Potentially bioavailable iron delivery by iceberg-hosted sediments and atmospheric dust to the polar oceans

Raiswell, Robert, Hawkings, Jon R., Benning, Liane G., Baker, Alex R., Death, Ros, Albani, Samuel, Mahowald, Natalie, Krom, Michael D., Poulton, Simon W., Wadham, Jemma and Tranter, Martyn (2016) Potentially bioavailable iron delivery by iceberg-hosted sediments and atmospheric dust to the polar oceans. Biogeosciences, 13 (13). pp. 3887-3900. ISSN 1726-4170

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Abstract

Iceberg-hosted sediments and atmospheric dust transport potentially bioavailable iron to the Arctic and Southern oceans as ferrihydrite. Ferrihydrite is nanoparticulate and more soluble, as well as potentially more bioavailable, than other iron (oxyhydr)oxide minerals (lepidocrocite, goethite, and hematite). A suite of more than 50 iceberg-hosted sediments contain a mean content of 0.076 wt % Fe as ferrihydrite, which produces iceberg-hosted Fe fluxes ranging from 0.7 to 5.5 and 3.2 to 25 Gmoles yr−1 to the Arctic and Southern oceans respectively. Atmospheric dust (with little or no combustion products) contains a mean ferrihydrite Fe content of 0.038 wt % (corresponding to a fractional solubility of  ∼  1 %) and delivers much smaller Fe fluxes (0.02–0.07 Gmoles yr−1 to the Arctic Ocean and 0.0–0.02 Gmoles yr−1 to the Southern Ocean). New dust flux data show that most atmospheric dust is delivered to sea ice where exposure to melting/re-freezing cycles may enhance fractional solubility, and thus fluxes, by a factor of approximately 2.5. Improved estimates for these particulate sources require additional data for the iceberg losses during fjord transit, the sediment content of icebergs, and samples of atmospheric dust delivered to the polar regions.

Item Type: Article
Additional Information: © Author(s) 2016. This work is distributed under the Creative Commons Attribution 3.0 License.
Faculty \ School: Faculty of Science > School of Environmental Sciences
Depositing User: Pure Connector
Date Deposited: 24 Sep 2016 00:02
Last Modified: 22 Jul 2020 00:57
URI: https://ueaeprints.uea.ac.uk/id/eprint/59780
DOI: 10.5194/bg-13-3887-2016

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