Abstract
Oil sands surface mining and processing in Alberta generate large volumes of fluid tailings and process water high in salts and metals, which must be reclaimed. We investigated growth of four common plants (two native and two non-native) found in boreal oil sands reclamation sites as influenced by substrate type (tailings cake, and mixtures of cake-sand, cake-peat, and cake-forest floor mineral mix) and water quality (0%, 50%, and 100% oil sands process water). Overall, cake-peat supported the highest aboveground biomass among substrates whereas cake and cake-sand performed poorly, possibly due to high sodium and chloride concentrations. Adding process water to substrates generally reduced growth or increased mortality. Grasses had greater growth than forbs, and for each functional group, non-native species performed better than native species. Hordeum vulgare had the highest overall growth with no mortality followed by Agropyron trachycaulum with negligible (0.5%) mortality. Chamerion angustifolium was most affected by the treatments with the lowest growth and highest mortality (56%). Sonchus arvensis had higher growth than C. angustifolium but its slow growth makes it less suitable for reclaiming tailings. Our results indicate that H. vulgare and A. trachycaulum could be good candidates for use in initial reclamation of oil sands tailings.
Highlights
The oil sands deposits in northern Alberta, Canada, represent the world’s third largest oil deposit, with proven reserves of 165.4 billion barrels [1]
The extraction process generates large volumes of fluid fine tailings comprised of connate and process water, sand, silt, clay, residual bitumen, inorganic salts, and organic compounds [4,5,6]
We investigated the response of four native and non-native plant species commonly found in newly reclaimed areas in the boreal forest region of Canada: Chamerion angustifolium (L.) Holub, Sonchus arvensis L., Agropyron trachycaulum (Link) Malte, and Hordeum vulgare L
Summary
The oil sands deposits in northern Alberta, Canada, represent the world’s third largest oil deposit, with proven reserves of 165.4 billion barrels [1]. Oil sands surface mining results in severe forest disturbance. The Government of Alberta has implemented a directive for progressive reclamation to ensure that all fluid tailings from a mining project are ready to reclaim ten years after the end of mine life [3]. The extraction process generates large volumes of fluid fine tailings comprised of connate and process water, sand, silt, clay, residual bitumen, inorganic salts, and organic compounds [4,5,6]. Oil sands fluid fine tailings is generally composed of 70–80% water, 20–30% solids, and 1–3% residual bitumen [5], and is alkaline and slightly brackish with high concentrations of organic acids [4]. The suspended solids in oil sands tailings are dominated by quartz and clays from the McMurray Formation, predominantly kaolinite, illite, and montmorillonite [7]
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