Contribution by Giant petrels and Brown skuas to soil phosphatization in Harmony Point - Maritime Antarctica.

This research was conducted for the purpose to evaluate the contribution Giant petrels and Brown skuas nestings in the formation of ornithogenic soils by the phosphatization process in Harmony Point, Maritime Antarctic. Ten nests were selected to collect topsoil samples (0-20 cm), from 0 m up to 20 m away, with regular spacing of 2 m. The analysis of the samples included the physical, chemical, mineralogical and geochemical analyzes. Phosphate minerals were identified. The presence of high content of some trace elements, such as Zn, Cu and Sr is associated with the bird's excrements. Total-P and bioavailable-P recorded higher levels. This result demonstrates the importance of the time factor in the bird's nesting, as well as in the development of the soil in these soil-forming environment. Phosphatization in these areas is not restricted to the specific location of the nest, since high values of P have been identified at distances between 8 and 12 m, from de nest's top. This suggests the transport of P rich solutions and phosphatized material along fractures by the freeze-thaw cycles, contributing to increase the geographical expression of this phenomenon in this ice-free area, consequently the development of soils and the establishment of vegetation.