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Constraining the contribution of hydrothermal iron to Southern Ocean export production using deep ocean iron observations

Citation

Tagliabue, A and Bowie, AR and Holmes, T and Latour, PM and van der Merwe, P and Gault-Ringold, M and Wuttig, K and Resing, JA, Constraining the contribution of hydrothermal iron to Southern Ocean export production using deep ocean iron observations, Frontiers in Marine Science, 9 Article 754517. ISSN 2296-7745 (2022) [Refereed Article]


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Copyright Statement

Copyright 2022 Tagliabue, Bowie, Holmes, Latour, van der Merwe, Gault-Ringold, Wuttig and Resing. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) License (https://creativecommons.org/licenses/by/4.0/). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

DOI: doi:10.3389/fmars.2022.754517

Abstract

Hydrothermal iron supply contributes to the Southern Ocean carbon cycle via the regulation of regional export production. However, as hydrothermal iron input estimates are coupled to helium, which are uncertain depending on whether helium inputs are based on ridge spreading rates or inverse modelling, questions remain regarding the magnitude of the export production impacts. A particular challenge is the limited observations of dissolved iron (dFe) supply from the abyssal Southern Ocean ridge system to directly assess different hydrothermal iron supply scenarios. We combine ocean biogeochemical modelling with new observations of dFe from the abyssal Southern Ocean to assess the impact of hydrothermal iron supply estimated from either ridge spreading rate or inverse helium modelling on Southern Ocean export production. The hydrothermal contribution to dFe in the upper 250 m reduces 45 fold when supply is based on inverse modelling, relative to those based on spreading rate, translating into a 3673% reduction in the impact of hydrothermal iron on export production. However, only the spreading rate input scheme reproduces observed dFe anomalies >1 nM around the circum-Antarctic ridge. The model correlation with observations drops 3 fold under the inverse modelling input scheme. The best dFe scenario has a residence time for hydrothermal iron that is between 21 and 34 years, highlighting the importance of rapid physical mixing to surface waters. Overall, because of its short residence time, hydrothermal Fe supplied locally by circum-Antarctic ridges is most important to the Southern Ocean carbon cycle and our results highlight decoupling between hydrothermal iron and helium supply.

Item Details

Item Type:Refereed Article
Keywords:trace metals, hydrothermalism, Southern Ocean, biogeochemical modelling, iron cycle in oceans
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Chemical oceanography
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the environmental sciences
UTAS Author:Bowie, AR (Professor Andrew Bowie)
UTAS Author:Holmes, T (Dr Thomas Holmes)
UTAS Author:Latour, PM (Ms Pauline Latour)
UTAS Author:van der Merwe, P (Dr Pier van der Merwe)
UTAS Author:Gault-Ringold, M (Dr Melanie East)
UTAS Author:Wuttig, K (Dr Kathrin Wuttig)
ID Code:149124
Year Published:2022
Deposited By:Oceans and Cryosphere
Deposited On:2022-03-10
Last Modified:2022-04-08
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