The importance of kinetics and redox in the biogeochemical cycling of iron in the surface ocean
It is now well established that Iron (Fe) is a limiting element in many regions of the open ocean. Our current understanding of the key processes which control iron distribution in the open ocean have been largely based on thermodynamic measurements performed under the assumption of equilibrium cond...
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ftnuigalway:oai:https://researchrepository.universityofgalway.ie:10379/10958 2024-09-30T14:44:10+00:00 The importance of kinetics and redox in the biogeochemical cycling of iron in the surface ocean Croot, Peter L. Heller, Maija I. 2012-01-01 http://hdl.handle.net/10379/10958 https://doi.org/10.13025/27908 https://doi.org/10.3389/fmicb.2012.00219 unknown Frontiers Media SA Frontiers in Microbiology Croot, Peter L. Heller, Maija I. (2012). The importance of kinetics and redox in the biogeochemical cycling of iron in the surface ocean. Frontiers in Microbiology 3 , 1664-302X http://hdl.handle.net/10379/10958 https://doi.org/10.13025/27908 doi:10.3389/fmicb.2012.00219 Attribution-NonCommercial-NoDerivs 3.0 Ireland https://creativecommons.org/licenses/by-nc-nd/3.0/ie/ iron biogeochemistry iron solubility redox kinetics complexation kinetics north pacific-ocean fe(iii) hydroxide solubilities cathodic stripping voltammetry natural organic-ligands dissolved iron phytoplankton bloom atlantic-ocean southern-ocean equatorial pacific coastal waters Article 2012 ftnuigalway https://doi.org/10.13025/2790810.3389/fmicb.2012.00219 2024-09-17T14:44:30Z It is now well established that Iron (Fe) is a limiting element in many regions of the open ocean. Our current understanding of the key processes which control iron distribution in the open ocean have been largely based on thermodynamic measurements performed under the assumption of equilibrium conditions. Using this equilibrium approach, researchers have been able to detect and quantify organic complexing ligands in seawater and examine their role in increasing the overall solubility of iron. Our current knowledge about iron bioavailability to phytoplankton and bacteria is also based heavily on carefully controlled laboratory studies where it is assumed the chemical species are in equilibrium in line with the free ion association model and/or its successor the biotic ligand model. Similarly most field work on iron biogeochemistry generally consists of a single profile which is in essence a "snap-shot" in time of the system under investigation. However it is well known that the surface ocean is an extremely dynamic environment and it is unlikely if thermodynamic equilibrium between all the iron species present is ever truly achieved. In sunlit waters this is mostly due to the daily passage of the sun across the sky leading to photoredox processes which alter Fe speciation by cycling between redox states and between inorganic and organic species. Episodic deposition events, dry and wet, are also important perturbations to iron cycling as they bring in new iron to the system and alter the equilibrium between iron species and phases. Here we utilize new field data collected in the open ocean on the complexation kinetics of iron in the surface ocean to identify the important role of weak iron binding ligands (i.e., those that cannot maintain iron in solution indefinitely at seawater pH: alpha(FeL) < alpha(Fe')) in allowing transient increases in iron solubility in response to iron deposition events. Experiments with the thermal O-2(-) source SOTS-1 also indicate the short term impact of this species on iron ... Article in Journal/Newspaper Southern Ocean National University of Ireland (NUI), Galway: ARAN Pacific Southern Ocean |
institution |
Open Polar |
collection |
National University of Ireland (NUI), Galway: ARAN |
op_collection_id |
ftnuigalway |
language |
unknown |
topic |
iron biogeochemistry iron solubility redox kinetics complexation kinetics north pacific-ocean fe(iii) hydroxide solubilities cathodic stripping voltammetry natural organic-ligands dissolved iron phytoplankton bloom atlantic-ocean southern-ocean equatorial pacific coastal waters |
spellingShingle |
