A call for refining the role of humic-like substances in the oceanic iron cycle
Type | Article | ||||||||||||||||
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Date | 2020-04 | ||||||||||||||||
Language | English | ||||||||||||||||
Author(s) | Whitby Hannah9, 10, Planquette Helene1, Cassar Nicolas1, 2, Bucciarelli Eva10, Osburn Christopher L.3, Janssen David J.4, 5, Cullen Jay T.6, González Aridane G.1, 7, Völker Christoph8, Sarthou Geraldine1 | ||||||||||||||||
Affiliation(s) | 1 : CNRS, Univ Brest, IRD, Ifremer, LEMAR, F-29280, Plouzané, France 2 : Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA 3 : Marine, Earth, and Atmospheric Sciences, NC State University, Raleigh, NC, 27695, USA 4 : Institute of Ocean Sciences, Fisheries and Oceans Canada, 9860 W Saanich Rd, Sidney, BC, V8L 5T5, Canada 5 : University of Bern, Institute of Geological Sciences & Oeschger Center for Climate Change Research, Baltzerstrasse 1-3 3012, Bern, Switzerland 6 : School of Earth and Ocean Sciences, University of Victoria, 3800 Finnerty Road, Victoria, BC, V8P 5C2, Canada 7 : Instituto de Oceanografía y Cambio Global, IOCAG. Universidad de Las Palmas de Gran Canaria, ULPGC, Parque Científico Tecnológico de Taliarte, 35214, Telde, Spain 8 : Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570, Bremerhaven, Germany 9 : University of Liverpool, Liverpool, UK 10 : CNRS, Univ Brest, IRD, Ifremer, LEMAR, F-29280, Plouzané, France |
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Source | Scientific Reports (2045-2322) (Springer Science and Business Media LLC), 2020-04 , Vol. 10 , N. 1 , P. 6144 (12p.) | ||||||||||||||||
DOI | 10.1038/s41598-020-62266-7 | ||||||||||||||||
WOS© Times Cited | 26 | ||||||||||||||||
Abstract | Primary production by phytoplankton represents a major pathway whereby atmospheric CO2 is sequestered in the ocean, but this requires iron, which is in scarce supply. As over 99% of iron is complexed to organic ligands, which increase iron solubility and microbial availability, understanding the processes governing ligand dynamics is of fundamental importance. Ligands within humic-like substances have long been considered important for iron complexation, but their role has never been explained in an oceanographically consistent manner. Here we show iron co-varying with electroactive humic substances at multiple open ocean sites, with the ratio of iron to humics increasing with depth. Our results agree with humic ligands composing a large fraction of the iron-binding ligand pool throughout the water column. We demonstrate how maximum dissolved iron concentrations could be limited by the concentration and binding capacity of humic ligands, and provide a summary of the key processes that could influence these parameters. If this relationship is globally representative, humics could impose a concentration threshold that buffers the deep ocean iron inventory. This study highlights the dearth of humic data, and the immediate need to measure electroactive humics, dissolved iron and iron-binding ligands simultaneously from surface to depth, across different ocean basins. |
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