Temporal distribution of Fukushima-derived 137Cs in coniferous forest soil evaluated based on compartment-exponential model
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Based on the compartment and exponential models, the distribution of Fukushima-derived 137Cs was evaluated at four sampling dates in undisturbed coniferous forest soil. The compartment model was employed to evaluate the dynamic of 137Cs in the three sub-sections of the forest floor (FF), namely undergrowth (UG), litter layer (OL), and fragmented litter layer (OF), while the exponential model was administrated to describe its distribution below the FF. According to the compartment model, the derived ecological half-life of 137Cs in the UG, OL, and OF layers was 0.97, 1.1, and 4.9 years, respectively, indicating 137Cs resides much longer in the OF layer. Hence, this soil section remains a potential source of radiation dose mainly due to its high 137Cs content associated with low attenuation effect. Below the OF layer, the 137Cs distribution was well described by exponential model and its derived relaxation lengths were in the range of 0.8–1.4 cm, implying the migration of 137Cs in mineral soil is very slow and almost intact during the observation time. Collectively, our results highlighted that the compartment model for the FF and the exponential model for the soil below the FF are adequate enough to generate essential information. Thus, the potential decontamination measures should have to be chosen on their effect on the FF’s 137Cs.
Keywords137Cs Compartment model Exponential model Forest floor Relaxation length
The authors are very grateful for valuable discussion held with Dr. Coppin Frederic and Dr. Garcia-Sanchez Laurent. The study is supported by the Core Research for Evolutional Science and Technology (CREST) research project “Development of Innovative Technologies for Increasing in Watershed Runoff and Improving River Environment by the Management Practice of Devastated Forest Plantation” during the field data collection.
- Bunzl, K., Schimmack, W., Kreutzer, K., Schierl, R., 1989. Interception and retention of Chernobyl-derived 134Cs, 137Cs, and 106Ru in spruce stand. Sci. Total Environ.78, 77 – 87.Google Scholar
- Bunzl, K., Schimmack, W., Krouglov, S.V., Alexakhin, R.M., 1995b. Change with time in the migration of radiocesium in soil, as observed near Chernobyl and Germany, 1986 – 1994.Sci. Total Environ.175,49 – 56.Google Scholar
- Fujiyoshi, R., Sawamura S., 2004. Mesoscale variability of vertical profiles of environmental radionuclides (40K, 226Ra, 210Pb and 137Cs) in temperate forest soils in Germany. Sci Total Environ.320, 177 – 188.Google Scholar
- Fujiyoshi R, Yamaguchi T, Takekoshi N, Okamoto K, Sumiyoshi T, Kobal I, Vaupotic Y (2011) Tracing depositional consequences of environmental radionuclides (137Cs and 210Pb) in Slovenian forest soils. Cent Eur J Geosci 3:291–301Google Scholar
- Matsunaga T, Koarashi J, Atarashi-Andoh M, Nagao S, Sato T, Nagai H (2013) Comparison of the vertical distribution of Fukushima nuclear accident radiocesium in soil before and after the first rainy season, with physicochemical and mineralogical interpretations. Sci Total Environ 447:301–314CrossRefGoogle Scholar
- Takahashi S, Suchara I, Okamoto K, Sucharova J, Umegaki K, Fujiyoshi R (2017) Retention of 137Cs in forest floor at three temperate coniferous forests stands in the Czech Republic diversely affected by fallout after the Chernobyl disaster in 1986. J Radioanal Nucl Chem 311:929–935CrossRefGoogle Scholar
- Yoschenko V, Takase T, Konoplev A, Nanba K, Onda Y, Kivva S, Zheleznyak M, Sato N, Keitoku K (2017) Radiocesium distribution and fluxes in the typical Cryptomeria japonica forest at the late stage after the accident at Fukushima Dai-Ichi Nuclear Power Plant. J Environ Radioact 166:45–55CrossRefGoogle Scholar