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TitleAssessment of physicochemical properties in lentic water bodies of the Rankin Inlet area (Nunavut, Canada) for sublacustrine open talik detection
AuthorFaucher, BORCID logo; LeBlanc, A -MORCID logo; Utting, NORCID logo; Blade, M
SourceAmerican Geophysical Union Fall Meeting 2022, abstracts; 2022, 1 sheet
LinksOnline - En ligne
Alt SeriesNatural Resources Canada, Contribution Series 20220390
PublisherAmerican Geophysical Union
MeetingAmerican Geophysical Union Fall Meeting 2022; Chicago; US; 2022 12 12-16
Mediapaper; digital; on-line
File formatpdf
AreaRankin Inlet
Lat/Long WENS -92.5000 -92.0000 63.0000 62.7500
Subjectsgeochemistry; environmental geology; mineralogy; Nature and Environment; Science and Technology; chemical analyses; hydrologic properties; lacustrine environments; talik; lake water; mining; mining activities; groundwater; planning
Illustrationslocation maps; time series; tables; scatter diagrams; diagrams
ProgramGEM-GeoNorth: Geo-mapping for Energy and Minerals GEM Program Coordination
Released2022 12 12
In continuous permafrost regions, open taliks (layer of unfrozen ground that completely penetrates the permafrost) beneath lakes may connect surface waters to subpermafrost groundwater. With increasing mining activity in northern Canada, it is critical for mining projects to identify lakes potentially underlain by open taliks to assess effects on mining operations, lake water levels and quality, and regional groundwater systems. The presence of sublacustrine open taliks can be assessed with thermal models, but validating their presence remains challenging at a regional scale. The level of hydrological connectivity between the lakes and subpermafrost groundwater systems also remains largely unknown. This work explores the physical attributes and water chemistry of lakes in the Rankin Inlet area (Nunavut) to infer the presence (or absence) of sublacustrine open taliks. In particular, we evaluate if their chemical composition can inform on local surface and groundwater connections. We reach this goal by exploring archived water quality datasets (n=41) obtained from Environmental Impact Assessments, and Crown-Indigenous Relations and Northern Affairs Canada and Kivalliq Inuit Association reports. We demonstrate through statistical analyses that significant differences exist between the chemical compositions of open talik vs. no open talik lakes. Yet, those differences are likely not entirely due to surface-groundwater interactions. Results also suggest that rock-water interactions can explain the water chemistry in most of the lakes, but that some no open talik lakes are also affected by evaporation. We employ geochemical models to predict the chemical composition of open talik lakes once atmospherically equilibrated snow meltwaters have weathered local surficial deposits (i.e., till) and have subsequently mixed with hypersaline subpermafrost waters. A geochemical model is also utilized to model the predicted chemical evolution of no open talik lakes affected by evaporation. Overall, we lack sufficient empirical data to properly predict which lakes have sublacustrine open taliks below them. We ultimately propose a list of additional measurements, data, and laboratory analyses that should be considered to better assess potential surface-groundwater interactions in the Rankin Inlet area.
Summary(Plain Language Summary, not published)
At high latitudes, perennially frozen ground (i.e., permafrost) acts as a barrier for surface-groundwater interactions. However, unfrozen ground (i.e., open talik) where such exchanges may take place is often found below large lakes. Constructing mining facilities near those basins may cause significant problems (e.g., water infiltration within a mine; adverse effects on surficial waters): locating those is crucial for the management of safe and durable mining operations. Traditionally, open talik below lakes are detected using lacustrine morphometric and thermal properties, and few have tried to use lacustrine chemical properties to assess the occurrence of open taliks. We used the latter approach for lakes and ponds situated in the Rankin Inlet area. We found significant differences for the chemical composition of suspected open vs. no open talik basins. Yet, those differences are not imputable to influxes of groundwaters towards surficial water basins; land surface processes (i.e., weathering and evaporation) cause them. Hence, our study reveals that basic limnological properties cannot solely be used to detect open taliks in this area region.

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