Bioremediation of a soil contaminated with radioactive elements

Samples of a soil heavily polluted with radioactive elements and toxic heavy metals were subjected to bioremediation in lysimeters containing 50 kg (dry weight) of soil each. The soil treatment was connected with the solubilization of the pollutants located in the upper soil layers (mainly in the horizon A) and their removal from the soil by drainage waters percolating through the soil mass. The solubilization was carried out by the soil microflora whose activity was enhanced by suitable changes in the levels of some essential environmental factors such as water, oxygen and nutrient contents in the soil. The leaching of radioactive elements and of some toxic metals was efficient and their contents in the soil were decreased below the relevant permissible levels within 10 months of treatment. It was also possible to transfer portions of the pollutants into the deeply located soil layers (mainly in the horizon B(2)) where they were immobilised mainly as a result of the activity of the anaerobic sulphate-reducing bacteria.