Abstract
Micropedology studies by description of scanning electron microscopy images and electron micropobre analysis combined with field soil description, mineralogical, physical, and chemical laboratory analyses, can furnish valuable information about soil genesis in polar regions. The present study was carried out at Lions Rump (King George Island, Maritime Antarctica), where six pedons were selected to represent the main soil types found in the local ice-free areas, varying from bare (without vegetation) to well-vegetated ornithogenic soils, with high phosphate and organic matter content. Each pedon was described and sampled for mineralogical, micromorphological and microchemical studies, complemented by chemical and physical analyses. Phosphatization is the main forming process in these soils and two types of ornithogenic soils could be distinguished: Acid pH ornithogenic soils and Neutral pH ornithogenic soils. Phosphate-rich, deep, acid pH ornithogenic soils are the most developed soils and occur associated with abandoned penguin rookeries, with well-crystalline Al-phosphates (taranakite). Soils recently occupied by penguins have neutral pH and absence of crystalline phosphate minerals, although they are also rich in exchangeable P. Phosphate are found as illuvial coatings, infillings, reacting alteration cortex of clasts or compound the micromass of the aggregates. Although the microstructures of Lions Rump soils are related to frost-action, the phosphatization forming a particular well-developed rounded aggregates, under strong biological influence. The ornithogenesis depends on the time of exposure to birds' influence and decomposition stage of guano.
Published Version
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