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The role of iron and organic matter under investigation in the Southern Ocean- The ProIron team is about to finish their experiments on-board the RV Polarstern.

During the PS97 expedition in the Drake Passage (Southern Ocean) aboard RV-Polarstern, we conducted several experiments in 3 contrasted stations typical from High Nutrients Low Chlorophyll (HNLC) regions. We performed numerous incubation experiments at 0°C to investigate how iron chemistry and other trace elements control phytoplankton in this part of the ocean (Photo 1).


Photo 1 : Incubation set up to investigate the role of exopolymeric substances on Fe bioavailability.
Photo Credit: Sonia Blanco Ameijeiras (UNIGE)

At the end of each incubation, we collected a complete set of chemical and biological samples using normal and trace metal clean filtration techniques (Photos 2-4).


Labo Polarstern.jpg

Photo 2: Damien Cabanes doing filtration in the clean container from Bremen University. Photo Credit: Christel Hassler (UNIGE). Photo 3: Sonia Blanco Ameijeiras and Simon Heike doing filtration for pigments, POC and biogenic silica. Photo Credit: Christel Hassler (UNIGE).
Photo 4: Christel Hassler doing photo-physiology measurements at 0 °C. Photo Credit: Sonia Blanco Ameijeiras (UNIGE).


In parallel, on each station, we isolated psychrophilic bacteria and viruses typical from the Southern Ocean as well as in-situ dissolved organic matter by concentrating 1000L of filtered seawater using a tangential ultrafiltration system in trace metal condition as well (Photo 5).

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Photo 5: Left panel ultrafiltration using 1000 L for filtered seawater concentrating organic compounds based on size properties; Right panel: filtered and ultrafiltered seawater are slowly being passed through columns insuring a retention of organics based on chemical properties.

So far, we have pumped 18’000 L of seawater, done more than 1’000 filtrations, 600 55Fe analyses, ran 240 incubations and collected more than 2’000 samples for analysis back on shore.

Yyou can follow us on  Helmholtz expedition blog PS97

31 Mar 2016

News 2016