Polygonal terrain underlain by ice wedges (IWs) are a widespread feature in continuous permafrost and make up 20-35%vol of the ground ice in the upper few meters of permafrost. Despite the numerous contemporary studies examining factors that control ice wedge cracking, development and degradation, relatively few have explored ice wedge activity in relation with past climate and vegetation conditions. In the Eureka Sound region, ice wedge polygons dominate the permafrost terrain. Their degradation has started to occur, leading to growth of thaw slumps. The objective of this study is twofold, the principal objective is to investigate the timing of ice wedge activity in the Eureka Sound region using the ¹⁴CDOC dates. The second objective is to evaluate the use of ice wedges as paleotemperature proxies. In July 2018, four ice wedges were sampled at 3-4 depths with each core sample being ~1m in length. In the following summer, eight ice wedges were sampled from the surface, 3-5 core samples were extracted per wedge. Active layer and snow samples were also recovered. Laboratory analyses on the ice wedge samples includes dissolved organic carbon content (DOC) and δ¹³CDOC, radiocarbon dating of DOC, geochemical concentration, and stable water isotopes. The DOC and geochemical results show that snowmelt is the main moisture source for ice wedges in the Eureka Sound region with a minor contribution of leached surface organics. The age (¹⁴CDOC) and size of the studied ice wedges were compared against a cracking occurrence model developed by Mackay (1974), these ice wedges align well with this model and suggest that ice wedge growth is non-linear. Ice wedges in the Eureka Sound region were active during the early to late Holocene (9-2.5 ka). The majority of the activity occurred in the later stage of the early Holocene following regional deglaciation and marine regression. ¹⁴CDOC, high resolution δ¹⁸O and D-excess suggests the occurrence of peripheral cracking in both large and small ice wedges. Rayleigh-type isotopic fractionation was found to occur with depth. As well, post depositional isotopic modification of snow and snowmelt accounts for up to a 4‰ difference of δ18O in surface ice wedge samples. δ¹³CDOC of surface ice wedge samples suggest a habitat transition during the late Holocene from dry meadows to polygonal terrain and the geochemical composition of ice wedges closely reflects that of glacial ice core records.

Permafrost is vulnerable to climate changes and the associated landscape changes that are enhanced by amplification processes and feedbacks unique to the Arctic. Permafrost degradation leads to important changes in terrestrial and aquatic ecosystems, and determining regions that are sensitive to permafrost degradation therefore represents an urgent issue. The Tombstone Territorial Park (TTP) and its surroundings (Ogilvie Mountains, central Yukon) represent one of those sensitive permafrost environment that should be monitored. The central Yukon is an enigmatic permafrost environment that reflects both Pleistocene and Holocene permafrost and climate conditions. The area is particularly intriguing because of the extensive presence of permafrost landforms that are more typical of areas much further north, especially ice-wedge (IW) polygons. It also represents a major transportation corridor linking multiple northern communities (Dempster Highway). Despite access along the road, and signs of permafrost degradation, there have been a limited number of studies addressing permafrost and ground ice conditions throughout the landscape. Consequently, this PhD thesis aims to characterize IW polygons, define the type and magnitude of landscape changes, and model permafrost distribution, conditions and sensitivity to climate changes in the study area. Characterization of IW polygons reveals that they occupy 2.6% of the TTP and preferentially develop in woody sedge peat, glaciofluvial and alluvial deposits along the lower reaches of the Blackstone and East Blackstone rivers on hillslopes of ≤1°. Vegetation type, surface wetness, and polygon spatial pattern are influenced by the development stage of ice-wedge polygons, while the size and angles of polygons seem independent of the development stage. A Landsat-based landscape change analysis of the TTP and surrounding region covering the 1986-2021 period shows that statistically significant spectral changes occurred in 24% of the study area, and most of these changes are associated with vegetation succession and hydrological processes (i.e., erosion and deposition). Other landscape changes included wildfires, slumps, changes to riverbanks and lake shores, earlier melting of icings in the summer, degradation on the peripheries of some ice wedge polygonal terrain, and potential insect damage to forests. The analysis reveals that the extent and magnitude of landscape changes in the study area are influenced by the geomorphic setting, ecological succession and glacial history of the region. Modeling current and future permafrost conditions in the study area using the Northern Ecosystem Soil Temperature (NEST) model indicate that permafrost has persisted through the 20th century and beginning of the 21st century and is currently present throughout the area. Modeled mean permafrost depth (113.8 ± 49.6 m), active layer thickness (2.45 ± 7 m), surface, near-surface, and deep ground temperatures (−1 ± 1.2°C, −1.6 ± 1.2°C, −2.4 ± 1.3°C, respectively) are in the range of other local and regional measurements. Predicted ALTs and permafrost depth show areas of permafrost loss by 2100 (22% of study area under RCP4.5, and 29% under RCP8.5). Permafrost degradation in the study area could greatly impact slope stability and conditions of aquatic systems, and shrubification could contribute to increased degradation.

