Correlações entre as distribuições de Césio e Potássio ao longo de plantas tropicais

• Autor(a) principal: Sanches, Newton Lima
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal Fluminense (RIUFF)
• Texto Completo: https://app.uff.br/riuff/handle/1/17363
• topic: Radioecologia; Fisiologia vegetal; Correlações entre 137Cs e 40K; Gamma-ray spectrometry; Radioproteção ambiental.; CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA

Measures were taken to concentration of 137Cs and 40K over different species of tropical plants herbaceous and woody: cassava (Manihot esculenta), banana (Musa paradisiacal), papaya (Carica papaya), guava (Psidium guajava), and mango (Mangifera indica). For both, were analyzed samples of soil, roots (and tubers, in the case of cassava), stems, twigs, shoots, leaves and fruit, using the technique of spectroscopy of gamma radiation. These analyses were performed with the use of detectors of NaI(Tl) and HPGe, available in the laboratory of Radioecology (LARA) of the Institute of Physics of the Universidade Federal Fluminense (IF-UFF). The results showed that concentrations of 137Cs and 40K were higher in the compartments of growth (bark, buds, leaves and fruit) that the inner part of the main stem for cassava, guava and mango trees, which are woody trees. In the case of herbaceous plants (banana and papaya), these compartments of growth showed concentrations of 137Cs and 40K lower than the values obtained in the main stem. From two-dimensional analysis on transversal sections of main stem was possible to observe effects of asymmetry and heterogeneity in the distribution of 137Cs and 40K on the disks of banana and papaya plants contaminated by caesium, whose effect was not observed in conventional radial distributions. The concentration factors (FC) shown to be important tools in the evaluation of the accumulation and transport of radionuclides, because from them was possible to see more clearly their distributions in groups of plants studied. It was observed that changes in the basic properties of soil (pH and humidity, for example), can produce changes in the values of concentration factors (FC), however, the values of the discrimination factors K/Cs (FD) showed always be coming the unit for all species analyzed in this work. Indicating that potassium and caesium have similar behaviors, and therefore 137Cs can be a good candidate as a marker or crawler monovalent inorganic ions, present in plant nutrition.