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Title: Histórico de acumulação de metais traço em sedimentos estuarino dos Rio Iguaçu e da região da área de proteção ambiental de Guapimirim, Baía de Guanabara, RJ.
Keywords: Baía de Guanabara;  Metais-traço;  Contaminação ambiental;  Testemunho de sedimento;  210Pb em excesso;  Guanabara Bay;  Trace metals;  Environmental contamination;  sediment core;  210Pb excess
Issue Date: 25-Feb-2008
Abstract: The aim of the present work is to study the input of trace metals of environmental interest, such as Pb, Zn, Ni, Cu, V, Ba, Co e Cd, in sediments from the Iguaçu River and the Guapimirim Environmental Protection Area estuaries, comparing the degrees of metal accumulation between these environments. Two sediment cores were collected in 2007, one from the mudflat inside the Iguaçu River (RED3) and the other near the Guapi and Guarai river mouths (MAC). The sediment core RED3 presented sediments predominately composed for silte and clay, with a maximum sand content of 3%. The sediment core MAC also presented fine granulometric size, however it showed up to 20% of sand in some sedimentary layers. Both sediment cores showed a change in sedimentation rates from the second half of the twentieth century, which might be reflecting the beginning of an accelerated industrialization process and development of the Rio de Janeiro Metropolitan Area. The sediment core RED3 presented a large concentration variation of organic carbon, trace metals, Fe and Mn. This might be a reflection of the high Iguaçu River hydrodynamic. All the trace metals, Fe and Mn presented a concentration increase in the second half of the 1980 s, suggesting a vertical redistribution due the process diagenetic. The trace metal concentration found in the MAC core showed two background levels. The first level consists of concentrations measured from the core bottom up to 75 cm, which was equivalent to records up to 1872. Moreover, the sediments from those environmental conditions predominantly presented clay, aloctone organic matter and low concentrations of trace metals. From the mentioned depth onwards, there were concentration increases. Once increased, the concentration remained constant until the top of the core (except Zn and Pb). These increases were probably influenced by the new environmental conditions catchment in the end of XIX century, possibly due to a deforestation process, which occasioned major erosion and weathering. Inventory, flux and trace metal enrichment factors showed highest in the Iguaçu River than in the Guapimirim Environmental Protection Area other estuaries and the others important estuaries of the world.
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