Comparison of Chemical Bioaccumulation Models to Assist in Model Selection for Ecological Assessments and TMDL Development

This paper describes a recent EPA-sponsored study (Imhoff et al., 2004) that analyzed and compared the capabilities of advanced chemical bioaccumulation models that are currently available to support the evaluation of ecological effects in aquatic ecosystems. These models are commonly used to establish the linkage of a variety of water quality targets and sources, and to provide a means for comparing various watershed and waterbody management strategies. EPA's Office of Research and Development (ORD), National Environmental Research Laboratory (NERL), Ecosystem Research Division (ERD), is currently supporting EPA's Office of Emergency Response and Remediation (OERR) by addressing priority research needs related to assessing the fate and transport of pollutants via contaminated sediment and bioaccumulation. The results of the first support effort by ERD, an evaluation of currently available numerical models useful for assessing fate and transport of contaminated sediments (Imhoff et al., 2003), were presented at the fall 2003 WEF TMDL Conference (Imhoff, 2003). The work effort presented in this paper constitutes the second element of the support effort by ERD, a parallel evaluation of currently available numerical models useful for assessing chemical bioaccumulation. Eight models were identified that were judged superior to all others in their promise as tools for chemical bioaccumulation analysis. To provide ERD with a basis on which to compare these models, a head-to-head comparison of the models was developed applying a high level of scrutiny to both model science and model usability. Finally, the study considered the issues and strategies involved in linkage of the bioaccumulation models to models of adjacent environment compartments.