High particulate iron(II) content in glacially sourced dusts enhances productivity of a model diatom

Elizabeth M. Shoenfelt; Jing Sun; Gisela Winckler; Michael Kaplan; Alejandra Borunda; Kayla R. Farrell; Patricio Moreno; Diego M. Gaiero; Cristina Recasens; Raymond N. Sambrotto; Benjamin C. Bostick

High particulate iron(II) content in glacially sourced dusts enhances productivity of a model diatom
Shoenfelt, Elizabeth M.
Sun, Jing
Winckler, Gisela
Kaplan, Michael
Borunda, Alejandra
Farrell, Kayla R.
Moreno, Patricio
Gaiero, Diego M.
Recasens, Cristina
Sambrotto, Raymond N.
Bostick, Benjamin C.
Lamont-Doherty Earth Observatory
Earth and Environmental Engineering
Environmental Science (Barnard College)
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Science Advances
Data underlying this article can be found at: https://doi.org/10.7916/D8223137
Little is known about the bioavailability of iron (Fe) in natural dusts and the impact of dust mineralogy on Fe utilization by photosynthetic organisms. Variation in the supply of bioavailable Fe to the ocean has the potential to influence the global carbon cycle by modulating primary production in the Southern Ocean. Much of the dust deposited across the Southern Ocean is sourced from South America, particularly Patagonia, where the waxing and waning of past and present glaciers generate fresh glaciogenic material that contrasts with aged and chemically weathered nonglaciogenic sediments. We show that these two potential sources of modern-day dust are mineralogically distinct, where glaciogenic dust sources contain mostly Fe(II)-rich primary silicate minerals, and nearby nonglaciogenic dust sources contain mostly Fe(III)-rich oxyhydroxide and Fe(III) silicate weathering products. In laboratory culture experiments, Phaeodactylum tricornutum, a well-studied coastal model diatom, grows more rapidly, and with higher photosynthetic efficiency, with input of glaciogenic particulates compared to that of nonglaciogenic particulates due to these differences in Fe mineralogy. Monod nutrient accessibility models fit to our data suggest that particulate Fe(II) content, rather than abiotic solubility, controls the Fe bioavailability in our Fe fertilization experiments. Thus, it is possible for this diatom to access particulate Fe in dusts by another mechanism besides uptake of unchelated Fe (Fe′) dissolved from particles into the bulk solution. If this capability is widespread in the Southern Ocean, then dusts deposited to the Southern Ocean in cold glacial periods are likely more bioavailable than those deposited in warm interglacial periods.
Environmental sciences
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Elizabeth M. Shoenfelt, Jing Sun, Gisela Winckler, Michael Kaplan, Alejandra Borunda, Kayla R. Farrell, Patricio Moreno, Diego M. Gaiero, Cristina Recasens, Raymond N. Sambrotto, Benjamin C. Bostick, , High particulate iron(II) content in glacially sourced dusts enhances productivity of a model diatom, Columbia University Academic Commons, .

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