Partitioning and redistribution of exogenous Ra226 in farm soils from the vicinity of the First Brazilian Mine and Mill

A sequential selective extration method was employed to assess the partitioning and redistribution of exogenous 226Ra into geochemical fractions of farm soils collected around the first Brazilian Uranium Mine and Mill. Six soil samples were contaminated in the laboratory by 226a solution, simulating an irrigation procedure. After selective extractions, 226Ra was analysed in six geochemical fractions: soluble (A); exchangeable (E); bound to carbonates (C); reducible (R); oxidizable (O); residual or matricial (M). The same method was also used in these soils before and after cultivation. The exogenous 226Ra was mainly associated to the (R) and (O) fractions followed by the (E) and (C) ones. Exchangeable 226Ra (fractions (A) + (E)) represents 21.8%. Statistically significant differences before and after cultivation were obtained only in the fractions (C) and (M). (Author)