9. The DREAM Model and the Environmental Impact Factor: Decision Support for Environmental Risk Management

DREAM (Dose-related Risk and Effect Assessment Model) is a three-dimensional, time-dependent numerical model that computes transport, exposure, dose, and effects in the marine environment. The model can simulate complex mixtures of chemicals. Each chemical component in an effluent mixture is described by a set of physical, chemical, and toxicological parameters. Because petroleum hydrocarbons constitute a significant fraction of many industrial releases, DREAM incorporates a complete surface slick model, in addition to the processes governing contaminant behavior and fates in the water column. The model can also calculate exposure, uptake, depuration, and effects for fish and zooplankton simultaneously with physical–chemical transport and fates. The Environmental Impact Factor (EIF), first developed for the water column, has been extended to include ecological stresses in the benthic community. The EIF is a standardized method for marine environmental risk assessment that does not require explicit information on the local biological resources. This makes the methodology relatively easy to apply to new geographical areas, and it has been used in northern and southern European, as well as in North American, South American, and African waters. This chapter gives an overview of the model system and a summary of ongoing developments.