Frequent resuspension of glaciomarine coastal sediments as an important source of reactive iron to the West Antarctic Peninsula

Southern Ocean primary productivity is often limited by the availability of the essential micronutrient iron (Fe), and sediment-derived fluxes of Fe from the Antarctic shelf have been linked with hotspots of productivity. Glacial meltwater along the West Antarctic Peninsula delivers significant volumes of Fe-rich glacially weathered material to shelf surface sediments. Measured acoustic doppler current profiler and acoustic backscatter turbidity data indicate ongoing resuspension of sediment in the coastal region. Onboard mesocosm experiments simulated resuspension of oxic sediments, rich in highly reactive Fe (2–9 mg g−1), in the nearshore glaciated West Antarctic Peninsula across King George Island, Anvers Island, and Adelaide Island. These experiments produced a high sustained bottom water enrichment in dissolved Fe of ∼ 4–12 nM over the 48 h experiment duration.

Our observations support a dissolved Fe flux to the water column of 0.18–4.0 µmol m−2 d−1 by resuspension within the glaciated fjords, demonstrating that resuspension of reactive oxic nearshore sediments is a key source of dissolved and reactive particulate Fe to Antarctic shelf waters, the export of which could potentially supply bioavailable Fe to Fe-limited Southern Ocean waters.