Distribution of dissolved iron in Antarctic sea ice: Spatial, seasonal, and inter‐annual variability

Abstract

Results from recent field studies in Antarctic sea ice show no clear differences in dissolved iron (dFe) concentrations between pack ice sampled in East Antarctica (2.6–20.5 nmol/L), in the Weddell Sea (0.7–36.8 nmol/L), and in the Bellingshausen Sea (1.1–30.2 nmol/L). Dissolved Fe concentrations were also similar in land‐fast ice collected in East Antarctica (0.7–4.3 nmol/L) and in the Ross Sea (1.1–6.0 nmol/L). In contrast, we observed a remarkable seasonal drawdown of dFe in sea ice for all reported studies. Furthermore, large inter‐annual variations in depth‐averaged dFe and organic matter concentrations were observed in sea ice collected in the East Antarctic sector between expeditions in late austral winter‐spring of 2003 and 2007. Variability in the water column productivity and in the magnitude of the “new” Fe supply (e.g., upwelling, resuspended shelf sediments) at the time of sea ice formation could explain such differences.