CGRG Bibliography of Canadian Geomorphology
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Author : Barker, J.; Sharp, M.; Klassen, J.; Foght, J.; and Turner, R.
Date : 2004.
Title : Organic carbon dynamics in glacier systems.
Publication : American Geophysical Union Fall Meeting. December 13-17, 2004. San Francisco, California.
Issue :
Page(s) :
Abstract
The biogeochemical cycling of organic carbon (OC) has important implications for aquatic system ecology because the abundance and molecular characteristics of OC influence contaminant transport and bioavailability, and determine its suitability as a substrate for microbial metabolism. There have been few studies of OC cycling in glacier systems, and questions remain regarding the abundance, provenance, and biogeochemical transformations of OC in these environments. To address these questions, the abundance and molecular characteristics of OC is investigated in three glacier systems. These systems are characterized by different thermal and hydrological regimes and have different potential OC sources. John Evans Glacier is a polythermal glacier in arctic Canada. Outre Glacier is a temperate glacier in the Coast Mountains of British Columbia, Canada. Victoria Upper Glacier is a cold-based glacier in the McMurdo Dry Valleys of Antarctica. To provide an indication of the extent to which glacier system OC dynamics are microbially mediated, microbial culturing and identification is performed and organic acid abundance and speciation is determined. Where possible, samples of supraglacial runoff, glacier ice and basal ice and subglacial meltwater were collected. The dissolved organic carbon (DOC) concentration in each sample was measured by combustion/non-dispersive infrared gas analysis. Emission and synchronous fluorescence spectroscopy were used to characterize the molecular properties of the DOC from each environment. When possible, microbial culturing and identification was performed and organic acid identification and quantification was measured by ion chromatography. DOC exists in detectable quantities (0.06-46.6 ppm) in all of the glacier systems that were investigated. The molecular characteristics of DOC vary between glaciers, between environments at the same glacier, and over time within a single environment. Viable microbes are recoverable in significant (ca. 10$^{3}$ colony forming units/ml) levels from John Evans Glacier and Victoria Upper Glacier. Identification of these organisms has revealed similarities to bacteria isolated previously from glacier ice and arctic and antarctic terrestrial environments. Organic acid concentrations are higher in the basal ice than in the glacier ice at John Evans Glacier and Victoria Upper Glacier. These results suggest that environmental conditions, such as overridden soil and vegetation type, influence the characteristics of DOC and that microbial cycling of OC is active in glacier systems.
Bibliography of Canadian Geomorphology