The Impact of Road Dust on Arctic Aquatic Ecosystems, Northwest Territories, Canada
Gunter, Rebecca Anne
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The Canadian Arctic is currently undergoing rapid environmental and climatic changes. Resource development in northern regions also continues to expand, which requires more infrastructure such as roads. The Dempster Highway is a potential source for calcareous road dust since construction was completed in AD1979. Along the same timeline, the regional air temperatures began increasing, with the warming beginning around AD1970. Previous research indicates that dust from gravel highways has an impact on vegetation, and that the roadbed itself can alter near-surface permafrost temperature regimes. This research aims to employ paleolimnological methods to examine the potential impact of calcareous road dust on the aquatic ecosystems close to the Dempster Highway, as well as the possible effects from a warming climate. Lake sediment cores were taken from two impacted lakes adjacent to the highway (FM02 and FM04) and from one reference lake (FM06) located a far enough distance away that it is outside the range of dust transport. Through analyses of water chemistry, it was discovered that both the dust from the Dempster Highway and retrogressive thaw slumps in the surrounding area have an extensive impact on certain water chemistry variables (i.e. conductivity, pH, Ca+2, etc.); However, elemental profiles of the sediment cores revealed no signal from calcareous road dust in lake FM02. The NPP exhibited a clear shift to genera that prefer both warmer and more humid climates, as well as increased nutrients, all products of regional warming and increased influx of calcareous road dust during construction of the Dempster Highway. This research will help the Department of Transportation and Department of Natural Resources in making regulatory decisions regarding new infrastructure in the Canadian Arctic.