GEOSCAN Search Results: Fastlink


TitleWhat killed Frame Lake? A precautionary tale for urban planners
AuthorGavel, M J; Patterson, R T; Nasser, N A; Galloway, J M; Hanna, B W; Cott, P A; Roe, H M; Falck, H
SourcePeerJ vol. 2018, 6, e4850, 2018 p. 1-31, (Open Access)
Alt SeriesNatural Resources Canada, Contribution Series 20180210
Mediaon-line; digital
File formatpdf
ProvinceNorthwest Territories
AreaFrame Lake; Yellowknife
Lat/Long WENS-114.5000 -114.0000 62.5000 62.2500
Subjectsenvironmental geology; geochemistry; surface waters; lakes; water quality; urban planning; limnology; land use; arsenic; iron; mercury; mining; mineral processing; core samples; lake sediment cores; microfaunal assemblages; lake sediment geochemistry; radiometric dating; radiocarbon dating; lead lead dates; remote sensing; airphoto interpretation; water circulation patterns; macrophytes; ecology; Protozoa; Arcellinida; Cucurbitella tricuspis; Hirudinea; leeches; bioindicators; contamination; urban development; loss on ignition; minerogenics; organics; eutrophication; catchment basins; winter fish-kills; Phanerozoic; Cenozoic; Quaternary
Illustrationslocation maps; satellite images; aerial photographs; photographs; stratigraphic columns; tables; profiles; plots; charts
ProgramEnvironmental Geoscience, Metal Mining: northern baselines
Released2018 06 14
AbstractFrame Lake, located within the city of Yellowknife, Northwest Territories, Canada, has been identified as requiring significant remediation due to its steadily declining water quality and inability to support fish by the 1970s. Former gold mining operations and urbanization around the lake have been suspected as probable causes for the decline in water quality. While these land-use activities are well documented, little information is available regarding their impact on the lake itself. For this reason, Arcellinida, a group of shelled protozoans known to be reliable bioindicators of land-use change, were used to develop a hydroecological history of the lake. The purpose of this study was to use Arcellinida to: (1) document the contamination history of the lake, particularly related to arsenic (As) associated with aerial deposition from mine roaster stacks; (2) track the progress of water quality deterioration in Frame Lake related to mining, urbanization and other activities; and (3) identify any evidence of natural remediation within the lake. Arcellinida assemblages were assessed at 1-cm intervals through the upper 30 cm of a freeze core obtained from Frame Lake. The assemblages were statistically compared to geochemical and loss-on-ignition results from the core to document the contamination and degradation of conditions in the lake. The chronology of limnological changes recorded in the lake sediments were derived from 210Pb, 14C dating and known stratigraphic events. The progress of urbanization near the lake was tracked using aerial photography. Using Spearman correlations, the five most significant environmental variables impacting Arcellinida distribution were identified as minerogenics, organics, As, iron and mercury (p<0.05; n=30). Based on CONISS and ANOSIM analysis, three Arcellinida assemblages are identified. These include the Baseline Limnological Conditions Assemblage (BLCA), ranging from 17-30 cm and deposited in the early Holocene >7,000 years before present; the As Contamination Assemblage (ACA), ranging from 7-16 cm, deposited after ~1962 when sedimentation began in the lake again following a long hiatus that spanned to the early Holocene; and the Eutrophication Assemblage (EA), ranging from 1-6 cm, comprised of sediments deposited after 1990 following the cessation of As and other metal contaminations. The EA developed in response to nutrient-rich waters entering the lake derived from the urbanization of the lake catchment and a reduction in lake circulation associated with the development at the lake outlet of a major road, later replaced by a causeway with rarely open sluiceways. The eutrophic condition currently charactering the lake - as evidenced by a population explosion of eutrophication indicator taxa Cucurbitella tricuspis - likely led to a massive increase in macrophyte growth and winter fish-kills. This ecological shift ultimately led to a system dominated by Hirudinea (leeches) and cessation of the lake as a recreational area.
Summary(Plain Language Summary, not published)
This study uses paleolimnology to investigate past changes in Frame Lake, Yellowknife, subarctic Canada. In the past the lake supported fish but urban development is suspected to have altered the water quality of the lake. Testate lobose ameobae preserved in lake sediments show that organic matter loading and geochemical changes have altered the water quality. Following development of a road, the lake became eutrophic and this ultimately led to winter fish-kills.