Fate of caesium in the environment: Distribution between the abiotic and biotic components of aquatic and terrestrial ecosystems

Interest in the fate of radiocaesium in the environment has heightened considerably in recent years in the wake of the Chernobyl accident in 1986. The distribution of released 137Cs and 134Cs is related to the chemical properties of Cs+, which generally dictate a high degree of mobility and bioavailability of the radionuclide. The partitioning of Cs+ between abiotic (i.e. soils, sediments, water) and biotic components of terrestrial and aquatic ecosystems is complex and dependent on a number of factors, e.g. inorganic mineral content of the solid substrates and the abundance of monovalent cations. Direct biological Cs accumulation from the environment occurs readily in lower organisms and primary producers, e.g. microorganisms and plants; Cs+ accumulation by higher animals results predominantly from consumption of contaminated foodstuffs, although direct inhalation/absorption from the environment may also occur. The evidence discussed here indicates that radiocaesium continues to be recirculated in biological systems for many years following a pulse of contamination.