Decoupling of particles and dissolved iron downstream of Greenlandic glacier outflows

• dFe and Fe speciation of suspended sediment were studied in West Greenland fjords. levels largely capped at 10 nM, regardless particulate speciation. Fe(II)-rich biotite-like particles dominated fjords with Precambrian shield geology. Fe(III)-rich nanoparticles a fjord tertiary basalt decoupled on the spatial scale Glaciers can be significant locally dominant source iron (Fe), biologically essential micronutrient, high latitude coastal seas. The vast majority this glacial delivery is associated particles, yet solid-phase specifically relationships that govern exchange between dissolved phases these environments are poorly described. In work, we performed measurements situ (dFe) along meltwater particle plumes three transects around Disko Bay Ameralik Fjord (West Greenland). Measurements combined K-edge X-ray absorption spectroscopy analysis ?40 samples obtained from same select depth profiles down to 300 m. We observed relatively constant (4 nM for nearly all measurements) across widely varying Fe(II) contents (from 20 90% Fe(II)), indicating concentrations had little dependence oxidation state sediment. Particulate data grouped by underlying bedrock geology, consisting 80-90% geology poorly-ordered Fe(III) (<20-30% Fe(II)) one sediments derived basalts. Our characterization indicated no change average bonding environment transects, implying coordination not readily labile form scale. results suggest glacially-modified waters buffered low concentration due factors other than mineralogy glacier-derived inert