Absorption of radionuclides in soil and their availability to plants

A sequential extraction procedure was used to assess the plant availability of radionuclides in 10 Japanese soils. The procedure identifies 4 nuclide fractions in soil, namely, in soil water, inorganic sites, organic sites, oxides and the residue fraction. Cesium was very low in soil water with the majority fixed in the residue in a non-extractable form. Sr was the most abundantly available nuclide in soil water. Plant uptake (Cucumis sativus L.) of nuclides showed significant correlation with the soil water fraction. The fraction of organically bound divalent ions was not readily available, but that of Cs and Rb was potentially available for plant uptake. (author)