Growth and survival of native wetland species in shallow capped centrifuged tailings and co-mixed tailings: a meso-scale greenhouse study

Abstract

This three-year meso-scale greenhouse study used 55-gallon columns to evaluate the survival and growth of boreal wetland communities planted on centrifuge (CF) tailings and co-mixed (CM) tailings capped with different reclamation cover soil capping designs. The CF tailings were capped with a shallow layer (10 and 30 cm) of peat reclamation material (PRM) and the CM tailings were capped with a shallow layer (5 cm) of PRM above (15 or 35 cm) of reclamation subsoil (till). After three years, plant survival and growth on CF tailings showed significant improvement with a 10 cm PRM cap compared to the uncapped tailings, and plants growing on a 30 cm PRM cap outperformed those on the 10 cm PRM cap. Plant growth on CM tailings was significantly improved with a soil cover containing 5 cm PRM and at least 15 cm till. Among the seven native wetland species included in this study, the top performing species survival and above-ground biomass were Salix bebbiana, Scirpus microcarpus and Carex aquatilis.

Growth and survival of native upland and wetland species in shallow capped thickened tailings: a meso-scale greenhouse study

“…This delayed response is likely a result of plant roots extending from their soil plugs into the TT, or from the PMM into the TT, increasing the root area exposed to TT at different times, depending on the treatment. Similar trends have been observed in other 3 year column studies (Degenhardt et al 2023) and highlight the importance of long-term monitoring of greenhouse or field studies to better understand the plant response to different tailings capping designs.…”

“…Similar greenhouse column studies also found that thin reclamation caps of peat reclamation material significantly improved plant growth on CF tailings (Degenhardt et al 2023) and reclamation caps of peat reclamation material and till significantly improved growth on CM tailings (Degenhardt et al 2023). Luna Wolter and Naeth (2014) found that soil caps (either PRM or LFH [upland surface soil coversoil]) improved the growth of native grasses on mature fine tailings (MFT), Lalonde et al (2020) found that soil caps (PRM, FFM [upland surface soil coversoil] or both) improved the growth of Populus tremuloides and Salix bebbiana on CF tailings, and Zhang et al (2020) found that the addition of top soil and PMM to non-segregated tailings significantly improved the growth of native woody species (Zhang et al 2020).…”

“…In similar 3 year greenhouse column studies using co-mix tailings (CM) and centrifuge tailings (CF), overall plant survival in uncapped tailings was lower (72% and 55%, respectively) compared to survival in the current study's uncapped TT (Degenhardt et al 2023). Furthermore, Salix bebbiana survival was higher in the current study's uncapped TT (100%) compared to survival in uncapped CF (75%) and CM (42%), indicating the better tolerance of TT relative to other types of treated tailings.…”

“…Salix bebbiana is an adaptive species tolerant of a wide range of soil conditions (Hardy BBT Limited 1989). Salix bebbiana performed similarly well in other studies with capped treated tailings (Lalonde et al 2020;Degenhardt et al 2023) The ability of Salix bebbiana to easily reproduce vegetatively also make it a good candidate for reclamation (Alberta Environment 2010).…”

“…While reclamation of overburden dumps and sanddominated tailings deposits has been implemented at Syncrude's Sandhill Fen, South Bison Hill, and Gateway Hill (Wytrykush et al 2012;Grant et al 2013;Syncrude Canada Ltd. 2013), reclamation of treated fine tailings deposits is still in its infancy. A few greenhouse capping studies have been conducted using centrifuge tailings (Lalonde et al 2020;Omari et al 2021;Degenhardt et al 2023); however, this type of treated fine tailings has different chemical and physical properties from TT (Cossey et al 2021). Most research involving TT (or consolidated tailings) has focused on the phytotoxicity of its release water (Renault et al 1998(Renault et al , 2003Armstrong et al 2010;Cutter 2013) or its physical properties and consolidation behaviour (McKenna et al 2016;Wilson et al 2018;Demoz 2022).…”