Tracing continental weathering and water mass mixing in the Atlantic sector of the Southern Ocean with neodymium and hafnium isotopes

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The subject of this study is a detailed investigation of the distribution of neodymium (Nd) and hafnium (Hf) isotopes in dissolved and particulate form in the water column of the Atlantic sector of the Southern Ocean. Nd isotopes have been shown to be a powerful geochemical tracer for present and past water masses in the ocean. The combination with Hf isotopes was applied for the characterization of continental weathering regimes. So far there are, however, nearly no data for the water column of the Southern Ocean, which severely restricts the reliable application of this combination of tracers for present day studies and reconstructions of the past. We collected large volume water samples and the suspended particulate fraction from the same locations during RV Polarstern Expedition ANT XXIV/3 along the Zero meridian and further across the Weddell Sea and the Drake Passage. We will determine the isotope composition of Nd and for the first time Hf in dissolved and particulate form to characterize the isotope composition of the different Southern Ocean water masses and their sources and to gain new insight into the influence of Antarctic weathering processes on the geochemical properties of the Southern Ocean. These data will serve as a basis for more reliable application of these isotopes as tracers in paleo-oceanography.