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Biogeochemistry of U, Ni, and As in two meromictic pit lakes at the Cluff Lake uranium mine, northern Saskatchewan

Konstantin von Gunten, Tyler Warchola, Mark W. Donner, Manuel Cossio, Weiduo Hao, Christopher Boothman, Jonathan Lloyd, Tariq Siddique, Camille A. Partin, Shannon L. Flynn, Arden Rosaasen, Kurt O. Konhauser and Daniel S. Alessi
Biogeochemistry of U, Ni, and As in two meromictic pit lakes at the Cluff Lake uranium mine, northern Saskatchewan
Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre (May 2018) 55 (5): 463-474

Abstract

Open pits, which remain after uranium (U) mining operations cease, can form meromictic lakes that develop suitable conditions for the containment of dissolved and colloidal metals. In this study, the distribution and speciation of U, nickel (Ni), and arsenic (As) in the water column of two meromictic pit lakes was investigated at the decommissioned Cluff Lake mine in northern Saskatchewan. The 28 m deep and older D pit had a chemocline at a 13 m depth, below which it turned anoxic and its meromixis was controlled by iron (Fe) cycling. Below the chemocline both Fe(III) and As(V) were reduced to Fe(II) and As(III), respectively. Iron cycling had a large effect on U distribution because reducing conditions prevented sulfide oxidation and a drop in pH in deeper layers. Metal-reducing bacteria were found to be present at, and below, the chemocline. In the deeper (90 m), larger and more recently flooded DJX pit, two chemoclines were observed at depths of 15 and 65 m. Both were linked to sharp U and Ni concentration gradients. Unlike the D pit, a transition to reducing conditions was not observed in the DJX pit's water column. However, colloidal U, primarily associated with aluminum oxyhydroxides, was found below the first chemocline. Overall, the meromixis type determined the distribution and speciation of metals and bacteria in the investigated pit lakes, thus providing insights into the use of pit lakes as a potential bioremediation strategy.


ISSN: 0008-4077
EISSN: 1480-3313
Coden: CJESAP
Serial Title: Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre
Serial Volume: 55
Serial Issue: 5
Title: Biogeochemistry of U, Ni, and As in two meromictic pit lakes at the Cluff Lake uranium mine, northern Saskatchewan
Affiliation: University of Alberta, Department of Earth and Atmospheric Sciences, Edmonton, AB, Canada
Pages: 463-474
Published: 201805
Text Language: English
Summary Language: French
Publisher: National Research Council of Canada, Ottawa, ON, Canada
References: 62
Accession Number: 2018-055852
Categories: Environmental geologyHydrochemistry
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables, sketch map
N58°22'00" - N58°22'00", W109°31'60" - W109°31'60"
Secondary Affiliation: University of Manchester, GBR, United KingdomUniversity of Saskatchewan, CAN, CanadaAREVA Resources Canada, CAN, Canada
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Reference includes data from Canadian Science Publishing, NRC Research Press, Ottawa, ON, Canada. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 2018
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