PRELIMINARY CHARACTERIZATION OF WIND-BLOWN DUST FROM THE MCMURDO DRY VALLEYS OF ANTARCTICA

The McMurdo Dry Valleys, Antarctica is an arid desert ecosystem with bare soils, perennial ice-covered lakes and ephemeral streams. Aeolian processes play a dominant role in the transport of materials, on the biogeochemistry of the ecosystem, and in the evolution of the landscape. Wind-blown sediment from Alatna Valley, Victoria Valley, Miers Valley, and the Taylor Valley (Taylor Glacier, East Lake Bonney, Lake Fryxell, and Explorer’s Cove) was collected approximately 1 meter above ground in summer and winter for 2013/2014 and 2014/2015 seasons and examined using SEM for preliminary characterization. Much of the material collected in the sediment traps is 1mm or larger and lithologically similar, with moderately weathered quartz, feldspar, pyroxene, amphibole, biotite, apatite, and volcanic ash comprising many of the grains, but differences in rock type and encrusting material are apparent. Predominately euhedral salt encrustations were seen in many of the sites, with NaCl dominating the coastal sites of Lake Fryxell and Explorer’s Cove, while CaSO₄ is more prevalent in the other locations. All sites have evidence of biologic material either as parts of microbial mats (Lake Fryxell, Miers Valley) or organic mats/biofilms filling mineral etch pits (Alatna Valley, Taylor Glacier, East Lake Bonney). Pieces of large organisms, such as diatoms, algae, or amoeba, were observed at some sites (Lake Fryxell, Explorer’s Cove, Alatna Valley, East Lake Bonney). The large size of the mineral grains and the diversity of material encrusting the surface of the grains attest to wind as a substantial driving force for the redistribution of nutrients, salts, organic matter, and organisms in the McMurdo Dry Valleys. Our work suggests that the material is primarily derived from local sources, as previous soluble salt analysis and isotopic studies have indicated.