Spatial Patterns and Dimensions: Antarctica
Antarctica is the continent most south of the Antarctic Circle and is surrounded by the Southern Ocean. It is approximately 5000 kilometres south of Australia. It has latitude of 90 degrees south and a longitude of 0 degrees east. It covers an area approximately 14million square kilometres (280,000 sq km ice-free, 13.72 million sq km ice covered). If all the ice were to melt, the level of the world’s oceans would rise by 65-70m, and if the weight of the ice were removed, it is estimated that the underlying rock would rise by 700m to 1000m. It has a coastline of approximately 17,968km. Antarctica is extremely high in altitude. It is the highest continent on the planet with an average altitude of 2500m. Antarctica’s lowest point is -2555m at Bentley Subglacial Trench and its highest point is 4897m at Vinson Massif. Biophysical Interactions:
Antarctica has severe low temperatures that vary with latitude, elevation and distance from the ocean. Higher temperatures occur in January along the coast and average slightly below freezing. Antarctica is the windiest continent with the highest wind speed measured at Dumont d’Urville (327km/hr). It is also one of the driest continents in the world. It averages just over 5cm per year. The coldest temperature ever recorded on the planet was at the Russian Station Vostok in 1863, recording a freezing -89 degrees Celsius. Natural hazards that have occurred on Antarctica include gravity driven winds that blow coastward from the high interior, frequent blizzards form near the foot of the plateau, and cyclonic storms form over the ocean and move clockwise along the coast. The Antarctic landscape is dominated by glaciers, barren expanses of rock and exposed soils, ice-covered closed basin lakes, and glacial melt water streams. There are no large indigenous terrestrial plants or animals, although soils are inhabited by nematodes, rotifers, and tardigrades, and some streams and lakes have extensive benthic algal communities. The formation of calcium phosphate rock coating and its influence in geomorphic processes were investigated on the Yalour Islands (Antarctica). amples of coating on the metamorphosed andesitic rock are composed of a 25 μm-thick, white, shiny, relatively hard layer of hydroxylapatite (Hp) with traces of calcite and quartz. Scanning electron micrographs, X-ray diffractograms, Fourier Transform Infrared (FTIR) spectra, and in situ analysis of the chemical composition of the coatings suggest that the calcium phosphate coating is formed mainly through the decomposition of penguin excrement from nearby penguin rookeries and subsequent precipitation of Hp in micropits on the surface of the rock from solutions containing high amounts of calcium and phosphorus. These coatings undergo abiotic and biotic weathering processes that lead to the accumulation of secondary Hp as “flakes” and infillings in microcracks. The coatings give the dark, metamorphosed andesitic rock a shiny, light-colored surface. The coatings can decrease the permeability and increase the albedo of the rock, thereby limiting moisture infiltration (into the rock) and changing the rock's temperature. Based on theoretical estimates, a change of albedo from 0.2 to 0.3 significantly decreases the radioactive heating of the rock during the summer months. These changes to rock properties will influence geomorphic processes such as freeze-thaw, thus affecting rock weathering and hence the evolution of the local landscape. Antarctica plays an important role in the earth’s climate and weather patterns, and is of vital interest for scientists studying the earth’s evolution and atmosphere. Layers of ice, compacted over millions of years, provide a history of the earth’s climate. By studying cores drilled out of the ice, scientists can detect changes over the centuries. Trapped air bubbles record...
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