DISTRIBUTION OF WATER-SOLUBLE SALTS IN SOILS OF THE SHACKLETON GLACIER REGION, ANTARCTICA AND IMPLICATIONS FOR SOIL HABITABILITY

Ice-free areas within the Transantarctic Mountains of Antarctica are believed to be some of the oldest exposed terrestrial environments on the continent. These extreme environments experience low temperatures and are hyper-arid, leading to soils with high concentrations of salts. Specialized organisms have adapted to these harsh conditions and persist in both terrestrial and aquatic environments, but the controls on their distribution, specifically regarding ecosystem assembly, are not fully understood. In addition, it is uncertain how biotic and abiotic factors that control biological assemblages will change in a warming future. It has been assumed that two prominent factors controlling the limits of life in terrestrial environments are a lack of surface water and toxic salt concentrations. In this work, we have measured water-soluble salt concentrations from 3 transects at 11 locations along the Shackleton Glacier (83.5°S) in the Transantarctic Mountains. This landscape represents a wide range of soil environments, particularly with respect to the age of soil surfaces (i.e. advance and retreat of the East Antarctic Ice Sheet) and surface material accumulations. Soluble salt concentrations were mapped to help estimate areas where ecosystem structure and assembly may be most diverse. Major soluble cation (K⁺, Na⁺, Ca²⁺, Mg²⁺) and anion (F­^-, Cl^-, Br^-, NO₃^-, SO₄^2-, PO₄^3-) concentrations vary greatly along the transects at each location. Our previously published work suggests that water soluble nitrate concentrations can be used to determine “wetting ages” or when these soils were last exposed to liquid water. In turn, these ages may also represent past locations of glacier movement. These new data from the Shackleton Glacier are compared to our previous work along the Beardmore Glacier region, as well as soils from the McMurdo Dry Valleys. Our results demonstrate the importance of climate in shaping soil environments in Antarctica.