Input and output budgets of radiocesium concerning the forest floor in the mountain forest of Fukushima released from the TEPCO's Fukushima Dai-ichi nuclear power plant accident

Abstract

Estimations of radiocesium input and output concerning the forest floor within a mountain forest region have been conducted in the north and central part of the Abukuma Mountains of Fukushima, northeast Japan, after a 2-3 year period following the TEPCO Fukushima Dai-ichi nuclear power plant accident. The radiocesium input and output associated with surface washoff, throughfall, stemflow, and litterfall processes at experimental plots installed on the forest floor of evergreen Japanese cedars and deciduous Konara oaks have been monitored. Despite the high output potential in the mountainous forest of Fukushima, the results at both monitoring locations show the radiocesium input to be 4-50 times higher than the output during the summer monsoon in Fukushima. These results indicate that the radiocesium tends to be preserved in the forest ecosystem due to extremely low output ratios (0.05%-0.19%). Thus, the associated fluxes throughout the circulation process are key issues for the projecting the environmental fate of the radiocesium levels, along with the subsequent reconstruction of life emphasized within the setting.

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

“…These results suggest that the proportion of mushroom samples with radiocesium concentrations above 100 Bq/kg did not dramatically change in Fukushima over 8 years. Radiocesium concentrations in mushrooms can be affected by many factors of forest, such as species, mycelium habitat and depth, minerals in the soil and contamination level of soil [ 6 , 26 – 28 ]. Long-term comprehensive follow-up should be conducted because the existing data is insufficient to characterize risk.…”

“…[ 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].…”

Impact of clearcutting on radiocesium export from a Japanese forested catchment following the Fukushima nuclear accident

“…This strong association leads to 137 Cs mobilization via soil erosion. 137 Cs transport on the forested hillslopes, however, was less than 1.1% of the initial inventory for 5 months to 1 year [19–21], and annual 137 Cs export via streams was less than 0.3% of the total inventory in the forested catchments [22,23]. These results suggest that 137 Cs removal from forest ecosystems is limited in Japan.…”

Horizontal and vertical distributions of 137Cs in seabed sediments around the river mouth near Fukushima Daiichi Nuclear Power Plant

“…Understanding the features of 137 Cs transport from contaminated mountain forests to coastal sinks is key to the revitalization of marine industries. Therefore, evaluations of forest ecosystems and fluvial and lacustrine environments have been conducted (e.g., Funaki et al 2014;Yamaguchi et al 2014;Kitamura et al 2014;Kurikami et al 2014;Yamada et al 2015;Dohi et al 2015;Niizato et al 2016). 137 Cs distribution in shallow seas, which are major settlement areas for particle-sorbed 137 Cs, is a very important factor when studying 137 Cs transport from contaminated mountain forests to coastal sinks.…”