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Resupply of mesopelagic dissolved iron controlled by particulate iron composition


Bressac, M and Guieu, C and Ellwood, MJ and Tagliabue, A and Wagener, T and Laurenceau-Cornec, EC and Whitby, H and Sarthou, G and Boyd, PW, Resupply of mesopelagic dissolved iron controlled by particulate iron composition, Nature Geoscience, 12 pp. 995-1000. ISSN 1752-0894 (2019) [Refereed Article]

Copyright Statement

© The Author(s), under exclusive licence to Springer Nature Limited 2019

DOI: doi:10.1038/s41561-019-0476-6


The dissolved iron supply controls half of the oceansí primary productivity. Resupply by the remineralization of sinking particles, and subsequent vertical mixing, largely sustains this productivity. However, our understanding of the drivers of dissolved iron resupply, and their influence on its vertical distribution across the oceans, is still limited due to sparse observations. There is a lack of empirical evidence as to what controls the subsurface iron remineralization due to difficulties in studying mesopelagic biogeochemistry. Here we present estimates of particulate transformations to dissolved iron, concurrent oxygen consumption and iron-binding ligand replenishment based on in situ mesopelagic experiments. Dissolved iron regeneration efficiencies (that is, replenishment over oxygen consumption) were 10- to 100-fold higher in low-dust subantarctic waters relative to higher-dust Mediterranean sites. Regeneration efficiencies are heavily influenced by particle composition. Their make-up dictates ligand release, controls scavenging, modulates ballasting and may lead to the differential remineralization of biogenic versus lithogenic iron. At high-dust sites, these processes together increase the iron remineralization length scale. Modelling reveals that in oceanic regions near deserts, enhanced lithogenic fluxes deepen the ferricline, which alter the vertical patterns of dissolved iron replenishment, and set its redistribution at the global scale. Such wide-ranging regeneration efficiencies drive different vertical patterns in dissolved iron replenishment across oceanic provinces.

Item Details

Item Type:Refereed Article
Keywords:iron ocean cycle, bacterial remineralization, mesopelagic zone
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Biological oceanography
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the earth sciences
UTAS Author:Bressac, M (Dr Matthieu Bressac)
UTAS Author:Laurenceau-Cornec, EC (Mr Emmanuel Laurenceau)
UTAS Author:Boyd, PW (Professor Philip Boyd)
ID Code:137339
Year Published:2019
Web of Science® Times Cited:9
Deposited By:Ecology and Biodiversity
Deposited On:2020-02-10
Last Modified:2020-04-02

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