Exposure and ecotoxicity estimation for environmental chemicals (E4CHEM): Application of fate models for surface water and soil

Abstract

The e4chem (Exposure and Ecotoxicity Estimation for Environmental CHEMicals) model system was developed for exposure and hazard assessment of environmental chemicals. Two e4chem fate models, exwat and exsol , for surface waters and soil, respectively, are tested and validated by comparing experimental with calculated results. The concentrations of a volatile compound (tetrachloroethene) in the river Main can be predicted by exwat , taking into account the average consumption values along the river and an empirically derived proportionality factor for the release rate (0.6% for tetrachloroethene). A sensitivity analysis shows the dominance of volatilisation over dilution. The transport and fate of the herbicide, 2,4,5-trichlorophenoxyacetic acid, are simulated for four German soils under various climatic conditions. Downward movement is underestimated by laboratory sorption measurements. Sorption coefficients derived from field trials have lower values and lower variabilities than those from laboratory sorption studies.