| Titre | What killed Frame Lake? A precautionary tale for urban planners |
| Auteur | Gavel, M J; Patterson, R T; Nasser, N A; Galloway, J M; Hanna, B W; Cott, P A; Roe, H M; Falck, H |
| Source | PeerJ vol. 2018, 6, e4850, 2018 p. 1-31, https://doi.org/10.7717/peerj.4850 (Accès ouvert) |
| Année | 2018 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20180210 |
| Éditeur | PeerJ |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.7717/peerj.4850 |
| Media | en ligne; numérique |
| Formats | pdf |
| Province | Territoires du Nord-Ouest |
| SNRC | 85J/08 |
| Lat/Long OENS | -114.5000 -114.0000 62.5000 62.2500 |
| Sujets | eaux de surface; lacs; qualité de l'eau; planification urbaine; limnologie; utilisation du terrain; arsenic; fer; mercure; exploitation minière; traitement des minerais; échantillons carrotés; carottes de
sediments lacustres; assemblages microfauniques; géochimie des sediments lacustres; datation radiométrique; datation au radiocarbone; datations au plomb-plomb; télédétection; interprétation de photos aériennes; réseaux de circulation de l'eau;
macrophytes; écologie; Arcellinide; développement urbain; géologie de l'environnement; géochimie; Phanérozoïque; Cénozoïque; Quaternaire |
| Illustrations | location maps; satellite images; aerial photographs; photographs; stratigraphic columns; tables; profiles; plots; charts |
| Programme | Géosciences
environnementales, Exploration minérale: conditions de base au nord |
| Diffusé | 2018 06 14 |
| Résumé | (disponible en anglais seulement)
Frame 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. |
| Résumé | (Résumé en langage clair et simple, non publié)
Cette étude utilise la paléolimnologie pour étudier les changements passés à Frame Lake, Yellowknife, Canada subarctique. Ce lac servait à
soutenir le poisson, mais on soupçonne que le développement urbain a modifié la qualité de l'eau du lac. Les lobose ameobae testés conservés dans les sédiments lacustres montrent que le chargement en matière organique et les changements géochimiques
ont modifié la qualité de l'eau. Après le développement d'une route, le lac est devenu eutrophique, ce qui a finalement conduit à la mort de poissons d'hiver. |
| GEOSCAN ID | 311126 |
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