As our climate continues to shift, it is fundamental to understanding these unprecedented changes through field research done in biomes most critically impacted. Due to the remoteness and extreme climatic nature of these research stations, they are typically either hastily built flat pack constructions or sterile pill boxes with little consideration of the immediate surrounding. This investigation looks at structuring the restrictions of environment to give the architecture a sense of place, rather than looking at these extremes as limitations. This proposal is sited in the Alaskan Arctic circle, where research is being conducted to understand the intertwined issues of climate change and permafrost melt. It is the intent of this project to present a prototype of a responsible and responsive architecture for Toolik Station, Alaska,a renowned destination for arctic climate research. This thesis synthesizes unpredictable site and environmental factors, elements which will become increasingly commonplace as our planet's climate shifts. The proposal for the Northern Reach interrogates and responds: How are we best equipped to live and work in a rapidly changing measure of extremes? What imbues an architecture with a sense of place when that place is inherently mercurial? / Master of Architecture / To best understand the unprecedented effects of climate change on critical, research is often conducted in remote and often extreme areas of the planet, where the living conditions are less than ideal which affects the longevity and effectiveness of said research. This project investigates the extremes of living and working as a field scientist in Toolik Station, Alaska, and proposes housing and accommodations which are more sensitive and appropriate for its site than what is currently being used. The proposed project can be used as a prototype to replace other buildings at the chosen site.

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The abstract presents an architectural proposal for the Churchill Wildlife Information and Indigenous Culture Centre in Churchill, Northern Manitoba. The project aims to create a dynamic and educational space that showcases the town's rich history, celebrates its Indigenous heritage, and emphasizes the harmonious coexistence with the diverse local wildlife. Situated at the historically significant Rocket Range site, the centre seamlessly integrates with the natural landscape, offering visitors an immersive and captivating journey. Through carefully designed teaching spaces, interactive wildlife exhibitions, and curated displays of indigenous historical photographs, art, and artifacts, the centre provides a comprehensive exploration of Churchill's cultural and environmental heritage. Sustainability and cultural exchange are core principles guiding the design approach. The centre incorporates an artist-in-residence program, facilitating hands-on demonstrations of indigenous crafts while fostering dialogue and mutual learning. With a focus on addressing the need for an updated space that accurately reflects Churchill's unique culture and history, the centre endeavours to inspire a renewed connection with the environment and indigenous traditions. By promoting appreciation, knowledge, and a sense of responsibility towards wildlife, the centre aspires to become a beacon of education and conservation in Churchill's remarkable landscape.

