Аннотация:Forms of 226Ra and 232Th in soddy-podzolic-gley concretion soil are studied. It has been shown that the sum of 226Ra fractions available for plants (water-soluble and exchangeable) and mobile (water-soluble,
exchangeable, and mobile) is 2–10 times higher as compared to 232Th under regular excessive moistening
by surface waters and alternation of reduction and oxidation conditions. Segregated ferruginous concretions formed in the eluvial horizons of this soil exert a slight effect on the mobility of 226Ra but significantly reduce that of 232Th, a significant portion of which is firmly fixed inside the crystal lattices of newly formed minerals.