Microbial processes with the potential to mobilize As from a circumneutral-pH mixture of flotation and roaster tailings

Eva Pakostova, David M. Hilger, David W. Blowes, Carol J. Ptacek

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The Northwest Tailings Containment Area at the inactive Giant Mine (Canada) contains a complex mixture of arsenic-containing substances, including flotation tailings (84.8 wt%; with 0.4 wt% residual S), roaster calcine wastes (14.4 wt% Fe oxides), and arsenic trioxide (0.8 wt%) derived from an electrostatic precipitator as well as As-containing water (21.3 ± 4.1 mg L−1 As) derived from the underground mine workings. In the vadose zone the tailings pore water has a pH of 7.6 and contains elevated metal(loid)s (2.37 ± 5.90 mg L−1 As); mineral oxidizers account for 2.5% of total 16S rRNA reads in solid samples. In the underlying saturated tailings, dissolved Fe and As concentrations increase with depth (up to 72 and 20 mg L−1, respectively), and the mean relative abundance of Fe(III)-reducers is 0.54% of total reads. The potential for As mobilization via both reductive and oxidative (bio)processes should be considered in Giant Mine remediation activities. The current remediation plan includes installation of an engineered cover that incorporates a geosynthetic barrier layer.
Original languageEnglish
Article number23048
Number of pages10
JournalScientific Reports
Issue number1
Early online date27 Dec 2023
Publication statusPublished - Dec 2023

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Funding for this research was provided by Crown-Indigenous Relations and Northern Affairs Canada (CIRNAC), the NSERC TERRE-NET program (grant NETGP 479,708–15), and the Northern Scientific Training Program. The authors gratefully acknowledge logistical support provided by Parsons Corporation and Nuna Logistics Limited. This research used resources of the Canadian Light Source (CLS) and its funding partners with assistance provided by Scott Coleville (CLS) and Joyce McBeth (Universities of Regina and Saskatchewan). We are grateful for technical assistance provided by Jeff Bain, Daniel Birch, Lisa Kester, Steven P. Holland, Laura Groza, Joy Hu, Sara Fellin, David Wilson, and Krista Elena (all from the University of Waterloo).


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