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TitleAn investigation of gas seeps and aquatic chemistry in Fisherman Lake, southwest Northwest Territories
AuthorSmith, I R; Grasby, S E; Lane, L S
SourceGeological Survey of Canada, Current Research (Online) no. 2005-A3, 2005, 8 pages, (Open Access)
PublisherNatural Resources Canada
Mediaon-line; digital
File formatpdf
ProvinceNorthwest Territories
AreaFisherman Lake; Fort Liard
Lat/Long WENS-123.8333 -123.6667 60.4000 60.3000
Subjectshydrogeology; environmental geology; fossil fuels; lake water geochemistry; water analyses; water geochemistry; lake water; water quality analyses; methane; methane hydrate; gas seeps; biogenic gas; limnology; methanogenesis
Illustrationssketch maps; tables; photographs
ProgramCentral Foreland NATMAP Project
Released2005 09 01
AbstractConcerns about water quality in Fisherman Lake led to the discovery of 13 gas seeps. Analyses of 13C isotope compositions of two gas samples (d13CCH4 -73.1 and -70.9; d13CCO2 -19.4) indicate that they are biogenic methane produced by CO2 reduction. This rules out the possibility that the gas is thermogenic methane seeping through fractures connected to the underlying Pointed Mountain gas field. What is
unknown is what effect, if any, methane production might have on Fisherman Lake aquatic chemistry and ecology. In a eutrophic lake, methane can produce winter anoxia. If this occurred in Fisherman Lake, it could produce the unpleasant water odour, taste and fish kills reported by residents. However, these same conditions could be the product of phytoplankton blooms and/or eutrophication, independent of methane generation. Further studies of seasonal and stratigraphic limnology, and paleolimnological records would be required to answer these and other questions.