Fe-binding organic ligands in coastal and frontal regions of the western Antarctic Peninsula

Abstract. Organic ligands are a key factor determining the availability of dissolved iron (DFe) in high-nutrient low-chlorophyll (HNLC) areas Southern Ocean. In this study, organic speciation Fe is investigated along natural gradient western Antarctic Peninsula, from an ice-covered shelf to open ocean. An electrochemical approach, competitive ligand exchange – adsorptive cathodic stripping voltammetry (CLE-AdCSV), was applied. Our results indicated that surface water on associated with ice-algal exudates, possibly combined melting sea ice. deeper supplied via resuspension slope or sediments. Further offshore, most likely related development phytoplankton blooms ocean waters. On shelf, total concentrations ([Lt]) were between 1.2 and 6.4 nM eq. Fe. The offshore ranged 1.0 3.0 southern boundary Circumpolar Current (SB ACC) separated bloom-associated offshore. Overall, always exceeded DFe (excess concentration, [L?] = 0.8–5.0 Fe). made up 80 % [Lt], suggesting any additional input can be stabilized form complexation. denser modified Deep Water (mCDW) showed highest complexation capacity (?Fe'L; product conditional binding strength ligands, KFe'Lcond). Since also by sediments glacial discharge, high over keep available for local primary productivity later season upon sea-ice melting.