Mitigation of 210Po in topsoil due to plant uptake and leaching to subsoil: a case study of Vietnamese croplands

Besides the radioactive decay process, the leaching to subsoil and uptake by plants are two processes that reduce the activity concentrations of radionuclides in the topsoil. In this study, the leaching rate (R_ℓ) and uptake rate (R_p) of ²¹⁰Po were estimated for topsoils (0–20 cm) of 20 agricultural fields in Vietnam. The soil-to-plant transfer factor (TF) and solid/liquid partition coefficient (K_d) of this radionuclide were also reported. The ranges of R_ℓ and R_p of ²¹⁰Po were 0.067 to 1.064 Bq kg^–1 y^–1 and 0.108 to 0.294 Bq kg^–1 y^–1, respectively. The rates are significant but only contribute a small portion to the total mitigation rate. Because of the short half-life (138.3 days), radioactive decay is the most important process that mitigates the activity concentration of ²¹⁰Po in the topsoil.