Effects of Capping Strategy and Water Balance on Salt Movement in Oil Sands Reclamation Soils

Abstract

The success of oil sands reclamation can be impacted by soil salinity depending on the materials used for soil reconstruction and the capping strategies applied. Using both a greenhouse-based column experiment and numerical modeling, we examined the potential pathways of salt migration from saline groundwater into the rooting zone under different capping strategies (the type and the thickness of the barrier layer) and water balance scenarios. The experimental results showed that there would be salinity issues in the cover soil within several growing seasons if there was a shallow saline groundwater table and if the soil was not properly reconstructed. The thickness of the barrier layer was the most significant factor affecting the upward movement of saline groundwater and salt accumulation in the cover soil. The suitable thickness of the barrier layer for preventing the upward movement of saline groundwater and salt accumulation in the cover soil for each material varied. A numerical simulation for a 15-year period further indicates that, when the cover soil was 50 cm of peat-mineral soil mix and when wet, dry, or normal climatic conditions were considered, the minimum barrier thickness to restrain salt intrusion into the cover soil in the long term was about 75 or 200 cm for coarse tailings sand or overburden barrier material, respectively. In view of the above, to minimize salt migration into the rooting zone and ensure normal plant growth, oil sands reclamation should consider salt migration when designing soil capping strategies.

Understanding Willow Transcriptional Response in the Context of Oil Sands Tailings Reclamation

“…Recently, S. bebbiana has been reported as a potentially suitable species for OST reclamation and showed high survival rate in un-capped tailings but significantly different growth responses in capped and un-capped treated tailings ( Lalonde et al, 2020 ). Although, various visual plant stress symptoms, including chlorosis, necrosis and stunted growth of willows, were observed in different types of OST ( Wolter and Naeth, 2014 ; Lalonde et al, 2020 ; Li et al, 2020 ), the molecular-level responses of willows to multiple OST-associated stresses are yet unclear. Recently, RNA sequencing (RNAseq) technology has emerged as a powerful tool that facilitates the identification of expression patterns and regulatory mechanisms of differentially expressed genes (DEGs) in plants ( Xia et al, 2021 ).…”