Distribution characteristics and application of Pu isotopes in soils and lake sediments of China

Plutonium (Pu) is an important radionuclide that exists in the environment in trace or ultra-trace level, which is closely associated with the nuclear industry. The distribution characteristics, migration behavior and the application in geochemistry of ^239+240Pu in soil and lake sediments in recent years in China were reviewed. The results showed that the sedimentation fluxes of ^239+240Pu in soils were estimated at from 7.31 MBq/km² to 554.00 MBq/km²; while that of ^239+240Pu in lake sediments were from 4.80 MBq/km² to 240.60 MBq/km², varying with the environment and latitude in the study area. ²⁴⁰Pu/²³⁹Pu isotope ratios from soils and lake sediments were found to be within 0.048-0.307 and 0.164-0.193, with an average of 0.181±0.026 and 0.179±0.021, respectively. Global atmospheric nuclear test sedimentation was the main source of^239+240Pu in China. As an important long-lived radionuclide, the combination of Pu isotope with other radionuclide tracing methods (e. g. ¹³⁷Cs, ²¹⁰Pb and ⁷Be tracing methods), remote sensing technology and traditional research methods should be strengthened in future research, which was conducive to improving the analysis accuracy of Pu in large-scale environmental areas and the tracing efficiency of ^239+240Pu radionuclide tracing technology.