Heavy metal attenuation and mobility in the Wood Creek Sand Channel aquifer: Correlation of experimental and field study

Macoura Koné, K. Ulrich Mayer, Ania C. Ulrich

Dans les comptes rendus d’articles de la conférence: GeoMontréal 2013: 66th Canadian Geotechnical Conference; 11th joint with IAH-CNC

Session: Mineral and Gas II

ABSTRACT: The storage of oil sands process water (OSPW) in tailings ponds over glacial till formations in the oil sands region in Alberta (Canada) has the potential to cause contamination of groundwater and surface water with trace metals and dissolved major ions. To predict the fate of contaminants in the aquifers underlying and adjacent to tailings impoundments, a detailed understanding of the processes controlling metal release and attenuation is required. In this study, column experiments were performed under anaerobic conditions to simulate interactions between the Wood Creek Sand Channel aquifer soils and OSPW. Experimental results were compared with and correlated to field observations obtained from monitoring of groundwater wells located in an oil sands facility over a time period of 6 years. Results from the column experiments indicated that Fe, Mn, Ba, and Si were released from the sediments while other trace metals present in OSPW (Zn, Cr, Ni, U, Mo, As, B, etc.) were either weakly attenuated or completely retained by the soils. A DNA extraction performed on the column sediments identified iron and sulphate reducers suggesting that microbial reductive dissolution of Mn(IV) and Fe(III) oxides is likely the geochemical process by which the metals were released and mobilized into the effluent solution. The groundwater monitoring results are in agreement with those from the columns. However, observed metal concentrations are much higher in the field than in the columns. Variation in the released amounts may be attributed to different material characteristics, but are most likely due to longer residence times, and longer flow paths. Results also demonstrate that microbial reduction of Mn(IV) and Fe(III) may have important environmental implications on water quality. Potential metals of concerns include Fe, Mn, Zn, Cr and B. Concentrations of these elements measured in both the column effluent and the groundwater wells were above environmental standards. These results have important applications in the prediction, protection and potential evaluation of remedial technologies for the immobilization of metals.

Please include this code when submitting a data update: GEO2013_319

Retrouver cet article:
Les membres de la Société canadienne de géotechnique peuvent accéder à cet article, ainsi qu'à tous les autres articles de la Conférence Géotechnique Canadienne, dans le Espace membre. Les comptes rendus d'articles sont également disponibles dans de nombreuses bibliothèques.

Citer cet article: