Rapid Colorimetric Indicator for Oil Sands Process-Affected Water: An Alternative to Vertebrate Assays for Whole Effluent Toxicity Determination

The Athabasca oil sands in northern Alberta are estimated to hold over 170 billion barrels of crude oil reserves. The bitumen mining and extraction process generates large amounts of oil sands process-affected water (OSPW), the discharge of which is currently prohibited. One of the federal regulatory guidelines emphasizes using Whole Effluent Toxicity (WET) to determine aquatic acute and chronic toxicity. This process is costly and lengthy and involves potentially ethically concerning fish assays. This study proposes a rapid colorimetric indicator based on the selective chemical labeling of toxic components in OSPW. The new method can aid the development of treatment monitoring systems and discharge guidelines as an alternative to conventional approaches. The developed method was tested on raw and photocatalytically treated OSPWs sourced from industry. An s-shaped dose–response curve was obtained between the WET to rainbow trout (Oncorhynchus mykiss) and the sensor signal. Furthermore, a clear correspondence was established between signals from the proposed method and the established biomimetic extraction method, demonstrating comparable mechanisms and accuracy. This method presents a new tool for OSPW treatment monitoring toward natural resource reclamation.