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TitleTechniques géoscientifiques dans la résolution des défis de l'évaluation des risques environnementaux en aval des mines métalliques: un exemple des milieux récepteurs du site Aldermac en Abitibi, Québec
AuthorAlpay, S; McNeil, R J; Grenier, A
SourceCongrès Québec Mines; 2013 p. 1-47
Year2013
Alt SeriesEarth Sciences Sector, Contribution Series 20130216
MeetingCongrès Québec Mines; Québec; CA; November 14, 2013
Documentbook
Lang.French
Mediaon-line; digital
File formatpdf
ProvinceQuebec
NTS32D/03; 32D/06
AreaAbitibi; Aldermac; Lac Dasserat; Lac Arnoux
Lat/Long WENS-79.5000 -79.1667 48.3333 48.1667
Subjectsenvironmental geology; heavy metals contamination; environmental impacts; environmental studies
Illustrationslocation maps; photographs; flow charts; plots
ProgramTools for environmental impacts and adaptation for metal mining, Environmental Geoscience
LinksOnline - En ligne
AbstractThe main objectives of the Lac Dasserat study, downstream of the Aldermac site, include optimizing lake sediment coring, surveys of surface water and bottom sediments as geoscience techniques for environmental risk characterization. Specific goals achieved include: determining the spatial extent of metal contamination, assessing pre-development metal distributions in receiving environments and capturing an early environmental response to the restoration of a former mine upstream. Deployment of portable total X-ray fluorescence for metal analysis of surface waters and portable X-ray fluorescence for metal analysis of sediments provided rapid analytical results while in the field; results showed good correlation with traditional laboratory analyses (e.g., ICP-MS). Additionally, regionally-distributed sediment coring sites provided the basis to estimate local naturally-occurring background metal concentrations.

Results demonstrate that typical baseline studies of sites to be developed for mining can be inadequate to assess: pre-development conditions, environmental effects of additional effluent from new development or the accumulation of effects from previous contamination in receiving environments. Identification of contaminant sources, that include natural mineralization, historical mining, active mineral exploitation, long-range atmospheric transport or residual contamination after environmental restoration, can be obscured in areas of multiple mining developments. Cumulative effects studies would benefit from lake sediment coring as a complement to surface water surveys coupled with bottom sediment surveys.

The former Aldermac mine, located 15 km west of Rouyn-Noranda, produced Cu, Zn, Au and Ag from 1932-1943 and discharged acid mine drainage to the watershed downstream that includes Lac Dasserat. The watershed is providing an ideal field location to develop geoscience techniques for environmental risk assessment. It is representative of both a common mineral deposit and the legacy of historical mining practices. Contamination and adverse effects on aquatic habitats were demonstrated to the point where the Aldermac property became the site of a government-led environmental restoration. Further mining development within the watershed is foreseeable. Therefore, environmental management plans, that are required before any new development begins there and at comparable sites, can take advantage of the geoscience tools developed in this study.
Summary(Plain Language Summary, not published)
The study is developing geoscience techniques for use in environmental risk assessment in watersheds downstream of metal mining. The techniques include lake sediment coring as a complement to surveys of surface water chemistry and bottom sediments. New analytical techniques, which can provide rapid results while in the field, are also being developed to measure water and sediment chemistry. The ultimate goasl is to improve environmental risk assessments using these geoscience tools throughout the mining life cycle.
GEOSCAN ID293035