Toxicity of weathered sediment-bound dilbit to freshwater fish and invertebrates

Abstract

Bitumen from the Alberta oil sands must be diluted to form diluted bitumen (dilbit) to facilitate transport through pipelines, yet little is known about its effects on aquatic organisms after a spill. Environmental weathering processes such as evaporation and sediment interaction manipulate spilled dilbit, which could affect its fate and toxicity in the environment. However, most studies to date that have characterized effects of dilbit to aquatic organisms have not incorporated weathering. In the present study, zebrafish (Danio rerio) embryos and adult freshwater amphipods (Hyalella azteca) were exposed to weathered sediment-bound dilbit. Sediment-bound dilbit exacerbated adverse effects associated with dilbit exposure due to oil-mineral aggregates directly interacting with amphipods and zebrafish embryos during exposure. As oil sands production expands, it is important to incorporate weathering processes when testing the toxicity of dilbit to aquatic organisms because sediment-bound dilbit can severely affect the health of freshwater fish and invertebrates.