CONICET | Buscador de Institutos y Recursos Humanos

The depth profile concentration of both natural and anthropogenic gamma-ray-emitter nuclides were determined in soil samples collected in an area located at 34º 54.452´ S, 58º 8.365´ W, down to 50 cm in depth, using an hyper-pure Ge spectrometer. The soil samples were also characterized by means of Mössbauer spectrometry and X-ray diffraction. The activities of 238U and 232Th natural chains remain constant in depth at 41 Bq/kg and 46 Bq/kg, respectively, while the 40K activity increases from 531 Bq/kg to 618 Bq/kg between 2.5 cm y 25.5 cm of depth. The only anthropogenic detected nuclide is 137Cs, whose activity changes form 1.4 Bq/kg to values lower than the detection limit (LD) for depths below 25 cm, exhibiting a maximum at 10 cm beneath the surface. The Mössbauer spectra show two magnetic sextets associated with a-Fe2O3 and Fe3O4, as well as two Fe+3 and Fe+2 doublets, probably originated in octahedral and tetrahedral sites of paramagnetic phases. The Fe3+ paramagnetic signal relative fraction increases up to 82% at the expense of the a-Fe2O3 one when the depth increases. No correlation between Fe3O4 and the 137Cs was identified.