Vertical migration studies of 137Cs from nuclear weapons fallout and the Chernobyl accident.
The vertical migration of (137)Cs originating from nuclear weapons fallout (NWF) and the Chernobyl accident has been studied at 33 sampling sites in western Sweden. An attempt to describe the present depth distribution with a solution to the convection-diffusion equation (CDE) with a pulse-like fallout event as the initial condition was made. A sum of two CDEs describing the NWF and Chernobyl debris was fitted to the actual depth profiles measured by soil sampling. The fitted depth profiles were used to correct in situ measurements for the actual depth distribution, showing good agreement with the accumulated activities in soil samples. As expected, the vertical migration was very slow and most caesium was still present in the upper soil layers. The ranges of the apparent convection velocity, v, and apparent diffusion coefficient, D, were between 0 and 0.35 cm/year and 0.06 and 2.63 cm(2)/year, respectively.
Almgren
S
S
Department of Radiation Physics, Göteborg University, Sahlgrenska University Hospital, SE-413 45 Göteborg, Sweden. sara.almgen@radfys.gu.se <sara.almgen@radfys.gu.se>
Isaksson
M
M
D002588:Cesium Radioisotopes / Q000032:analysis*; D047852:Chernobyl Nuclear Accident; D004784:Environmental Monitoring / Q000706:statistics & numerical data*; D008962:Models, Theoretical; D011847:Radioactive Fallout / Q000032:analysis*; D012987:Soil / Q000032:analysis*; D013548:Sweden
D002588:Cesium Radioisotopes; D011847:Radioactive Fallout; D012987:Soil