Solos e paisagens do setor oeste da ilha Deception, Ant?rtica Mar?tima

• Ano de defesa: 2011
• Autor(a) principal: Tostes, Juliana de Oliveira
• Orientador(a): Francelino, M?rcio Rocha
• Banca de defesa: Schaefer, Carlos Ernesto Gon?alves Reynaud, Aranha, Paulo Roberto Antunes
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal Rural do Rio de Janeiro
• Programa de Pós-Graduação: Programa de P?s-Gradua??o em Agronomia - Ci?ncia do Solo
• Departamento: Instituto de Agronomia
• País: Brasil
• Palavras-chave em Português: Permafrost. .; Radar de Penetra??o no Solo; N?veis de intemperismo
• Palavras-chave em Inglês: Permafrost; Ground Penetrating Radar; Levels of weathering
• Área do conhecimento CNPq: Agronomia
• Link de acesso: https://tede.ufrrj.br/jspui/handle/jspui/3735

The aims of this study were: to propose a Predictive Model of Stages of Soil Weathering (PMSSW) in the west sector of Deception island; to propose a new standard for description of levels of soil weathering, specific to Maritime Antarctica; and to use Ground Penetrating Radar (GPR) to characterize the active layer and to identify permafrost depth in three sites in the study area. A new classification of the degree of soil development in the Maritime Antarctica was performed, highlighting their specificities. The following indicators were considered for weathering intensity: depth in soils with presence or absence of permafrost, cryoturbation, proportion and shape of the fractions> 2 mm, organic matter content, and distinctness of horizons. To generate the PMSSW there were selected the environmental variables: climate, altitude, aspect and curvature and degree of slopes, albedo, lithology, fauna and vegetation. The themes were generated in the ENVI 4.5 and ArcGIS 9.3 software, and they were reclassified with weights between 0 and 1, as indicators of limitations or favoring conditions to weathering. In order to identify which environmental variables most influenced soil weathering degree, it was performed a Principal Component Analysis ? PCA, using PCORD 4.01 software. The results of this analysis were used to examine the themes overlie. The comparison between the stages of weathering indicated by PMSSW, the field soil description, and the ACP revealed identical results in 75% and 87.5% of analyzed profiles, respectively. The differences occurred in the profiles where features not assessed by the predictive model were taken in account, which suggests that the proposed methodology is valid. There was an increasing trend in the soil development in low albedo and low slope environments, which provide greater stability and available moisture. Added to these variables was the vicinity of animal colonies and presence of vegetation, which promotes deposition of organic matter in the soil and allow development of soil structure. The proposition of new weathering levels was essential for better soil characterization in the western sector of Deception Island, reflecting the variability of the pedoenvironment where such soils developed. For the GPR antennas of 200 and 900 MHz were used, and for each antenna three scans at each site were performed, with lines of 120 m length at site 1, and of 30 m at sites 2, 3 and 4. The 200 MHz antenna allowed the identification of reflectors and the visualization of deeper soil layers pattern. However, it did not detect the interface between frozen ground and thawed soil, neither the permafrost base. The 900 MHz antenna was best suited to assist in monitoring the permafrost and the active layer, since it recorded the permafrost top depth, its subsidence and pattern, if erratic or continuous. The results showed that GPR is an effective tool for determining the interface between thawed soil and the permafrost, allowing monitoring alterations as a result of climate changes.