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We report our findings on the translocation and distribution of radiocesium inside fruit trees after radiocesium (Cs) was released by the accident at the Fukushima Daiichi Nuclear Power Plant.

We examined the differences in the rooting depth of grapes and figs and the translocation of radiocesium from the soil to the plants. Much of the radiocesium fallout from the nuclear accident remained on the surface soil layer; however, in environments such as orchards, radiocesium translocates more easily to aboveground parts of trees with shallower roots than of those with deeper roots. It was observed that if the old branches were the source of radiocesium, translocation occurred to both the new aboveground organs, such as leaves and fruits, and the underground parts, including pioneer roots. It was clarified that translocation from old organs contributed a much higher proportion of accumulated radiocesium to fruits than that from the soil. We reported that immediately after the accident, radiocesium that accumulated on the bark quickly infiltrated inside the trees. However, several months after the accident, it is possible that a decreased proportion translocated from the outer bark to the internal parts of trees, such as the wood. The translocation of radiocesium and potassium (K) into fruits and leaves may show some differences. Explaining the behavior of radiocesium translocation in perennial crops using K as an index is even more difficult than that in annual crops. To predict the radiocesium concentrations in the harvested fruits, the concentrations in the thinned fruits and the harvested fruits were compared. The results showed that there is a strong correlation between the two. However, since some trees were outliers, predictions must be made carefully.

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.

The distribution of radiocesium within trees in the forests of Mimamisoma, Fukushima, Japan, was studied between 2012 and 2013 after the Fukushima Nuclear Power Plant accident. Most of the radiocesium was contained in the foliage and bark of the examined trees of Japanese cedar () and Japanese red pine (), although considerable concentrations were detected in the xylem of . At higher positions in the trunk, there was more radiocesium in heartwood than in sapwood. Radiocesium in the xylem of a tree with its root system removed before the nuclear accident suggests that most of the radiocesium was not transferred through the root system but was likely translocated via the foliage.

The accident at the Fukushima Daiichi Nuclear Power Plant in March 2011 emitted 1.2 × 10 Bq of cesium-137 (Cs) into the surrounding environment. Radioactive substances, including Cs, were deposited onto forested areas in the northeastern region of Japan. Cs is easily adsorbed onto clay minerals in the soil; thus, a major portion of Cs can be transported as eroding soil and particulate organic matter in water discharge. Dissolved Cs can be taken up by microbes, algae, and plants in soil and aquatic systems. Eventually, Cs is introduced into insects, worms, fishes, and birds through the food web. To clarify the mechanisms of dispersion and export of Cs, within and from a forested ecosystem, we conducted intensive monitoring on the Cs movement and storage in a forested headwater catchment in an area approximately 50 km from the Nuclear Power Plant. Two major pathways of Cs transport are as follows: (1) by moving water via dissolved and particulate or colloidal forms and (2) by dispersion through the food web in the forest-stream ecological continuum. The Cs concentrations of stream waters were monitored. Various aquatic and terrestrial organisms were periodically sampled to measure their Cs concentrations. The results indicate that the major form of exported Cs is via suspended matter. Particulate organic matter may be the most important carrier of Cs. High water flows generated by a storm event accelerated the transportation of Cs from forested catchments. Estimation of Cs export from the forested catchments requires precise evaluation of the high water flow during storm events. The results also suggested that because the biggest pool of Cs in the forested ecosystem is the accumulated litter and detritus, Cs dispersion is quicker through the detritus food chain than through the grazing food chain.

Radioactive cesium (Cs) released by nuclear accidents is sorbed and fixed onto soil surfaces, which then radiate strong gamma rays (rays). Decontamination around dwelling areas is now eagerly being implemented but more efforts are necessary to reduce the air radiation dose. Paddy field ponding, from the viewpoint of cost-effectiveness, is considered to be an effective practice for reducing the air radiation dose in the environment. In this study, field experiments were conducted at Sasu and Komiya regions in Iitate Village to verify the effectiveness of paddy field ponding, and numerical experiments were also conducted using the formula for uncollided -ray fluxes passing through the shield material.

