PARENT SESSION

1L (1) - Exposure Modelling
Hall 4
1:45 PM - 3:30 PM, Wednesday, 30 April 2003
Chair: Lammel, G.¹, ¹
Co-chair: Dachs, J.², ²

(WE4/15) Integrated modelling of eutrophication and organic contaminant fate in rivers.

Deksissa, Tolessa¹, Vanrolleghem, Peter A.¹, ¹ Ghent University-BIOMATH, Ghent, Belgium, Belgium

ABSTRACT- Eutrophication and contamination by toxic organic pollutants are the major problems in water quality management. Despite the fact that both problems have been subjected to extensive research and modelling, they have traditionally been treated separately. Because they are single-issue models, many interactions between nutrient and organic contaminant cycles are missed. Linking these models is essential to evaluate the fate and risk of the contaminants in aquatic ecosystems subjected to dynamic nutrient and trace organic contaminant loading. Thus, the aim of this study is to develop an integrated exposure model that links an eutrophication model with an organic contaminant fate model. Although there are many eutrophication models available in literature, most of them lack an appropriate description of, for example, dissolved and particulate organic carbon (DOC and POC, respectively), or do not consider bacteria as state variables. Subsequently, the IWA River Water Quality Model number 1 (RWQM1), in which bacteria are explicitly considered as state variables, is selected. Both DOC and POC dynamics, which are essential for the fate modelling of contaminants that associate strongly with POC or DOC, are considered. Using a multi-compartment model (air, water and benthic sediment), and a conceptual dynamic hydraulic model (continuously stirred tank in series), a one-dimensional dynamic exposure model has been developed, and integrated with RWQM1. The model was evaluated with Linear Alkylbenzene Sulfonates (LAS) as a case study in the river Lambro (Italy). Based on monitoring data collected in February and May 1998 within the GREAT-ER project, the general trend of the simulated data are shown to agree well with the measured time series. The proposed model is compatible with wastewater treatment models, and is useful for integrated water quality studies.

Key words: Exposure, Dynamic, Modelling