O efeito de alterações climáticas sobre os micro-organismos ainda é incerto, pois pouco se conhece sobre as espécies que habitam regiões extremas como o gelo, solo antártico, e o solo permanentemente congelado (permafrost). O permafrost tem como característica a preservação de material biológico por milhões de anos, servindo como fonte para estudos de evolução e biogeografia de micro-organismos. O objetivo deste trabalho foi estudar a diversidade microbiana em amostras de gelo, solo exposto por recuo de geleira e permafrost polares, e a diversidade funcional do gene alcano monoxigenase (alk). Métodos independentes de cultivo baseados no gene 16S rRNA foram utilizados, como DGGE, clonagem e pirossequenciamento. As geleiras da Ilha Rei George (Península Antártica) e do Pólo Sul Geográfico possuem cerca de 3.104 cél./mL e são compostas por micro-organismos diferentes, com predominância dos Filos Proteobacteria, Actinobacteria, Firmicutes e Cyanobacteria, muitos dos quais já descritos em outros ambientes criogênicos. O solo em frente à geleira Baranowski apresenta uma estrutura de comunidade diferente do gelo. O solo exposto por recuo de geleira apresenta uma sucessão ecológica, com predominância de heterotróficas durante todo o processo. Fixadores de nitrogênio no solo foram compostos por cianobactérias no início, e por Rhodopseudomonas e Rhodobacter no final da sucessão. Estes resultados foram melhor observados com o pirossequenciamento. As mudanças observadas podem estar relacionadas ao aumento de K, Mg+, NH4+, NO3- e/ou CO2 detectados após 15-20 anos de exposição do solo. A comunidade de permafrosts varia com o local e a idade de congelamento (de 5.000 a 8 milhões de anos). O gene alkM foi detectado em permafrosts do Ártico com 3 milhões de anos, e o gene alkB em amostras do Ártico com 15.000 e 120.000 anos, e em solos modernos da Antártica. Alguns clones indicam que podem representar novos genes para alcano monoxigenases. As contribuições deste projeto abrangem os objetivos do Ano Polar Internacional (IPY 2007-2009), sobretudo na avaliação da ecologia microbiana da Antártica. / The effect of climate changes on microorganisms is still unclear, because little is known about the species that inhabit the extreme regions as the glacial ice, antarctic soils and the permanently frozen soil (permafrost). The permafrost is able to preserve the sedimented biological materials by thousands or even millions of years, being an important source for microbiological studies. The objective was to study the microbial diversity in cryogenic samples: glacial ice, soil exposed by glacial retreat and polar permafrosts, as well as to study the functional diversity of alkane monooxygenase genes (alk) in the permafrost. Cultivationindependent methods based on the 16S rRNA gene were used, as DGGE, clone library and 454 Pyrosequencing. Analysis of the King George Island (Antarctic Peninsula) glaciers and the South Pole ice revealed about 3x104 cells/mL each, and different micro-organisms were detected, predominantly members from Proteobacteria, Actinobacteria, Firmicutes and Cyanobacteria, many of which already described in other cryogenic environments. The soil in front of the Baranowski Glacier has a different community structure compared with the ice. Soils exposed by glacier retreat revealed an ecological succession, and heterotrophic bacteria occurred all through the process. Nitrogen-fixing populations were composed by cyanobacteria at the early stages, and shifted to Rhodopseudomonas and Rhodobacter in the older soils. The observed changes may be related to an increase of K, Mg+, NH4 +, NO3- and/or CO2, detected after 15-20 years of soil exposure. The community of permafrosts varies by location and age (5,000 - 8 millions of years). The alkM gene was detected in old Arctic permafrosts (3 millions of years), while alkB genes were found on Arctic samples from 15,000 to 120,000 years, and in Antarctic modern soils. Some of these clones may represent new alk genes. The contributions of this project covers the goals of the International Polar Year (IPY 2007-2009), particularly in assessing the microbial ecology of Antarctica.

