Investigations of Iron and Manganese Fluxes from Hydrothermal Sources in the South Atlantic Ocean

Makoto Saito, Marine Chemistry and Geochemistry



In recent decades the micronutrient iron has been shown to have a major role in controlling the key oceanic processes of primary productivity and nitrogen fixation. Yet our understanding of the major sources of iron to the oceans has been constrained by a severe lack of measurements, particularly in the deep ocean. Recently, we documented the presence of a large >1000km wide dissolved iron hydrothermal plume in the South Atlantic Ocean. While recent studies in the Pacific and Southern Oceans have found similar scale dissolved hydrothermal iron plumes, a recent modeling study does not predict a significant contribution of hydrothermal iron flux in the slow-spreading ridge basins, such as the South Atlantic Ocean. We propose to determine the extent of this South Atlantic hydrothermal iron plume through the collection of ~600 dissolved iron and manganese samples to create a full-depth meridional ocean section from 13oS to 33oS along the Southern Mid-Atlantic ridge on a German hydrothermal vent cruise. This study will help to constrain the importance of slow-spreading basins to the global oceanic iron inventory and allow improvements in global models.