Response of three native grass species on dry tailings reclamation substrate amended with petroleum coke

Surface mining around the world has produced large quantities of waste materials with ecological impacts. Oil sands mining in Canada generates large volumes of petroleum coke and tailings every year, which are stockpiled in the mining areas and must be reclaimed through capping or used in reclamation substrates. A greenhouse study was conducted to determine whether substrates of various mixes of dry tailings (DT), tailings sand (TS), and peat mineral mix (PMM) with coke amendment would support emergence and growth of three grass species commonly used in land reclamation. After 16 wk in the greenhouse, plant performance varied with substrate and amendment. Treatment with DT/TS/PMM (50:25:25) with 40% coke had greatest cover, biomass, and density and the best plant health. Plant growth was inhibited in treatments with DT (100%) and coke (100%) due to high concentrations of hydrocarbons, undesirable exchangeable ions, and salinity that restricted soil water retention (gravimetric water content, hydraulic conductivity) relative to treatments with PMM. Agrostis scabra Willd. and Festuca saximontana. showed poor growth or did not survive on DT and DT/TS with coke. Elymus trachycaulus (Link) Gould ex Shinners performed better in all DT mixes and performed the best in DT/TS/PMM with 40% coke. Results from this study indicate that mixing with PMM could improve the reclamation potential of DT and coke.