Dry Mature Fine Tailings as Oil Sands Reclamation Substrates for Three Native Grasses

Abstract

Mature fine tailings (MFT) are a by-product of oil sands mining that must be reclaimed through capping or use as a reclamation substrate. Some chemical and physical properties of MFT make it inhospitable for plant growth, such as high concentrations of sodium, sulfate, chloride, and hydrocarbons. A greenhouse study assessed whether substrates of various mixes of dry MFT, overburden sand, and peat mineral soil mix (PMM) and caps of forest floor organic material (LFH) and PMM would support the emergence and growth of three native grass species commonly used in land reclamation. Select vegetation properties were monitored for 16 wk in the greenhouse; select chemical and physical substrate properties were determined in the laboratory. was more tolerant of dry MFT than and . Mean aboveground and belowground biomass were more than twice as high on substrates with <60% MFT than on 100% MFT. Aboveground biomass was two to four times greater with capping than without and 30% greater on LFH than PMM caps. Cover and density followed similar trends. Belowground biomass on capped substrates was at least double that on uncapped substrates. Aboveground biomass was almost doubled with the use of fertilizer. High concentrations of hydrocarbons and exchangeable ions were associated with reduced plant growth and health. Results from this study show that capping, amendments, and fertilizer may improve the reclamation potential of dry MFT.

Fine root dynamics in lodgepole pine and white spruce stands along productivity gradients in reclaimed oil sands sites

“…According to the optimality theory (Espeleta and Donovan 2002), trees growing in a nutrient and water-limited environment would be expected to maximize their nutrient uptake by increasing their fine root productivity and turnover rate. This has been demonstrated in previous studies that focused on water and nutrient limitations in reclaimed sites with tailings sand as a substrate (Naeth et al 2011;Jung et al 2014;Luna Wolter and Naeth 2014). Fine root growth is typically influenced by available nutrients in forest ecosystems (Ingestad and Agren 1991) and given the significant response for fine root biomass and turnover rate across the productivity gradient that is likely the case in our study.…”

“…; Jung et al. ; Luna Wolter and Naeth ). Fine root growth is typically influenced by available nutrients in forest ecosystems (Ingestad and Agren ) and given the significant response for fine root biomass and turnover rate across the productivity gradient that is likely the case in our study.…”

Capping dewatered oil sands fluid fine tailings with salvaged reclamation soils at varying depths to grow woody plants

“…Plants do not grow well directly in oil sands tailings (Renault et al 2004;Luna Wolter and Naeth 2014). Boldt-Burisch et al (2018) grew slender wheatgrass (Elymus trachycaulus) and bird's-foot trefoil (Lotus corniculatus) in dry MFT, coarse tailings sand (CTS), and in sandy soil, and found that both species had reduced growth in both the MFT and CTS compared with the sandy soil.…”

“…Renault et al (2000) also found that seedling survival in conifers was reduced to as low as 55% when grown directly in dry MFT. For this reason, adding a capping material plays an important role in reclamation by improving plant growth (Hargreaves et al 2012;Luna Wolter and Naeth 2014;Huang et al 2015), increasing water storage (Zettl et al 2011), and improving soil conditions to support self-sustaining ecosystems.…”

“…FFMM salvages the upper forest floor organic layer and the underlying A and B horizons to an approximate depth of 0.3 m (Pinno and Das Gupta 2018), which can result in a forest floor to underlying mineral soil volume ratio of 1:5 (Pinno et al 2012). Some studies suggest FFMM provides a more suitable material than PMM for supporting plant growth (Mackenzie and Naeth 2010;Jamro et al 2014;Luna Wolter and Naeth 2014;Pinno et al 2017;Dietrich and MacKenzie 2018) because FFMM is typically richer in nutrients. Other studies found PMM to be well suited to support aspen growth as it is higher in organic matter and has a greater water-holding capacity (Pinno et al 2012;Pinno and Errington 2015).…”