Soil Chemistry of Radionuclides

Abstract

The naturally occurring radionuclides that are found in soils in significant amounts include 14C, 40K, 87Rb and members of the uranium, actinium and thorium series. Over 300 radioisotopes may be produced by fission and neutron induction, but as most of these will have short half lives, they will not normally be detected in soils. Yttrium, praseodymium, promethium, thorium, proactinium, zirconium and niobium occur in soils but are either very strongly adsorbed by the clay particles or are present as insoluble oxides or hydroxides. In either of these states these elements will be immobile in the soil and largely unavailable to plants. The radioactive elements found in soils which tend to have a degree of mobility include strontium, barium, uranium, radium, lead, manganese, cobalt, zinc, iron, ruthenium, chromium, potassium, rubidium, calcium and carbon. In considering the mobility of any particular ion in a soil mass, the effect of all other ions must be taken into account. The amount and species of the complementary ions will have a strong influence on the redistribution of these isotopes in the soil profile and will affect plant uptake.