Atmospheric Direct Uptake and Long-term Fate of Radiocesium in Trees after the Fukushima Nuclear Accident

Mahara, Yasunori; Ohta, Tomoko; Ogawa, Hideyuki; Kumata, Atsushi

doi:10.1038/srep07121

Cited by 52 publications

(31 citation statements)

References 19 publications

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“…This shows that the Cs concentrations in forest ecosystems reached an equilibrium between stable isotopes and other elements. Conversely, since the Fukushima accident, 137 Cs concentrations in konara oak and cedar trees have not reached an equilibrium, and continue to increase (Mahara et al 2014). This may provide insight into 137 Cs dynamics in konara oak trees, but does not present the overall picture.…”

mentioning

confidence: 99%

The Effects of Radioactive Contamination on the Forestry Industry and Commercial Mushroom-Log Production in Fukushima, Japan

Miura

2016

Agricultural Implications of the Fukushima Nuclear Accident

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The accident at the Fukushima Daiichi nuclear power plant in 2011 left surrounding residential, agricultural, and forested areas contaminated with radiation on a massive scale. To encourage evacuees to return to their homes and resume agricultural practices, large-scale decontamination of radioactive zones is ongoing in residential and agricultural areas. However, contamination of forests is extensive and decontamination efforts have been limited by remote access, significant labor requirements, and the considerable amount of anticipated radioactive waste. Consequently, there has been no large-scale effort to decontaminate forests as there has been for residential and agricultural land. In this paper, we examine the current protection of forests from radioactive contamination and discuss measures required to promote forest restoration. In addition, we consider how forest contamination relates to radiation exposure in humans and summarize the state of the forestry industry since the Fukushima accident. We also consider how radiation affects forest products in Fukushima, emphasizing mushroom-log production. Finally, we examine the challenges surrounding the reconstruction and revival of forests and forestry in Fukushima.

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confidence: 99%

The Effects of Radioactive Contamination on the Forestry Industry and Commercial Mushroom-Log Production in Fukushima, Japan

Miura

2016

Agricultural Implications of the Fukushima Nuclear Accident

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“…Mainly 137 Cs was detected in litters in forest [5] but 137 Cs was detected to depth of 10 cm in soil without litter [15]. Because rainy force is buffered in litters when the surface of soils has litters, rain is hard to directly enter to the deep part of the soil.…”

Section: Resultsmentioning

confidence: 99%

“…On March 15-17 and 21-23, deposition increased in the areas surrounding Fukushima prefecture because north-easterly, easterly, and south-easterly winds under a lowpressure system transported the radionuclides from the Fukushima NPP, and subsequent precipitation associated with the same system washed radioactive materials out of the radioactivity plume, thereby effectively depositing them on land [1][2][3][4][5]. In addition to the radioactive plume that covered the Fukushima Prefecture, two other large plumes suffered severe radioactive contamination over north Japan.…”

Section: Introductionmentioning

confidence: 99%

Speciation of 137Cs and 129I in Soil After the Fukushima NPP Accident

Ohta

Mahara

Fukutani

et al. 2016

Radiological Issues for Fukushima’s Revitalized Future

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We evaluated the migration of radionuclides ( 131 I, 129 I, 134 Cs, 136 Cs, 137 Cs, and 132 Te) in the surface soil after the Fukushima nuclear accident. The radionuclides in the soil collected late March in 2011 were barely leached with ultrapure water, indicating that these are insoluble. We observed the chemical behavior of 137 Cs and 129 I in soil: (1) 137 Cs was predominantly adsorbed within a depth of 2.5 cm from the ground surface; (2) 137 Cs was hardly released from soil by the water leaching experiments that lasted for 270 days; (3) approximately, more than 90 % of 137 Cs was adsorbed on organic matters and the residual fractions, while 129 I was mainly fixed on the Fe-Mn oxide and organically bounded fraction. Therefore, we conclude that 137 Cs and 129 I in soil seldom leach into the soil water and migrate downward because of the irreversible adsorption. The shallow groundwater which residence time is short.

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“…On the other hand, in a Japanese cedar forest, throughfall migration of 137 Cs was negligible after only a single year, even though a considerable amount of 137 Cs remained in the leaves. The low rates of throughfall were attributed to most of the 137 Cs being captured (Koizumi et al, 2013), absorbed, and cycled within the internal tissues of the trees (Tagami et al, 2012;Mahara et al, 2014;Nishikiori et al, 2015). Thus, in this model, the initial deposition onto the forest crown (leaf compartment) should be reduced, and the actual crown interception should consider throughfall migration.…”

Section: Uncovered Processes In Forothcs and Upcoming Challengesmentioning

confidence: 99%

Modeling radionuclide Cs and C dynamics in an artificial forest ecosystem in Japan -FoRothCs ver1.0-

Nishina

Hayashi

2015

Front. Environ. Sci.

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Predicting the environmental fate of Cs radionuclides in forest ecosystems is important for the effective management and assessment of radioactively contaminated forest areas. A large proportion of the radioactively contaminated areas in Japan consist of forest ecosystems, and most of these areas are artificial forests that are used for timber production [e.g., Japanese cedar (Cryptomeria japonica) and red pine (Pinus densiflora)]. Determining the long-term redistribution of 137 Cs in forest ecosystems is important for estimating human doses and understanding the ecological impacts and challenges associated with managing contaminated forests. To facilitate the management and 137 Cs decontamination of these forests, we developed a new open-source 137 Cs cycling model, ForRothCs, that considers C cycling within forests, as well as biomass production and soil decomposition processes. For the 137 Cs inventory, this model estimates the dynamics (Bq m −2 ) and activity (Bq kg −2 ) of 137 Cs on a decadal time scale, primarily in the leaves, branches, stems, litter layer, and the soil. This model is based on the biomass production and the dynamics of the C cycle models. We tested the model by considering a simple scenario of forest management, i.e., thinning and harvesting, for the first five years following a fallout event. The results showed that these activities have a limited impact on the 137 Cs inventory due to the rapid migration of 137 Cs from vegetation to soil. Our projections also showed the examined forest management practices resulted in reduced litterfall, which in turn reduced C input to the forest floor and increased the concentration of 137 Cs in the litterfall and soil organic layer. Although further validation of the ForRothCs model is required using field observation data, the model can be used to evaluate long-term 137 Cs dynamics associated with commonly used forest and decontamination management scenarios.

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Atmospheric Direct Uptake and Long-term Fate of Radiocesium in Trees after the Fukushima Nuclear Accident

Cited by 52 publications

References 19 publications

The Effects of Radioactive Contamination on the Forestry Industry and Commercial Mushroom-Log Production in Fukushima, Japan

The Effects of Radioactive Contamination on the Forestry Industry and Commercial Mushroom-Log Production in Fukushima, Japan

Speciation of 137Cs and 129I in Soil After the Fukushima NPP Accident

Modeling radionuclide Cs and C dynamics in an artificial forest ecosystem in Japan -FoRothCs ver1.0-

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