Silver [Ag, 47]

Silver (Ag) reveals chalcophilic properties and, after rock's weathering, easily precipitates in alkaline media. Silver was discovered about 4000 BC, when it was used in jewelry and a medium of exchange in bullion. It has very high electrical and thermal conductivity, and antibacterial properties, especially in forms of nanoparticles. Data for mean Ag concentrations in ocean waters are variable. According to Andren and Bober, these values vary from <0.024 to 0.56 ng/L. Silver occurs naturally, mainly in the form of its very insoluble and immobile oxides, sulfides, and some salts. It has occasionally been found in groundwater, surface water, and drinking water at concentrations about 5000 g/L. Most of the Ag transported in the blood is bound to globulins. Metallic Ag is not soluble in aqueous solutions nor is it readily solubilized by any physiological mechanisms. Soluble Ag compounds are absorbed by the body more readily as a result of their ability to bind to proteins, DNA, and RNA.