Fosfatização em solo e rocha em ilhas oceânicas brasileiras

• Ano de defesa: 2008
• Autor(a) principal: Oliveira, Fábio Soares de
• Orientador(a): Abrahão, Walter Antônio Pereira
• Banca de defesa: Costa, Liovando Marciano da , Simas, Felipe Nogueira Bello , Viana, João Herbert Moreira
• 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: Ilhas oceânicas; Pedogênese; Fosfatização; Indicadores paleoambientais
• Palavras-chave em Inglês: Oceanic islands; Phosphatization; Paleoenvironmental indicators
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::CIENCIA DO SOLO
• Link de acesso: http://locus.ufv.br/handle/123456789/5403

Oceanic islands are breeding places for several migratory species of birds whose their excrements are deposited on to the surface, besing subject to phosphatization. The occurrence of phosphatization has been related to specific environmental conditions and, for this reason, it is capable to indicate past environmental changes, associated to climate, oceanic currents, sea level changes, amongst others. Besides, it has strong influence in nutrients cycling and biological productivity of adjacent sea. Despite that, litte is known about this process, and how it can affect the formation of insular soils. Based on that, this work aimed at characterizing the phosphatization in São Pedro and São Paulo Archipelagos (ASPSP) and Fernando de Noronha (AFN), more specifically in Belmonte and Rata Islands, respectively. Samples of rocks and soils were collected in those two islands, and were submitted to chemical, physics, and microscopic analyses. The rocks were also submitted to total elements chemical analyses, X-Ray diffraction and scanning electronic microscopy. Six products of phosphatization were observed in ASPSP. Phosphates rocks were characterized by the accumulation and/or interaction of P- rich solutions with the substrate. Among them, it thick phosphates crusts occur on milonitizaded peridotites, phosphates espeleotems on the borders and inner fractures. Also we find phosphates filling out weathering fractures or constituting framboidals coats on their borders, as well as rich greenish phosphate crusts with Ni and Cr, guano and ornitogenic soils. The latter is represented by a Lithosol with high P content and fragmentary lithic character. In Rata Island, Noronha Arquipelago, we identified sloping Neosols, associates with calcarenites dissolution, whose physical and chemical properties indicate signs of pedogenetic evolution, and Cambisols in the rest of the island. These Cambisols are originated from calcarenites and basalts under low weathering degree. Phosphatization of these soils was processed in past conditions, under vanying humid to arid conditions. Colluviation processes mixed to phosphatizaded carbonatic san with a Al-P coating. Through this, it is observed a variscitization of P-Ca fragments, constituting P-Al oolitic aggregates.