Abstract

Background: For the purpose of baseline data collection and enhancement of environmental monitoring the distribution studies of $^{137}Cs$ and $^{90}Sr$ in the soil of Uljin province was performed and the relation between surface soil activities and soil properties (pH, TOC and median of the surface soil) was analyzed. Materials and Methods: For 14 spots within 10 km from the NPP surface soil samples were collected and soils for depth profile were sampled for 3 spots in April 2011. Using ${\gamma}$-ray spectrometry with HPGe detector, the concentrations of $^{137}Cs$ were determined and the concentrations of $^{90}Sr$ were measured by counting ${\beta}$-activity of $^{90}Y$ (in equilibrium with $^{90}Sr$) in a gas flow proportional counter. Results and Discussion: The concentration ranges of $^{137}Cs$ and $^{90}Sr$ were $<0.479-39.6Bq{\cdot}(kg-dry)^{-1}$ (avg. $7.51Bq{\cdot}(kg-dry)^{-1}$) and $0.209-1.85Bq{\cdot}(kg-dry)^{-1}$ (avg. $0.74Bq{\cdot}(kg-dry)^{-1}$) which were similar to the reported values from other regions in Korea. The activity ratio of $^{137}Cs$ to $^{90}Sr$ in surface soils was around 9.67, which is much bigger than the initial value of 1.75 for worldwide fallouts because of faster downward movement of $^{90}Sr$ after fallout than that of $^{137}Cs$. For depth profile studies soils were collected down to 40 cm depth for the locations of Deokgu, Hujeong and Maehwa. The $^{137}Cs$ concentration distribution of the first two showed maximum values at top soils and decreased rapidly in exponential manner, while $^{90}Sr$ showed two local maximum values for soils near top and about 30 cm depth. Through linear fittings between the $^{137}Cs$ and $^{90}Sr$ concentrations of surface soil and pH, TOC and median of the surface soil, the only probable relationship obtained was between $^{137}Cs$ and TOC (determination coefficient $R^2=0.6$). Conclusion: The concentration ranges of $^{137}Cs$ and $^{90}Sr$ in Uljin were similar to the reported values from other regions in Korea. The only probable relationship obtained between activities and soil properties was between $^{137}Cs$ and TOC.

Keywords

• Environmental radioactivity;
• $^{137}Cs$;
• $^{90}Sr$;
• Soil;
• Uljin

• 환경방사능;
• 토양;
• 울진;

File

Download PDF

Acknowledgement

Supported by : 한국연구재단

References

1. Korea Institute of Nuclear Safety. The annual report on the environmental radiological surveillance and assessment around the nuclear facilities. KINS/AR-140. Daejeon, Republic of Korea. 2010;46-51.
2. KNS Committee on the Fukushima Accident. Final report on Fukushima NPP accident analysis. Korean Nuclear Society. 2013;60-69.
3. Cooper JR, Randle K, Sokhi RS. Radioactive releases in the environment. 1st Ed. John Wiley & Sons. 2003;1-24.
4. Cha HJ, et al. Vertical distribution of $^{137}Cs$ and $^{90}Sr$ activities in the soils of Korea. Journal of Radiation Protection and Research. 2004;29(3):197-204.
5. Willard HH, Goodspeed EW. Separation of strontium, barium, and lead from calcium and other metals - by precipitation as nitrates. Ind. Eng. Chem. 1936;8(6):414-418.
6. Korea Institute of Nuclear Safety. Environmental radioactivity survey in Korea. KINS/ER-028. Daejeon, Republic of Korea. 2011;85-86.
7. Kirchner TB, Whicker FW, Otis MD. PATHWAY: A simulation model of radionuclide-transport through agricultural food chains. Third International Conference on State-of-the Art in Ecological Modeling, Colorado State Univ. Ft. Collins, CO. 1982 May 24-28;10.
8. Thornthwaite CW, Mather JR, Nakamura JK. Movement of radiostrontium in soils. Science. 1960;131(3406):1015-1019. https://doi.org/10.1126/science.131.3406.1015
9. Russell RS. Deposition of $^{90}Sr$ and its content in vegetation and in human diet in the United Kingdom. Nature. 1958;182:834-839. https://doi.org/10.1038/182834a0
10. He Q, Walling DE. Interpreting particle size effects in the adsorption of $^{137}Cs$ and unsupported $^{210}Pb$ by mineral soils and sediments. J. Environ. Radioact. 1996;30(2):117-137. https://doi.org/10.1016/0265-931X(96)89275-7