Hyperfine and radiological characterization of soils of the provincia de Buenos Aires-Argentina

M.L. MONTES, M. A.TAYLOR, F. SIVES AND J. DESIMONI

VIENNA, AUSTRIA

Conferencia; ICAME09; 2009

HYPERFINE AND RADIOLOGICAL CHARACTERIZATION OF SOILS OF THE PROVINCIA DE BUENOS AIRES-ARGENTINA M.L. Montes, M. A.Taylor, F. Sives and J. Desimoni Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata. Instituto de Física La Plata-CONICET, Argentina. CC67, 1900 La Plata, Argentina The northeastern Pampas of Buenos Aires province is known as the ‘Pampa Ondulada’, its undulating topography results from erosion by tributary streams of the Rio Paraná and the Rio de la Plata. The mild climate has mean annual temperature and precipitation of approximately 17 ºC and 1000 mm/m2, respectively. The Pampa Ondulada is a plateau mainly composed by clayey and sandy silts that have been grouped into two or more stratigraphic units. The upper fine-grained mantle, several meters thick, is generally interpreted as a loess cover [1,2] and is subdivided into different stratigraphic units (La Postrera, Ensenada and Buenos Aires formations) [3, 4]. These sediments referred to as typical loess but including stratigraphic intervals of reworked silty deposits [5], are underlain by more compact and moderately indurate sandy silt loesslike or loessoid deposits of the Ensenada Formation [6]. This is an important agricultural and industrial area. As the concentration of metals and radionuclides in uncontaminated soil is primarily related to its origin and to pedogenic processes, a complete soil characterization to established baselines becomes an important issue since the enrichment of the soil in some element as the result of anthropogenic activities can occur. Human activities can strongly modify the natural concentrations due to the presence of dangerous residues or accumulation of elements due to the release to the environment of effluents, representing a risk for the health and the environment since they can affect the soil ecology, the agricultural production and food and water quality. Aimed to contribute to a characterization of the soils of the Provincia de Buenos Aires, the concentration of natural and anthropogenic gamma-ray-emitter nuclides was determined in surface and depth for two soils samples using an HPGe spectrometer. Mössbauer hyperfine characterization in transmission geometry with a 5 mCi 57CoRh source was also performed together with structural and chemical determinations in order to set an environmental baseline and to find a correlation between hyperfine parameters and anthropogenic pollution. Preliminary Mössbauer Room Temperature results indicate the presence of hematite, Fe(III) and Fe(II) compounds. Evolution of the relative fraction of every interaction was depth dependent. Slight changes on the activities of natural radioactive chains 234Th and 238U related with geological conditions. Small decrease on 40K activity with depth was observed. Presence of the 137Cs anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. activity with depth was observed. Presence of the 137Cs anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. related with geological conditions. Small decrease on 40K activity with depth was observed. Presence of the 137Cs anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. activity with depth was observed. Presence of the 137Cs anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. respectively. The Pampa Ondulada is a plateau mainly composed by clayey and sandy silts that have been grouped into two or more stratigraphic units. The upper fine-grained mantle, several meters thick, is generally interpreted as a loess cover [1,2] and is subdivided into different stratigraphic units (La Postrera, Ensenada and Buenos Aires formations) [3, 4]. These sediments referred to as typical loess but including stratigraphic intervals of reworked silty deposits [5], are underlain by more compact and moderately indurate sandy silt loesslike or loessoid deposits of the Ensenada Formation [6]. This is an important agricultural and industrial area. As the concentration of metals and radionuclides in uncontaminated soil is primarily related to its origin and to pedogenic processes, a complete soil characterization to established baselines becomes an important issue since the enrichment of the soil in some element as the result of anthropogenic activities can occur. Human activities can strongly modify the natural concentrations due to the presence of dangerous residues or accumulation of elements due to the release to the environment of effluents, representing a risk for the health and the environment since they can affect the soil ecology, the agricultural production and food and water quality. Aimed to contribute to a characterization of the soils of the Provincia de Buenos Aires, the concentration of natural and anthropogenic gamma-ray-emitter nuclides was determined in surface and depth for two soils samples using an HPGe spectrometer. Mössbauer hyperfine