Release of geogenic uranium and arsenic results in water-quality impacts in a subarctic permafrost region of granitic and metamorphic geology ...

• Main Authors: Skierszkan, Elliott Karl, Dockrey, John William, Mayer, K. Ulrich, Beckie, Roger D.
• Format: Text
• Language: English
• Published: Elsevier 2022
• Subjects: Dawson; permafrost; Subarctic; Yukon
• Online Access: https://dx.doi.org/10.14288/1.0391904; https://doi.library.ubc.ca/10.14288/1.0391904

This study investigates geogenic U and As mobilization in relation to bedrock geology, groundwater geochemistry, and the presence of mineral deposits in the Dawson Range, Yukon, Canada, a remote subarctic region that has drawn recent interest from mining industry. Elevated concentrations of U and As occur through natural weathering processes. For this study we compiled and interpreted a geochemical dataset from the region that includes 1,075 rock samples, 365 sediment samples, 3,189 surface water samples, and 384 groundwater samples. Median U concentrations exceed the Canadian guideline for the protection of aquatic life of 15 µg/L (long-term exposure) at 8 % of 547 surface-water monitoring locations and the maximum observed concentration is 337 µg/L. 39 % of monitoring wells have median groundwater U concentrations above this guideline and the maximum observed concentration is 589 µg/L. Uranium mobilization is driven by weathering of granitic and metamorphic bedrock that has contents near or slightly above ...