Elena Aleksandrovna Alyokhina

Speciation of ²²⁶Ra and ²³²Th in sod-podzolic-gley concretionary soil are studied. It has been shown that with periodic overmoistening by surface waters and alternation of reducing and oxidizing conditions, the mobility and availability to plants of ²²⁶Ra is substantially higher than ²³²Th. The sum of fractions available to plants (water-soluble and exchangeable) and mobile (water-soluble, exchangeable and mobile) of ²²⁶Ra is 2-10 times higher than ²³²Th. Segregated ferruginous nodules formed in the eluvial horizons of this soil have a weak effect on the mobility of ²²⁶Ra, but significantly reduce the mobility of ²³²Th, much of which is substantially fixed inside the crystal lattices of newly formed minerals.