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TitleApplication of the tracer radon-222 to identify groundwater discharge hotspots along the Lake Simcoe shoreline
DownloadFree download (whole publication) (pdf 1047 KB)
AuthorRobinson, C; Wallace, H; Ji, T
SourceRegional-scale groundwater geoscience in southern Ontario: an Ontario Geological Survey and Geological Survey of Canada groundwater geoscience open house; by Russell, H A J; Ford, D; Priebe, E H; Geological Survey of Canada, Open File 8212, 2017 p. 31, https://doi.org/10.4095/299798
Year2017
PublisherNatural Resources Canada
MeetingOntario Geological Survey and Geological Survey of Canada groundwater geoscience open house; Guelph; CA; March 1-2, 2017
Documentopen file
Lang.English
RelatedThis publication is contained in Russell, H A J; Ford, D; Priebe, E H; (2017). Regional-scale groundwater geoscience in southern Ontario: an Ontario Geological Survey and Geological Survey of Canada groundwater geoscience open house, Geological Survey of Canada, Open File 8212
ProvinceOntario
NTS31D/03; 31D/04; 31D/05; 31D/06; 31D/11; 31D/12
AreaLake Simcoe
Lat/Long WENS -80.0000 -79.0000 44.7500 44.0000
Subjectshydrogeology; geochemistry; environmental geology; groundwater; aquifers; groundwater resources; resource management; planning; groundwater discharge; discharge rates; surface waters; lakes; shorelines; isotopic studies; isotopes; radon; water quality; pollutants; geochemical surveys; groundwater regimes; models; mass balance
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Location
 
Natural Resources Canada Library - Ottawa (Earth Sciences)
 
Released2017 02 22
AbstractGroundwater discharge can be an important pathway for transporting pollutants, including nutrients, metals, and chloride into large inland lakes. Quantification of groundwater inputs into large lakes is often challenging due to high spatial variability in discharge patterns. While prior studies have identified offshore groundwater discharge locations (submarine hollows and vents) into Lake Simcoe, there is limited understanding of the magnitude of groundwater discharge to the lake including identification of areas that may be hotspots for discharge. The objective of this study was to evaluate the use of the natural tracer radon-222 (222Rn) for evaluating groundwater discharge along the shoreline of Lake Simcoe. 222Rn is a suitable tracer for quantifying groundwater discharge to inland lakes as its concentrations are typically 3-4 orders of magnitude higher in groundwater than in surface water. Regional scale 222Rn boat surveys were conducted along the shoreline of Lake Simcoe in summer 2015 and 2016 to identify potential groundwater discharge hotspots. Measurements were conducted using portable radon instrumentation (RAD 7 and RAD AQUA, Durridge Inc.). Groundwater discharge hotspots were located along the north shore of Kempenfelt Bay and along the south shore of Lake Simcoe. Regional-scale survey results were compared with hydrogeological studies previously conducted for subwatersheds around Lake Simcoe to gain understanding of the hydrogeological controls on the detected groundwater hotspot areas. High spatial resolution 222Rn surveys were also carried out in identified hotspot areas and a steady-state mass balance model which considers the various sources and sinks of 222Rn (e.g., air evasion, offshore mixing) was applied to estimate groundwater discharge rates. The challenge of applying a 222Rn mass balance is minimizing uncertainties associated with 222Rn loss through air evasion, as well as adequately characterizing 222Rn concentrations in the groundwater endmember. High resolution survey results confirmed high groundwater discharge in the hotspot areas with discharge highest near the shore and decreasing offshore. The development of regional-scale methods such as 222Rn for evaluating groundwater discharge to large inland waters including Lake Simcoe is critical for developing effective and targeted management plans aimed reducing the contribution of groundwater pollutants to degrading lake water quality.
GEOSCAN ID299798