The distribution of dissolved thallium in the different water masses of the western sector of the Ross Sea (Antarctica) during the austral summer |
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Institution: | 1. Dipartimento di Scienze Biologiche, Geologiche e Ambientali (BiGeA), University of Bologna, Piazza di Porta San Donato 1, Bologna, Italy;2. General and Analytical Chemistry, Montanuniversität Leoben, Franz-Josef-Str. 18, Leoben, Austria |
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Abstract: | Vertical profiles for total dissolved thallium were obtained at five sites in the western sector of the Ross Sea (Southern Ocean), Antarctica. 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). 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. 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). 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. |
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