Open WL Archief (OWA)

t]) were between 1.2 and 6.4 nM eq. Fe. The organic ligands offshore ranged between 1.0 and 3.0 nM eq. Fe. The southern boundary of the Antarctic Circumpolar Current (SB ACC) separated the organic ligands on the shelf from bloom-associated ligands offshore. Overall, organic ligand concentrations always exceeded DFe concentrations (excess ligand concentration, [

′] = 0.8–5.0 nM eq. Fe). The [

′] made up to 80 % of [

t], suggesting that any additional Fe input can be stabilized in the dissolved form via organic complexation. The denser modified Circumpolar Deep Water (mCDW) on the shelf showed the highest complexation capacity of Fe (

Fe'L; the product of [

′] and conditional binding strength of ligands, KcondFe'L). Since Fe is also supplied by shelf sediments and glacial discharge, the high complexation capacity over the shelf can keep Fe dissolved and available for local primary productivity later in the season upon sea-ice melting.