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TitleDetecting the presence of localized ground water inputs into high Arctic lakes
AuthorHarasyn, M L; Lamoureux, S F; Normandeau, AORCID logo
SourceGeoOttawa 2017, proceedings; 2017 p. 233-234
Alt SeriesNatural Resources Canada, Contribution Series 20170103
MeetingGeoOttawa 2017 - 70th Canadian Geotechnical Conference and the 12th Joint CGS/IAH-CNC Groundwater Conference; Ottawa; CA; October 1-4, 2017
Mediaon-line; digital
File formatpdf
AreaCape Bounty; Melville Island
Subjectshydrogeology; surficial geology/geomorphology; Nature and Environment; Science and Technology; groundwater flow; permafrost
Released2017 10 01
AbstractThis research investigated the presence of ground water seepage within two High Arctic lakes situated in continuous permafrost at Cape Bounty, Melville Island, Nunavut. Small isolated depressions (21) were identified at the bottom of each lake using 2-meter resolution swath bathymetric data in East and West Lake (unofficial names). It was hypothesized that these depressions could be the sites of ground water seepage into the lakes, which was tested through the collection of CTD water column casts and bottom water sampling in 2016. Water chemistry and water column data were used as indicators of ground water seepage, and were expected to have properties similar to the source of the groundwater, generating a change in water chemistry at seepage sites. Water chemistry shows site-specific changes at the bottom of both lakes. Ionic ratios for the northern, deeper sites in both lakes differ from ratios of the rest of the sample sites, as well as the ambient water column of each lake. These locations are on strike and in the vicinity of the boundary between two major geologic units. Water column properties (temperature, SpC and DO) showed no measurable change within East Lake, while a localized change within the lower 9 m of the West Lake had increased electrical conductivity and temperature, as well as a corresponding decrease in dissolved oxygen. Despite measured differences in water column properties between the lakes, bottom water ionic composition is more similar to marine water than to catchment surface runoff or the respective lake water columns. These results suggest that highly localized ground water seepage is likely occurring in these High Arctic lakes. Potential pathways for ground water flow beneath these lakes have been identified based on knowledge of water source characteristics and permafrost dynamics and likely represent either subpermafrost water or brines rejected during permafrost growth or sufficiently saline to be mobile as intrapermafrost groundwater.
Summary(Plain Language Summary, not published)
The focus of this research project is to determine the presence of groundwater seepage within two High Arctic lakes located in continuous permafrost on south-central Melville Island, NU. Both lakes are located at the Cape Bounty Arctic Watershed Observatory (CBAWO; 75°N, 109°W) and have been subject to physiochemical monitoring between 2003-16. Our results suggest that highly localized groundwater seepage is likely occurring in these High Arctic lakes.

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