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TitleLake sediment grab sampling versus coring for environmental risk assessment of metal mining
LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorAlpay, SORCID logo; Alpay, R J; Grenier, A; Gould, W D
SourceGeological Survey of Canada, Scientific Presentation 26, 2014, 1 sheet, Open Access logo Open Access
PublisherNatural Resources Canada
MeetingGeological Association of Canada - Mineralogical Association of Canada Joint Annual Meeting; Fredericton; CA; May 21-23, 2014
Mediaon-line; digital
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; Aldermac Mine
Illustrationslocation maps; photographs; plots; tables
ProgramEnvironmental Geoscience Tools for environmental impacts and adaptation for metal mining
Released2015 05 06
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 of 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), 25 km west of Rouyn-Noranda in Abitibi, Quebec, operated from 1932-1943 and discharged acid mine drainage to the watershed downstream. The study site 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 government of Quebec led an environmental restoration of the Aldermac property (2008-11). Further mining development is foreseeable in the watershed. Surveys of sediment grab samples (2011-13) were done by Petite Ponar with a penetration depth of approximately 5-10 cm at 32 sites. Co-located sediment coring surveys were conducted using a 10-cm diameter gravity corer, modified with extension rods, to a sediment depth of 30-45 cm. Cores were sub-sampled at discrete depth intervals in two exercises: one survey with a larger regional distribution and thicker sediment slices (32 sites) and the other at 1-cm interval sections at 5 sites for detailed study. Grab sampling generated rapid results that permitted estimates of the current environmental reference state (baseline before new development), metal contaminant sources, and the spatial extent of metal contamination. Sediment coring produced estimates of naturally-occurring metal concentrations (pre-industrial background), the current baseline metal concentrations, metal contaminant sources, the duration of contamination, and its spatial extent. Although surveys of surface sediment grabs are faster and simpler and provide more sample material, they are imprecise snapshots without temporal scales. Sediment coring offers chronology of metal contaminant deposition, more precision, and potential for more targeted data (e.g., to fingerprint metal contaminant sources, assess diagenetic metal mobility, determine stability of metal-bearing phases). Cores can be taken in a reasonably rapid and simple manner, but less efficiently than grab sampling with less sample material for each core slice if sub-sampled at high resolution. Grab sampling offers a first approximation that may be sufficient for an initial environmental risk assessment. However, when further investigation is warranted, sediment coring can be optimized for efficiency and provide insight into accumulated metal contamination over time and an estimate of the range of metal levels in a naturally mineralized region (natural background).
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 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 accumulated metal contamination over time, higher precision, and more targeted data (e.g., to identify contaminant sources and metal mobility).

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