Natural iron-organic carbon colloids as geochemical nanovectors for phosphorus transport in Arctic environments

Seasonal waterlogging and/or drying of Arctic peat soils commonly results in leaching of reduced iron [Fe(II)] and organic carbon (OC). These natural iron organic carbon (Fe-OC) flocs contain OC and phosphorus species with high bioavailability, which are critical for primary productivity as these flocs are delivered into Arctic oceans. We request 12 shifts of beamtime at ID21 to produce spatially resolved P and Fe K-edge µ-XANES maps of Fe-OC flocs that were collected along a 30-km transect of a peat-draining river in South Iceland. Our aim is to determine changes in structure, distribution and chemical speciation of phosphorus and iron in these Fe-OC flocs that occur during their transport via rivers from peatlands to marine environments. Our results will allow us to determine the contribution and role of such Fe-OC flocs in P and Fe cycling in Arctic environments.