| Popis: |
The stoichiometry and affinity (conditional stability constants) of Cu chelation by naturally-occurring organic ligands were determined by numerical solutions of Scatchard relationships. These values were then used in the geochemical speciation model, GEOCHEM, to determine the relative importance of each Cu species in dynamic equilibrium with competing metals and ligands. The accumulation of Cu by and toxicity of Cu to the soft water cladoceran Simocephalus serrulatus (Daphnidae) were measured and related to Cu speciation. When 10 μg Cu · L −1 were added to pond water in the fall, the distribution of Cu was: Cu ++ , 36.0%; Cuorganic, 63%; CuOH − , 0.5% and CuSO 4 , 0.5%. The organics in pond water reduced Cu accumulation and toxicity. However, when the 24 h-LC 50 values were reported as Cu ++ , this species of copper was more toxic in pond water than well water. |
