Physical weathering intensity controls bioavailable primary iron(II) silicate content in major global dust sources

Elizabeth Shoenfelt, Gisela Winkler, Amber L Annett, Katharine R Hendry, Benajmin C Bostick

Research output: Contribution to journalArticle (Academic Journal)peer-review

3 Citations (Scopus)
80 Downloads (Pure)

Abstract

The speciation of iron (Fe) reaching the ocean, for instance in wind-blown dust and coastal sediments, impacts its bioavailability to phytoplankton and its impact on atmospheric carbon dioxide (CO2) and climate. For dust reaching the Southern Ocean, primary Fe(II) silicates that are physically weathered from bedrock are highly bioavailable compared to more chemically weathered, Fe(III)-rich species, suggesting that weathering in dust source regions impacts the bioavailable Fe supply. However, this phenomenon has not been studied in other important terrestrial Fe sources, where weathering regimes and source geology vary. Here, we use Fe X-ray absorption spectroscopy on marine sediment cores to show that major global dust and sediment sources impacted by high physical weathering contain abundant primary minerals, and thus are overlooked as a source of highly bioavailable Fe globally. Thus, it is important to consider the role of physical versus chemical weathering in Fe fertilization and biotic CO2 cycling.
Original languageEnglish
Pages (from-to)10854-10864
Number of pages11
JournalGeophysical Research Letters
Volume46
Issue number19
Early online date11 Sep 2019
DOIs
Publication statusPublished - 16 Oct 2019

Keywords

  • dust
  • iron
  • physical weathering
  • bioavailability
  • mineralogy
  • carbon cycle

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