Modulation of cupric ion activity by pH and fulvic acid as determinants of toxicity in Xenopus laevis embryos and larvae
- Oregon State Univ., Corvallis, OR (United States). Toxicology Program
- ManTech Environmental Technology, Inc., Corvallis, OR (United States)
- East Tennessee State Univ., Johnson City, TN (United States). Dept. of Environmental Health
An ion-specific electrode measured cupric ion activity modulated by fulvic acid (FA) and pH in a series of modified Frog Embryo Teratogenesis Assay--Xenopus (FETAX) toxicity assays. Hydrogen ion concentration was the primary determinant of cupric ion activity, while FA played a smaller but significant role. Fulvic acid was a weak copper complexing agent at pH 5.50. At pH 5.50 there was slight reduction of ionic activity and a subsequent attenuation of copper toxicity with 5.0 mg/L FA. At pH 7.50, FA also had a mild attenuating effect on copper toxicity. At pH 6.50, copper was strongly complexed by FA at total copper (TCu) concentrations below its pH-dependent solubility limit. At TCu concentrations above the solubility limit FA enhanced toxicity. There was more cupric ion activity measured in the presence of 0.5 and 5.0 mg/L FA than without it at TCu concentrations above the solubility limit. The proposed mechanism for this behavior was FA action as a nucleation inhibitor. Under the chemical conditions of the pH 6.50 experiments, a stable supersaturation of copper was formed, resulting in a more toxic aqueous matrix.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 268032
- Journal Information:
- Environmental Toxicology and Chemistry, Vol. 15, Issue 4; Other Information: PBD: Apr 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
Copper binding by dissolved organic matter. I. Suwannee River fulvic acid equilibria
Effect of chronic copper and pentachlorophenol exposure to early life stages of Xenopus laevis