IEDA IRMA LAMAS CUNHA
108 resultados
Resultados de Busca
Agora exibindo 1 - 10 de 108
Artigo IPEN-doc 22663 A model of recent sedimentation in the Cananeia–Iguape estuary, Brazil2006 - SAITO, R.T.; FIGUEIRA, R.C.L.; TESSLER, M.G.; CUNHA, I.I.L.Coastal systems, in particular estuaries, are the first depositional environment to receive sediments transported by rivers to the coastal ocean. As a consequence of the geochemical processes involved, a part of the sediment may be deposited in the estuary and the remainder flows into the ocean, being transported and deposited under the influence of tides and maritime currents. This study was carried out in the Cananeia–Iguape estuary on the southern coast of São Paulo state, Brazil. The vertical distribution of 210Pb and 137Cs in sediments has been used as a tool for estimating the sedimentation rates in the coastal environment. Concentrations of 210Pb and 137Cs, as well as heavy metals (lead, zinc, copper) were determined in four sediment cores collected in the Cananeia–Iguape estuary. The estimated sedimentation rates were from 5.3 mm yr−1 to 12.7 mm yr−1. The highest sedimentation rate obtained for Valo Grande corresponds with an accelerated expansion of the sand and clay banks of the Mar Pequeno channel, a growth of the mangrove areas, and a decrease in the depth of the main channel of navigation, a fact that has been affecting the navigation in the area very seriously. The data obtained for the metals showed a sedimentary dynamics in agreement with that obtained in the studies of sedimentation rates, thus contributing to the understanding of the hydrodynamic mechanisms of the system.Artigo IPEN-doc 22612 Determination of trace elements in aerosol samples by instrumental neutron activation analysis1990 - PAIVA, R.P.; MUNITA, C.J.S.; CUNHA, I.I.L.; ROMANO, J.; ALONSO, C.D.Two nuclear techniques, Energy-Dispersive X-Ray Fluorescence Analysis (EDXRF) and Instrumental Neutron Activation Analysis (INAA), were used to analyze aerosol samples collected in the city of Sao Paulo, Brazil. Na, CI, Mn, V, A1, Sm, Mo, W, La, As, Br, Sb, K, Ba, Se, Th, Cr, Rb, Ca, Fe, Ce, and Sc were determined by INAA, and A1, Si, P, S, C1, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, As, Se, Br, Rb, Sr, Hg, and Pb were determined by EDXRF. A preliminary identification of the main source of the atmospheric aerosol was performed based on enrichment factor and correlation coefficient calculations.Artigo IPEN-doc 22589 Distribution of 137Cs, 238Pu and 239 + 240Pu in sediments of the southeastern Brazilian shelf–SW Atlantic margin2006 - FIGUEIRA, RUBENS C.L.; TESSLER, MOYSES G.; MAHIQUES, MICHEL M. de; CUNHA, IEDA I.L.Resumo IPEN-doc 17431 Rate of sedimentary in the coastal systems and on the souther continental plataform of the state of São Paulo, Brazil2000 - TESSLER, M.G.; CUNHA, I.I.L.; SAITO, R.T.; FIGUEIRA, R.C.Analyses of the concentrations of the natural radionuclideos 210Pb and 226 Ra, scattered in the environment in vestigial amounts in witnesses of the coastal and occeanic areas provide a historical record of events and make it possible to estimate the background and variations in the volume of sediments laid down extensive periods of time. The results of the analyses of the rates of sedimentation obtained in the coastal systems (Cananeia-Igaupe system) and the souther continental platform of the state of São Paulo, by means of the calculation of the 210Pb and 226Ra by gama spectrometry, are presented in this study.A detector of hyperpure Germanium with a low level of bottom radiation and a study of the phototype of these radionuclideos was used for the analysis of these same radionuclideos in the marine sediments. The analysis of the 210Pb was undertaken by means of the gama emission of 47Kev and that of 226Ra by the gama emission of the Bi (609 Kev). Additionally a sedimentation rate was calculated for purposes of comparison on the basis of the levels of 137 Cs present in the witnesses, the biennium 1963/1964 being taken as the maximum pcak of atmospheric emission by nuclear explosions as from witch time on the atmospheric emission of this radionuclid diminishes and its rate of deposition on the earth’s crust is considered constant. The rates of sedimentation obtained for the coastal system show agreement of the values obtained for 210Pb (5.33mm/yr) with those obtained through the dating method for 137Cs (5.46mm/yr). The sedimentation rates obtained for the continental platform correspond to values some five times inferior to those obtained in the coastal systems.Artigo IPEN-doc 10438 Níveis de chumbo, cobre e zinco em amostras de sedimentos do sistema costeiro Cananeia-Iguape (São Paulo, Brasil)2001 - SAITO, ROBERTO T.; FIGUEIRA, RUBENS C.L.; TESSLER, MOYSES G.; CUNHA, IEDA I.L.Artigo IPEN-doc 19164 Niveis de metais pesados (Pb, Cu e Zn) na plataforma continental e talude superior do Estado de São Paulo2001 - TESSLER, MOYSES G.; FIGUEIRA, RUBENS C.L.; SAITO, ROBERTO T.; CUNHA, IEDA I.L.Publicação IPEN-doc 03056 Estabelecimento de um procedimento radioquimico para obtencao do titanato de estroncio1988 - CUNHA, I.I.L.; ANDRADE e SILVA, L.G.Publicação IPEN-doc 01434 Extracao de alguns produtos de fissao com a tetraciclina: Influencia da acidez e da natureza de alguns anios inorganicos1982 - CUNHA, I.I.L.; NASTASI, M.J.C.Publicação IPEN-doc 00546 Burn-up determination of irradiated uranium oxide by means of direct gamma spectrometry and by radiochemical method1981 - CUNHA, I.I.L.; NASTASI, M.J.C.; LIMA, F.W.Capítulo IPEN-doc 01949 Application of neutron activation analysis to trace element in environmental aerosol samples in Sao Paulo1992 - SEPULVEDA MUNITA, C.J.A.; PAIVA, R.P.; CUNHA, I.I.L.