INSTITUTO DE FISICA LA PLATA
Unidad Ejecutora - UE
congresos y reuniones científicas
Radiological and Hyperfine Characterization of soils from the Northeastern region of the Province of Buenos Aires, Argentina
Conferencia; LACAME 2010; 2010
Universidad de San Marcos
The depth profile activity concentrations of both natural( 40K, 226Ra and 232Th) and anthropogenic 137Cs) gamma-ray emitter nuclides were determined in soil samples collected in areas (inland and coastal area of the La Plata River) located at the Northeastern region of the Province of Buenos Aires, Argentina. These studies have been complemented with a Mössbauer effect hyperfine characterization, pH, texture and organic carbon content measurements. According to Mössbauer results, sample compositions differ from one site to the other. In the coastal area soils, Fe3O4 was not detected, the a-Fe2O3 contribution is lower and the relative fractions are nearly constant in depth. In the in land area, Fe3+ fraction increases up to 82%, mainly at the expense of the a-Fe2O3 one. The main observed activity resulted originated from the decay of the 40K (540 Bq/kg -750 Bq/kg) with following in importance those of 238U 60 Bq/kg 92 Bq/kg ) and 232Th (37 Bq/kg - 46 Bq/kg ) chains. The activity of 235U resulted in all the cases lower than the detection limit (LD= 0.02 Bq/kg). The only detected anthropogenic nuclide was 137Cs, arising from the fallout of the South Pacific weapon tests. Differences in depth distributions were detected, three of then follow a Gaussian type behavior associated to a convective-diffusive process. It was observed a correlation between the natural nuclides activities and the Mössbauer relative fractions, while there is not an apparent correlation between the 137Cs profile and the relative fraction of Fe3O4, as well as with other iron species.