Application of biomimetic extraction to measure toxicity of oil sands process-affected water to aquatic organisms

Accumulation of oil sands process-affected water (OSPW) in Alberta's Oil Sands Region poses a potential environmental problem if it encounters natural waters. As a result of Alberta's zero-discharge policy, OSPW is stored on site. One potential treatment solution being tested at the pilot scale is a constructed wetland treatment system (CWTS). This study aims to measure chronic toxicity of OSPW to aquatic organisms and assess the treatment efficacy of Imperial Oil's Kearl treatment wetland using passive sampling to measure changes in OSPW toxicity as it flows through the wetland. Biomimetic extraction (BE) using solid-phase micro-extraction (SPME) fibers measures freely dissolved concentrations of the acid-extractable organic (AEO) fraction of OSPW and gives insight into the toxicity of OSPW through calibration with in-vivo toxicity metrics from chronic toxicity tests. This passive sampling method has the potential to replace traditional animal toxicity testing for whole effluent screening. Chronic toxicity testing was performed with walleye (Sander vitreus) early life stages (ELS) and an aquatic invertebrate (Ceriodaphnia dubia) with untreated and wetland-treated OSPW to calibrate BE-SPME and determine OSPW treatment efficiency. Walleye and C. dubia exhibited similar sensitivity to OSPW for sublethal endpoints (IC25 = 64% and 64% OSPW, respectively). However, walleye survival was more sensitive to OSPW than C. dubia (LC50 = 71% and >100%, respectively). A reduction in toxicity to C. dubia survival and reproduction after wetland treatment and agreement between in-vivo toxicity testing and BE-SPME measurements was observed. These results support the application of constructed wetlands to treat OSPW and the feasibility of BE-SPME passive sampling as a monitoring tool.