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TitleArcellaceans (Testate Lobose Amoebae) as proxies for arsenic and heavy metal contamination in the Baker Creek Watershed, Northwest Territories, Canada
AuthorNassar, N; Patterson, R T; Neville, L A; Macumber, A L; Galloway, J MORCID logo; Falck, H; Roe, H M; Kokelj, S V
SourceNorthwest Territories Geoscience Office, Yellowknife Geoscience Forum Abstracts Volume 2013, 2013 p. 43 Open Access logo Open Access
LinksOnline - En ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20130441
PublisherNorthwest Territories Geoscience Office
Meeting41st Annual Yellowknife Geoscience Forum; Yellowknife; CA; November 19-21, 2013
File formatpdf
ProvinceNorthwest Territories
Subjectsenvironmental geology; hydrogeology; arsenic; heavy metals contamination; environmental impacts; environmental analysis; Baker Creek Watershed (BCW); Giant Mine
ProgramEnvironmental Geoscience environmental impacts and adaptation in the northern environment
Released2013 01 01
AbstractThe Baker Creek Watershed (BCW) near Yellowknife, NT is known to be contaminated by arsenic and other contaminants derived from the adjacent Giant Mine. This mining operation drove a post-WWII economic boom for the territory, but left behind a legacy of arsenic contamination, both on site and within the adjacent BCW; enough to cause serious environmental concern. While mine on-site arsenic trioxide sequestration is currently the focus of a massive remediation project, the impact on the surrounding BCW is less well understood. Arcellaceans (testate lobose amoebae) are benthic protist primary consumers that have been previously shown to respond to a variety of contaminants (e.g. As, Hg and various heavy metals) associated with mining activities. The aim of this study is to utilize arcellaceans as biological proxies of arsenic and heavy metal contamination in the BCW, and to contribute to the quantification of the environmental impact of the Giant Mine on the BCW.
Arcellaceans were analyzed in sediment-water interface samples from sixty-one lakes across the region surrounding the Giant Mine. Samples were also analyzed for other proxies (e.g. geochemical, micropaleontological and sedimentological). Q and R cluster analyses of arcellacean results were used to group samples with similar species distribution, and to determine which species or strains tend to co-occur. Redundancy analysis (RDA) was also performed to determine species-environment relationships, and to provide a better understanding of the observed clustering. Tentative results indicate that there is a close correlation between environmental variables of concern (e.g. As, Pb) and the distribution of arcellacean species. Samples from these contaminated lake stations were characterized by a relatively low Shannon Diversity Index (SDI=1.5 -1.8) and were dominated by faunas that are known to reflect environmental stress (e.g. Centropyxis constricta ¿aerophila¿ and Centropyxis constricta ¿constricta¿).
The preliminary results of this ongoing research suggest that arcellaceans will prove to be reliable proxies for recognizing contamination associated with mining activities. They will be particularly useful in the examination of cores from lakes in the BCW where they will be used to determine pre-mining baseline environmental conditions, the response of lakes to mining impact and for gauging the success of post-mining remediation. These results will provide valuable insight into the impact of Giant Mine on the BCW that will be of use to policy makers and planners when evaluating the merit of various remediation programs.
Summary(Plain Language Summary, not published)
The Baker Creek watershed near Yellowknife (NWT) is important fish habitat. This area is proximal to the Giant Mine, a gold mine now in remediation and closure phase with a legacy of arsenic release to the environment. We evaulate the use of arcellaceans, a testate amoebae, as indicators of heavy metals in lake sediments. Arcellaceans were analyzed in sediment-water interface samples from 61 lakes across the region. Samples were also analyzed for geochemical and sedimentological parameters. Preliminary results indicate a statistical relationship between certain arecellean species and elements of concern (As, Pb). Samples from sites with relatively high concentrations of As and Pb had low Shannon Diversity Indices and were dominated by faunas known to reflect environmental stress. Our results suggest that arecellacea may be valuable tools to evaluate ecosystem health of lake benthos.

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