Ecosystem Monitoring of Radiocesium Redistribution Dynamics in a Forested Catchment in Fukushima After the Nuclear Power Plant Accident in March 2011

Abstract

The accident at the Fukushima Daiichi Nuclear Power Plant in March 2011 emitted 1.2 Â 10 16 Bq of cesium-137 ( 137 Cs) into the surrounding environment. Radioactive substances, including 137 Cs, were deposited onto forested areas in the northeastern region of Japan. 137 Cs is easily adsorbed onto clay minerals in the soil; thus, a major portion of 137 Cs can be transported as eroding soil and particulate organic matter in water discharge. Dissolved 137 Cs can be taken up by microbes, algae, and plants in soil and aquatic systems. Eventually, 137 Cs is introduced into insects, worms, fishes, and birds through the food web. To clarify the mechanisms of dispersion and export of 137 Cs, within and from a forested ecosystem, we conducted intensive monitoring on the 137 Cs movement and storage in a forested headwater catchment in an area approximately 50 km from the Nuclear Power Plant. Two major pathways of 137 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 137 Cs concentrations of stream waters were monitored. Various aquatic and terrestrial organisms were

Movements and Storages of Radiocesium in a Forest Ecosystem in Fukushima

“…Meanwhile, some of the 137 Cs that was deposited on fallen leaves and the like on the forest floor was absorbed through roots before being transferred to new leaves. The 137 Cs concentration exceeded 10,000 Bq kg -1 in most bark samples from jolcham oak during the same period in 2012 11) . The marginal difference in concentration between the sapwood and the heartwood of Japanese cedar as compared to jolcham oak in both 2012 and 2013 (Figure 2) indicates a much faster translocation of radioactive cesium in a tree trunk of Japanese cedar.…”

“…Moreover, standing trees in the main forest were cut down and sampled in November of both 2012 and 2013 to estimate the amount of radioactive cesium buildup above the ground. The samples were divided into live leaves, branches, and trunks (bark, sapwood, and heartwood) to measure the radioactive cesium concentration 10,11) .…”

“…This paper reports the survey results using data obtained by the end of FY2014 to consider necessary surveys and measures for the future. It may be noted that most of the findings have already been published in the references [10][11][12] .…”

Agricultural Implications of the Fukushima Nuclear Accident (III)

“…Our four-year monitoring study since early 2012 at a forested headwater catchment in the northern part of Fukushima have demonstrated that radiocesium movement has been most drastic during the early years after the accident (Ohte et al 2013(Ohte et al , 2016. Observed results have shown that radiocesium has continuously moved from the forest canopies to the forest floor with throughfall, stemflow and litter fall (Endo et al 2015).…”

Developing an OGC Standard-Based Platform for Integration of Radiation Monitoring Data from Fukushima Area, Japan

“…Therefore, citizens who are interested in practical results from this research will meet difficulties in access. Some other successful studies trying to monitor the level of radioactive contamination along with its impact on many of the aspects of life can be considered, for instance, Stein (2017) had monitored the status of beef [5], Ohte et al (2016) was concerned about movement of radiocesium in a forested catchment, Matsuda et. al.…”