Uptake of radionuclide thorium by twelve native plants grown in uranium mill tailings soils from south part of China

•Screen dominant plants grown in uranium mill tailings soils.•Quantify the content of 232Th of soil samples from uranium mill tailings.•Quantify the transfer factor, bioconcentration factor and phytoremediation factor.•Screen out the plant species capable of remediating radionuclide contaminated soils.•Guide the reuse of study area in future.

The concentrations of thorium (232Th) in soil from a uranium mill tailings repository in South China were analyzed. The results showed that all the soil samples were acidic and the concentrations of 232Th in all the soil samples were more than the natural radionuclide content in soil of China. Through the field investigation, twelve kinds of dominant plants were discovered. The total quantity of 232Th in the whole plant is highest in rice flat sedge. We also found that Miscanthus floridulus has the greatest transfer factor (TF) for 232Th, rice flat sedge has the greatest bioconcentration factor (BF) for 232Th. At the mean time, M. floridulus has the greatest phytoremediation factor (PF) for 232Th. On the basis of the above conclusions and the definition for hyperaccumulator, rice flat sedge and M. floridulus could be the candidates of phytoremediation for radionuclide 232Th in the soil.