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EFFECTS OF WATER CHEMISTRY ON COPPER TOXICITY - WHAT'S MISSING FROM CURRENT MODELS?
Citation:
Erickson, R J. EFFECTS OF WATER CHEMISTRY ON COPPER TOXICITY - WHAT'S MISSING FROM CURRENT MODELS? Presented at 22nd Annual SETAC Meeting, Baltimore, MD, November 11-15, 2001.
Description:
Current models for the acute toxicity of cationic metals to aquatic organisms focus on the binding of free metal ions to gill surfaces. This binding, and the resultant toxicity, can be reduced by metal-complexing ligands in the exposure water, which lower the activity of the free metal ions, and by other cations in the exposure water, which compete with the metal ions for the binding sites on the gill. The validity of such mechanisms has been experimentally established and these models have been demonstrated to account for a large proportion of the effects of water chemistry on metal toxicity in some cases. However, some experimental data also has shown significant deviations from predictions and it is uncertain what mechanisms should be invoked to adequately explain the effects of water chemistry on metal toxicity. The adherence of models to various published copper toxicity data sets was examined and observed deviations were evaluated with respect to potential mechanisms not accounted for in the models. In particular, pH shifts in the microenvironment adjacent to gill surfaces were concluded to be important for explaining some deviations of model predictions from observed toxicity relationships.