It was found that the a ponding water depth of 20–25 cm can drastically reduce the number of -ray photons emitted from the paddy fields, and the reduction in radiation dose was related to water depth. However, some differences were also observed between field and numerical experiments. The numerical calculation showed that the radiation dose decreased exponentially when the depth increased; however, field experiments showed a linear decrease. The cause might be the build-up effect caused by Compton scattering, but the details are unclear. It is necessary to explain these differences before ponding becomes a useful practice.

Iitate village in Fukushima was evacuated after the Fukushima Daiichi Nuclear Power Plant accident due to the high concentration of radioactive contamination. To revive the serious disaster area, residents, universities, research institutions, experts, and volunteers have collaborated through the nonprofitable organization “Resurrection of Fukushima.” The organization is functioning effectively and smoothly based on the members’ background, personal connections, and experiences.

The large-scale release of radioactive substances from the Fukushima Daiichi Nuclear Power Plant operated by the Tokyo Electric Power Company in March 2011 caused significant damage to local fisheries. The Fukushima Prefectural Federation of Fisheries Cooperative Associations immediately suspended all commercial fishing activities within Fukushima. The national government issued instructions prohibiting the sale of certain marine products caught in the waters off Fukushima Prefecture due to food safety concerns. The prohibition is gradually being lifted; in June 2012, the Fisheries Cooperative Associations resumed commercial fishing of three species (two octopus species and one shellfish species) as trial operations. Subsequently, the list has expanded, and as of January 2015, 58 species have been approved for trial operations. The scale of operations is far smaller than before the tsunami and nuclear accident. A full recovery of Fukushima fisheries cannot be realized until the government lifts prohibitions on the sale of all remaining marine species, and the timing of such a decision remains unclear.

Since the Great East-Japan Earthquake and the following nuclear power plant accident, consumer anxiety on food and environmental contamination of radioactive substances have spread widely. This chapter examines the change in consumer attitude towards foods, focusing on beef, produced in disaster affected area based on the 6 times of web-based survey from 2011 October to 2014 March. The results showed that the risk of radioactive substances through beef consumption are not regarded as high as microbial hazards. And trust on radiation risk management implemented by government as well as food business were recovering. However, the ratio of those who stated zero WTP for foods produced in disaster affected area were rather increasing or remain constant since 2012. The results of choice experiment indicated providing information of radiation risk and risk management is effective to recover WTP for beef produced in Fukushima while knowledge level remained relatively low. We believe that continuous and accessible communication with consumers would contribute to the recovery of devastated area.

Various radioisotope imaging techniques have been used at the Graduate School of Agricultural and Life Sciences, University of Tokyo, to analyze samples containing radiocesium (Cs and Cs). There are two types of samples: (1) environmental samples contaminated by the fallout from the Fukushima Daiichi nuclear power plant accident, which contain relatively low concentrations of radiocesium and (2) laboratory samples from tracer experiments conducted at the radioisotope institution containing relatively high concentrations of Cs. The first technique used to visualize radiocesium in soil and plants was radioluminography (RLG). RLG, which makes use of an imaging plate, has a dynamic range that is large enough to detect both environmental and tracer-added samples. To quantify radiocesium distributions, the samples were frozen and sliced before contact with the imaging plate. This freezing procedure after sampling is for preventing radiocesium movement during slicing and measurement of Cs distribution. After slicing, two detection methods were employed: RLG and microautoradiography (MAR). MAR is the conventional and older method for imaging radioisotopes based on the daguerreotype process. We applied this method to frozen sections and obtained Cs distributions at a higher resolution than with RLG. Following this, we employed a non-destructive method for imaging Cs movement in a living plant. We developed the visualization technique called real-time radioisotope imaging system and then demonstrated Cs movement from soil to rice plants using a chamber containing paddy soil, water, and rice plants. Lastly, K obtained by Ar–K generation enabled a comparison between the movement of Cs and K. The mechanism of Cs transport has been reported to have some relationship with the K transport system, so experiments using both Cs and K would be useful for clarifying the mechanism in more detail.