Solos e geoambientes da porção norte da ilha Seymour (Marambio), Antártica

• Ano de defesa: 2013
• Autor(a) principal: Gjorup, Davi Feital
• Orientador(a): Schaefer, Carlos Ernesto Gonçalves Reynaud
• Banca de defesa: Mendonça, Bruno Araujo Furtado de , Fernandes Filho, Elpídio Inácio
• 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: Geoambientes; Ilha Seymour; Marambio
• Palavras-chave em Inglês: Geoenvironments; Seymour island; Marambio
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::CIENCIA DO SOLO
• Link de acesso: http://locus.ufv.br/handle/123456789/5524

The Seymour/Marambio island (ISM) is located in the northern sector of the Weddell Sea, at the Antarctic Peninsular area, representing a transitional zone between Maritime and Continental Antarctica, with a subpolar, semiarid climate. The ISM is predominantly composed by marine sedimentary rocks of Cretaceus to Eocene age. The aims of this work were: identifying, mapping and characterization of the geoenvironmental units at the northern part of ISM landscape, as well as studying chemical, physical, mineralogical and morphological attributes, across a selected, representative toposequence. Also, pedogenetic processes and factors were discussed. The geoenvronmental stratification was based on pedo-litogeomorphological attributes, in an integrated landscape approach, in which sectors with similar attributes were grouped together. For the soil study, nine profiles were described, collected and analysed, following a toposequence according to different parent materials and landforms. Samples were subjected to textural analysis, routine chemical analysis, chemical extractions by ammonium oxalate and CBD, as well as X ray diffraction. Thirteen geoenvironments were identified, representing periglacial environments at this transitional climatic zone. The geology exerts a control on the geoenvironments, with great influence on landforms and soils. Permafrost is continuous and widespread, generally at depths of less than 100 cm, so the Gelisols order (Soil Taxonomy), or Cryosols (WRB), are the dominant soils. Cryoturbation and organic matter accumulation were not observed. Soils were separated into two groups: acid-sulphate soils and alkaline soils, unaffected by sulphates. The first are the best developed in the study area, meaning a significant physico-chemical and mineralogical alteration. Low pH and high Al saturation and potential acidity are typical. This accounts for primary mineral dissolution, and its absence in the clay fraction. Secondary minerals are those related to sulphide oxidation: soluble and insoluble sulphates, low crystalline Fe-hydroxides and little crystalline Fe phases. The peculiar yellowish colour of these soils are attributed to the presence of Fe-oxides and Jarosite. The presence of 2:1 clays (smectite and illite) in the Clay fraction despite the acidity is due to low leaching. The alkaline soils, non affected by sulphates do not showed any marked weathering or transformation, with high pH, low potencial acidity and zero Al saturation. The main process is cryoclastic and haloclastic weathering. Primary minerals are present even in the clay fraction, corroborating its low weathering degree and chemical alteration. The landform is determinant for the chemical status of theses soils, by favoring or reducing leaching. Sulphurization and halomorphism are the dominant soil-forming processes in Seymour-Marambio island.