Behaviour of Technetium in Freshwater Environments

Abstract

Currently the major sources of 99Tc released to the environment in the United States are gaseous diffusion plants that enrich reprocessed nuclear fuel. At present these facilities are located on freshwater streams into which liquid effluents are released. Of the total amount of 99Tc that escapes these facilities more than 90% may enter the liquid pathway [I]. Information on the behaviour of technetium in aquatic ecosystems is limited; most data on the uptake of technetium by aquatic organisms are restricted to marine environments. Most of the information available on technetium in freshwater ecosystems is based on data from an experimental pond study with 95mTc [2,3]. Concentration factors of 11, 75 and 121 were reported for carp (Cyprinus carpio), mosquitofish (Gambusia affinis) and snails (Helisoma sp.), respectively [2]. Recently, concentration factors were reported for other freshwater organisms based on laboratory studies with 95mTc. The freshwater mussel (Margaritifera margaritifera) had a whole-body concentration factor of 0·9; the newt (Taricha granulosa) had a wholebody concentration factor of II [4]. In similar studies with the crayfish Pacifactacus leniusculus and the snail Juga silicula, whole-body concentration factors were 1·6 and 41, respectively [5]. In previous pond studies [2] periphyton and macrophytes accumulated technetium rapidly and contributed to the concentration of95mTc in higher trophic levels via the food chain pathway. Concentrations in zooplankton Information on the behaviour of tc in aquatic ecosystems is limited; most data on the uptake of tc by aquatic organisms are restricted to marine environments. Looks at uptake of Tc by different organisms in the environment