SILVER: METAL BINDING, AQUATIC TOXICITY AND FATE RELATIVE TO ANTISEPTIC ASPECTS

Ag, a precious metal, typically at low pico-molar (pM) concentration in natural waters, is elevated in urban areas to nano-molar (nM) levels due to discharge of Ag in wastes. "Free Ag ions" are toxic to a wide range of aquatic organisms at low nM levels. But Ag is non-toxic when bound to a strong ligand(SL). SL is typically a sulfide or organo-sulfide ligand. Most use of Ag now is as a disinfectant. The disinfectant action of Ag depends on Ag being as a "free" ion. Examples of Ag-binding, toxicity results and distributions of "free" and bound Ag in nature are given along with SL sources and fate.