title: Photoreduction of Terrigenous Fe-Humic Substances Leads to Bioavailable Iron in Oceans.
abstract: Humic substances (HS) are important iron chelators responsible for the transport of iron from freshwater systems to the open sea, where iron is essential for marine organisms. Evidence suggests that iron complexed to HS comprises the bulk of the iron ligand pool in near-coastal waters and shelf seas. River-derived HS have been investigated to study their transport to, and dwell in oceanic waters. A library of iron model compounds and river-derived Fe-HS samples were probed in a combined X-ray absorption spectroscopy (XAS) and valence-to-core X-ray emission spectroscopy (VtC-XES) study at the Fe K-edge. The analyses performed revealed that iron complexation in HS samples is only dependent on oxygen-containing HS functional groups, such as carboxyl and phenol. The photoreduction mechanism of FeIII-HS in oceanic conditions into bioavailable aquatic FeIIforms, highlights the importance of river-derived HS as an iron source for marine organisms. Consequently, such mechanisms are a vital component of the upper-ocean iron biogeochemistry cycle.
authors.affiliation: Institut für Biophysikalische Chemie Fakultät für Chemie Universität Wien Althanstraße 14 1090 Vienna Austria.
authors.forename: Amir
authors.initials: A
authors.lastname: Blazevic
authors.affiliation: Institute of Inorganic Chemistry Faculty of Chemistry University of Vienna Währinger Straße 42 1090 Vienna Austria.
authors.forename: Ewelina
authors.initials: E
authors.lastname: Orlowska
authors.affiliation: Institute of Inorganic Chemistry Faculty of Chemistry University of Vienna Währinger Straße 42 1090 Vienna Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kandioller
authors.affiliation: Institute of Inorganic Chemistry Faculty of Chemistry University of Vienna Althanstraße 14 1090 Vienna Austria.
authors.forename: Franz
authors.initials: F
authors.lastname: Jirsa
authors.affiliation: Institute of Inorganic Chemistry Faculty of Chemistry University of Vienna Währinger Straße 42 1090 Vienna Austria.
authors.forename: Bernhard K
authors.initials: BK
authors.lastname: Keppler
authors.affiliation: Institut für Angewandte Synthesechemie Technische Universität Wien Getreidemarkt 9/163-AC 1060 Vienna Austria.
authors.forename: Myrvete
authors.initials: M
authors.lastname: Tafili-Kryeziu
authors.affiliation: Institut für Angewandte Synthesechemie Technische Universität Wien Getreidemarkt 9/163-AC 1060 Vienna Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Linert
authors.affiliation: Institute of Inorganic Chemistry Faculty of Chemistry University of Vienna Althanstraße 14 1090 Vienna Austria.
authors.forename: Rudolf F
authors.initials: RF
authors.lastname: Krachler
authors.affiliation: Institute of Inorganic Chemistry Faculty of Chemistry University of Vienna Althanstraße 14 1090 Vienna Austria.
authors.forename: Regina
authors.initials: R
authors.lastname: Krachler
authors.affiliation: Institut für Biophysikalische Chemie Fakultät für Chemie Universität Wien Althanstraße 14 1090 Vienna Austria.
authors.forename: Annette
authors.identifier: 0000-0002-5919-0553
authors.initials: A
authors.lastname: Rompel
keywords: Eisenchelatoren; Fe-K-Kante; Gelöste organische Materie; Komplexiertes Eisen; Natürliche organische Materie