Effects of non-segregated tailings on growth of oil sands reclamation plants

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Land reclamation of oil sands mining areas is highly challenging due to the harsh climatic conditions and the severity of land disturbance. Oil sands mining produces large volumes of tailings, which must be reclaimed. These tailings have commonly elevated levels of compounds that are potentially injurious to plants. Oil sands companies have developed different approaches to minimize the effects of tailings on reclamation plants. Canadian Natural Resources Limited has developed technology that uses thickeners in combination with carbon dioxide to consolidate tailings and produce the non-segregated tailings (NST) with lower sodium content. However, the existing knowledge of how the chemical composition of oil sands tailings affects growth and function of boreal plant species that are used for this tailings material is limited. The present project will characterize the chemical and physical properties of NST tailings and will examine the effects of tailings chemistry on growth and physiological processes in different plant species that are commonly planted in the oil sands reclamation sites. The project will also investigate the uptake of potentially toxic trace elements by plants and the effects of tailings on beneficial fungi associated with plant roots. The main general objective of the study is to generate knowledge that is required to develop optimal strategies for the reclamation of areas affected by the NST tailings. The specific objectives of the study are to i) characterize the effects and potential toxicity of NST tailings on plants, ii) determine the suitability of different plant species for the reclamation of sites affected by NST , iii) develop thorough understanding of the mode of action of NST tailings on plants, and iv) examine the benefits of mycorrhizal associations in selected reclamation plants. The project consists of seven studies that will be carried out over the next four years in growth rooms under controlled conditions. The results of the study will be used to improve revegetation success of the areas affected by the oil sands tailings.