Radiocesium in timber of Japanese cedar and Japanese red pine, in the forests of Minamisoma, Fukushima

Abstract

The distribution of radiocesium within trees in the forests of Mimamisoma, Fukushima, Japan, was studied between 2012 and 2013 after the Fukushima Nuclear Power Plant accident. Most of the radiocesium was contained in the foliage and bark of the examined trees of Japanese cedar (Cryptomeria japonica) and Japanese red pine (Pinus densiflora), although considerable concentrations were detected in the xylem of C. japonica. At higher positions in the trunk, there was more radiocesium in heartwood than in sapwood. Radiocesium in the xylem of a tree with its root system removed before the nuclear accident suggests that most of the radiocesium was not transferred through the root system but was likely translocated via the foliage.