Toxicity of sediment oiled with diluted bitumens to freshwater and estuarine amphipods

Barron, M.G.; Moso, E.M.; Conmy, R.N.; Meyer, P.; Sundaravadivelu, D.

Toxicity of sediment oiled with diluted bitumens to freshwater and estuarine amphipods

2021

Barron, M.G. | Moso, E.M. | Conmy, R.N. | Meyer, P. | Sundaravadivelu, D.

To address knowledge gaps and the lack of benchmarks on the toxicity of dilbit oiled sediments, weathered Cold Lake Blend (CLB) and Western Canadian Select (WCS) were assessed in 10-day sediment tests with the amphipods Hyalella azteca and Leptocheirus plumulosus. Lowest observed effect concentrations (LOECs) and 20% effect levels (EC20s) were determined for wet weight sediment concentrations of TPH and total PAHs normalized to 1% organic carbon. LOECs and EC20s for TPH ranged from 216 to 1165 mg/kg sediment in H. azteca, and from 64 to 75 mg/kg sediment in L. plumulosus. Dilbit LOECs and EC20s for total PAHs ranged from 2.9 to 11.8 mg/kg sediment in H. azteca, and from 0.75 to 0.87 mg/kg in L. plumulosus. Comparison of toxicity-based benchmarks derived from the current study to sediment concentrations from past spills indicate that dilbit spills in aquatic habitats may pose substantial risks to freshwater and estuarine benthic organisms.

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