| Title: | Variations in U concentrations and isotope signatures in two Canadian lakes impacted by U mining: A combination of anthropogenic and biogeochemical processes |
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| Authors: | ID Wang, Wei, School of the Environment, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada (Author)
ID Dang, Duc Huy, School of the Environment, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada (Author)
ID Novotnik, Breda, School of the Environment, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada; Department of Geoscience, University of Calgary, Calgary, AB T2N 1N4, Canada (Author)
ID Phan, Thai T. (Author)
ID Evans, R. Douglas, School of the Environment, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada; Water Quality Center, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada (Author) |
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| Files: |
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| Language: | English |
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| Work type: | Not categorized |
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| Typology: | 1.01 - Original Scientific Article |
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| Organization: | UNG - University of Nova Gorica
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| Abstract: | Temporal and vertical variations in uranium (U) concentrations and U isotope (δ238U, ‰) signatures were
examined in sediment cores collected seven times over a one year period, from two lakes in Ontario, Canada,
which are contaminated with U by historical mining activities. Bow Lake is holomictic, experiencing seasonal
anoxia, while the sediments of meromictic Bentley Lake are permanently anoxic. Average annual peak concentrations
of U in Bow Lake subsurface sediments were approximately 300 μg L−1 and 600 μg g−1 in porewater
and bulk sediments, respectively. Similar ranges of concentrations (900 μg L−1 and 600 μg g−1, respectively)
were observed in Bentley Lake sediments. The exceedingly high levels of U observed in the porewaters of both
lakes, as well as the seasonal variability in U levels, challenge the traditional paradigm regarding U chemistry,
i.e., that reduced U(IV) should be insoluble under anoxic conditions.
The average annual δ238U ‰ values at the sediment-water interface of both lakes were similar (i.e.,
0.47 ± 0.09‰ and 0.50 ± 0.16‰, relative to IRMM-184). The deep sediments in both Bentley Lake and Bow
Lake record U isotope composition with a typical fractionation of 0.6‰ relative to the surface water, confirming
authigenic U accumulation, i.e., negligible contribution of particulate material from the tailings. Also, the δ238U
values in porewater have an average offset of ca. −0.1‰ relative to bulk sediments in anoxic zones and are
reversed in the oxic sediment layer. |
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| Keywords: | Uranium
Isotope composition
Uranium tailings
Biogeochemical cycling
Redox chemistry |
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| Publication version: | Version of Record |
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| Year of publishing: | 2019 |
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| Number of pages: | 58-67 |
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| Numbering: | 2019, 506 |
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| PID: | 20.500.12556/RUNG-4777-536fdb5e-10ac-7178-43e7-7ddef72b5628 |
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| COBISS.SI-ID: | 5460987 |
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| DOI: | https://doi.org/10.1016/j.chemgeo.2018.12.029 |
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| NUK URN: | URN:SI:UNG:REP:BBQZTVK6 |
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| Publication date in RUNG: | 09.10.2019 |
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| Views: | 3918 |
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| Downloads: | 0 |
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