Mars is one of the best candidates among planetary bodies for supporting life. The presence of water in the form of ice and atmospheric vapour together with the availability of biogenic elements and energy are indicators of the possibility of hosting life as we know it. The occurrence of permanently frozen ground – permafrost, is a common phenomenon on Mars and it shows multiple morphological analogies with terrestrial permafrost. Despite the extreme inhospitable conditions, highly diverse microbial communities inhabit terrestrial permafrost in large numbers. Among these are methanogenic archaea, which are anaerobic chemotrophic microorganisms that meet many of the metabolic and physiological requirements for survival on the martian subsurface. Moreover, methanogens from Siberian permafrost are extremely resistant against different types of physiological stresses as well as simulated martian thermo-physical and subsurface conditions, making them promising model organisms for potential life on Mars. The main aims of this investigation are to assess the survival of methanogenic archaea under Mars conditions, focusing on methanogens from Siberian permafrost, and to characterize their biosignatures by means of Raman spectroscopy, a powerful technology for microbial identification that will be used in the ExoMars mission. For this purpose, methanogens from Siberian permafrost and non-permafrost habitats were subjected to simulated martian desiccation by exposure to an ultra-low subfreezing temperature (-80ºC) and to Mars regolith (S-MRS and P-MRS) and atmospheric analogues. They were also exposed to different concentrations of perchlorate, a strong oxidant found in martian soils. Moreover, the biosignatures of methanogens were characterized at the single-cell level using confocal Raman microspectroscopy (CRM). The results showed survival and methane production in all methanogenic strains under simulated martian desiccation. After exposure to subfreezing temperatures, Siberian permafrost strains had a faster metabolic recovery, whereas the membranes of non-permafrost methanogens remained intact to a greater extent. The strain Methanosarcina soligelidi SMA-21 from Siberian permafrost showed significantly higher methane production rates than all other strains after the exposure to martian soil and atmospheric analogues, and all strains survived the presence of perchlorate at the concentration on Mars. Furthermore, CRM analyses revealed remarkable differences in the overall chemical composition of permafrost and non-permafrost strains of methanogens, regardless of their phylogenetic relationship. The convergence of the chemical composition in non-sister permafrost strains may be the consequence of adaptations to the environment, and could explain their greater resistance compared to the non-permafrost strains. As part of this study, Raman spectroscopy was evaluated as an analytical technique for remote detection of methanogens embedded in a mineral matrix. This thesis contributes to the understanding of the survival limits of methanogenic archaea under simulated martian conditions to further assess the hypothetical existence of life similar to methanogens on the martian subsurface. In addition, the overall chemical composition of methanogens was characterized for the first time by means of confocal Raman microspectroscopy, with potential implications for astrobiological research. / Der Mars ist unter allen Planeten derjenige, der aufgrund verschiedener Faktoren am wahrscheinlichsten Leben ermöglichen kann. Das Vorhandensein von Wasser in Form von Eis und atmosphärischem Dampf zusammen mit der Verfügbarkeit biogener Elemente sowie Energie sind Indikatoren für die Möglichkeit, Leben, wie wir es kennen, zu beherbergen. Das Auftreten von dauerhaft gefrorenen Böden, oder auch Permafrost, ist ein verbreitetes Phänomen auf dem Mars. Dabei zeigen sich vielfältige morphologische Analogien zum terrestrischen Permafrost. Permafrostgebiete auf der Erde, welche trotz extremer, Bedingungen durch eine große Zahl und Vielfalt mikrobieller Gemeinschaften besiedelt sind, sind hinsichtlich möglicher Habitate auf dem Mars die vielversprechendste Analogie. Die meisten methanogenen Archaeen sind anaerobe, chemolithotrophe Mikroorganismen, die auf der Marsoberfläche viele der metabolischen und physiologischen Erfordernisse zum Überleben vorfinden. Methanogene Archaeen aus dem sibirischen Permafrost sind zudem extrem resistent gegenüber unterschiedlichen Formen von physiologischem Stress sowie simulierten thermo-physikalischen Marsbedingungen. Die Hauptziele dieser Untersuchung bestehen darin, das Überleben der methanogenen Archaeen unter Marsbedingungen zu beurteilen, wobei der Fokus auf methanogenen Archaeen aus dem sibirischen Permafrost liegt, sowie deren Biosignaturen mit Hilfe der Raman-Spektroskopie zu charakterisieren, einer starken Technologie zur mikrobiellen Identifikation, welche bei der ExoMars-Mission zum Einsatz kommen wird. Zu diesem Zweck wurden methanogene Archaeen aus dem sibirischen Permafrost sowie aus Nicht-Permafrost-Habitaten in Simulationen Marsbedingungen ausgesetzt, wie Austrocknung durch Langzeitversuche bei ultraniedrigen Temperaturen unter dem Gefrierpunkt (-80ºC), Mars-analogen Mineralien (S-MRS und P-MRS) sowie einer Marsatmosphäre. Weiterhin wurden die Kulturen verschiedenen Konzentrationen von Magnesiumperchlorat, einem starken Oxidant, der im Marsboden nachgewiesenen wurde, ausgesetzt. Ferner wurden die Biosignaturen einzelner Zellen der methanogenen Archaeen mit Hilfe der konfokalen Raman-Mikrospektroskopie (CRM) charakterisiert. Die