Grant: Strategic Projects - Group

Permafrost refers to ground that remains frozen for two or more consecutive years, and it presently covers about 22% of the land surface in the Northern Hemisphere. Canada occupies about one third of this area covered by permafrost. With projected global warming, climate modelers predict that, by 2100, the land area covered by permafrost will shrink by 8-9 million km2 in the Northern Hemisphere, an area roughly the size of Australia. Thawing permafrost will therefore take place on a continental scale, and it will affect our landscapes, ecosystems, and freshwater resources. Despite the extent and speed of these changes, very little is known about how thawing permafrost will affect global geochemical cycles and our freshwater resources. We propose to assess the impact of thawing permafrost on freshwaters on the Mackenzie Delta in Nunavut, and in Old Crow Flats in the Yukon. We will identify lakes affected by recent permafrost thaw slumps with aerial photographs, and we will compare lakes receiving large discharges from thawing permafrost with lakes where permafrost degradation is less apparent. We will compare water quality variables in these lakes (organic contaminants, metals, nutrients) to determine the extent that melting permafrost affects water quality. We will use this information to develop methods to track permafrost degradation in lakes. By extracting lake sediment cores, we will apply these tools to reconstruct the history of permafrost degradation in lakes, and determine if chemical releases by permafrost thawing diminish over time. Finally, we will determine if contaminants released by degrading permafrost are accumulating in freshwater food webs that constitute an important part of traditional diet and lifestyle. This study will constitute the first systematic assessment of thawing permafrost on contaminants in northern lakes and their ecosystems.