Environmental Biogeochemistry

Projects

Glacier Biogeochemistry

Far from being sterile, frozen blocks of ice, glacier systems are biologically rich aquatic ecosystems where microbially mediated biogeochemical processes cycle biologically important elements such as carbon, nitrogen and sulphur.  We have sampled glacier ice, basal ice, and glacier meltwater from a variety of glacier environments in the McMurdo Dry Valleys of Antarctica, the Canadian high arctic, the Canadian Rocky Mountains, Bhutan, and the Southern Alps of New Zealand.

We apply a variety of analytical and statistical techniques to characterize changes in OM from different glacier environments and at different time scales to try to gain an understanding of how OM is modified in glacier systems, and how this modification fits into global nutrient cycles.

The Role of Legacy Organic Matter in Contemporary Ecosystem Processes

We have identified several key sites in Antarctica and the Canadian Arctic where ancient organic material has been preserved beneath valley glaciers and permafrost, and is now being exposed due to climate change.  Notably, we received funding from the National Science Foundation for a field investigation at a site in the Canadian Arctic during the summer of 2010, and continue to work there today.  This site is the location of a mummified forest deposit that contains mummified tree trunks, branches, cones, seeds, leaves, and insects.  These forest remains are likely Pliocene in age, and represent a forest ecosystem at the very northern edge of an ancient treeline at a time when Arctic climate was changing from conditions that were much warmer than today‚Äôs to conditions that are more similar to those that exist presently.  This site might yield important clues regarding how quickly ecosystems respond to climate change and how Arctic climate change occurred both in the Pliocene and, potentially, how it may respond to future warming.

Black Carbon Deposition and Post-Depositional Redistribution on Glacier Surfaces

Black carbon (BC) is a byproduct of the incomplete combustion of organic matter and absorbs solar radiation in the atmosphere and decreases the albedo of snow-covered surfaces.  The deposition of BC onto glacier surfaces not only provides a historical record of atmospheric BC concentration in ice cores, but also has th potential to accelerate glacier melt.  In collaboration with the Ice For Paleoclimatology Group at the Byrd Polar and Climate Research Center, we are analyzing ice cores from the Tibetan Plateau, Devon Island, and Greenland to document historical trends in BC deposition globally.  We are also sampling surface snow and snowmelt from southern Himalaya glaciers in Nepal and Bhutan to examine spatial trends and post-depositional processes involving BC along the southern Himalayan mountains.