title: Flocculated meltwater particles control Arctic land-sea fluxes of labile iron.
abstract: Glacial meltwater systems supply the Arctic coastal ocean with large volumes of sediment and potentially bioavailable forms of iron, nitrogen and carbon. The particulate fraction of this supply is significant but estuarine losses have been thought to limit the iron supply from land. Here, our results reveal how flocculation (particle aggregation) involving labile iron may increase horizontal transport rather than enhance deposition close to the source. This is shown by combining field observations in Disko Fjord, West Greenland, and laboratory experiments. Our data show how labile iron affects floc sizes, shapes and densities and consequently yields low settling velocities and extended sediment plumes. We highlight the importance of understanding the flocculation mechanisms when examining fluxes of meltwater transported iron in polar regions today and in the future, and we underline the influence of terrestrial hotspots on the nutrient and solute cycles in Arctic coastal waters.
authors.affiliation: Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen, Denmark.
authors.forename: Thor Nygaard
authors.initials: TN
authors.lastname: Markussen
authors.affiliation: Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen, Denmark.
authors.forename: Bo
authors.initials: B
authors.lastname: Elberling
authors.affiliation: Center for Marine Environmental Sciences (MARUM), University of Bremen, Leobener Str., D-28359 Bremen, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Winter
authors.affiliation: Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen, Denmark.
authors.forename: Thorbjørn Joest
authors.initials: TJ
authors.lastname: Andersen
mesh_terms: D001110:Arctic Regions; D005427:Flocculation; D007501:Iron / Q000032:analysis*; D009792:Oceans and Seas; D010316:Particle Size; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D007501:Iron