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Variability in iron (II) oxidation kinetics across diverse hydrothermal sites on the northern Mid Atlantic Ridge

Variability in iron (II) oxidation kinetics across diverse hydrothermal sites on the northern Mid Atlantic Ridge
Variability in iron (II) oxidation kinetics across diverse hydrothermal sites on the northern Mid Atlantic Ridge
One of the recently recognized main sources of iron to the deep ocean inventory is the hydrothermal activity associated with mid-ocean ridges. Little is known about the oxidation kinetics of iron(II) within these environments, especially the dependence on physico-chemical parameters such as temperature (T), pH, particle size-fractionation and the effect of organic matter.

Following sample collection during the GA13 section cruise, the iron(II) oxidation at six hydrothermal vent sites (Menez Gwen, Lucky Strike, Rainbow, Lost City, Broken Spur and TAG) along the Mid-Atlantic Ridge were investigated, revealing high variability. The Fe(II) oxidation rate constant analysis from multiple stations at two sites (Rainbow and TAG), revealed that factors, other than T and pH, controlled the oxidation process. Experiments on the effect of particle size-fractionation and organic matter at different pH showed that the presence of organic ligands and colloidal size particles delayed the oxidation process, while not affecting the overall pH dependency.

Extending our analysis to the broader relationship between the Fe(II) oxidation rate constants across a range of temperatures (between 2 and 25 °C) and pH (between 7 and 8) on a set of selected hydrothermal samples allowed us to derive a multiparametric equation to model the iron(II) oxidation rate constants in the ocean. This equation covers a larger range of temperatures than previous published equations, improving its applicability for global biogeochemical models.
Fe(II) half-life time, Fe(II) oxidation kinetics, Hydrothermal, Kinetic equation, Mid Atlantic Ridge
0016-7037
143-157
González-santana, David
0c11c0bc-3c1b-4399-8f41-9066a5b4d4c6
González-dávila, Melchor
4253f234-7c8a-45c8-8db4-c6ba462ec288
Lohan, Maeve C.
6ca10597-2d0f-40e8-8e4f-7619dfac5088
Artigue, Lise
8dfc3629-ad86-49de-a233-2ba6319d9c78
Planquette, Hélène
39d0733f-37e4-4fe4-bb32-c7157dd8e1e7
Sarthou, Géraldine
0073ad71-3180-44e7-b76a-1f2fb1178bbc
Tagliabue, Alessandro
23ecb1dd-3cf4-46eb-b059-637a04f2439b
Santana-casiano, J. Magdalena
06121ef7-ece8-452d-b608-60115015e1a4
González-santana, David
0c11c0bc-3c1b-4399-8f41-9066a5b4d4c6
González-dávila, Melchor
4253f234-7c8a-45c8-8db4-c6ba462ec288
Lohan, Maeve C.
6ca10597-2d0f-40e8-8e4f-7619dfac5088
Artigue, Lise
8dfc3629-ad86-49de-a233-2ba6319d9c78
Planquette, Hélène
39d0733f-37e4-4fe4-bb32-c7157dd8e1e7
Sarthou, Géraldine
0073ad71-3180-44e7-b76a-1f2fb1178bbc
Tagliabue, Alessandro
23ecb1dd-3cf4-46eb-b059-637a04f2439b
Santana-casiano, J. Magdalena
06121ef7-ece8-452d-b608-60115015e1a4

González-santana, David, González-dávila, Melchor, Lohan, Maeve C., Artigue, Lise, Planquette, Hélène, Sarthou, Géraldine, Tagliabue, Alessandro and Santana-casiano, J. Magdalena (2021) Variability in iron (II) oxidation kinetics across diverse hydrothermal sites on the northern Mid Atlantic Ridge. Geochimica et Cosmochimica Acta, 297, 143-157. (doi:10.1016/j.gca.2021.01.013).

Record type: Article

Abstract

One of the recently recognized main sources of iron to the deep ocean inventory is the hydrothermal activity associated with mid-ocean ridges. Little is known about the oxidation kinetics of iron(II) within these environments, especially the dependence on physico-chemical parameters such as temperature (T), pH, particle size-fractionation and the effect of organic matter.

Following sample collection during the GA13 section cruise, the iron(II) oxidation at six hydrothermal vent sites (Menez Gwen, Lucky Strike, Rainbow, Lost City, Broken Spur and TAG) along the Mid-Atlantic Ridge were investigated, revealing high variability. The Fe(II) oxidation rate constant analysis from multiple stations at two sites (Rainbow and TAG), revealed that factors, other than T and pH, controlled the oxidation process. Experiments on the effect of particle size-fractionation and organic matter at different pH showed that the presence of organic ligands and colloidal size particles delayed the oxidation process, while not affecting the overall pH dependency.

Extending our analysis to the broader relationship between the Fe(II) oxidation rate constants across a range of temperatures (between 2 and 25 °C) and pH (between 7 and 8) on a set of selected hydrothermal samples allowed us to derive a multiparametric equation to model the iron(II) oxidation rate constants in the ocean. This equation covers a larger range of temperatures than previous published equations, improving its applicability for global biogeochemical models.

Text
Gonzalez-Santanaetal2021_kFe_Manuscript - Accepted Manuscript
Restricted to Repository staff only until 22 January 2023.
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More information

Accepted/In Press date: 13 January 2020
Published date: 15 March 2021
Keywords: Fe(II) half-life time, Fe(II) oxidation kinetics, Hydrothermal, Kinetic equation, Mid Atlantic Ridge

Identifiers

Local EPrints ID: 448627
URI: http://eprints.soton.ac.uk/id/eprint/448627
ISSN: 0016-7037
PURE UUID: 1e6b5ff7-de40-400f-90ef-b31ed647e514
ORCID for Maeve C. Lohan: ORCID iD orcid.org/0000-0002-5340-3108

Catalogue record

Date deposited: 28 Apr 2021 16:32
Last modified: 26 Nov 2021 03:00

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Contributors

Author: David González-santana
Author: Melchor González-dávila
Author: Maeve C. Lohan ORCID iD
Author: Lise Artigue
Author: Hélène Planquette
Author: Géraldine Sarthou
Author: Alessandro Tagliabue
Author: J. Magdalena Santana-casiano

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