During the monitoring of an open ocean diatom bloom in the Atlantic Sector of the Southern Ocean (Polarstern cruise ANT-XXVIII/3) for 3 weeks in January/February2012, we collected 0.2-μm-filtered samples for analysis of cobalt (Co), cadmium (Cd), manganese (Mn), and nickel (Ni) involved in its biogeochemical cycle . In one station, we also analyzed samples unfiltered and filtered by 53 μm to try to infer the cycling of the particulate fraction of these metals. Co, Cd, Mn and Ni were determined by inductively coupled plasma - mass spectrometry (ICP-MS).