Preliminary evaluation of potential impacts of non-petroleum oils on the aquatic environment

Abstract

Non-petroleum oils, specifically crude and refined corn and safflower oils, and refined sunflower and soybean oils, have been shown to form stable emulsions, with the amount of emulsion being proportional to the initial oil/water ratio and the severity of the mixing. These oils have also shown to deplete dissolved oxygen (DO) from freshwater, and the depletion occurred whether the oil was mixed into or simply layered onto the water. The rate and level of depletion was dependent on the specific oil. Crude corn oil caused the most rapid and significant depletion; the final DO concentration is less than the current U.S. regulatory minimum. Water accommodated fractions (WAFs) of the oils showed varying levels of toxicity to Ccriodaphnia dubia, a freshwater test organism, and to freshwater benthic macroinvertebrates (BMI); leachate from crude corn oil was the most toxic. Since BMI evaluations were carried out with continuous aeration of the test water samples, toxicity is not solely due to oxygen depletion. These preliminary data suggest that in a spill situation non-petroleum oils are not environmentally benign, and they support the current federal oil spill prevention and response regulations.