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2P Modelling ecotoxic effects (MOP/144) Geography-referenced bioavailability modelling in risk assessment: a case study of copper in Swedish surface waters. De Laender, Frederik1, Verdonck, Frederik1, Deschamphelaere, Karel2, Janssen, Colin2, Vanrolleghem, Peter1, 1 Ghent University - BIOMATH, Gent, Oost-Vlaanderen, Belgium2 Ghent University - Laboratory of Environmental Toxicology and Aquatic Ecology, Gent, Oost-Vlaanderen, Belgium ABSTRACT- Until recently, water quality standards and risk assessment procedures for heavy metals in surface waters were predominantly based on total and/or dissolved metal concentrations. Moreover, one Predicted No Effect-Concentration (PNEC) had to cover a whole area and one large time period, without taking into account the PNEC's spatial and temporal variations. However, the importance of bioavailability and toxicity modifying factors like pH, hardness and DOC, is increasingly being recognized, as well as its spatial and temporal variability. These factors were addressed in this study (i) to cover the effect of the modifying factors, a Biotic Ligand Model (BLM) was used, (ii) to account for the spatial variability, a Geographic Information System (GIS) was applied and (iii) to account for temporal variability, a Monte Carlo simulation was used. Significant improvements in PNEC predictions were found compared to the conventional risk assessment approach (one PNEC for entire region and time period). The advantages of using these approaches are thus a more accurate way to account for the influence of water characteristics, temporal and spatial variations on the toxicity of metals in surface water. Key words: toxicity modifying factors, PNEC, BLM, Monte Carlo |
