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TitleCharacterization of the boron, lithium, and strontium isotopic variations of oil sands process-affected water in Alberta, Canada
AuthorHarkness, J S; Warner, N R; Ulrich, A; Millot, R; Kloppmann, W; Ahad, J M E; Savard, M M; Gammon, P R; Vengosh, A
SourceApplied Geochemistry vol. 90, 2018 p. 50-62,
Alt SeriesEarth Sciences Sector, Contribution Series 20150145
Mediapaper; on-line; digital
File formatpdf
NTS74D; 74E; 84A; 84H; 84B; 84G; 73M; 83O; 83P
AreaPeace River; Athabasca River; Cold Lake Region; Fort McMurray
Lat/Long WENS-117.0000 -114.0000 58.0000 53.0000
SubjectsNature and Environment; Health and Safety; geochemistry; oil sands; water quality; water geochemistry; isotopic studies; boron geochemistry; lithium geochemistry; strontium geochemistry; health hazards; bituminous sands; bitumen; heavy metals contamination
Illustrationslocation maps; sample location charts; stratigraphic charts; ternary diagrams; tables; plots
ProgramCoal & Oil Resources Environmental Sustainability, Environmental Geoscience
AbstractOil sands operations in Alberta, Canada generate large volumes (>840×106 m3) of oil sands process-affected water (OSPW) that contains contaminants that are toxic to aquatic life. OSPW is stored in open tailings ponds and leakage from the ponds presents a potential long-term environmental risk. However, the presence of naturally occurring saline water in the oil sands region in Alberta presents a challenge for delineating the impact of OSPW in cases where OSPW is leaked to the environment. Here, we characterize the inorganic chemistry and isotopic variations of boron (delta11B), lithium (delta7Li), and strontium (eSrSW) of OSPW from tailings ponds in order to evaluate the source of salinity in OSPW and the potential utilization of these isotope ratios as forensic tracers of OSPW migration in the environment. In addition to generating new data, we compiled published data to build a comprehensive dataset of the geochemical composition of different water sources in the oil sands region of Alberta. OSPW is brackish (TDS - 1800 mgL-1), with elevated chloride (392±184 mgL-1), boron (2.2±0.4 mgL-1), and lithium (0.12 ± 0.11 mg L-1) concentrations relative to the Athabasca River that is used for bitumen extraction. OSPW is characterized by narrow ranges of delta11B (23.7 ± 1.8(permil)), =delta7Li (16.3 ± 1.7(permil)), and 87Sr/86Sr ratios (eSrSW=-3.9 ± 19.2). The geochemical and isotope ratios in OSPW reflect mixing of residual, saline formation water from Lower Cretaceous units with fresh surface water that has been modified by interactions with the solid oil sands. The elevated boron and lithium concentrations and delta11B, delta7Li and eSrSW variations we observed are distinct from the compositions of a shallow freshwater aquifer in the area (8.1 ± 5.0 (permil), 11.3 ± 0.9 (permil) and 9.7 ± 5.6, respectively) and the local rivers (15.6 ± 4.7 (permil), 15.1 ± 1.4 (permil) and 30.3 ± 16.0). However, groundwater and saline springs in the region presents a wider range of geochemical and isotopic values that are not always distinguishable from OSPW. The integration of boron, lithium, and strontium isotopes provides a potential monitoring tool for tracing OSPW release to local freshwater sources.
Summary(Plain Language Summary, not published)
Potential seepage of wastewater stored in tailings ponds is one of the main concerns for environmental monitoring in Canada's oil sands region. This paper reports a novel method which utilises geochemical and isotopic ratios of several inorganic constituents (boron, lithium and strontium) that are present in tailings pond wastewater and also found in underlying geological material to differentiate between natural and anthropogenic inputs. The results demonstrate that several of these parameters (boron and lithium isotopes combined with B/Cl and Li/Cl ratios) may be useful as tracers for delineating tailings pond wastewater migration in the Athabasca watershed.