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TitleLake sediment grab sampling versus coring for environmental risk assessment of metal mining
AuthorAlpay, SORCID logo; McNeil, R J; Grenier, A; Gould, W D
SourceGeological Association of Canada-Mineralogical Association of Canada, Joint Annual Meeting, Abstracts Volume vol. 37, 2014 p. 8 Open Access logo Open Access
LinksOnline - En ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20130452
MeetingGeological Association of Canada - Mineralogical Association of Canada Joint Annual Meeting; Fredericton; CA; May 21-23, 2014
RelatedThis publication is related to Lake sediment grab sampling versus coring for environmental risk assessment of metal mining
File formatpdf
NTS32D/03; 32D/06
AreaLac Labyrinthe; Lac Dasserat; Lac du Monarque; Lac Arnoux; Lac Denim; Lac Desvaux; Lac Berthemet; Lac Montbray; Lac Larochelle; Lac Opasatica
Lat/Long WENS -79.5333 -79.2000 48.3500 48.0000
Subjectseconomic geology; environmental geology; environmental studies; environmental impacts; mining methods; mining; heavy metals contamination; copper; zinc; gold; silver
ProgramEnvironmental Geoscience Tools for environmental impacts and adaptation for metal mining
Released2014 01 01
AbstractCurrent practices for baseline studies of sites to be developed for mining include surface grab sampling of sediments in aquatic receiving environments. In contrast, vertical sediment coring is a universal tool in paleolimnological research. This study evaluates the effectiveness of sediment grab sampling versus sediment coring for environmental risk assessment of metal mining. The former Aldermac mine (Cu, Zn, Au and Ag), 15 km west of Rouyn - Noranda in Abitibi, Quebec, operated from 1932 - 1943 and discharged acid mine drainage into the watershed downstream. The study area is representative of both a common mineral deposit type and historical mining practices. Surveys of bulk sediment grab samples (2011 - 13) were done using a Ponar sampler that penetrated to a depth of approximately 5 - 10 cm at 34 sampling sites. Co - located sediment cores, 30 - 45 cm long, were collected using a modified 10 - cm diameter gravity corer at 33 sites and were subsampled at 0.5 to 5 - cm depth intervals. Geochemical results from quick regional grab sampling provided estimates of baseline metal concentrations in surface sediments, contaminant sources, and the spatial extent of metal contamination. Sediment samples retrieved by longer cores produced estimates of both spatial and temporal factors: naturally - occurring metal concentrations (pre - industrial background), current metal concentrations, contaminant sources, and the duration and spatial extent of contamination. Although regional grab samples provide more sample material and are faster and simpler to collect than gravity coring, the results are imprecise because they are bulk data integrated over roughly 5 - 10 cm of depth; they also lack a time dimension. Coring, core extrusion, and subsampling at distinct depth intervals provide chemical stratigraphy of metal deposition. Coring also affords potential for more targeted data to fingerprint contaminant sources, assess diagenetic metal mobility, and determine stability of metal - bearing phases at discrete sediment horizons. These research-grade investigations can be optimized for practical use in environmental risk assessment. Bulk grab sampling offers a first approximation of regional metal distributions in shallow sediments. However, when more detailed investigation is warranted under environmental risk assessment regulations, sediment coring can not only provide estimates of the true ranges of naturally - occurring metal concentrations (natural background), but also measurements and timelines of metal increases from industrial activities.
Summary(Plain Language Summary, not published)
Different methods of aquatic sediment sampling downstream from a known contaminated site (the former Aldermac mine in Abitibi, Quebec) are presented to demonstrate options for environmental risk assessment of metal mining. Shallow bulk sediment samples can be taken quickly and the results can be used to estimate baseline conditions (before new development), contaminant sources, and the spatial extent of contamination, although the method generates imprecise data without time scales. When further investigation is warranted, sediment coring provides results that can determine accumulated metal contamination over time, higher precision, and more targeted data (e.g., to identify contaminant sources and metal mobility).

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