Speciation of 226Ra and 232Th in Soddy-Podzolic-Gley Concretion Soil

Resumo

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.