Ocorrência e distribuição de produtos da oxidação de sulfetos, hidrogeoquímica e mineralogia de sedimentos na Península Keller, Antártica

• Ano de defesa: 2010
• Autor(a) principal: Souza, José João Lelis Leal de
• Orientador(a): Abrahão, Walter Antônio Pereira
• Banca de defesa: Silva, Juscimar da , Simas, Felipe Nogueira Bello
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Solos e Nutrição de Plantas
• Departamento: Fertilidade do solo e nutrição de plantas; Gênese, Morfologia e Classificação, Mineralogia, Química,
• País: BR
• Palavras-chave em Português: Geoquímica ambiental; Mineralogia; Península Keller
• Palavras-chave em Inglês: Environmental Geochemistry; Mineralogy; Keller Peninsula
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::CIENCIA DO SOLO
• Link de acesso: http://locus.ufv.br/handle/123456789/5442

Located on Admiralty Bay, King George Island, Keller Peninsula has an area of approximately six square kilometers and there are records of presence of basalt, volcanic tuff, basalt-andesite and andesite in the geologic base. The latter two show veins of sulfides of late mineralizationhave high levels of sulfides, which shows a natural potential generation of acid rock drainage. In order to analyze the presence and influence of the acid rock drainage process on the availability of metals in water discharged into the sea in the Keller Peninsula, water samples at various points in watercourse to the sea, were collected during the months of February and March 2009, on different lithologies and drainage basin. Sediment samples were also collected from the bottom of the waterways. The water samples were acidified and filtered on cellulose ester membrane of porosity 0.45 μm. Were determined the following elements by Spectrophotometry of Optical Emission in Induzed Plasma: Al, As, B, Cd, Co, Cr, Cu, Fe, K, Mn, Mo, Ni, Pb, S, Ti, V, Zn. The chemical conditions of water samples showed pH values close to neutrality even in close proximity of sulfide deposits and in some places, even on these. It was observed that the drainage basin are divided between: a) basins strongly affected by sulfides oxidation; b) basins affected by sulfides oxidation and c) basins not affected by sulfides oxidation. It was also found that concentrations of ions in solution were always higher in the watershed affected by sulfides indicating a breakthrough in the chemical weathering process in these areas. Four sulfide deposits not previously reported in geological manuscripts were recorded and it was observed that these are always associated with geological faults. Among the secondary minerals dominated the species of the jarosite, as well as the Schwertmannite and other low crystallinity minerals. The presence of low crystallinity minerals, with high adsorption capacity minerals, founded too in beaches and marine terraces, suggests that a large portion of the concentration recorded in the waterways is not actually available in the pH environmental conditions recorded at the time of samples collection. Moreover, although the secondary minerals observed are of high instability it was not observed more crystalline forms of oxides and Iron oxyhydroxides. Due to the chemical conditions of pH of the samples recorded at the time of collection it is suggested that the term acid rock drainage is not suitable for this case. The process that occurs in the Keller Peninsula is the occasional generation of acidic waters influenced by the dynamics oxidation of sulfides, its soil gradation and mineral species, and against neutralization by melting and consumption of acidity by carbonates and silicates.