Radiocesium distribution and fluxes in the typical Cryptomeria japonica forest at the late stage after the accident at Fukushima Dai-Ichi Nuclear Power Plant

Yoschenko, Vasyl; Takase, Tsugiko; Konoplev, A.; Nanba, Kenji; Onda, Yuichi; Kivva, Sergiy; Zheleznyak, Mark; Sato, Noriyosi; Keitoku, Koji

doi:10.1016/j.jenvrad.2016.02.017

Cited by 51 publications

(24 citation statements)

References 25 publications

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“…It has recently been estimated that the 137 Cs inventory in the litter layers of this forest decreases over time with an ecological half-life of approximately one year 32 . Taken together, these observations suggest that most of the deposited 137 Cs had already migrated from the litter layer to the underlying mineral soil through litter decomposition by July 2014 when the litter-removal decontamination was conducted [32][33][34][35][36] . This is the most likely cause of the litter-removal decontamination employed here being ineffective in reducing the inventories of 137 Cs in both the litter and topsoil layers of this forest.…”

Section: Discussionmentioning

confidence: 80%

Effectiveness of decontamination by litter removal in Japanese forest ecosystems affected by the Fukushima nuclear accident

Koarashi

Atarashi-Andoh

Nishimura

et al. 2020

Sci Rep

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The Fukushima Daiichi nuclear power plant accident caused serious radiocesium ( 137 Cs) contamination of forest ecosystems over a wide area. The removal of the forest floor litter layer has been considered a potential method for forest decontamination; however, its effectiveness remains largely unknown. We conducted a pilot-scale decontamination study in a deciduous broadleaved forest in Fukushima. The entire forest was decontaminated by removing the litter layer in July 2014, approximately 3.3 years after the accident, with the exception of two untreated plots. For three years after decontamination, we quantified 137 Cs contamination levels in the litter and topsoil layers and in the tree leaves, in the untreated and decontaminated areas. The decreased inventories of litter materials and the litter-associated 137 Cs in the decontaminated areas were observed only in the first year after decontamination. Generally, no decontamination effects were observed on the 137 Cs transfer in tree leaves. The primary reason for this was the rapid shift in the main reservoir of 137 Cs from litter layers to the underlying mineral soil, which differs from the observations in post-Chernobyl studies of European forest ecosystems. The results suggest that litter-removal decontamination can only be successful if it is implemented more quickly (within 1-2 years after the accident) for Japanese forest ecosystems.The accident at the Fukushima Daiichi nuclear power plant (NPP) in March 2011 released large quantities of radionuclides into the atmosphere 1 and consequently caused serious radioactive contamination of terrestrial ecosystems over a wide area of eastern Japan 2 . Among the radionuclides deposited onto the terrestrial ecosystems, radiocesium ( 137 Cs), with a physical half-life of 30.1 years, is the primary cause for concern because 137 Cs-contaminated ecosystems can increase the radiation exposure to the local population for many years, via both an elevated ambient dose rate in the air (external exposure) and the consumption of contaminated food products (internal exposure) 3 .Decontamination is an important post-accident countermeasure to reduce the radiological impact of a nuclear accident on humans and ecosystems 3,4 . Although since the Fukushima NPP accident, decontamination efforts have been progressing in residential and agricultural areas, forested areas have received a low priority in the decontamination decision-making process, as in the case of the Chernobyl NPP accident 3 , and has not been carried out on a large scale 5 , even though forests provide a wide range of social, cultural, and economic values. This is because the forested areas are vast, occupying approximately 70% of the land in the heavily contaminated area 6 , but are generally not where people live permanently or regularly spend much time. Another reason may be that the forested areas in Japan are concentrated in mountainous and hilly regions with steep terrain, which makes them very sensitive areas to soil erosion. Technical, radiological, and econ...

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Section: Discussionmentioning

confidence: 80%

Effectiveness of decontamination by litter removal in Japanese forest ecosystems affected by the Fukushima nuclear accident

Koarashi

Atarashi-Andoh

Nishimura

et al. 2020

Sci Rep

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“…For example, 22-44% of total 137 Cs fallout was noted in a forest canopy of Japanese cedar in Fukushima, and 56-78% was in the forest floor around 6 months after the deposition [34]. By contrast, another forest canopy in a similar situation reduced the occupancy ratio to 6% while the forest floor increased that to 74% years later [42]. These observations are not always consistent with models based on the Chernobyl experience, in that a proportion of the radionuclides within the tree parts of forests would disappear within 5 years at most in Fukushima (e.g., [43]).…”

Section: The Contamination Status Quo In Forests/trees Of the Disastementioning

confidence: 99%

“…After canopy interception, 131 I physically decayed within a few months, and major portions of the longer half-lived rCs fallout transferred from the canopy to the soil over time [38][39][40][41][42].…”

Section: The Contamination Status Quo In Forests/trees Of the Disastementioning

confidence: 99%

“…Sometimes, the phases can be divided into two phases with the combination of "acute reduction phase" and "medium-term phase" or "medium-term phase" and "long-term phase" [51]. Subsequently, rCs fallout in forests is presently in a quasi-stable phase with a kind of elemental circulation including root uptake [42].…”

Section: The Contamination Status Quo In Forests/trees Of the Disastementioning

confidence: 99%

“…This translocation process does not actually reduce the amount of rCs from trees, but rather decreases the concentration, and thus is referred to as a "growth dilution" [52]. Root uptake of rCs is still not obvious in this phase; however, it becomes increasingly more evident over time [42,51,52]. The major factors in the "medium-term phase" are the tree species and their living conditions, such as soil conditions and climatic conditions of the ecosystem.…”

Section: The Contamination Status Quo In Forests/trees Of the Disastementioning

confidence: 99%

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Leaf Ecology and Radiocesium Contamination in Trees/Forests

Yoshihara¹

2017

Plant Ecology - Traditional Approaches to Recent Trends

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Nonessential elements enter/accumulate in trees at certain ratios via the same uptake/ translocation systems as essential elements. This phenomenon may not only damage the ecosystem but also result in human health problems. As one such nonessential element, the fate of radiocesium in trees has been extensively studied after the nuclear accident at Fukushima in 2011. Here, to better our understanding of the fate of radiocesium in nature and contribute to plan countermeasures, a review based on recent data for the Fukushima accident will be explicated with historical experiences of the global fallout, the Chernobyl accident, and many laboratory studies. In particular, the effects of specific leaf ecology (deciduous and evergreen), types of radiocesium exposure (dry/wet depositions or root uptake), and decomposition of litter on the fate of radiocesium will be precisely described with a specific uptake/translocation system of potassium, which can be recognized as the most possible entrance of radiocesium into trees.

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References

2019

Industrial and Medical Nuclear Accidents

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Radiocesium distribution and fluxes in the typical Cryptomeria japonica forest at the late stage after the accident at Fukushima Dai-Ichi Nuclear Power Plant

Cited by 51 publications

References 25 publications

Effectiveness of decontamination by litter removal in Japanese forest ecosystems affected by the Fukushima nuclear accident

Effectiveness of decontamination by litter removal in Japanese forest ecosystems affected by the Fukushima nuclear accident

Leaf Ecology and Radiocesium Contamination in Trees/Forests

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