Ergebnisse zeigten für alle untersuchten methanogenen Stämme Überleben und Methanbildung, nachdem diese simulierten Austrocknungsbedingungen ausgesetzt worden waren. Nach Versuchen mit Temperaturen unter dem Gefrierpunkt zeigten die Stämme aus dem sibirischen Permafrost eine schnellere Wiederaufnahme der Stoffwechseltätigkeit, wohingegen bei den Referenzorganismen aus Nicht-Permafrost-Habitaten die Zell¬membranen im größeren Ausmaß intakt blieben. Der Stamm Methanosarcina soligelidi SMA-21 aus dem sibirischen Permafrost zeigte nach dem Belastungstest mit Marsboden und Mars-analoger Atmosphäre signifikant höhere Methanbildungsraten. Zudem überlebten alle untersuchten Stämme die Zugabe von Magnesiumperchlorat in der entsprechenden Konzentration, die auf dem Mars vorkommt. Weiterhin konnten durch die Raman-Spektroskopie beachtliche Unterschiede in der chemischen Zusammensetzung zwischen methanogenen Archaeen aus Permafrost- und Nicht-Permafrost-Habitaten, trotz ihrer phylogenetischen Verwandtschaft, ermittelt werden. Die Konvergenz der chemischen Zusammensetzung der Permafrost-Stämme könnte das Resultat ihrer Anpassung an die Umgebung sein, was auch die Unterschiede hinsichtlich ihrer Resistenz verglichen mit Nicht-Permafrost-Stämmen erklären könnte. Als Teil dieser Studie wurde die Raman-Spektroskopie als Analyse-Technik zur Ferndetektion von methanogenen Archaeen, welche in eine Mineral-Matrix eingebettet sind, evaluiert. Diese Dissertation trägt zu einem besseren Verständnis hinsichtlich der Grenzen für ein Überleben von methanogenen Archaeen unter simulierten Marsbedingungen bei und damit zu einer Beurteilung der Hypothese, ob es ähnliches Leben unter der Marsoberfläche geben könnte. Darüber hinaus wurde erstmalig die chemische Zusammensetzung von methanogenen Archaeen mit Hilfe der Raman-Mikrospektroskopie charakterisiert. Dieser Technologie kommt eine wesentliche Bedeutung für weitere Forschungstätigkeit in der Astrobiologie zu.

L'étude du permafrost des parois alpines est essentielle pour comprendre son rôle dans le déclenchement des écroulements rocheux. Pour estimer la distribution du permafrost dans les parois du massif du Mont Blanc, nous avons développé trois axes de recherche appuyés sur trois méthodes d'investigation. La mesure continue de la température des parois sur le site pilote de l'Aiguille du Midi, à leur surface depuis 2005 et jusqu'à 10 m de profondeur dans trois forages depuis 2010, révèle les caractéristiques locales du permafrost : coexistence de secteurs de permafrost chaud (>-2°C) et froid, couche active comprise entre c. 2 m et c. 6 m selon l‘exposition, flux latéraux de chaleur, effets variables de la neige et de la fracturation. La modélisation statistique de la distribution du permafrost suggère une présence sporadique du permafrost dès 1900 m en face nord et 2300 m en face sud dans les secteurs localement favorables, puis plus continue à partir de respectivement 2600 m et 3000 m d'altitude. Cette modélisation, réalisée sur un MNA à 4 m de résolution, a été comparée au même modèle implémenté sur un MNA à 30 m de résolution : la résolution métrique est apparue nécessaire pour une prédiction pertinente à l'échelle locale. Enfin, la tomographie de résistivité électrique a été appliquée sur huit profils de 160 m de long et 25 m de profondeur sur six faces subverticales du massif dont deux répétés en 2012 et 2013. Les résultats permettent (i) la caractérisation 2D du permafrost : identification de permafrost chaud, du contrôle topographique dans les secteurs très escarpés, suggestion des effets de la neige et de la fracturation; et (ii) l'évaluation de notre modèle de distribution à 4 m  la résolution à 30 m étant trop grossière. Si le modèle paraît réaliste, il surestime toutefois l'occurrence du permafrost dans les secteurs caractérisés par la présence de glaciers, sans doute du fait du rayonnement réfléchi et diffus exacerbé par la surface glaciaire. Nos résultats ont été mobilisés pour analyser la distribution de 523 écroulements ayant affecté les parois d'altitude en 2003 et entre 2007 et 2014. Près de 90% de ces écroulements sont survenus dans des parois à permafrost chaud, ce qui confirme que la dégradation du permafrost est un facteur majeur de leur déclenchement. Le développement futur de modèles physiques permettra d'améliorer la compréhension systémique de la distribution et de l'évolution du permafrost. / Rockwall permafrost investigation is essential for understanding of its role in the triggering of rock falls. To estimate permafrost distribution in the Mont Blanc massif rockwalls, we developed three axes of research based on three methods. The monitoring of rockwall temperatures at the pilot-site, Aiguille du Midi, at the surface since 2005, and down to 10-m-deep since 2010, reveals local characteristics of permafrost: warm (>-2°C) and cold permafrost areas coexist, active