The chemical speciation of technetium in the environment: a literature survey

This report reviews the current understanding of the chemical forms and behaviour of technetium in the environment. Technetium (VII) is the dominant species in most systems, however when reducing conditions arise technetium (IV) species predominate. Pertechnetate is a highly mobile ion in aqueous media and can exhibit significant environmental transfer. Technetium (IV) is readily sorbed by sediments and is able to complex with various ligands which subsequently determine its fate. Complexation with high molecular weight organic moieties reduces the availability of technetium although this is not necessarily the case with smaller molecules. In plants, technetium is absorbed as TcO4- and can become incorporated into organic molecules. The technetium present in such forms is generally considered less available for uptake by the ingesting animal than aqueous TcO4-, although significant transfer of this element has been reported from food into eggs. Areas of potential future interest are suggested. (author)