Evan Jones, MSc Candidate, Smol Lab Tracking the long-term limnological impacts of silver mining near Keno City on the traditional territory of the First Nation of Na-Cho Nyäk Dun (Yukon, subarctic Canada) Mining in Northern Canada has caused many major environmental problems; however, historical data are often non-existent. Here, a multi-proxy (metals, bioindicators, pigments) paleolimnological approach is used to reconstruct the historical impacts of mining activity near Keno City, on the traditional land of the First Nation of Na-Cho Nyäk Dun in central Yukon (Canada). Silver was discovered in the Keno region in the early 1900s and intensive mining has taken place ever since.
Christal Lake, a shallow water body, lies near many historical and current mines, and was once the site of a processing mill. A sediment core was retrieved from Christal Lake in September 2022. Geochemical data from the dated sediment core were used to reconstruct metal inputs linked to the mining activity. The largest shift in biological indicators was a striking decline in sedimentary chlorophyll-a concentrations, indicating declining algal populations. Meanwhile, subfossil diatom assemblages only changed subtly in response to mining. There was no biological evidence of acidification, likely due to the neutralizing effect of the carbonate-rich catchment. The Hanson lakes are situated ~10 km from Keno City and are outside the Christal Lake watershed. These lakes are being studied to determine the potential extent of aerial deposition of mining contaminants. A sediment core was retrieved from a basin in the Hanson lakes system in October 2023. Preliminary results indicate that, despite proximity to mines, it is climate that is the major driver of ecological change in this system. Collectively, the data from these two sites help document the long-term impacts of silver mining in this subarctic environment. Comments are closed.
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