Seasonal variation of radionuclides in surface sediments off the east coast of Shandong Peninsula and its environmental implications

Surface sediment samples were collected off the east coast of Shandong Peninsula in April, July, October and December of 2019 respectively. Radionuclides ⁷Be, ²¹⁰Pb_ex, ²²⁸Th_ex and ¹³⁷Cs of the surface sediments are analysed and discussed for different seasons. The results suggest that the seasonal distributions of ⁷Be and ²²⁸Th_ex are different from ²¹⁰Pb_ex and ¹³⁷Cs at same station, and the seasonal distribution of the same radionuclide vary from station to station. The variations of radionuclides seem to have nothing to do with the grain size of surface sediments. The seasonal variations of ⁷Be and ²²⁸Th_ex are significantly affected by the transport and settlement of suspended matter, while ²¹⁰Pb_ex and ¹³⁷Cs are more closely related to sediment redistribution. Comparing to the station H02, the changes of radionuclides in surface sediments at the station H01 are less affected by atmospheric sedimentation. H01 and H02 are located in different parts of the omega-shaped (Ω) mud deposits, owing to different sediment sources and dynamic environments. The study results further confirm that ⁷Be、²¹⁰Pb_ex、²²⁸Th_ex and ¹³⁷Cs are good tracers for illustrating sediment transport and deposition.