Dissolved REE could therefore be used as tracers to understand the deep circulation of the SO (Pacific sector). Some of the HSSW samples show enrichment in Neodymium (Nd). A significant increase in Terbium (Tb) concentration was observed in the HSSW and ISW, the two principal water masses contributing to the formation of Antarctic Bottom Water (AABW) in the Ross Sea area, and in LSSW. Our results show significant differences between the REE patterns of the main water masses present in the SO: we could observe specific signature in the High Salinity Shelf Water (HSSW), Ice Shelf Water (ISW) and Low Salinity Shelf Water (LSSW).
4 samples were collected and analysed in the framework of a test experiment, as part of the WISSARD Project (Whillans Ice Stream Subglacial Access Research Drilling). The REEs were measured in the water samples collected during the 06 austral summers. The present essay contributes to the existing literature on rare earth elements (REEs) in the southern hemisphere by presenting the first data, to our knowledge, on the vertical profiles of dissolved REEs in 71 samples collected in the central-western sector of the Ross Sea (Southern Ocean-SO). Thallium appears to have a nearly conservative distribution in seawater as highlighted also from the comparison with the profiles of two seawater conservative elements: molybdenum and uranium however it also highlights the presence of a reactive component of thallium, which is more influenced by the presence of particulate matter, oxygen content and fluorescence. The analyses were performed using an ICP-SFMS that has enabled us to obtain reliable Tl concentration measurements with a relative standard deviation of better than 2.5% and a detection limit, calculated as three times the standard deviation of the “blank signal” of 0.69 pmol L− 1 (1.60 pmol L− 1, obtained analysing four blank solutions (n = 5) prepared with the same water and acid used for the dilution/acidification steps). Our samples show a concentration varying from 22 to 55 pmol L− 1 with a mean value of 46 pmol L− 1, depending on depth, dissolved oxygen, salinity and local topographic characteristics. Thallium is estimated to have a natural mean seawater concentration between 50 and 65 pmol L− 1 with higher values in the North Pacific (65 ± 5 pmol L− 1) and lower in the Bay of Biscay and Irish Sea (49 ± 3 pmol L− 1). Vertical profiles for total dissolved thallium were obtained at five sites in the western sector of the Ross Sea (Southern Ocean), Antarctica.
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