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Geochronology of anthropogenic radionuclides in Ribeira Bay sediments, Rio de Janeiro, Brazil |
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| Authors: | de Carvalho Gomes Franciane Godoy José Marcus Godoy Maria Luiza D P de Carvalho Zenildo Lara Lopes Ricardo Tadeu Sanchez-Cabeza Joan-Albert Osvath Iolanda de Lacerda Luiz Drude |
| Institution: | a Programa de Engenharia Nuclear, COPPE/UFRJ, Cidade Universitária, Caixa Postal 68.509, 21945-970 Rio de Janeiro, Brazil b Instituto de Radioproteção e Dosimetria (IRD), Caixa Postal 37750, Barra da Tijuca, 22642-970 Rio de Janeiro, Brazil c Departamento de Química, Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Rua Marquês de São Vicente 225, 22453-900 Rio de Janeiro, Brazil d IAEA Marine Environment Laboratories, 4 Quai Antoine Premier, MC98000 Principality of Monaco, Monaco e Laboratório de Ciências do Mar, Universidade Federal do Ceará, Fortaleza, Ceará, Brazil |
| Abstract: | Ribeira Bay is located approximately 130 km south of the city of Rio de Janeiro and receives discharges of liquid effluent from the Angra dos Reis nuclear power plant (NPP) site, where two pressurized water reactors are located. To test whether the presence of anthropogenic radionuclides in sediments in Ribeira Bay could be correlated to the NPP operations, we sampled seven sediment cores and determined accumulation rates and chronologies. Only one sediment core did not exhibit a superficial mixing layer; this sample was used for dating purposes. Cesium-137 and 207Bi were observed in this sediment profile, but their presence was associated with atmospheric fall-out rather than the nearby NPP. The exponential decay of 210Pb concentration with sediment layer depth was verified below a superficial mixing layer for all other sediment cores. Calculated accumulation rates ranged from 1.2 mm y−1 in the inner bay to 6.2 mm y−1 close to its entrance. |
| Keywords: | Pb-210 dating Sediments Ribeira bay 137Cs Brazil |
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