Six-year monitoring study of radiocesium transfer in forest environments following the Fukushima nuclear power plant accident

Kato, Hiroaki; Onda, Yuichi; Saidin, Zul Hilmi; Sakashita, Wataru; Hisadome, Keigo; Loffredo, Nicolas

doi:10.1016/j.jenvrad.2018.09.015

Cited by 48 publications

(32 citation statements)

References 65 publications

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“…According to the studies conducted in Europe after the Chernobyl nuclear accident and as confirmed by studies conducted in Japan after the FDNPP accident, the 137 Cs deposited on forests is expected to circulate within the forest ecosystems. At the time of the fallout, needles/leaves, branches, and stems trapped 137 Cs, and a part of the fallout was deposited directly on the soil surface 2,3 . However, these distributions drastically change with time, particularly within a couple of years 3 .…”

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confidence: 99%

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New predictions of 137Cs dynamics in forests after the Fukushima nuclear accident

Hirano

Imamura

Kaneko

et al. 2020

Sci Rep

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Most of the area contaminated by the Fukushima Daiichi Nuclear Power Plant accident is covered by forest. In this paper, we updated model predictions of temporal changes in the 137Cs dynamics using the latest observation data and newly provided maps of the predicted 137Cs activity concentration for wood, which is the most commercially important part of the tree body. Overall, the previous prediction and latest observation data were in very good agreement. However, further validation revealed that the migration from the soil surface organic layer to the mineral soil was overestimated for evergreen needleleaf forests. The new prediction of the 137Cs inventory showed that although the 137Cs distribution within forests differed among forest types in the first 5 years, the difference diminished in the later phase. Besides, the prediction of the wood 137Cs activity concentrations reproduced the different trends of the 137Cs activity concentrations for cedar, oak, and pine trees. Our simulation suggests that the changes of the wood 137Cs activity concentration over time will slow down after 5–10 years. Although the model uncertainty should be considered and monitoring and model updating must continue, the study provides helpful information on the 137Cs dynamics within forest ecosystems and the changes in wood contamination.

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confidence: 99%

“…Specifically, the trapped 137 Cs moves from the tree to the soil surface via rainfall and by the shedding of dead needles/leaves. Eight years have passed since the FDNPP accident, and many studies have demonstrated the dynamic migration and recycling of 137 Cs within forests in Japan [2][3][4][5] .…”

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confidence: 99%

New predictions of 137Cs dynamics in forests after the Fukushima nuclear accident

Hirano

Imamura

Kaneko

et al. 2020

Sci Rep

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“…Radiocesium deposited on canopies has migrated downwards over time by throughfall, stemflow and litter fall [47]. Soon after the deposition, throughfall played an important role in radiocesium removal from the contaminated canopy and resulting migration to forest floor, whereas a few years after the deposition, litter fall became the most important pathway [48]. Now, much of the deposited radiocesium is found near ground level, including in the litter layer and top soil.…”

Section: Deposited Radionuclidesmentioning

confidence: 99%

“…Accordingly, in cedar forest, the air dose reduction was a little slower than physical decay within a few years after the accident, whereas in mixed deciduous forest, it has been a little faster than physical decay [41]. Some of the deposited radiocesium is considered to have recycled within a tree body; trend of radiocesium concentration in leaves and bark was reported to differ according to tree species [48]. In forested environments, radiocesium moves within the forest system and rarely escapes out of the system [49].…”

Section: Deposited Radionuclidesmentioning

confidence: 99%

Temporal Change in Radiological Environments on Land after the Fukushima Daiichi Nuclear Power Plant Accident