layer ranges from ca. 2 m and ca. 6 m according to exposure, lateral heat fluxes, variables effects from snow and fractures. The statistical modelling of permafrost distribution suggests sporadic occurrences of permafrost from 1900 m asl. on north faces and 2300 m asl. on south faces in locally favourable conditions, its presence is more continuous from 2600 and 3000 m asl., respectively. The model has been implemented on a 4-m-resolution DEM and has been comapred to the same model based on a 30-m-resolution DE%: the metric resolution appeared necessary for a relevant prediction at the local scale. Finally, electrical resistivity tomography has been applied on eight 160-m-long and 25-m-deep profiles on six subvertical rock faces, two of which being repeated in 2012 and 2013. The results allow for (ii) a 2D characterisation of permafrost: identification of warm permafrost areas, of the topographical control on sharp crests, suggestion of snow and fracturing effects; and (ii) evaluation of the 4-m-resolution model  the 30-m-resolution being to coarse. Even though the model seems realistic, it overestimates permafrost occurrence in areas characterized by the presence of glaciers, certainly because of the reflected and diffuse radiations that are intensified by the glacial surface. Our results have been used to analyse the distribution of 523 rockfalls triggered from high alpine rockwalls in 2003 and from 2007 to 2014. Nearly 90% of these rockfalls have been triggered in warm permafrost rockwalls, which corroborates that permafrost degradation is a triggering factor of rockfall. Futur developments of physic-based models will allow improving of systemic understanding of the distribution and evolution of permafrost.

Made available in DSpace on 2015-03-26T13:53:23Z (GMT). No. of bitstreams: 1 texto completo.pdf: 3804010 bytes, checksum: a7e6fd6b0be4482ad931d87955437622 (MD5) Previous issue date: 2012-02-16 / Periglacial environments constitute one of the most important components of the global landscape, especially with regards to regulatory processes of water, temperature and carbon. Weathering processes related to ice action and the presence of permafrost are peculiar characteristics of these environments, which include regions of high altitude and/or latitude around the globe. Among the general processes of weathering and soil formation common to free ice areas of Antarctica, it is observed that some of these processes take major or minor importance when they are observed in details for the formation of specific landscapes. The Seymour Island (Marambio) is located in the Northern portion of the Weddell Sea and it is composed of sediments dating from the Late Cretaceous to the Lower Tertiary, cut by basaltic dikes. These sediments are constituted of glauconitic sands, bituminous silts, sulfides and carbonates coming from fossil. The main factors which influence the pedogenesis are the arid and cold climates favoring the presence of soluble salts in abundance, the occurrence of sediments rich in sulfides and the bird activity leading to the formation of ornithogenic soils. Thus, this work aimed at describing properties of soils developed on polar semi desert of Seymour Island, identifying and analyzing pedogenic factors and processes in different pedological systems of the island; and, finally, classifying such soils according to Soil Taxonomy and WRB (FAO) classification systems. It was described profiles of representative soils from different pedoambientes and collected samples of pedogenic horizons. In samples of fine ground dried on air, it was promoted a pretreatment to remove soluble salts. It was also promoted chemical and physical routines as soil pH, potential acidity (H + Al), extraction and determination of exchangeable bases; the total organic carbon, electrical conductivity, particle size and dry soil color. The profiles were classified according to the Soil Taxonomy and the World Reference Base for Soil Resources classification systems. Most of the soils showed permafrost inside the control section and, consequently, they were classified as Gelisols and Cryosols by the Soil Taxonomy and WRB/FAO, respectively. In general, they presented little cryoturbation, which is explained by the low humidity of the system (dry permafrost). The physical weathering is less active than those observed in the Antarctic Maritime due to the decreased cryoclastic. Similarly, the soils indicate lower chemical weathering compared to more humid regions of Antarctica, since the high aridity is a limiting factor for triggering chemical reactions in general. It was emphasized the salinisation, phosphate and sulfurization as the main processes of soil formation on the island. The soils are mostly saline, nátric, eutrophic, alkaline, and contain high CTC. According to the interpretation of the morphological, physical, chemical, mineralogical