Hyperfine and radiological characterization of soils of the province of Buenos Aires, Argentina

• Autores: Montes, María Luciana; Taylor, Marcela Andrea; Mercader, Roberto C.; Sives, Flavio Rubén; Desimoni, Judith
• Año de publicación: 2010
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Ciencias Exactas; Mossbauer spectroscopy; Gamma rays; Soils; Buenos Aires; Argentina
• Institución: Universidad Nacional de La Plata

The depth profile concentration of both natural and anthropogenic gamma-ray-emitter nuclides were determined in soil samples collected in an area located at 34° 54.452′ S, 58° 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 (L_D) for depths below 25 cm, exhibiting a maximum at 10 cm beneath the surface. The Mössbauer spectra show two magnetic sextets associated with α-Fe₂O₃ and Fe₃O₄, as well as two Fe⁺³ 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 α-Fe₂O₃ one when de depth increases. No correlation between Fe₃O₄ and the ¹³⁷Cs was identificated.
Facultad de Ciencias Exactas
Instituto de Física La Plata