Effects of Phosphorus Modified Bio-char on Metals in Uranium-Containing Soil

The level of radioactivity in the soil has been increasing unpredictably due to the human uranium mining exploitation of uranium over the past 100 years. Remediation of metals in actual soil confronts many challenges, remaining poorly understood. This study intends to investigate the concentrations and distributions of U, Cd, Zn, Pb, and Cu in soils surrounded by a uranium mill tailing pond. Furthermore, a phosphorus-modified bio-char was prepared in order to determine its role in immobilizing uranium in soil samples. Results show that the contents of U and Pb are much higher than that of the background values, due to the influence of the uranium mill tailing pond. Phosphorus can enhance the immobilization efficiency of U, Cd, Pb, and Cu in soil samples. The concentration of uranium in the leaching supernatant of phosphorus-modified bio-char group is lower than that of control and unmodified bio-char groups due to the fact that the biosorption occurred in the exterior surface of the biomass, which imply that phosphorus-modified bio-char is a potential immobilization material to reduce the leaching rate of metals. These findings can provide references for remediation technology of metals in natural soil.