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Research on the distribution of natural radionuclides in Antartica is rare and thus, there is great interest in to know their occurrence and factors related to its mobilization, transference and accumulation in this extremely fragile environment. Natural radionuclides have been used intensively as tracers in the ocean, helping to better understand processes as sinking and particle ressuspention, water masses mixture and oceanic circulation. Th (t1⁄2 = 24.1 days) is a particle-reactive radionuclide produced continuously in seawater by the decay of its soluble precursor conservative with salinity U (t1⁄2 = 4.5 10 years). Since Th presents relatively short half-life, it is used to quantify processes that occur in temporal scale varying from days to weeks. The disequilibrium Th/ U in the surface ocean has been applied to estimate carbon fluxes exported via sinking material. The flux of particles biologically productive out of the euphotic zone in the Southern Ocean has special attention due to its importance in the control of CO2 atmospheric concentrations. The radionuclides Pb (t1⁄2 = 22.3 years) and Po (t1⁄2 = 138 days) are also particle-reactive. The disequilibrium Po/ Pb has been used to estimate fluxes of particles exported in the ocean in the time scale of weeks. The long-lived Ra isotopes, Ra (t1⁄2 = 1,600 years) and Ra (t1⁄2 = 5.75 years) are soluble in seawater, presenting unique properties that make them excellent tracers of water masses. This research work had the aim to

Evolução temporal das distribuições dos radionuclídeos naturais U-238, Th-234, Ra-226, Ra-228, Pb-210 e Po-210 no estreito de Bransfield, Peninsula Antártica