DEVELOPMENT OF A LABORATORY SIMULATION FOR FREEZE-THAW OF AEOLIAN SEDIMENTS IN GLACIAL SYSTEMS

Glacial systems play a crucial role in supplying trace metals, nutrients, and weathering products to proglacial and marine ecosystems. Previous research has mainly focused on subglacial and proglacial systems, with diminished emphasis on weathering processes in the most upstream sources: snow and supraglacial ice. Aeolian sediments found on glaciers and snowbanks have a lower albedo than snow and can generate meltwater when solar irradiance is high. However, during cloudy days, when the sun is obstructed by topographic highs, or the sun dips below the horizon, the meltwater can refreeze around the sediment grains. This freeze-thaw process can occur several times in a single day, yet it is still unclear whether chemical weathering due to contact with the water or physical weathering because of freeze-thaw is the dominant mechanism in releasing nutrients for downstream ecosystems.

For this investigation, we developed a robust methodology to simulate freeze-thaw in natural glacial environments, which includes an initial wetting, a variety of freeze-thaw cycles ranging from 1 to 60, and recommendations for adaptation. The method was developed and tested using aeolian sediments and soils collected from the McMurdo Dry Valleys, Antarctica. Leachate produced from the freeze-thaw will be analyzed by ion chromatography for major ions, continuous flow nutrient analysis for major nutrients, and inductively coupled plasma optical emission spectroscopy (ICP-OES) for metals. The results of the freeze-thaw will improve our understanding of the dominant processes generating solutes in glacial systems. Additionally, the development of a tested and formalized freeze-thaw methodology will enable researchers in glacial systems to adapt the methodology for numerous applications.