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(392) Refinement and validation of a biotic ligand model predicting acute copper toxicity for Daphnia magna. De Schamphelaere, Karel1, Heijerick, Dagobert1, Bossuyt, Bart1, Janssen, Colin1, 1 ABSTRACT- The development and application of Biotic Ligand Models (BLM), aimed at predicting metal bioavailability in surface waters, is receiving increased attention from academic and regulatory communities. To date, BLMs for predicting acute copper toxicity have been developed for fish (Di Toro et al., in press Environ. Toxicol. Chem.) and daphnids (Santore et al., in press Environ. Toxicol. Chem.; De Schamphelaere and Janssen, submitted to Environ. Sci. Technol.). Both models need to be refined and validated for a broader range of water quality characteristics like pH, DOC-content and concentrations of the major cations Ca, Mg and Na before incorporation in environmental risk assessment and (site-specific) water quality criteria setting. Refinement of the BLM for D. magna was performed based on the toxicity data of 25 acute bioassays in 25 different randomly prepared artificial test media. Water quality characteristics were varied based on the variation found in natural European waters. After this refinement, the BLM was validated by performing acute bioassays using field collected water samples from Belgium, Sweden, The Netherlands and the United kingdom representing the whole range of water quality characteristics present in European surface waters. With the refined BLM 48-hour EC50s of copper for D. magna could be predicted within a factor 2 to 3. This study demonstrates the applicability of BLMs in setting site specific criteria for metals in natural aquatic environments. Key words: biotic ligand model (BLM), Daphnia magna , acute copper toxicity, bioavailability |
