EFFECT OF HIGH SALINITY TAILINGS WATERS PRODUCED FROM GYPSUM TREATMENT OF OIL SANDS TAILINGS ON PLANTS OF THE BOREAL FOREST

Bitumen extraction methods currently in use in the operating oil sands plants produce large volumes of fluid tailings. Ions leached from the ore and added by process chemicals during the extraction process resu lt in tailings waters containing elevated ionic content relative to th e non-process-affected waters of the area, in particular the sodium, s ulfate, and chloride ions. It is anticipated that the areas requiring reclamation will be affected by this high salinity of the process wate rs. The objectives of this study were to test the impact of a tailings alternative (consolidated tailings process, based on gypsum treatment of extraction tailings) on the viability of plant species of the nort hern boreal forest and to determine the relative salt tolerance and su itability of selected plant species for land reclamation. Seedlings we re grown for 4 weeks in a greenhouse in solution culture containing mi neral nutrients and various dilutions of consolidated tailings water a nd with Na2SO4 additions (1 g L-1 and 3 g L-1). Of all examined plant species, raspberry and strawberry seedlings were the most susceptible to damage, while the seedlings of white spruce, black spruce and lodge pole pine survived, but showed some effects. In the willow and aspen s eedlings, there was a rapid loss of leaves, which were quickly replace d by new, morphologically different leaves. Dogwood and hybrid poplar showed high tolerance to all treatments. (C) 1998 Elsevier Science Ltd . All rights reserved.