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TitleGeochemistry of lakes across ecozones in the Northwest Territories and implications for the distribution of arsenic in the Yellowknife region. Part 1: Sediments
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AuthorGalloway, J M; Palmer, M; Jamieson, H E; Patterson, R T; Nasser, N; Falck, H; Macumber, A L; Goldsmith, S A; Sanei, H; Normandeau, P; Hadlari, T; Roe, H M; Neville, L A; Lemay, D
SourceGeological Survey of Canada, Open File 7908, 2015, 49 pages, https://doi.org/10.4095/296954
Year2015
PublisherNatural Resources Canada
Documentopen file
Lang.English
Mediaon-line; digital
File formatreadme
File formatpdf; rtf; xls
ProvinceNorthwest Territories
NTS75M; 75N; 76C; 76D; 85
AreaYellowknife; Great Slave Lake; Prosperous Lake; South Tibbitt Lake
Lat/Long WENS-120.0000 -109.0000 65.5000 60.0000
Subjectshydrogeology; environmental geology; geochemistry; lake sediment geochemistry; lake sediments; arsenic; arsenic geochemistry; heavy metals contamination; concentration; soil samples; soil geochemistry; sediments; sediment geochemistry; sediment properties
Illustrationslocation maps; tables; photographs; plots
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Location
 
Natural Resources Canada Library - Ottawa (Earth Sciences)
 
ProgramTools for environmental impacts and adaptation for metal mining, Environmental Geoscience
Released2015 11 18
AbstractWe obtained near total element geochemistry on 211 near-surface sediment samples from lakes along a transect across the Western Interior Platform to the central portion of the Slave Geological Province with a focus near the City of Yellowknife, Northwest Territories, to document regional concentrations of arsenic (As) and other elements in lake sediments. Concentrations of major and trace elements, including elements of potential human and ecological concern (As, Cd, Cr, Cu, Pb, Zn), were extracted from sediments using a modified aqua regia digestion. Concentrations of As exceed Canadian federal guidelines for the protection of aquatic life in most of the lakes sampled in the Slave Geological Province. Seventy one percent (n=149) of all sediment samples contain As concentrations higher than the Canadian Council of Ministers of the Environment (CCME) Interim Freshwater Sediment Quality Guideline of 5.9 mg/kg and 54% (n=114) of the samples contain As concentrations that exceed the CCME Probable Effect Level of 17 mg/kg. Sediments with the highest As concentrations are from lakes near the City of Yellowknife and likely reflect a combination of contamination associated with past industrial activity and geogenic input from mineralized bedrock and derived surficial materials (median As concentration 107.9 mg/kg, range 6.30->10,000+, n=95). Arsenic concentrations in lake sediments sampled elsewhere in the central Northwest Territories are lower (Ingraham Trail, median As concentration 10.6 mg/kg, range 1.9-101.6, n=27; Tibbitt to Contwoyto Winter Road, median As concentration 7.9 mg/kg, 0.3-101.4, n=52; Western Interior Platform, median As concentration 1.1 mg/kg, 0.1-7.1, n=37). Based on our data and a review of existing literature, background As concentration in lake sediments appear to ~25 mg/kg for the Yellowknife region, and lower for other regions in the central NWT. Other elements (Cr, Cu, Pb, Zn) are below sediment quality guidelines in the majority of lake sediments sampled.
Summary(Plain Language Summary, not published)
We obtained near total element geochemistry on 211 near-surface sediment samples from lakes in the central Slave Geological Province, Northwest Territories, with a focus near the City of Yellowknife to document regional concentrations of As and other elements. Seventy one percent (n=149) of all sediment samples contain As concentrations higher than the Canadian Council of Ministers of the Environment (CCME) Interim Freshwater Sediment Quality Guideline of 5.9 mg/kg and 54% (n=114) of the samples contain As concentrations that exceed the CCME Probable Effect Level of 17 mg/kg. Sediments with the highest As concentrations are from lakes near the City of Yellowknife and likely reflect a combination of contamination associated with past industrial activity and geogenic input from mineralized bedrock and derived surficial materials. Other elements (Cr, Cu, Pb, Zn) are below sediment quality guidelines in the majority of lakes sampled. We suggest that background As concentrations in lake sediments of the Yellowknife area are in the 20s of mg/kg.
GEOSCAN ID296954