et al. 2019

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Massive environmental monitoring has been conducted continuously since the Fukushima Daiichi Nuclear Power accident in March of 2011 by different monitoring methods that have different features together with migration studies of radiocesium in diverse environments. These results have clarified the characteristics of radiological environments and their temporal change around the Fukushima site. At three months after the accident, multiple radionuclides including radiostrontium and plutonium were detected in many locations; and it was confirmed that radiocesium was most important from the viewpoint of long-term exposure. Radiation levels around the Fukushima site have decreased greatly over time. The decreasing trend was found to change variously according to local conditions. The air dose rates in environments related to human living have decreased faster than expected from radioactive decay by a factor of 2-3 on average; those in pure forest have decreased more closely to physical decay. The main causes of air dose rate reduction were judged to be radioactive decay, movement of radiocesium in vertical and horizontal directions, and decontamination. Land-use categories and human activities have significantly affected the reduction tendency. Difference in the air dose rate reduction trends can be explained qualitatively according to the knowledge obtained in radiocesium migration studies; whereas, the quantitative explanation for individual sites is an important future challenge. The ecological half-lives of air dose rates have been evaluated by several researchers, and a short-term half-life within 1 year was commonly observed in the studies. An empirical model for predicting air dose rate distribution was developed based on statistical analysis of an extensive car-borne survey dataset, which enabled the prediction with confidence intervals. Different types of contamination maps were integrated to better quantify the spatial data. The obtained data were used for extended studies such as for identifying the main reactor that caused the contamination of arbitrary regions and developing standard procedures for environmental measurement and sampling. Annual external exposure doses for residents who intended to return to their homes were estimated as within a few millisieverts. Different forms of environmental data and knowledge have been provided for wide spectrum of people. Diverse aspects of lessons learned from the Fukushima accident, including practical ones, must be passed on to future generations.

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“…In the marine environment, 238 U, 210 Pb, 210 Po, and 40 K are the most abundant natural radionuclides and are ultimately derived from the weathering of rocks or fallout from the atmosphere in the form of rain and are transported by river discharge (Cochran 1982 ; Chen et al 2016 ; Filizok and Uğur Görgün 2019 ; Mohan et al 2019 ; Peng et al 2019 ). Three main sources of isotopes of artificial radionuclides exist, namely, nuclear weapons testing, the nuclear accidents at Chernobyl as well as Fukushima, and waterborne discharges from nuclear reprocessing plants (Beresford et al 2020 ; Hirose et al 1999 ; Kaizer et al 2017 ; Kato et al 2018 ; Kawamura et al 2017 ; McKenzie and Dulai 2017 ; Nishikiori and Suzuki 2017 ; Ogata 2013 ; Ramzaev et al 2008 ; Savino et al 2017 ; Vlasova et al 2015 ). Other sources contribute less contamination, e.g., ocean dumping of nuclear waste, routine discharges from nuclear power plants, sunken nuclear submarines, lost satellites as well as nuclear weapons, and the use of radioisotopes in medicine, industry, and science (IAEA 2005 ).…”

Section: Introductionmentioning

confidence: 99%

Gross alpha and gross beta activities in selected marine species in Vietnam

Duong

Luong

Châu

et al. 2020

Environ Sci Pollut Res

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The measured gross alpha and gross beta activities in the edible muscle tissues of eleven selected marine species along the coast of North Vietnam varied from 10.2 ± 1.5 to 73.2 ± 8.1 Bq/kg (wwt) and from 10.6 ± 0.4 to 68.8 ± 2.8 Bq/kg (wwt), respectively. The lowest gross alpha activity was recorded for bigfin reef squid (Sepioteuthis lessoniana) as a result of its carnivorous diet, and the highest alpha activity was noted for blood cockle (Anadara granosa) as a result of its omnivorous diet. However, the gross beta activities in both carnivorous and omnivorous species were similar. The highest and lowest gross beta activities were observed for narrow-barred Spanish mackerel (Scomberomorus commerson) and for bigfin reef squid and squid (Teuthida), respectively. All three aforementioned species have carnivorous diets. The calculated annual committed effective dose resulting from the consumption of 25 kg of muscle tissue per year varied from 192 to 1375 μS with an average of 689 μS.

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Six-year monitoring study of radiocesium transfer in forest environments following the Fukushima nuclear power plant accident

Cited by 48 publications

References 65 publications

New predictions of 137Cs dynamics in forests after the Fukushima nuclear accident

New predictions of 137Cs dynamics in forests after the Fukushima nuclear accident

Temporal Change in Radiological Environments on Land after the Fukushima Daiichi Nuclear Power Plant Accident

Gross alpha and gross beta activities in selected marine species in Vietnam

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