@misc{oai:repo.qst.go.jp:00083712,
 author = {Kumar Sahoo, Sarata and Kavasi, Norbert and Arae, Hideki and Sorimachi, Atsuyuki and Omori, Yasutaka and Aono , Tatsuo and Sahoo, Sarata and Kavasi, Norbert and Hideki, Arae and Tatsuo, Aono},
 month = {Sep},
 note = {There was a large distribution of 137Cs and 90Sr in surrounding environment of the damaged Fukushima dai-ichi nuclear power station (FDNPS). A soil column was collected after six years of the Fukushima accident (2017) in the Futaba city with elevated contamination at a hot spot with limited area (less than 1 sq m) to study the vertical migration of 90Sr.  

The 137Cs and 90Sr activity concentration results in 1cm sequences deep down to 5 cm were analyzed. The highest activity concentration for 137Cs and 90Sr was in the 3 cm section (11,718±12 kBq/kg and 758±37 Bq/kg, respectively whereas the lowest activity concentrations noticed in the 5 cm section (5,934±21 kBq/kg and 269±18 Bq/kg, respectively).

The 90Sr/137Cs activity ratio is in the range of 4.53x10e-5 and 6.51x10e-5 which is significantly lower than the value of 2x10e-4 as reported by Hirose (2017). The explanation of the difference could be based on the result of the distribution coefficient (Kd) of Cs and Sr in the Fukushima soil samples. In our Kd studies, we observed Cs bound to the Fukushima soil particles is stronger than the Sr attachment (Kasar et al. 2021). Therefore, Sr has a more intensive migration pattern and it is reflected in the decrement of 90Sr/137Cs activity ratio from 2x10e-4 to 4.53x10e-5 during five years.
The 90Sr migration has a sharp break after 3 cm and in the 5 cm section the 90Sr contamination is around three times lower than in the 3 cm section. Deeper sections below 5 cm are also contaminated slightly but need further investigation to confirm the assumption., Environmental Dynamics of Radionuclides and Biological Effects of Low Dose-Rate Radiation},
 title = {Vertical profile of Sr-90 in a Fukushima soil column},
 year = {2021}
}