characteristics, classification and specific environmental conditions, the soils from the Seymour Island were divided into three groups. They are: immature alkaline soils on sandstones and siltstones; sulfate and ornithogenic soils. It was observed that the definition of the different pedological systems on the island is closely connected to the difference of the relief, which is decisive for the presence of permafrost dried or coated by ice. Another important factor is the constitution of the original material with lower or higher content of sulfides, carbonates and other minerals. Several features of the landscape suggest a more humid paleoenvironmental condition. Both phosphate and sulfurization are important sources of acidity for this alkaline system. The Soil Taxonomy and WRB/FAO systems do not have adequate classification criteria to classify all the soils developed in areas of climate transitions that are affected by salts, phosphate and sulphidesoxidise. / Os ambientes periglaciais constituem um dos mais importantes componentes da paisagem global, principalmente no que diz respeito a processos regulatórios de água, temperatura e carbono. Processos intempéricos relacionados à ação do gelo e presença de permafrost são características peculiares desses ambientes, que englobam regiões de elevada altitude e/ou latitude por todo o planeta. Dentre os processos gerais de intemperismo e de formação de solo comuns às áreas livres de gelo da Antártica, observa-se que alguns desses processos tomam maior ou menor importância quando observados em detalhe para a formação de paisagens específicas. A ilha Seymour (Marambio) encontra-se na porção setentrional do Mar de Weddell e é formada por sedimentos originados desde o Cretáceo Superior até o Terciário Inferior, cortados por diques basálticos. Esses sedimentos são compostos por areias glauconíticas, siltes betuminosos, sulfetos e carbonatos advindos de fósseis. Os principais fatores que influenciam a pedogênese são: o clima árido e frio, favorecendo a presença de sais solúveis em abundância, a ocorrência de sedimentos ricos em sulfetos e a atividade da avifauna levando à formação de solos ornitogênicos. Nesse sentido, os objetivos desse trabalho foram descrever propriedades de solos desenvolvidos em semideserto polar da Ilha Seymour; identificar e analisar fatores e processos pedogenéticos nos diferentes pedoambientes da ilha; e classificar tais solos nos sistemas de classificação Soil Taxonomy e WRB (FAO). Foram descritos perfis de solos representativos de diferentes pedoambientes e coletados amostras dos horizontes pedogenéticos. Em amostras de terra fina seca ao ar, promoveu-se o pré-tratamento para remoção de sais solúveis; rotinas químicas e físicas como pH em água, acidez potencial (H + Al), extração e determinação de bases trocáveis; carbono orgânico total, condutividade elétrica, granulometria e cor do solo seco. Os perfis foram classificados segundo a Soil Taxonomy e pelo sistema de classificação da World Reference Base for Soil Resources. A maioria dos solos apresentaram permafrost dentro da seção de controle, sendo, portanto, enquadrados como Gelisols e Cryosols pela Soil Taxonomy e WRB/FAO, respectivamente. De forma geral, apresentaram pouca crioturbação, explicada pela pouca umidade do sistema (permafrost seco). O intemperismo físico é menos atuante do que se observa na Antártica Marítima devido à diminuição da crioclastia. Da mesma forma, os solos indicam menor intemperismo químico em relação a regiões mais úmidas da Antártica, uma vez que a elevada aridez é fator limitante para o desencadeamento de reações químicas em geral. Destacamos a salinização, a fosfatização e a sulfurização como principais processos de formação de solos na ilha. Os solos são em sua maioria salinos, nátricos, eutróficos, alcalinos e com elevada CTC. De acordo com interpretação das características morfológicas, físicas, químicas, mineralógicas, classificação e condições ambientais específicas, os solos da Ilha Seymour foram agrupados em três grupos: solos alcalinos pouco evoluídos sobre arenitos e siltitos; solos sulfatados e solos ornitogênicos. Observou-se que a definição dos diferentes pedoambientes na ilha está intimamente ligada à diferenciação do relevo sendo este, determinante para a presença de permafrost seco ou cimentado por gelo. Outro fator determinante é a constituição do material de origem, com menor ou maior conteúdo de sulfetos, carbonatos e outros minerais. Diversos traços da paisagem sugerem uma condição paleoambiental mais úmida. Tanto a fosfatização, quanto a sulfurização são importantes fontes de acidez para esse sistema generalizadamente alcalino. Os sistemas Soil Taxonomy e WRB/FAO não possuem critérios de classificação adequados para classificar todos os solos desenvolvidos em áreas de transição climática que sejam afetados por sais, fosfatização e sulfidização.