Refining an In-stream Fate Model of Organic Contaminants: a Case Study of Las in the River Lambro

Most of the models describing the fate and transport of xenobiotic organic chemicals in natural streams are steady state models (e.g. EXAMS, SYMPTOX4, GREATER,…). In view of ecological risk assessment, the current Predicted Environmental Concentration (PEC) estimation method in the European Union (EU) member states is based on a steady state in-stream fate model (OECD, 1999). These models assume continuous and uniform flow emissions, which is not justifiable as, in reality, the flow varies significantly with time. In such cases, a dynamic modelling approach is more realistic because it accounts for the temporal variability (Verdonck et al., 2002). Thus, the refinement of in-stream fate models is required for realistic exposure assessment.