Investigating predictive tools for refinery effluent hazard assessment using stream mesocosms.

Hazard assessment of refinery effluents is challenging due to their compositional complexity. Therefore, a weight of evidence approach using a combination of tools is often required. Previous research has focused on several predictive tools ranging from sophisticated chemical analyses - biomimetic extraction to quantify the potentially bioaccumulative substances (PBS), two dimensional gas chromatography (GCxGC), modelling approaches to link oil composition to toxicity (PETROTOX) and Whole Effluent Toxicity (WET) assessments using bioassays. The present study aims at investigating the value of these tools by comparing predicted effects to actual effects observed in stream mesocosm toxicity studies with refinery effluents. Three different effluent samples, with and without fortification by neat petroleum substances, were tested in experimental freshwater streams. Results indicate that the biological community shifted at higher exposure levels, consistent with chronic toxicity effects predicted by both modelled toxic units (TUs) and PBS measurements. The study has demonstrated the potential of the predictive tools and the robustness of the stream mesocosm design to improve our understanding of the environmental hazards posed by refinery effluents. This article is protected by copyright. All rights reserved.