Na, K, Ca, Mg, and U-series in fossil bone and the proposal of a radial diffusion–adsorption model of uranium uptake
| Autor: | H. Velasco, A.S. Cid, Cibele B. Zamboni, Kita Macario, Renan Pereira Cardoso, D.L. Valladares, L. Kovacs, C. Goso, A. Corona, Roberto Meigikos dos Anjos, D. Perea, Marcelo Costa Muniz |
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| Rok vydání: | 2014 |
| Předmět: |
RDA
Health Toxicology and Mutagenesis Mineralogy chemistry.chemical_element Fossil bone Spatial distribution Ciencias de la Tierra y relacionadas con el Medio Ambiente Diffusion Adsorption U-uptake Animals Environmental Chemistry Neutron activation analysis Waste Management and Disposal Mammals Series (stratigraphy) Macrauchenia patachonica Tibia Fossils Paleontology Neutron Activation Analysis General Medicine Metals Light Models Theoretical Uranium Pollution Spectrometry Gamma Archaeology chemistry Radial diffusion Macrauchenia-patachonica Ciencias Medioambientales Calcium CIENCIAS NATURALES Y EXACTAS |
| Zdroj: | Journal of Environmental Radioactivity. 136:131-139 |
| ISSN: | 0265-931X |
| Popis: | Fossil bones are often the only materials available for chronological reconstruction of important archeological sites. However, since bone is an open system for uranium, it cannot be dated directly and therefore it is necessary to develop models for the U uptake. Hence, a radial diffusion–adsorption (RDA) model is described. Unlike the classic diffusion–adsorption (D–A) model, RDA uses a cylindrical geometry to describe the U uptake in fossil bones. The model was applied across a transverse section of a tibia of an extinct megamammal Macrauchenia patachonica from the La Paz Local Fauna, Montevideo State, Uruguay. Measurements of spatial distribution of Na, K, Ca, and Mg were also performed by neutron activation analysis (NAA). Gamma-ray spectrometric U-series dating was applied to determine the age of the bone sample. From U concentration profile, it was possible to observe the occurrence of a relatively slow and continuous uranium uptake under constant conditions that had not yet reached equilibrium, since the uranium distribution is a ∪-shaped closed-system. Predictions of the RDA model were obtained for a specific geochemical scenario, indicating that the effective diffusion coefficient D/R in this fossil bone is (2.4 ± 0.6)10−12 cm2s−1. Mean values of Na, K, Ca, and Mg contents along the radial line of the fossil tibia are consistent with the expected behavior for spatial distributions of these mineral elements across a modern bone section. This result indicates that the fossil tibia may have its mineral structure preserved. Fil: Cid, A. S.. Universidade Federal Fluminense. Instituto de Física. Laboratorio de Radioecologia e Alteraçoes Ambientais; Brasil Fil: Anjos, R. M.. Universidade Federal Fluminense. Instituto de Física. Laboratorio de Radioecologia e Alteraçoes Ambientais; Brasil Fil: Zamboni, C. B.. Centro do Reator de Pesquisa. Instituto de Pesquisas Energ eticas e Nucleares; Brasil Fil: Cardoso, R.. Universidade Federal Fluminense. Instituto de Física. Laboratorio de Radioecologia e Alteraçoes Ambientais; Brasil Fil: Muniz, M.. Universidade Federal Fluminense. Instituto de Física. Laboratorio de Radioecologia e Alteraçoes Ambientais; Brasil Fil: Corona, A.. Universidad de la Republica. Facultad de Química y Facultad de Ciencias; Uruguay Fil: Valladares, Diego Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Matemática Aplicada de San Luis; Argentina Fil: Kovacs, L.. Centro do Reator de Pesquisa. Instituto de Pesquisas Energ eticas e Nucleares; Brasil Fil: Macario, K. . Universidade Federal Fluminense. Instituto de Física. Laboratorio de Radioecologia e Alteraçoes Ambientais; Brasil Fil: Perea, D.. Universidad de la Republica. Facultad de Química y Facultad de Ciencias; Uruguay Fil: Goso, C.. Universidad de la Republica. Facultad de Química y Facultad de Ciencias; Uruguay Fil: Velasco, Ricardo Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Matemática Aplicada de San Luis; Argentina |
| Databáze: | OpenAIRE |
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