| Summary: | Degree: Doctor of Philosophy Abstract: Ice masses in the Antarctic, Greenland, and Canadian Arctic cover approximately 10% of the Earth’s surface, contain approximately 70% of the Earth’s freshwater, and are the top contributors to eustatic sea level rise. In recent years, these polar glacier systems have experienced significant increases in mass loss and melt rates, and the quantity of melt in these regions is expected to increase further under a warming climate. Existing research indicates that the physical, chemical, and microbial characteristics of these ice masses and the meltwater they produce are often distinct from those of other natural water sources. Their characteristics also show high temporal and spatial variability that may result from the combined presence of distinct and variable biogeochemical environments, particularly on the glacier surface and near the bed, and the strong variations in hydrological dynamics that often occur in glacial systems. This study examines glacier ice and meltwater from the Antarctic, Greenland, and Canadian Arctic to (1) investigate the variability in microbial assemblages and nutrient species/concentrations in the various biogeochemical environments that exist within and between polar glacier systems, and (2) evaluate how glacier hydrology influences the development and export of microbes and nutrients from these systems. Results of this study indicate that distinct biogeochemical environments exist in glacial systems, that they can function as sources and/or sinks for specific nutrients and microbes, and that the nutrients and microbes exported in glacial meltwater can vary according to the meltwater sources, flow paths, and residence times within the glacial system. Consequently, the biogeochemical characteristics of glacier ice and meltwater can differ between glaciers with different features, thermal regimes and/or hydrological systems, can change over the course of the melt season as the hydrological system within a glacier evolves, and can show different ...
|
|---|