Spatiotemporal patterns of mining-associated metals in lake sediments near Yellowknife, Northwest Territories

The data collected for this study were used to identify the spatial extent of the Giant and Con mine emissions footprint in the Yellowknife area using primarily arsenic, antimony, and lead concentrations found in lake sediments. Solid-phase metal concentrations were analyzed by ALS Laboratories (Waterloo, ON) following EPA standards 200.2/6020A on lake sediments collected using a Uwitec gravity corer in June 2018. Sediment cores were collected from eight lake sites located at distances between 10 and 80 km from Giant and Con mines in the downwind direction (NW). Lake water samples were also collected at the time of core collection to characterize total and dissolved metal concentrations using a 1 L nalgene at a depth of 5 cm from the water surface. Additional analysis of lake sediment has included the measurement of carbon and nitrogen isotopic composition using a continuous flow isotope ratio mass spectrometer (CF-IRMS) at the University of Waterloo to determine relative sources of organic matter within lakes and identify whether there is evidence of hydrological change. Lake sediments were also subject to a standard loss-on-ignition analyses to determine relative organic matter, carbonate, mineral matter, and water content. Finally, lake sediments were radiometrically dated using measurements of 210Pb and 137Cs on an Ortec HPGE Digital Gamma Ray Spectrometer at the University of Waterloo to assign ages to sediment depths and ultimately determine when contaminants were deposited.

The purpose was to identify the spatial extent of the Giant and Con mine emissions footprint in the Yellowknife area using primarily arsenic, antimony, and lead concentrations found in lake sediments.