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TitleSeasonal variation of arsenic and antimony in surface waters of small subarctic lakes impacted by legacy mining pollution near Yellowknife, NT, Canada
AuthorPalmer, M J; Chételat, J; Richardson, M; Jamieson, H E; Galloway, J MORCID logo
SourceScience of the Total Environment vol. 684, 2019 p. 326-339, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20190082
PublisherElsevier BV
Mediapaper; on-line; digital
File formatpdf (Adobe® Reader®); html
ProvinceNorthwest Territories
NTS85J/07; 85J/08; 85J/09; 85J/10
AreaYellowknife; Yellowknife Bay; Great Slave Lake; Handle Lake; Lower Martin Lake; Long Lake
Lat/Long WENS-114.5333 -114.3167 62.5333 62.3833
Subjectsenvironmental geology; geochemistry; Economics and Industry; mining properties; mineral processing; surface waters; lakes; pollutants; lake water geochemistry; lake sediment geochemistry; arsenic geochemistry; antimony geochemistry; ice; oxygen geochemistry; iron geochemistry; manganese geochemistry; lake water depths; bathymetry; biogeochemistry; bedrock geology; lithology; granitic rocks; mafic rocks; sedimentary rocks; igneous rocks; volcanic rocks; morphometry; geochemical surveys; Giant Mine; Con Mine; Yellowknife Greenstone Belt; Atmospheric emissions
Illustrationsschematic representations; plots; location maps; geoscientific sketch maps; tables; time series
ProgramEnvironmental Geoscience Metal Mining: northern baselines
Released2019 05 21
AbstractThe seasonal variation in lake water arsenic (As) and antimony (Sb) concentrations was assessed in four small (<1.5 km2) subarctic lakes impacted by As and Sb emissions from legacy mining activities near Yellowknife, Northwest Territories, Canada. Substantial variation in As concentrations were measured over the two-year period of study in all but the deepest lake (maximum depth 6.9 m), including a four-fold difference in As in the shallowest lake ([As]: 172-846 micrograms/L; maximum depth 0.8 m). Arsenic concentrations were enriched following ice cover development in the three shallowest lakes (50-110%) through a combination of physical and biogeochemical processes. Early winter increases in As were associated with the exclusion of solutes from the developing ice-cover; and large increases in As were measured once oxygen conditions were depleted to the point of anoxia by mid-winter. The onset of anoxic conditions within the water column was associated with large increases in the concentration of redox sensitive elements in lake waters (As, iron [Fe], and manganese [Mn]), suggesting coupling of As mobility with Fe and Mn cycling. In contrast, there was little difference in Sb concentrations under ice suggesting that Sb mobility was controlled by factors other than Fe and Mn associated redox processes. A survey of 30 lakes in the region during fall (open-water) and late-winter (under-ice) revealed large seasonal differences in surface water As were more common in lakes with a maximum depth <4 m. This threshold highlights the importance of winter conditions and links between physical lake properties and biogeochemical processes in the chemical recovery of As-impacted subarctic landscapes. The findings indicate annual remobilization of As from contaminated lake sediments may be inhibiting recovery in small shallow lakes that undergo seasonal transitions in redox state.
Summary(Plain Language Summary, not published)
Seasonal variation of Arsenic concentration were assessed in surface waters in four small lakes in a subarctic region impacted by legacy gold mineral processing. Substantial variation is observed over the period of study three of the shallowest lakes, where a four-fold increase of surface water arsenic occurred during winter under ice through a combination of physical and biogeochemical processes related to redox state the interaction with other elements.

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