New predictions of 137Cs dynamics in forests after the Fukushima nuclear accident

Abstract

Most of the area contaminated by the Fukushima Daiichi Nuclear Power Plant accident is covered by forest. In this paper, we updated model predictions of temporal changes in the 137Cs dynamics using the latest observation data and newly provided maps of the predicted 137Cs activity concentration for wood, which is the most commercially important part of the tree body. Overall, the previous prediction and latest observation data were in very good agreement. However, further validation revealed that the migration from the soil surface organic layer to the mineral soil was overestimated for evergreen needleleaf forests. The new prediction of the 137Cs inventory showed that although the 137Cs distribution within forests differed among forest types in the first 5 years, the difference diminished in the later phase. Besides, the prediction of the wood 137Cs activity concentrations reproduced the different trends of the 137Cs activity concentrations for cedar, oak, and pine trees. Our simulation suggests that the changes of the wood 137Cs activity concentration over time will slow down after 5–10 years. Although the model uncertainty should be considered and monitoring and model updating must continue, the study provides helpful information on the 137Cs dynamics within forest ecosystems and the changes in wood contamination.

Radiocesium concentrations in mushrooms collected in Kawauchi Village five to eight years after the Fukushima Daiichi Nuclear Power Plant accident

“…[ 30 ]. In addition, previous studies have made significant contributions to addressing the reasons for the lack of activity reductions over time [ 28 , 31 ]. Hashimoto S, et al [ 31 ] investigated whether the 137 Cs concentration of wild mushrooms would be spatially biased or influenced by the 137 Cs or exchangeable potassium concentrations in soils because the concentration fluctuates among the same species growing within a given area.…”

“…[30]. In addition, previous studies have made significant contributions to addressing the reasons for the lack of activity reductions over time [28,31].…”

“…Hashimoto S, et al [31] investigated whether the 137 Cs concentration of wild mushrooms would be spatially biased or influenced by the 137 Cs or exchangeable potassium concentrations in soils because the concentration fluctuates among the same species growing within a given area.…”

Impact of the 2019 typhoons on sediment source contributions and radiocesium concentrations in rivers draining the Fukushima radioactive plume, Japan

“…The role of forests as a potential perennial supply of sediment and associated 137 Cs to river systems in this region in general, and in the more densely inhabited coastal areas in particular, remains one of the main challenges for investigation in the future. After complex processes of transfer and migration of 137 Cs from the canopy, the tree trunk, and the litter to mineral horizons of soils beneath woodlands [Hashimoto et al, 2020], forests may continue supplying contaminated material to rivers and ultimately to the Pacific Ocean, where 137 Cs may desorb [Takata et al, 2020] and it may incorporate marine biota or seafloor sediment [Buesseler, 2020]. Accordingly, the reduction in potential downstream transfers of 137 Cs from forested regions through remediation and/or ongoing 137 Cs management will likely be an important priority for local inhabitants [Koarashi et al, 2020].…”

Spectroscopic Studies of in Vitro Exposure to Low-Dose Gamma Rays from 137Cs Radioactivity on Some Human Blood Components (Plasma and Red Blood Cells)

“…Consequently, the radioactive cesium-137 with a half-life of 30 years caused contamination that was a serious concern because of the deleterious effect of radioactive cesium-137 on the environment or on humans [2][3][4]. Radioactive cesium-137 has been found in contaminated soil [5], forest [6], seawater [7][8][9], and freshwater [10], In addition, there are several reports that showed that radioactive cesium-137 has contaminated seawater sheries. Wada et al2013 determined that radioactive cesium contamination had occurred in marine products that took place during April 2011 to October 2012.…”