Genesis and classification of semi-arid soils from James Ross Island, Weddell Sea region, Antarctica

• Ano de defesa: 2018
• Autor(a) principal: Paula, Mayara Daher de
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa; Solos e Nutrição de Plantas
• Palavras-chave em Português: Solos - Formação - Antártica, Península; Solos - Classificação; Ciência do solo; Ciência do Solo
• Link de acesso: https://locus.ufv.br//handle/123456789/29294

The objective of this research was to investigate pedogenetic processes and soil formation factors in the region of the Weddell Sea and South Shetland Islands in the Peninsular Antarctic region. The work was divided into three papers. In the first paper the objective was to investigate the pedogenesis of a volcano-sedimentary topolithosequence, located in the James Ross Island, Weddell Sea region, through morphological, physical, chemical and mineralogical characterization, and classification of soils according to the international systems Soil Taxonomy and WRB / FAO. Soils are predominantly Gelisols/Cryosols and present cryoturbation features. Vegetation is scarce and nesting birds are absent, so that most soils can be characterized as ahumic. All profiles have a skeletic character, with a high percentage of coarse materials. The soil pH varied from neutral to alkaline and the potential acidity values were null. The mineralogy of the clay fraction presented kaolinite, which was likely inherited from warmer and wetter paleoclimatic conditions during sedimentation. The soils have mixed properties between maritime and continental Antarctic, such as cryoturbation and redoximorphism, side-by-side with desert pavements and ahumic character. In the second paper, the soils developed on different parent materials along the Ulu Peninsula, located on James Ross Island were analyzed geochemically through the quantification of major oxides and traces in soils, as well as the study of the uniformity of the parent material and the degree of weathering of soils, through geochemical indexes. Based on the major and trace oxides geochemistry, the soil types are well differentiated indicating that geochemical composition of soils is highly affected by their parent materials. Therefore, based on the major oxides abundances, chemical weathering seems insignificant. According to the high chemical index of alteration and mineralogical composition which have kaolinite in the clay fraction, soils developed on sedimentary rock of showed a pre-weathered nature. In the third paper the objective was to construct a database with all soil profiles collected since 2002 in the South Shetland Islands Group and the James Ross Islands Group to statistically analyze the physical and chemical properties of these soils located in different climatic regions. The results support the predominance of physical weathering rather than chemical weathering. However, in certain areas, chemical weathering and/or the parent material are more influential. The mean pH values of JRIG soils are closer to those found in Continental Antarctica. SSIG soils are the most acidic in Antarctica, given both the presence of sulfides, and the biological influence associated with the area’s greater precipitation and temperature. The highest P values (Mehlich-1) found in the two island groups were due to the influence of birds, mainly penguins, which are more significant in the SSIG. In the two island groups, the soils affected by avifauna activity have the highest amount of organic material, thereby resulting in high total organic carbon content. Climate is the factor that most influences the development of SSIG soils. Greater precipitation combined with higher temperatures considerably increases the organic matter content in these soils, in addition to the leaching of base elements, resulting in a more acidic pH, and more developed soils.