Organic matter control on the distribution of arsenic in lake sediments impacted by ~65years of gold ore processing in subarctic Canada

Jennifer M Galloway; Graeme T Swindles; Heather E Jamieson; Michael Palmer; Michael B Parsons; Hamed Sanei; Andrew L Macumber; R Timothy Patterson; Hendrik Falck

doi:10.1016/j.scitotenv.2017.10.048

Organic matter control on the distribution of arsenic in lake sediments impacted by ~65years of gold ore processing in subarctic Canada

Sci Total Environ. 2018 May 1:622-623:1668-1679. doi: 10.1016/j.scitotenv.2017.10.048. Epub 2017 Oct 28.

Authors

Jennifer M Galloway¹, Graeme T Swindles², Heather E Jamieson³, Michael Palmer⁴, Michael B Parsons⁵, Hamed Sanei⁶, Andrew L Macumber⁷, R Timothy Patterson⁷, Hendrik Falck⁸

Affiliations

¹ Natural Resources Canada/Ressources naturelles Canada Geological Survey of Canada/Commission géologique du Canada, 3303 33rd Street N.W., Calgary, Ab, T2L 2A7, Canada. Electronic address: Jennifer.Galloway@canada.ca.
² School of Geography, University of Leeds, Leeds, LS2 9JT, United Kingdom.
³ Department of Geological Sciences and Geological Engineering, Queen's University, Kingston, ON, KL7 3N6, Canada.
⁴ NWT Cumulative Impact Monitoring Program, Government of the Northwest Territories, Yellowknife, NT, X1A 2R3, Canada.
⁵ Natural Resources Canada/Ressources naturelles Canada Geological Survey of Canada/Commission géologique du Canada, 1 Challenger Drive, Dartmouth, NS, B2Y 4A2, Canada.
⁶ Natural Resources Canada/Ressources naturelles Canada Geological Survey of Canada/Commission géologique du Canada, 3303 33rd Street N.W., Calgary, Ab, T2L 2A7, Canada.
⁷ Department of Earth Sciences, Carleton University, Ottawa, ON, K1S 5B6, Canada.
⁸ Northwest Territories Geological Survey, Yellowknife, NT, X1A 2R3, Canada.

PMID: 29111252
DOI: 10.1016/j.scitotenv.2017.10.048

Abstract

Climate change is profoundly affecting seasonality, biological productivity, and hydrology in high northern latitudes. In sensitive subarctic environments exploitation of mineral resources led to contamination and it is not known how cumulative effects of resource extraction and climate warming will impact ecosystems. Gold mines near Yellowknife, Northwest Territories, subarctic Canada, operated from 1938 to 2004 and released >20,000t of arsenic trioxide (As₂O₃) to the environment through stack emissions. This release resulted in elevated arsenic concentrations in lake surface waters and sediments relative to Canadian drinking water standards and guidelines for the protection of aquatic life. A meta-analytical approach is used to better understand controls on As distribution in lake sediments within a 30-km radius of historic mineral processing activities. Arsenic concentrations in the near-surface sediments range from 5mg·kg^-1 to over 10,000mg·kg^-1 (median 81mg·kg^-1; n=105). Distance and direction from the historic roaster stack are significantly (p<0.05) related to sedimentary As concentration, with highest As concentrations in sediments within 11km and lakes located downwind. Synchrotron-based μXRF and μXRD confirm the persistence of As₂O₃ in near surface sediments of two lakes. Labile organic matter (S1) is significantly (p<0.05) related to As and S concentrations in sediments and this relationship is greatest in lakes within 11km from the mine. These relations are interpreted to reflect labile organic matter acting as a substrate for microbial growth and mediation of authigenic precipitation of As-sulphides in lakes close to the historic mine where As concentrations are highest. Continued climate warming is expected to lead to increased biological productivity and changes in organic geochemistry of lake sediments that are likely to play an important role in the mobility and fate of As in aquatic ecosystems.

Keywords: Arsenic; Climate change; Lake sediments; Mining; Organic matter; Subarctic.