Impacts on aquatic biota from salinization and metalloid contamination by gold mine tailings in sub-Arctic lakes. (1st June 2021)

• Record Type: Journal Article
• Authors: Perrett, Madi; Sivarajah, Branaavan; Cheney, Cynthia L.; Korosi, Jennifer B.; Kimpe, Linda; Blais, Jules M.; Smol, John P.
• Is Part Of: Environmental pollution. Volume 278(2021)
• Publication Date: 2021-06-01
• Subjects: Bio-indicators -- Consolidated mine -- Yellowknife -- Climate warming -- Urbanization -- Paleolimnology; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2021.116815
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Precious metal mining activities have left complex environmental legacies in lakes around the world, including some sites in climatically sensitive regions of the Canadian sub-Arctic. Here, we examined the long-term impacts of past regional gold mining activities on sub-Arctic lakes near Con Mine (Yellowknife, Northwest Territories) based on sediment core analysis (paleolimnology). In addition to receiving metal(loid)s from roaster stack emissions, the study lakes were also influenced by salt-rich mine drainage from Con Mine tailings. Water samples from these lakes had some of the highest concentrations for salinity-related variables (e.g. Ca 2+, Cl −, Na + ) and metal(loid)s (e.g. As, Cu, Ni, Sb) in the Yellowknife area. Furthermore, the presence of halophilic diatom (Bacillariophyceae) taxa ( Achnanthes thermalis and Navicula incertata ) in the recent sediments of Keg and Peg lakes suggest that the extreme saline conditions are strongly influencing the present biota, more than 10 years after the cessation of gold mining activities at Con Mine. The sedimentary metal(loid) profiles (e.g. As, Cu, Ni) of Kam Lake tracked the influence of regional gold mining activities, particularly those at Con Mine, while the algal assemblages recorded the biological responses to salinization and metal(loid) pollution (e.g. marked decreases in diatom species richness, Hill's N2 diversity, and chrysophyte cyst:diatom valve ratio). At Kam Lake, the algal assemblage changes in the post-mining era were indicative of climate-mediated changes to lake thermal properties (e.g. rise in planktonic diatoms), nutrient enrichment related to urbanization (e.g. increase in eutrophic Stephanodisucs taxa), and/or a combination of both stressors. The lack of biological recovery (i.e. return to pre-mining assemblages) is consistent with investigations of mine-impacted lakes in temperate regions where elevated contaminant levels and emerging stressors (e.g. climate warming, land-use changes) are influencing lake recovery. Graphical abstract: Image 1 Highlights: Sedimentary metal(loid) levels increased during mining era. Decreased diatom richness and diversity coincided with mining pollution. Elevated salinity and metal(loid) levels persist a decade after mining ended. Halophilic diatoms indicate biota are still affected by altered water chemistry. Biological recovery trajectories are now influenced by warming and urbanization.