Toxicity of five shale oils to fish and aquatic invertebrates

The chemical composition and toxicity of three shale crude oils (Tosco, Paraho, and Geokinetics), a hydrotreated oil (Paraho HDT), and a refined shale oil (Paraho JP-4) were assessed to determine the potential hazards to native fish species and food chain organisms posed by accidental spills of such materials. Colorado squawfish (Ptychocheilus lucius), fathead minnow (Pimephales promelas), cutthroat trout (Salmo clarki), and colonies of aquatic invertebrates were exposed to the watersoluble fractions of the shale oils for 96 hr to determine concentrations lethal to 50% of the exposed organisms (LC-50). The behavior of surviving fish was also measured to determine the sublethal influences of exposure. The composition of the five water-soluble fractions was similar to that of the crude and refined shale oils from which they were made. Hydrotreated and refined oils contained fewer aromatic compounds than the crude shale oils. The cutthroat trout, a species endemic to oil shale regions, was less tolerant of shale oil exposure than the other species tested; the LC-50 concentrations were 1.8 mg/L Geokinetics, 2.1 mg/L Tosco, and 1.3 mg/L Paraho. Exposure to concentrations of one-half to one-eighth those causing mortality reduced the swimming capacity of squawfish and significantly impaired their ability to capture prey. The number of invertebrate taxa, species, and organisms colonizing plate samplers declined with increasing oil concentration. The generaBaetis andIsoperla were most sensitive to shale oil exposure; significant mortality occurred at the lowest concentration (0.5–0.7 mg/L) tested for each shale oil.