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(M/EH086) Effect of suspended matter on toxicity of alkyltrimethyl ammonium salts to P. subcapitata. van Wijk, Dolf1, van den Bos, Mirjam1, Garttener-Arends, Irmgard1, Geurts, Marc1, 1 ABSTRACT- Ecotoxicological information is usually obtained from laboratory toxicity tests applying pure liquid media to optimize exposure. For risk assessment purposes such data have to be extrapolated to realistic environmental conditions. Phenomena like sorption to dissolved organic carbon or to suspended matter are known to reduce toxicity, but are likely to be underestimated in the case of quaternary ammonium salts. A thorough understanding of such phenomena and quantitative relationships for groups of compounds to describe the effect of these environmental conditions confounding toxicity facilitate incorporation in risk assessment procedures. The current study was undertaken to establish the influence of bioavailability on the ecotoxicity of alkyltrimethyl ammonium salts. Algae were used representing the most sensitive group of species for these chemicals. The effect of sorption to silica, montmorillonite and real sediment on toxicity was investigated for alkyl trimethyl ammonium salts with different chain lengths. Silica showed the smallest effect on detoxification and montmorillonite, reflecting the clay fraction of suspended matter, had the largest effect. The effect of real sediment was in-between, as expected. These findings are in accordance with the sorption characteristics of these chemicals to algae and to the sorbents tested. QSAR relationships based on the alkyl chain lengths could be established for all sorbents. Key words: algal toxicity, alkyltrimethyl ammonium salts, suspended matter, detoxification |
