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6692202 
Journal Article 
Review 
Metal speciation in natural waters with emphasis on reduced sulfur groups as strong metal binding sites 
Smith, DS; Bell, RA; Kramer, JR 
2002 
Yes 
Comparative Biochemistry and Physiology - Part C: Toxicology and Pharmacology
ISSN: 1532-0456
EISSN: 1878-1659 
ELSEVIER SCIENCE INC 
NEW YORK 
133 
1-2 
65-74 
English 
12356517 
WOS:000178949100005 
The proper application of biotic ligand models to predict metal toxicity depends on accurate prediction of metal binding to sites on natural organic matter (NOM) which compete with the 'biotic' ligand for available metal. A hard and soft metal classification along with associated ligand groups (carboxyl, phenolic, amino, sulfidic) are used as a basis to predict metal speciation in the presence of aqueous organic matter. Compilation of conditional metal formation constants (log K') are made for each ligand type using model ligands. Model ligands were chosen to reflect those found in NOM and bio-organic media. Total ligand concentration (L(T)) estimates for different natural settings and log K' values are then used to generate a L(T)-log K' distributions for a specific metal. A plot for Cu(II) gives a similar trend as a compilation of measured data for natural environments. A log K'-L(T) plot for Ag(I) shows a much more discrete binding pattern than for Cu(II). Estimation of speciation of a specific metal in a specific environmental setting and to design speciation and toxicological experiments requires accurate knowledge of the functional groups in NOM.