Phosphorus fractions in soils of Taylor Valley, Antarctica

Phosphorus studies in the cold desert ecosystem of the Antarctic Dry Valleys have been largely confined to stream sediments and orthinogenic regions. Expanding P studies to soils may augment the understanding of P biogeochemistry and habitat suitability in this extreme environment. Our objectives were to examine P fractionation in Antarctic Dry Valley soils and sediments and compare their relationship to other soil biogeochemical data. Samples were obtained along transects perpendicular to the Harnish and Priscu streams in Lake Fryxell and Lake Bonney basins, respectively. We utilized a sequential inorganic P extraction procedure, analyzing for a series of labile through resistant P fractions. We further analyzed soils for labile organic P and biomass P. Results showed the amount of inorganic P increased from soluble to Ca-bound P at both sites, with greater weathering of P-bearing minerals at the Fryxell site inferred from the greater P levels found in most fractions as compared with the Bonney site. Fryxell site soluble P findings correlated positively with the Al-bound phase, possibly facilitating P availability to microfauna. The P fraction distribution at both the Fryxell and Bonney sites fits the general relationship between weathering intensity and P distribution of other and ecosystems.