Influence of saline groundwater discharge on river water chemistry in the Athabasca oil sands region – A chloride stable isotope and mass balance approach

dc.contributor.authorGue, Anita
dc.contributor.authorGrasby, Stephen E.
dc.contributor.authorMayer, Bernhard
dc.date.accessioned2023-03-18T05:35:26Z
dc.date.available2023-03-18T05:35:26Z
dc.date.issued2017-12-01
dc.description.abstractA chloride mass and stable isotope (δ37Cl) balance approach was employed to calculate the effect of saline groundwater discharge into the Athabasca and Clearwater rivers in the Athabasca Oil Sands Region (AOSR) in north-eastern Alberta, Canada. Saline groundwater affected by halite, carbonate, and anhydrite dissolution discharges Na-Cl type water with total dissolved solids (TDS) up to 51,700 mg/L from exposed Devonian and Cretaceous units in the river valleys in this area. In this study, nine springs discharging groundwater with a median Cl concentration of 9800 mg/L were sampled and chloride stable isotope ratios were determined, with δ37Cl values ranging from 0.2 to 1.0‰. In contrast, river waters had historical monthly median Cl concentrations between 5.9 and 49.5 mg/L and δ37Cl values between −2.2 and −1.4‰. The discharge rate of saline groundwater was calculated to be 100 ± 20 L/s into the Clearwater River and 134 ± 68 L/s into the Athabasca River. The chemical composition and discharge rates of saline groundwater were used to estimate its contribution to the mass fluxes of major ions, metals, and PAHs in the Athabasca and Clearwater rivers. Overall, saline groundwater contributed less than 0.2% of river discharge, but 0.04–39% of major ion concentrations in the rivers, with highest contributions under winter low-flow conditions. In the Clearwater River, saline groundwater contributed 23–39% of average monthly Cl flux and 18–32% of average monthly Na flux. For the same major ion fluxes in the Athabasca River, saline groundwater contributed 12–18% and 6–12%, respectively. The influence of saline groundwater discharge on the mass flux of trace elements in the rivers was found to be negligible, contributing less than 1% of river fluxes of Cu, Ni, Pb, and Zn. Similarly, the influence on mass flux of PAHs in the rivers was found to be negligible (<0.03%) but quantifiable. These results provide important insights on the natural contributions of saline groundwater discharge to river chemistry in the AOSR, a necessary factor to consider when monitoring for anthropogenic effects of oil sands development on river water quality.en_US
dc.identifier.citationGue, A., Grasby, S. E., & Mayer, B. (2018). Influence of saline groundwater discharge on river water chemistry in the Athabasca oil sands region – A chloride stable isotope and mass balance approach. Applied Geochemistry, 89, 75–85. https://doi.org/10.1016/j.apgeochem.2017.10.004en_US
dc.identifier.doihttps://doi.org/10.1016/j.apgeochem.2017.10.004en_US
dc.identifier.urihttp://hdl.handle.net/1880/115944
dc.identifier.urihttps://doi.org/10.11575/PRISM/46061
dc.language.isoengen_US
dc.publisherElsevieren_US
dc.publisher.facultyScienceen_US
dc.publisher.hasversionacceptedVersionen_US
dc.publisher.institutionUniversity of Calgaryen_US
dc.publisher.policyhttps://www.elsevier.com/journals/applied-geochemistry/0883-2927/open-access-optionsen_US
dc.rightsUnless otherwise indicated, this material is protected by copyright and has been made available with authorization from the copyright owner. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.en_US
dc.subjectSaline groundwateren_US
dc.subjectAthabasca oil sandsen_US
dc.subjectChloride stable isotopesen_US
dc.subjectAthabasca Riveren_US
dc.subjectClearwater Riveren_US
dc.subjectAlbertaen_US
dc.titleInfluence of saline groundwater discharge on river water chemistry in the Athabasca oil sands region – A chloride stable isotope and mass balance approachen_US
dc.typejournal articleen_US
ucalgary.item.requestcopyfalseen_US
ucalgary.scholar.levelFacultyen_US
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