Bio-physicochemical effects of gamma irradiation treatment for naphthenic acids in oil sands fluid fine tailings

摘要

Naphthenic acids (NAs) are persistent compounds that are components of most petroleum, including those found in the Athabasca oil sands. Their presence in freshly processed tailings is of significant environmental concern due to their toxicity to aquatic organisms. Gamma irradiation (GI) was used to reduce the toxicity and concentration of NAs in oil sands process water (OSPW) and fluid fine tailings (FFT). This investigation systematically studied the impact of Gl on the biogeochemical development and progressive reduction of toxicity using laboratory incubations of fresh and aged tailings under anoxic and oxic conditions. GI reduced NA concentrations in OSPW by up to 97% in OSPW and in FFT by 85%. The Gl-treated FFT exhibited increased rates of biogeochemical change, dependent on the age of the tailings source. Dissolved oxygen (DO) flux was enhanced in Gl-treated FFT from fresh and aged source materials, whereas hydrogen sulfide (HS~) flux was stimulated only in the fresh FFT. Acute toxicity to Vibrio fischeri was immediately reduced following GI treatment of fresh OSPW. GI treatment followed by 4-week incubation reduced toxicity of aged OSPW to V. fischeri.