iron biogeochemistry iron solubility redox kinetics complexation kinetics north pacific-ocean fe(iii) hydroxide solubilities cathodic stripping voltammetry natural organic-ligands dissolved iron phytoplankton bloom atlantic-ocean southern-ocean equatorial pacific coastal waters Croot, Peter L. Heller, Maija I. The importance of kinetics and redox in the biogeochemical cycling of iron in the surface ocean |
topic_facet |
iron biogeochemistry iron solubility redox kinetics complexation kinetics north pacific-ocean fe(iii) hydroxide solubilities cathodic stripping voltammetry natural organic-ligands dissolved iron phytoplankton bloom atlantic-ocean southern-ocean equatorial pacific coastal waters |
description |
It is now well established that Iron (Fe) is a limiting element in many regions of the open ocean. Our current understanding of the key processes which control iron distribution in the open ocean have been largely based on thermodynamic measurements performed under the assumption of equilibrium conditions. Using this equilibrium approach, researchers have been able to detect and quantify organic complexing ligands in seawater and examine their role in increasing the overall solubility of iron. Our current knowledge about iron bioavailability to phytoplankton and bacteria is also based heavily on carefully controlled laboratory studies where it is assumed the chemical species are in equilibrium in line with the free ion association model and/or its successor the biotic ligand model. Similarly most field work on iron biogeochemistry generally consists of a single profile which is in essence a "snap-shot" in time of the system under investigation. However it is well known that the surface ocean is an extremely dynamic environment and it is unlikely if thermodynamic equilibrium between all the iron species present is ever truly achieved. In sunlit waters this is mostly due to the daily passage of the sun across the sky leading to photoredox processes which alter Fe speciation by cycling between redox states and between inorganic and organic species. Episodic deposition events, dry and wet, are also important perturbations to iron cycling as they bring in new iron to the system and alter the equilibrium between iron species and phases. Here we utilize new field data collected in the open ocean on the complexation kinetics of iron in the surface ocean to identify the important role of weak iron binding ligands (i.e., those that cannot maintain iron in solution indefinitely at seawater pH: alpha(FeL) < alpha(Fe')) in allowing transient increases in iron solubility in response to iron deposition events. Experiments with the thermal O-2(-) source SOTS-1 also indicate the short term impact of this species on iron ... |
format |
Article in Journal/Newspaper |
author |
Croot, Peter L. Heller, Maija I. |
author_facet |
Croot, Peter L. Heller, Maija I. |
author_sort |
Croot, Peter L. |
title |
The importance of kinetics and redox in the biogeochemical cycling of iron in the surface ocean |
title_short |
The importance of kinetics and redox in the biogeochemical cycling of iron in the surface ocean |
title_full |
The importance of kinetics and redox in the biogeochemical cycling of iron in the surface ocean |
title_fullStr |
The importance of kinetics and redox in the biogeochemical cycling of iron in the surface ocean |
title_full_unstemmed |
The importance of kinetics and redox in the biogeochemical cycling of iron in the surface ocean |
title_sort |
importance of kinetics and redox in the biogeochemical cycling of iron in the surface ocean |
publisher |
Frontiers Media SA |
publishDate |
2012 |
url |
http://hdl.handle.net/10379/10958 https://doi.org/10.13025/27908 https://doi.org/10.3389/fmicb.2012.00219 |
geographic |
Pacific Southern Ocean |
geographic_facet |
Pacific Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_relation |
Frontiers in Microbiology Croot, Peter L. Heller, Maija I. (2012). The importance of kinetics and redox in the biogeochemical cycling of iron in the surface ocean. Frontiers in Microbiology 3 , 1664-302X http://hdl.handle.net/10379/10958 https://doi.org/10.13025/27908 doi:10.3389/fmicb.2012.00219 |
op_rights |
Attribution-NonCommercial-NoDerivs 3.0 Ireland https://creativecommons.org/licenses/by-nc-nd/3.0/ie/ |
op_doi |
https://doi.org/10.13025/2790810.3389/fmicb.2012.00219 |
_version_ |
1811645621091696640 |