GREAT-ER: A NEW TOOL FOR MANAGEMENT AND RISK ASSESSMENT OF CHEMICALS IN RIVER BASINS Contribution to GREAT-ER # 10 D. Schowanek 1 *, K. Fox 2 , M. Holt 3 , F.R. Schroeder 4 , V. Koch 5 , G. Cassani 6 , M. Matthies 7 , G. Boeije 8 , P. Vanrolleghem 8 , A. Young 9 , G. Morris 10 , C. Gandolfi 11 and T.C.J. Feijtel 1 1: Procter & Gamble Eurocor, Temselaan 100, B-1853 Strombeek-Bever, Belgium; 2: Unilever Research Port Sunlight Laboratory, Quarry Road East, Bebington, Wirral L63 3JW, UK; 3: ECETOC, Avenue van Nieuwenhuyse 4, Box 6, B-1160, Brussels, Belgium; 4: Henkel, KGaA, D-40191 Düsseldorf; Germany; 5: Clariant AG, ESHA Chemicals, D-65840, Sulzbach, Germany; 6: Condea Augusta S.p.A. Research Center, Via Reali 4, I-20037 Padermo Dugnano, Italy; 7: University Osnabrück, Institute of Environmental Systems Research, Artilleriestrasse 34, D-49069 Osnabrück, Germany; 8: University Gent, Department of Applied Mathematics, Biometrics and Process Control, Coupure L-653, 9000 Gent, Belgium; 9: Institute of Hydrology, Crowmarsh Gifford, GB-Wallingford, Oxfordshire OX10 8BB, UK; 10: Environment Agency Laboratory Service, Olympia House, Gelderd Lane, Gelderd Road, LS 12 6DD Leeds, UK; 11: University of Milan, Istituto di Idraulica Agraria, Via Celoria 2, 20133, Milano, Italy. * corresponding author: schowanek.d@pg.com ABSTRACT The GREAT-ER (Geo-referenced Regional Exposure Assessment Tool for European Rivers) project team has developed and validated an accurate aquatic chemical exposure prediction tool for use within environmental risk assessment schemes. The software system GREAT-ER 1.0 calculates the distribution of predicted environmental concentrations (PECs) of consumer chemicals in surface waters, for individual river stretches as well as for entire catchments. The system uses an ARC/INFO - ArcView ( ESRI) based Geographical Information System (GIS) for data storage and visualization, combined with simple mathematical models for prediction of chemical fate. At present, the system contains information for four catchments in Yorkshire, one catchment in Italy, and two in Germany, while other river basins are being added. GREAT-ER 1.0 has been validated by comparing simulations with the results of an extensive monitoring campaign for two ‘down-the-drain’ chemicals, i.e. the detergent ingredients boron and Linear Alkylbenzene Sulphonate (LAS). GREAT-ER 1.0 is currently being expanded with models for the terrestrial (diffuse input), air and estuarine compartments. KEYWORDS Environmental Risk Assessment, Geographic Information Systems (GIS), GREAT-ER, River Basins, Model Validation