Phytomycoremediation of Uranium-Polluted Soil

Abstract

This study explores phytomycoremediation, a dual-biological approach combining fungal organic acid production and plant-based phytoextraction to increase uranium mobility and uptake from contaminated soils. A pot experiment was conducted using uranium-contaminated soil originating from a former uranium mining area in Zadní Chodov, Czech Republic. The soil was amended with spent mushroom substrate of the white rot fungus Pleurotus ostreatus, alongside the cultivation of Raphanus sativus (Brassicaceae). Two soils differing in uranium concentrations were used. The cultivation period lasted 2 months, during which soil solution was collected in weeks 2 and 6 using soil moisture samplers and analysed for low-molecular-weight organic acids (LMWOAs). In addition, uranium and other potentially toxic elements (including cadmium, lead, and arsenic) were quantified in the plant biomass. Among the detected LMWOAs, citrate concentrations increased significantly (p < 0.05) in the soil solution from the fungus-amended soil samples. However, the uranium concentrations in the plant tissues remained relatively low, with uranium predominantly retained in roots. Moreover, uranium uptake by plants tended to decrease in the presence of the fungus, which was confirmed as significant (p < 0.05) in roots. This pattern suggests that P. ostreatus SMS did not enhance uranium phytoextraction under the tested conditions and may have reduced plant-accessible uranium, although direct measurements of uranium speciation and fungal uranium retention are required to confirm this mechanism. Although P. ostreatus SMS increased LMWOA concentrations, particularly citrate, this did not translate into enhanced uranium uptake by plants. Further research involving additional fungal and plant species, as well as optimisation of environmental conditions, is needed to improve phytomycoremediation strategies for uranium-contaminated environments.