A call for refining the role of humic-like substances in the oceanic iron cycle


Contact
Christoph.Voelker [ at ] awi.de

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.



Item Type
Article
Authors
Divisions
Primary Division
Programs
Primary Topic
Peer revision
ISI/Scopus peer-reviewed
Publication Status
Published
Eprint ID
52514
DOI 10.1038/s41598-020-62266-7

Cite as
Whitby, H. , Planquette, H. , Cassar, N. , Bucciarelli, E. , Osburn, C. L. , Janssen, D. J. , Cullen, J. T. , González, A. G. , Völker, C. and Sarthou, G. (2020): A call for refining the role of humic-like substances in the oceanic iron cycle , Scientific Reports, 10 (1) . doi: 10.1038/s41598-020-62266-7


Download
[img]
Preview
PDF
Whitby20SciRep.pdf

Download (1MB) | Preview

Share


Citation

Research Platforms
N/A

Campaigns


Actions
Edit Item Edit Item