precludes a nanopyrite composition of hydrothermal dFe and instead suggests the presence of oxides or, more likely, binding of hydrothermal dFe by organic ligands in the distal plume. National Science Foundation (U.S.) (NSF Award 0645960) National Science Foundation (U.S.) (NSF-OIA Award EF-0424599) |
author2 |
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Boyle, Edward Fitzsimmons, Jessica Nicole Lee, Jong-Mi Kayser, Richard A Boyle, Edward A |
format |
Article in Journal/Newspaper |
author |
Conway, Tim M. Thyng, Kristen M. John, Seth G. Fitzsimmons, Jessica Nicole Lee, Jong-Mi Kayser, Richard A Boyle, Edward A |
spellingShingle |
Conway, Tim M. Thyng, Kristen M. John, Seth G. Fitzsimmons, Jessica Nicole Lee, Jong-Mi Kayser, Richard A Boyle, Edward A Dissolved iron and iron isotopes in the southeastern Pacific Ocean |
author_facet |
Conway, Tim M. Thyng, Kristen M. John, Seth G. Fitzsimmons, Jessica Nicole Lee, Jong-Mi Kayser, Richard A Boyle, Edward A |
author_sort |
Conway, Tim M. |
title |
Dissolved iron and iron isotopes in the southeastern Pacific Ocean |
title_short |
Dissolved iron and iron isotopes in the southeastern Pacific Ocean |
title_full |
Dissolved iron and iron isotopes in the southeastern Pacific Ocean |
title_fullStr |
Dissolved iron and iron isotopes in the southeastern Pacific Ocean |
title_full_unstemmed |
Dissolved iron and iron isotopes in the southeastern Pacific Ocean |
title_sort |
dissolved iron and iron isotopes in the southeastern pacific ocean |
publisher |
American Geophysical Union (AGU) |
publishDate |
2016 |
url |
http://hdl.handle.net/1721.1/110777 |
geographic |
Antarctic Pacific |
geographic_facet |
Antarctic Pacific |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_source |
Prof. Boyle via Chris Sherratt |
op_relation |
http://dx.doi.org/10.1002/2015GB005357 Global Biogeochemical Cycles 0886-6236 http://hdl.handle.net/1721.1/110777 Fitzsimmons, Jessica N.; Conway, Tim M.; Lee, Jong-Mi et al. “Dissolved Iron and Iron Isotopes in the Southeastern Pacific Ocean.” Global Biogeochemical Cycles 30, 10 (October 2016): 1372–1395 © 2016 American Geophysical Union orcid:0000-0002-6394-1866 |
op_rights |
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. |
op_doi |
https://doi.org/10.1002/2015GB005357 |
container_title |
Global Biogeochemical Cycles |
container_volume |
30 |
container_issue |
10 |
container_start_page |
1372 |
op_container_end_page |
1395 |
_version_ |
1768376864177389568 |