Utilização de proxies geoquímicos para análise dos padrões de sedimentação na plataforma continental interna adjacente a Foz do Rio Doce (ES)
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Data
2013-04-02
Autores
Franco, Tarcila
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Universidade Federal do Espírito Santo
Resumo
In the Linhares city (Espírito Santo State), the Doce River empties into the Atlantic Ocean forming a deltaic feature on the Continental Shelf. The sediments that make up the delta come from the Doce River basin that is the largest in volume flow e drainage area in the State of Espirito Santo. Over the last decades the basin has undergone an intense process of occupation, processing e direct interference in the main channel. The objective of this study was to analyze geochemical proxies present at the Doce River deltaic deposit e determine a pattern of behavior by these depositional elements. For analyzes were performed sedimentological characteristics, organic matter e nutrients contents, metals concentration e sedimentation rates in cores collected on the continental shelf adjacent to the mouth of the Rio Doce. The cores were DT01 SOUTH (collected south of the mouth), DT02 NORTE (collected north) e their replicas, DT01R SOUTH e DT02R NORTE. The cores presented a composition of higher percentage of fine sediments in DT01 SOUTH compared to DT02 NORTE. The set of results obtained for water content, density e porosity identified a package of sedimentary recent deposition in DT01R SOUTH e DT02R NORTE sediments with higher compression. Being the points equidistant from the mouth, the highest sedimentation rates found in DT01R SOUTH indicate the major input of sediment to the South compared to the North. The C/N ratio in DT01 SOUTH was unable to identify the source of the organic material since the results were located in the transition zone between land e marine sources. In DT02 NORTH became clear the importance of autochthonous production as the C/N ratio was in the range of organic matter with marine origin. Cu values were close to natural with some exceptions mainly in DT01 SOUTH. The values of Pb exceeded the value found in the background on both cores may indicate a greater influence of anthropic contribution. Thus, the results obtained through the behavior of proxies in the delta of Rio Doce was possible to identify a preferential deposition of fine sediment carried by the river via the Continental Shelf adjacent to the South of the mouth.
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Geochemical proxies , Proxies geoquímicos , Preferential deposition pattern , Padrão de deposição preferencial , Rio Doce subaqueous delta , Delta submerso do Rio Doce