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Update:December 25, 2017

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Radionuclides are more abundant in forest edges


Article title

Forest edge effect in a radioactivity contaminated forest in Fukushima, Japan

Author (affiliation)

Naohiro Imamura (a), Masahiro Kobayashi (b), Shinji Kaneko (a)

 (a) Center for Forest Restoration and Radioecology, FFPRI, Tsukuba, Ibaraki, Japan.
 (b) Department of Forest Soils, FFPRI, Tsukuba, Ibaraki, Japan.

Publication Journal

Journal of Forest Research, December 2017, DOI: 10.1080/13416979.2017.1396417( External link )

Content introduction

Radionuclides released in large quantities during the Fukushima Nuclear Power Plant accident contaminated forests over a wide geographical area. Therefore, accurate understanding of the abundance of radionuclides, which are highly variable across the polluted region, is required before activities in the forests can resume; this will also help determine countermeasures needed against contamination. In this context, factors to determine the extent of air contamination by radionuclides across the contaminated area must be identified.

We investigated air dose rate distribution in Kawauchi, Fukushima, where radionuclide particles spread in the form of dry deposition*. The investigation site was a cedar forest with an average tree height of 19 m and it was surrounded by farmlands and shrubs. We found that forest edge effect resulted in 1.9–4.5 times higher air dose rate in a 20-m range from the eastern forest edge facing the Fukushima Nuclear Power Plant (Figure). This study revealed that the influence of the forest edge effect is a factor in radionuclide distribution in forests arising from the Fukushima Nuclear Power Plant accident.

We found that selective decontamination of forest edges facing the Fukushima Nuclear Power Plant would reduce radiation exposure of forestry workers in forests where radionuclides spread through dry deposition. The results of this study are also expected to help forest managers avoid using contaminated forests for production and recreation, particularly near highly contaminated forest edges.

*: dry deposition: a form of deposition in a gas and/or particulate state instead of deposition by precipitation.


Figure: air dose rate distribution in the investigation site

Figure. air dose rate distribution in the investigation site.

Open circles indicate measurement points of air dose rate, whereas the arrow indicates the advection flow direction of the plume.