Dissolved iron in the Arctic shelf seas and surface waters of the Central Arctic Ocean: Impact of Arctic river water and ice-melt

• Published in: Journal of Geophysical Research: Oceans
• Main Authors: Klunder, Marten B., Bauch, Dorothea, Laan, Patrick, De Baar, Hein J. W., Van Heuven, Steven, Ober, Sven
• Format: Article in Journal/Newspaper
• Language: English
• Published: AGU (American Geophysical Union) 2012
• Subjects: Arctic; Arctic Ocean; Barents Sea; Kara Sea; Laptev Sea; laptev; Phytoplankton; Sea ice
• Online Access: https://oceanrep.geomar.de/id/eprint/13294/; https://oceanrep.geomar.de/id/eprint/13294/1/2011_Klunder_Bauch__ea__JGR_authorsfinal.pdf; https://oceanrep.geomar.de/id/eprint/13294/2/2012_Klunder_Bauch_etal_2011JC007133.pdf; https://doi.org/10.1029/2011JC007133

Key Points - DFe in the Arctic shelves and surface is linked to freshwater and alkalinity - Fluvial input main contributor to high DFe, low alkalinity in Central Arctic - Remineralisation and biological depletion determine DFe in the Arctic Shelf Seas Abstract Concentrations of dissolved (<0.2 μm) Fe (DFe) in the Arctic shelf seas and in the surface waters of the Central Arctic Ocean are presented. In the Barents and Kara seas, near-surface DFe minima indicate depletion of DFe by phytoplankton growth. Below the surface, lower DFe concentrations in the Kara Sea (~0.4-0.6 nM) than in the Barents Sea (~0.6-0.8 nM) likely reflect scavenging removal or biological depletion of DFe. Very high DFe concentrations (>10 nM) in the bottom waters of the Laptev Sea shelf may be attributed to either sediment resuspension, sinking of brine or regeneration of DFe in the lower layers. A significant correlation (R2 = 0.60) between salinity and DFe is observed. Using δ18O, salinity ,nutrients and total alkalinity data, the main source for the high (>2 nM) DFe concentrations in the Amundsen and Makarov Basins is identified as (Eurasian) river water, transported with the Transpolar Drift (TPD). On the North American side of the TPD, the DFe concentrations are low (< 0.8 nM) and variations are determined by the effects of sea-ice meltwater, biological depletion and remineralization and scavenging in halocline waters from the shelf. This distribution pattern of DFe is also supported by the ratio between unfiltered and dissolved Fe (high (> 4) above the shelf and low ( < 4) off the shelf).