Ornithogenic cryosols from Maritime Antarctica: Phosphatization as a soil forming process

Birds nesting activity during the short antarctic summer promotes intense localized sea–land transference of nutrients and organic matter, originating the ornithogenic soils. This study presents chemical, physical and mineralogical data as well as some micropedological and submicroscopical characteristics of ornithogenic and non-ornithogenic soils from the western coast of the Admiralty Bay, King George Island. Chemical analyses of selected soil properties show P and N enrichment in ornithogenic soils. Vegetation growth is enhanced and results in high soil organic C contents. A granular, sub-rounded structure composed by silt particles surrounded by illuvial phosphates is typical at ornithogenic horizons. These illuviation features characterize a distinct process of phosphatization, with P mobility and neoformation of secondary phosphates, such as taranakite, minyulite and leucophosphite. Ornithogenic sites are extremely important and constitute the most important locci of C sequestration in antarctic terrestrial ecosystems. A classification scheme for ornithogenic soils is proposed within the Soil Taxonomy and WRB classification systems.