[3J09-12] Fukushima 2

[3J09] Investigation on distribution of radioactive substances in Fukushima

(9) Temporal changes in the radiocesium in current-year tree roots of Japanese cedar forests

*Junko Takahashi¹, Takuya Sasaki¹, Satoshi Iguchi^1,2, Yuichi Onda¹ (1. Univ. of Tsukuba, 2. JAEA)

Keywords:fine tree roots, aggregated transfer factor, Root uptake, Forest decontamination, FDNPP accident

Findings on radiocesium dynamics in tree roots are still limited. In this study, we measured Cs-137 concentrations in fine tree roots picked up from samples collected using scraper plate in 2012, 2015, 2017, and 2020 in a young cedar forest. As results, Cs-137 concentrations in roots from 0-2 cm were positively correlated with those in litter layers and decreased with time. In contrast, Cs-137 concentrations in roots below 2 cm were positively correlated with those in soil layers and increase with time. Root biomass, which has a significant impact on Cs-137 inventory in roots, decreased exponentially with depth. Therefore, the progressive downward migration of Cs-137 in soil is expected to lead to a decrease in Cs-137 uptake by roots.