Dissolved Fe in the Deep and Upper Arctic Ocean With a Focus on Fe Limitation in the Nansen Basin

Fe‐Binding Organic Ligands in the Humic‐Rich TransPolar Drift in the Surface Arctic Ocean Using Multiple Voltammetric Methods

“…This DFe, and the HS it is mobilized by, is introduced into the Arctic Ocean via the major rivers surrounding it, increasing the potential for primary production. This enrichment is contained to the TPD (Table ), and prior study has already shown that outside the TPD Fe limitation already occurs in the surface waters over the Nansen Basin (Rijkenberg et al, ). In a future Arctic Ocean, subject to lesser sea ice extent and therefore a higher light availability and increased primary production (Arrigo & Van Dijken, ; Bhatt et al, ; Vancoppenolle et al, ), Fe‐limitation is expected to become more important and the difference in DFe and Fe‐binding organic ligands between surface waters inside and outside the flow path of the TPD will be exacerbated.…”

“…It then stands to reason that Fe‐binding organic ligands outside the TPD are of different origins, such as sea ice melt, marine biota, and even marine humics. Hence, we can now say that indeed all of the increased DFe transported across the Arctic Ocean (Rijkenberg et al, ) is complexed and predominantly by HS. This DFe, and the HS it is mobilized by, is introduced into the Arctic Ocean via the major rivers surrounding it, increasing the potential for primary production.…”

“…Titration results were fitted to a nonlinear Langmuir model (Gerringa et al, ), with modes for a single ligand class (L t ) and two ligand classes (L 1 and L 2 ) using R (R Development Core Team, ). DFe concentrations used in these calculations were derived from Flow Injection Analysis measurements (Rijkenberg et al, ) either from parallel samples onboard (stations 69, 99, and 125) or from the frozen samples in the home lab (stations 101 and 153). The Langmuir model yields the ligand concentration ([L t ] or [L 1 ] + [L 2 ]) in equivalent nanomole of Fe (Eq.…”

“…It is well established that the TPD transports riverine‐based water and ice from the shelf seas across the Arctic Ocean, eventually out to the Atlantic Ocean through the Fram Strait (Gordienko & Laktionov, ; Gregor et al, ). The flow path of the TPD varies yearly with the Arctic Oscillation Index (Macdonald et al, ) and has been constrained in the context of DOM and Fe biogeochemistry (Rijkenberg et al, ; Slagter et al, ). Given its susceptibility to rapid climate change (Intergovernmental Panel on Climate Change, ), the Arctic Ocean is a particularly important region to study the biogeochemistry of terrestrial matter.…”

Assessing the Role of High‐Frequency Winds and Sea Ice Loss on Arctic Phytoplankton Blooms in an Ice‐Ocean‐Biogeochemical Model

“…Iron limitation in the western North Atlantic has received little attention, but field measurements in summer 2010 captured surface iron concentrations near zero in Labrador Sea (Rijkenberg et al, ). Likewise, field measurements in the high‐latitude eastern North Atlantic and the central Arctic indicate that iron indeed limits phytoplankton productivity in some regions (Birchill et al, ; Nielsdóttir et al, ; Rijkenberg et al, ). These results suggest that further exploring iron limitation in the Labrador Sea could be a worthy target of future research.…”