Microbiological and geochemical characterization of As-bearing tailings and underlying sediments
Journal Article
·
· Journal of Hazardous Materials
- Univ. of Waterloo, ON (Canada)
- Univ. of Waterloo, ON (Canada); Coventry Univ. (United Kingdom)
- Canmet Mining and Mineral Sciences Laboratories, Ottawa, ON (Canada)
- Argonne National Laboratory (ANL), Argonne, IL (United States)
Over the past 100 years, extensive oxidation of As-bearing sulfide-rich tailings from the abandoned Long Lake Gold Mine (Canada) has resulted in the formation of acid mine drainage (pH 2.0-3.9) containing high concentrations of dissolved As (similar to 400 mg L-1), SO42-, Fe and other metals. Dissolved As is predominantly present as As(III), with increased As(V) near the tailings surface. Pore-gas O2 is depleted to < 1 vol% in the upper 30-80 cm of the tailings profile. The primary sulfides, pyrite and arsenopyrite, are highly oxidized in the upper portions of the tailings. Elevated proportions of sulfide-oxidizing prokaryotes are present in this zone (mean 32.3% of total reads). The tailings are underlain by sediments rich in organic C. Enrichment in δ34S-SO4 in pore-water samples in the organic C-rich zone is consistent with dissimilatory sulfate reduction. Synchrotron-based spectroscopy indicates an abundance of ferric arsenate phases near the impoundment surface and the presence of secondary arsenic sulfides in the organic-C beneath the tailings. The persistence of elevated As concentrations beneath the tailings indicates precipitation of secondary As sulfides is not sufficient to completely remove dissolved As. The oxidation of sulfides and release of As is expected to continue for decades. The findings will inform future remediation efforts and provide a foundation for the long-term monitoring of the effectiveness of the remediation program.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- Natural Sciences and Engineering Research Council of Canada (NERSC); USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF)
- Grant/Contract Number:
- AC02-06CH11357
- OSTI ID:
- 2282216
- Alternate ID(s):
- OSTI ID: 2570666
- Journal Information:
- Journal of Hazardous Materials, Journal Name: Journal of Hazardous Materials Vol. 466; ISSN 0304-3894
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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