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Binding of nickel and copper to fish gills predicts toxicity when water hardness varies, but free-ion activity does not

Journal Article · · Environmental Science and Technology
DOI:https://doi.org/10.1021/es980715q· OSTI ID:335348
; ; ; ;  [1]; ; ;  [2];  [3]
  1. Univ. of Wyoming, Laramie, WY (United States). Dept. of Zoology and Physiology
  2. HydroQual, Inc., Mahwah, NJ (United States)
  3. Univ. of Delaware, Newark, DE (United States). Dept. of Civil and Environmental Engineering
Based on a biotic-ligand model (BLM), the authors hypothesized that the concentration of a transition metal bound to fish gills ([M{sub gill}]) will be a constant predictor of mortality, whereas a free-ion activity model is generally interpreted to imply that the chemical activity of the aquo (free) ion of the metal will be a constant predictor of mortality. In laboratory tests, measured [Ni{sub gill}] and calculated [Cu{sub gill}] were constant predictors of acute toxicity of Ni and Cu to fathead minnows (Pimephales promelas) when water hardness varied up to 10-fold, whereas total aqueous concentrations and free-ion activities of Ni and Cu were not. Thus, the BLM, which simultaneously accounts for (a) metal speciation in the exposure water and (b) competitive binding of transition-metal ions and other cations to biotic ligands predicts acute toxicity better than does free-ion activity of Ni or Cu. Adopting a biotic-ligand modeling approach could help establish a more defensible, mechanistic basis for regulating aqueous discharges of metals.
OSTI ID:
335348
Journal Information:
Environmental Science and Technology, Journal Name: Environmental Science and Technology Journal Issue: 6 Vol. 33; ISSN ESTHAG; ISSN 0013-936X
Country of Publication:
United States
Language:
English