2020-01-102020-01-102016-01-28SILVA, Ellery Henrique Nascimento da. Caracterização geoquímica e assinatura isotópica de Pb dos sedimentos de fundo do estuário do rio Caeté, Bragança, nordeste do Pará. Orientador: Jean-Michel Lafon. 2016. 86 f. Trabalho de Curso (Bacharelado em Oceanografia) - Faculdade de Oceanografia, Instituto de Geociências, Universidade Federal do Pará, Belém, 2016. Disponível em: https://bdm.ufpa.br/jspui/handle/prefix/2731. Acesso em:.https://bdm.ufpa.br/jspui/handle/prefix/2731In fluvial environments, trace-metals composition is mainly controlled by rocks composition, but possible anthropogenic sources may also contribute to the metal accumulation. In consequence of this, aquatic organisms may be injured. It is suspected that the Caeté river estuary, located at the northeast coast of Pará, may be affected by anthropogenic sources related to Bragança city, the main urban pole along the Caeté river, 45 kilometers inside. Thus, this research aims to assess the Cu, Zn, Ni, Cr and Pb concentrations and the lead isotope ratios in stream sediments from Caeté river estuary for monitoring anthropogenic contributions possibly related to the population of this city. In addition, the research aims to contribute for implementation of methodology for analyzing the trace-element concentrations by quadrupole ICP-MS at the Isotope Geology Laboratory (IG-UFPA). The granulometric analysis with laser particle size analyzer shows that the sediments are predominantly sandy. X-rays diffraction analysis indicates that the main clay minerals are kaolinite, montmorillonite and illite. The organic matter average value, determined with organic carbon analyzer, is 6.64 %. In the method validation study, it has been found that the employing methodology (mass spectrometry – quadrupole ICP-MS) for obtaining elements concentrations may be utilized routinely for almost tested elements, including 4 metals of interest (Cu, Ni, Cr and Pb). Unfortunately, Zn was not approved in test. In the inner portion of the estuary, the exchangeable metals concentrations (Cu: 8.07; Ni: 3.44; Cr: 9.57; Pb: 7.21 mg kg-1), obtained by acid leaching with HNO3*** (5N), are compatible with natural concentrations of Guamá river, in the hydrographic system of Belém or they are lower. Ni, Cr and Pb values point to natural geochemistry, but Cu may indicate little anthropogenic contributions likely related to agriculture in Bacuriteua Villa. Metals show low or no correlation with organic matter, so the clay minerals and Fe and Mn oxi-hydroxides are likely preponderant in elements fixation. In the Ostras (Cu: 9.9; Ni: 11.4; Cr: 47; Pb: 22.8 mg kg-1) and Estiva (Cu: 10.3; Ni: 9.2; Cr: 43; Pb: 23.7 mg kg-1) channels, placed on the outer portion, in the left margin of the estuary, the concentrations are higher. This increment may be related to the higher clay proportions in the stream sediments of these localities. The 206Pb/207Pb values, determined by thermal-ionization mass spectrometry (TIMS), vary from 1.182 to 1.195. The lower signatures are found in the vicinities of Bragança (1.185) and Bacuriteua (1.184) and Juvêncio (1.182) villas, suggesting anthropogenic contributions associated to urban activity. Both samples from Ostras (1.182 - 1.184) and Estiva (1.184 - 1.186) channels appear to undergo anthropogenic influence. It is though that 206Pb/207Pb background of the Bragantina region is near the value of 1.196 – 1.200 (hydrographic system of Belém city background). Combined 206Pb/207Pb and 208Pb/206Pb isotopic data points to more than one anthropogenic contribution source, but, in addition to petroleum derivatives (1.136 – 1.153), the signatures of this source are not known.Acesso AbertoEstuários - Bragança (PA)Chumbo - Isotópos - Bragança (PA)Elementos - traçosMetais pesados - Caeté, Rio (PA)CNPQ::CIENCIAS EXATAS E DA TERRA::OCEANOGRAFIA::OCEANOGRAFIA QUIMICA::INTERACOES QUIMICO-BIOLOGICAS/GEOLOGICAS DAS SUBSTANCIAS QUIMICAS DA AGUA DO MARTrabalho de Curso - Graduação - Monografia