| Summary: | In the absence of long-term environmental monitoring prior to and during resource development, identifying the extent of pollution is challenging but important for assessing risks to ecosystem health. Legacy pollution from Giant Mine in the Northwest Territories is a concern because while gold smelting operations ceased in the late 1990s, the fine, toxic dust arsenic trioxide dispersed into the atmosphere, potentially creating repositories in the surrounding landscape. Lake water surveys and the sampling of surficial sediment have identified a confined emissions footprint within a 30-km radius of the mine. However, these measurements may not capture the range of aerial deposition of emissions from the mine, particularly peak emissions released during the 1950s. Paleolimnological studies from far-field locations have shown evidence of arsenic enrichment coinciding with the timing of peak mine emissions during the 1950s, suggesting further research is needed to characterize stores of legacy metals derived from Giant Mine pollution.To address this need, as part of the Sub-Arctic Metal Mobility Study, temporal patterns of metals (arsenic, antimony, and lead) deposition and hydrological conditions were reconstructed from sediment cores collected from eight lakes along an 80-km transect northwest of Yellowknife, following the prevailing wind direction. Two sediment cores were collected from each lake by using a Uwitec gravity corer fitted with PVC tubes (86-mm internal diameter). These lake sediment cores provide further characterization of the Giant Mine emission footprint, and the depositional and post-depositional history of arsenic and other metals in sub-arctic lakes and their catchments.
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