Bioavailability of radionuclides

Evaluating the bioavailability of radionuclides in contaminated soil using the diffusive gradients in thin films technique (DGT)

Alex Chapman

A key environmental challenge currently facing us is dealing with land contaminated with radioactive substances through the consequences of accidents (e.g. Fukushima and Chernobyl), past practices using radioactivity and planning for the disposal of nuclear waste arising from current and future nuclear power generation. However, to appropriately address contaminated land issues, we need to understand how radionuclides behave in the soil system. One aspect of environmental behaviour that requires further work is our appreciation of radionuclide bioavailability. Simple assessment has proved elusive because procedures have not considered the in situ speciation and dynamic supply from solid phase to solution. Diffusive Gradients in Thin films (DGT) is a well-established in-situ speciation technique for measuring mobile trace metals in water, soils and sediments. When deployed in soil, DGT has been shown to be a good predictor of metal concentrations in plants. However only limited radionuclide work has been conducted investigating DGT performance.

The aims of this studentship are to develop the DGT technique for the assessment of radionuclides in soils to (i) advance our understanding of radionuclide-soil binding and release kinetics and (ii) move towards the development of a rapid test for radionuclide bioavailability. The short-term behaviour of radionuclide contaminants and the kinetics of solid-solution partitioning in soils will be tested using soils that have been amended with radionuclides. Plant uptake experiments will allow comparison of plant and DGT data for the range of soil types under investigation, using both lab and field contaminated soils, and a mixture of pot and lysimeter experiments. 

Poster presented at Geowaste conference in 2015