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Sodium transport and attenuation in soil cover materials for oil sands mine reclamation

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dc.contributor.authorVessey, Colton
dc.contributor.authorLindsay, Matthew B. J.
dc.contributor.authorBarbour, S. Lee
dc.date.accessioned2022-09-27T22:23:13Z
dc.date.available2022-09-27T22:23:13Z
dc.date.issued2018-11-03
dc.description0883-2927/ © 2018 Elsevier Ltd. All rights reserved.en_US
dc.description.abstractReclamation soil covers are used in oil sands mine closure to support vegetative growth over tailings. Geochemical processes within these covers may impact solute transport during upward migration of oil sands process-affected water (OSPW) from the underlying tailings. In this study, we examined the geochemical processes controlling Na transport and attenuation within the peat and clay-till cover soils at Sandhill Fen in northern Alberta, Canada. We analyzed soil core samples collected along transects of this 54-ha pilot-scale oil sands mine reclamation wetland. The geochemical (Na, Ca, Mg, K, Cl, SO4, HCO3) and isotopic (δ2H, δ18O) compositions of extracted pore water were analyzed statistically to identify OSPW and fresh surface water within the cover. Depth-dependent trends in pore water sodium concentrations were not apparent, suggesting that the soil cover had been fully flushed by a mixture of OSPW and fresh surface water used to flood the fen. Relative concentrations of Na, Ca and Mg were used to define the extent of cation exchange within the clay cover. Complementary laboratory column experiments showed that cation exchange removed up to 50% of dissolved Na as the first pore volume of simulated OSPW passed through the peat and till. However, Na attenuation by these materials declined rapidly and was limited after 4 (peat) to 7 (till) pore volumes of OSPW flushing. Reactive transport modeling confirmed that cation exchange was the dominant control on Na attenuation and corresponding Ca and Mg release within the till and peat columns. Mineral precipitation-dissolution reactions also influenced dissolved Ca and Mg concentrations and, therefore, indirectly impacted Na attenuation. Overall, this study helps constrain the geochemical processes controlling Na transport and attenuation in oil sands reclamation soil covers exposed to OSPW, and indicates that the attenuation of Na from OSPW by these covers is short-lived.en_US
dc.description.sponsorshipFunding was provided to MBJL by the Natural Sciences and Engineering Council of Canada (NSERC) and Syncrude Canada Ltd. through the Industrial Research Chairs program (Grant No. IRCPJ 450684−13). Additional support awarded to CVJ through the Brian and Elaine Russel Undergraduate Research Fund and the NSERC Canadian Graduate Scholarships – Master’s (NSERC CGS-M) Program.en_US
dc.description.versionPeer Revieweden_US
dc.identifier.citationVessey, C.J., Lindsay, M. B. J. & Barbour, S. L. (2019). Sodium transport and attenuation in soil cover materials for oil sands mine reclamation. Applied Geochemistry, 100, 42–54. https://doi.org/10.1016/j.apgeochem.2018.10.023en_US
dc.identifier.doi10.1016/j.apgeochem.2018.10.023
dc.identifier.urihttps://hdl.handle.net/10388/14237
dc.language.isoenen_US
dc.publisherElsevieren_US
dc.subjectOil sandsen_US
dc.subjectReclamationen_US
dc.subjectSoil coversen_US
dc.subjectGeochemistryen_US
dc.subjectSodiumen_US
dc.titleSodium transport and attenuation in soil cover materials for oil sands mine reclamationen_US
dc.typeArticleen_US

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