First results of Uranium-236 in the South Atlantic Ocean

Trabajo presentado a la II International Conference on Radioecological Concentration Processes (50 years later), celebrada en Sevilla (España) del 6 al 9 de noviembre de 2016.
In the last years, 236U (T1/2=2.34·107 y), which is essentially an anthropogenic radionuclide, has been established as a new oceanographic tracer thanks to its conservative behaviour in seawater. At the Centro Nacional de Aceleradores (CNA), in Seville (Spain), it has been recently demonstrated that 236U can be determined at environmental levels on the 1 MV Accelerator Mass Spectrometry (AMS) system. In the framework of the existing collaboration between the National Marine Information and Research Centre (NatMIRC), in Namibia, and the IAEA Environment Laboratories in Monaco, 236U has been analysed by AMS at CNA in a set of seawater samples collected in the northern Benguela upwelling system, on the Namibian coast. In surface samples, 236U/238U atom ratios at the level of 10-10 have been obtained, in agreement with the expected values for the so-called global fallout. The 236U inventories reported up to now in seawater are discussed.
We thank the Namibian Ministry of Fisheries and Marine Resources (MFMR) for its support. This work has been financed from the project FIS2015-69673-P, provided by the Spanish Ministry of Economy and partially by Fundación Cámara Sevilla through a Grant for Graduate Studies. Financial support was provided by MFMR and NAEL.