characterization in transmission geometry with a 5 mCi 57CoRh source was also performed together with structural and chemical determinations in order to set an environmental baseline and to find a correlation between hyperfine parameters and anthropogenic pollution. Preliminary Mössbauer Room Temperature results indicate the presence of hematite, Fe(III) and Fe(II) compounds. Evolution of the relative fraction of every interaction was depth dependent. Slight changes on the activities of natural radioactive chains 234Th and 238U related with geological conditions. Small decrease on 40K activity with depth was observed. Presence of the 137Cs anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. activity with depth was observed. Presence of the 137Cs anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. related with geological conditions. Small decrease on 40K activity with depth was observed. Presence of the 137Cs anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. activity with depth was observed. Presence of the 137Cs anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. 2, respectively. The Pampa Ondulada is a plateau mainly composed by clayey and sandy silts that have been grouped into two or more stratigraphic units. The upper fine-grained mantle, several meters thick, is generally interpreted as a loess cover [1,2] and is subdivided into different stratigraphic units (La Postrera, Ensenada and Buenos Aires formations) [3, 4]. These sediments referred to as typical loess but including stratigraphic intervals of reworked silty deposits [5], are underlain by more compact and moderately indurate sandy silt loesslike or loessoid deposits of the Ensenada Formation [6]. This is an important agricultural and industrial area. As the concentration of metals and radionuclides in uncontaminated soil is primarily related to its origin and to pedogenic processes, a complete soil characterization to established baselines becomes an important issue since the enrichment of the soil in some element as the result of anthropogenic activities can occur. Human activities can strongly modify the natural concentrations due to the presence of dangerous residues or accumulation of elements due to the release to the environment of effluents, representing a risk for the health and the environment since they can affect the soil ecology, the agricultural production and food and water quality. Aimed to contribute to a characterization of the soils of the Provincia de Buenos Aires, the concentration of natural and anthropogenic gamma-ray-emitter nuclides was determined in surface and depth for two soils samples using an HPGe spectrometer. Mössbauer hyperfine characterization in transmission geometry with a 5 mCi 57CoRh source was also performed together with structural and chemical determinations in order to set an environmental baseline and to find a correlation between hyperfine parameters and anthropogenic pollution. Preliminary Mössbauer Room Temperature results indicate the presence of hematite, Fe(III) and Fe(II) compounds. Evolution of the relative fraction of every interaction was depth dependent. Slight changes on the activities of natural radioactive chains 234Th and 238U related with geological conditions. Small decrease on 40K activity with depth was observed. Presence of the 137Cs anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. activity with depth was observed. Presence of the 137Cs anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. related with geological conditions. Small decrease on 40K activity with depth was observed. Presence of the 137Cs anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. activity with depth was observed. Presence of the 137Cs anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. 234Th and 238U related with geological conditions. Small decrease on 40K activity with depth was observed. Presence of the 137Cs anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. activity with depth was observed. Presence of the 137Cs anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. 40K activity with depth was observed. Presence of the 137Cs anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. 137Cs anthropogenic isotope was found on the soil surface up to a depth of about 25 cm in agreement with the fallout of the South Pacific nuclear tests. Further experiments in order to identify the Mössbauer interaction and the magnetic properties of the samples are in progress. [1] F. González Bonorino, Revista de la Asociación Geológica Argentina 20 (1965) 67. [2] A. M. Blasi, A. M. Zárate, R.A. Kemp, Revista Asociación Argentina de Sedimentología 8 (2001) 77. [3] J. C. Bidegain, Quaternary of South America and Antarctic Peninsula 11 (1998) 207. [4] Bidegain, J.C. and Rico Y., Revista de la Asociación Geológica Argentina 59 (2004) 451. [5] P. A. Imbellone, A. Cumba, Revista de la Asociación Argentina de Sedimentología 10 (2003) 3. [6] J. C. Riggi,, F. Fidalgo, O. Martinez, N. Porro, Revista de la Asociación Geológica Argentina 44 (1986) 316.