Modeling Tools Available for Estimating Ecotoxicity of Oil Shale Constituents

Oil shale resource development has recently gained renewed interested due to the strong global demand for petroleum products. Oil shale-derived fuels and process water effluents exist as mixtures of thousands of compounds all of which contribute to varying degrees to observed ecotoxicity. Recent modeling advances show promise for application in estimating oil shale ecotoxicity. The ecotoxicity of complex hydrocarbon substances have been described successfully using an extension of the hydrocarbon block method that relies on a physicochemical properties database of individual hydrocarbons included in the PETROTOX oil-toxicity model. However, oil shale often has higher contents of polar organic compounds (e.g., phenols) as well as ionizable organic acids (e.g., naphthenic acids) that are not considered in current non-polar narcosis models used to evaluate the environmental hazard of petroleum products. A polyparameter-Linear Free-Energy Relationship (ppLFER) shows improved descriptions of both polar and non-polar organic compound ecotoxicity. Chemical speciation and other partitioning partitioning models have potential for describing the toxicity of ionizable compounds. Together these approaches show promise for addressing potential ecotoxicity issues related to the development of oil shale resources.