We performed a field survey to assess changes in biomass, nutrient ratios, and isotopic signatures of three different microbial mat types in two glacial meltwater streams in the McMurdo Dry Valleys, Antarctica. Samples were taken in January 2013 from pre-existing transects over Von Guerard Stream and the Relict Channel, and stretched from near the Von Guerard Glacier terminus to the stream outlets at Lake Fryxell.
Mineral apatite is the ultimate source of the essential nutrient phosphorus to the soil ecosystem. In order to assess the biogeochemical weathering of apatite grains in the dry, basic soils of the McMurdo Dry Valleys, we collected nine surface soil samples from the Fryxell and Bonney Basins of Taylor Valley. After separating more than 50 individual soil apatite grains from each sample, we used scanning electron microscopy to quantify the morphology and surface etching of apatite grains to determine the degree of weathering.