Effect of illite and birnessite on thallium retention and bioavailability in contaminated soils

► The application of birnessite (δ-MnO2) to the contaminated soils can effectively transform Tl from the labile (easily mobilizable) fraction to its reducible form, thus reducing Tl bioavailability. ► Birnessite added to the soils reduced substantially Tl uptake; Tl levels in plants decreased by up to 50%, compared to the non-amended soil. ► The use of birnessite like soil additive might be an efficient and environment-friendly solution for soil systems contaminated with Tl. ► The general applicability of illite for Tl stabilization in soils seems to be limited and strongly dependent on soil composition.