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Bioavailability of cadmium and zinc to the common carp, CYPRINUS carpio , in complexing environments: A test for the validity of the free ion activity model
Author(s) -
Ginneken Luc Van,
Chowdhury Mohammed J.,
Blust Ronny
Publication year - 1999
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620181026
Subject(s) - cadmium , ethylenediaminetetraacetic acid , chemistry , zinc , nitrilotriacetic acid , chelation , bioavailability , metal ions in aqueous solution , histidine , nuclear chemistry , cyprinus , carp , citric acid , inorganic chemistry , common carp , metal , environmental chemistry , amino acid , biochemistry , organic chemistry , biology , fish <actinopterygii> , bioinformatics , fishery
The uptake of cadmium and zinc by the common carp, Cyprinus carpio , was studied in chemically defined freshwater in the presence of different organic ligands (i.e., citrate, glycine, histidine, ethylenediaminetetraacetic acid, and nitrilotriacetic acid). In most cases, metal complexation decreased Cd and Zn uptake by reducing the free Cd and Zn ion activity. However, Cd and Zn uptake did not increase linearly with the free Cd and Zn ion activity in the solution. A good fit to the data was obtained when the observations were fitted to a Michaelis—Menten‐like model for carrier—mediated transport of the metal ions across the biological interface. In addition, the uptake of Cd in the presence of citrate, glycine, and histidine was markedly higher than expected on the basis of the free Cd ion activity. It was concluded that cadmium complexes of these low molecular weight, hydrophilic ligands contributed to the Cd bioavailability, probably by direct uptake of these complexes. Zinc uptake in the presence of the complexing agents could be predicted on the basis of the ambient free Zn ion activity, although uptake in the presence of citrate was lower than expected on the basis of the free Zn ion activity. These results provide a challenging test for the free ion activity model.