Method of diffusive gradients in thin films (DGT) compared with other soil testing methods to predict phytoavailability of uranium.

In the assessment of the potential impact of contaminants in soils and the requirement for the implementation of corrective actions, it is important to have an idea of the contaminant's mobility and bioavailability and the processes and parameters ruling it. Mobility and bioavailability of contaminants are among others affected by pollution type and origin, the element's physicochemical form and type and the physicochemical characteristics of the environment itself. Previous efforts to unravel the relation between 'available' forms of U and availability for plant uptake have not been very promising. A new approach to assess metal bioavailability in soils, the diffusive gradient in thin film (DOT) technique, was developed for sampling an available fraction in soil (Zhang and Davison, 1995). The aim of this study was to test potential bioavailability indices for soils with different histories of uranium contamination and distinct soil characteristics and to evaluate whether one of these methods could be proposed as a quantitative measure of U bioavailability. The indices that we screened were: DOT measured U concentration, U concentration in soil pore water, and U recovered following extraction with 2 conventional extractants.