Mechanisms of dissolved and labile particulate iron supply to shelf waters and phytoplankton blooms off South Georgia, Southern Ocean ...

• Main Authors: Schlosser, Christian, Schmidt, Katrin, Aquilina, Alfred, Homoky, William B., Castrillejo, Maxi, Mills, Rachel A., Patey, Matthew D., Fielding, Sophie, Atkinson, Angus, Achterberg, Eric P.
• Format: Article in Journal/Newspaper
• Language: English
• Published: ETH Zurich 2018
• Subjects: Antarc*; Antarctic; Southern Ocean
• Online Access: https://dx.doi.org/10.3929/ethz-b-000319246; http://hdl.handle.net/20.500.11850/319246

The island of South Georgia is situated in the iron (Fe)-depleted Antarctic Circumpolar Current of the Southern Ocean. Iron emanating from its shelf system fuels large phytoplankton blooms downstream of the island, but the actual supply mechanisms are unclear. To address this, we present an inventory of Fe, manganese (Mn), and aluminium (Al) in shelf sediments, pore waters, and the water column in the vicinity of South Georgia, alongside data on zooplankton-mediated Fe cycling processes, and provide estimates of the relative dissolved Fe (DFe) fluxes from these sources. Seafloor sediments, modified by authigenic Fe precipitation, were the main particulate Fe source to shelf bottom waters as indicated by the similar Fe ∕ Mn and Fe ∕ Al ratios for shelf sediments and suspended particles in the water column. Less than 1 % of the total particulate Fe pool was leachable surface-adsorbed (labile) Fe and therefore potentially available to organisms. Pore waters formed the primary DFe source to shelf bottom waters, ... : Biogeosciences, 15 (16) ...