PW09 Exposure and Effect Endpoints
Exhibit Hall
8:00 AM - Wednesday, 12 November 2003
(PW178) Evaluation of AQUATOX for Ecological Risk Assessments in the U.S. EPA Office of Pesticide Programs.
Echeverrķa, M1, Wellman, M1, Park, R2, Clough, J3, 1 U.S. Environmental Protection Agency, Washington, DC, USA2 Eco Modeling, Diamondhead, MS, USA3 Warren Pinnacle Consulting Inc., Warren, VT, USA
ABSTRACT- An aquatic ecosystem simulation model, AQUATOX (Release 2), was evaluated as a tool for ecological risk assessments in the EPA Office of Pesticide Programs (OPP). A comparative analysis between the fate components of AQUATOX and EXAMS 2.98.04, the current environmental fate and transport model used in OPP, was performed. The comparative analysis involved testing individual fate processes and testing the models with real chemical data. A number of fundamental differences between EXAMS and AQUATOX were identified and an effort was made to set up the simulations to minimize the impact of these differences on the comparison. The results of individually testing each loss process indicate that despite minor differences, fate processes are consistent between the two models. The results for the test chemicals show similar patterns of chemical concentration over time, but more disparity exists between the two models compared to the tests for the individual fate processes, probably due to propagated differences between the various fate processes and model assumptions. In addition, an example was developed to illustrate potential use of AQUATOX for evaluating integrated fate and effects in OPP. The standard OPP water body scenario used in EXAMS simulations for ecological assessments was combined with the AQUATOX average pond scenario to develop the example scenario. AQUATOX was run with and without perturbations that consisted of chlorpyrifos loadings generated by PRZM. Results illustrated how AQUATOX output, including biomass concentrations and biological rates for control and perturbed simulations, could be used to inform the risk assessment process.
Key words: AQUATOX, ecological risk assessment, ecosystem model