Assessment of the suitability of soil amendments to reduce 137Cs and 90Sr root uptake in meadows.

In situ remediation strategies are an alternative approach in the management of radioactive contaminated areas, especially when based on modification of soil properties by the addition of amendments. Here, this strategy is applied to reduce 137Cs and 90Sr soil-plant transfer in meadows from areas of Russia, Belarus, and Ukraine affected by the Chernobyl fallout. Meadows were established on podzolic and peaty soils. Amendments covered a wide range of materials, such as loamy and sandy soils, polygorskite clay, phosphorite, turf, and sapropel. Field experiments showed the poor efficiency of most of the materials: only the polygorskite clay provoked a notable reduction (1.5-2-fold) in 137Cs root uptake. Subsequent laboratory characterization showed the lack of significant changes in the radiocesium interception potential and soil solution composition in the amended soils, a fact that helped to explain the lack of effect on the reduction of transfer. Moreover, a laboratory methodology based on the quantification of the adsorption potential of the amendments and the reversibility of the adsorption process was applied. This methodology was first proposed for the correct selection of the suitable materials to be used to decrease radionuclide root uptake in future remediation actions and then validated with data of the previous field experiments.