Iron study during a time series in the western Weddell pack ice

Samples of sea ice, snow, brine and underlying seawater were collected in the western Weddell pack ice at the ISPOL drifting station (Ice Station POLarstern, 68°S/55°W) in spring–summer period (November 2004–January 2005). Total-dissolvable, dissolved and particulate Fe concentrations in the sea ice environment were determined every 5 days during the time series, together with relevant physical, chemical and biological parameters. From 29 November to 30 December, a decrease in all forms of Fe measured was observed, likely to be the result of enhanced ice permeability as summer proceeds. At the beginning of the time series, melting of the upper ice layer took place together with brine drainage process. This would enable the seeding of Fe from the ice matrix towards the upper water column below. 70% of this Fe was supplied during the first 10 days of the survey, while the ice cover is still present. Flux estimates from the sampled area furthermore highlight the relevant role of the pack ice in the biogeochemical cycle of Fe in the western Weddell Sea.