The Environmental Model Segment Approach for estimating potential environmental concentrations. II. Application of the model to p-dichlorobenzene and trichloroethene.

The Environmental Model Segment Approach introduced in Part I (R. Frische, W. Klöpffer, G. Rippen, and K. O. Günther, 1984, Ecotoxicol. Environ. Safety 8, 352-362) is applied to estimate potential environmental concentrations of p-dichlorobenzene and trichloroethene. Environmental concentrations of these chemicals can be estimated only with difficulty by other models because of many diffuse emission sources emitting mainly into the air. By comparison of the estimated with the measured environmental concentrations it is found that the claim of the model to yield values which apply to reasonable unfavorable environmental boundary conditions is satisfied for the medium air and for the biota (fish). Soil concentrations calculated by means of the model, assuming equilibrium with high air concentrations, are higher than the measured ones, while the calculated water concentrations are lower than the values often measured for river waters. The latter fact may be attributed to direct input of the substances into water which is not being taken into account.