The transfer of radiocesium from the bark to the stemflow of chestnut trees (Castanea crenata) contaminated by radionuclides from the Fukushima Dai-ichi nuclear power plant accident

Abstract

We report on the behavior of radiocesium in tree bark and its transfer into the stemflows of chestnut trees in a forest in the Fukushima Prefecture, Japan. In stems that were present at the time of the accident, the radiocesium concentration of the bark was found to be approximately 10 times that of the wood. The average (137)Cs concentration of the dissolved fraction (<0.45 μm) in the stemflow was measured to be around 10 Bq/L. The (137)Cs concentration ratio [present at the time of the accident (Bq/kg) in the bark/the dissolved fraction in the stemflow (Bq/L)] was approximately 10(3). A strong positive correlation was observed between the radiocesium concentration and the electrical conductivity of the dissolved fraction of the stemflow; this result suggests that radiocesium and electrolytes have the same elution mechanism from the tree. The size fractionation analysis of the <0.45 μm fraction through ultrafiltration revealed that the radiocesium was present as an almost dissolved species. Some of the particles in the particulate fraction (>0.45 μm) of the stemflow were strongly adsorbed radiocesium.

Accumulation mechanisms of radiocaesium within lichen thallus tissues determined by means of in situ microscale localisation observation

“…Similar broad distributions of radiocaesium were also found in the leaves of bamboo plants and samples from chestnut trees collected in Fukushima prefecture within three years after the Fukushima nuclear accident, although some spotty distributions were also observed [37,38]. Soudek et al [39] studied 137 Cs distributions in sunflower with hydroponic culture experiments using 137 CsCl solution.…”

Translocation of Radiocesium Released by the Fukushima Daiichi Nuclear Power Plant Accident in Japanese Chestnut and Chestnut Weevil Larvae

“…The average 137 Cs concentration of the dissolved fraction (< 0.45 μm) in the stemflow was measured to be around 10 Bq·L −1 (Sasaki et al, 2016). This result indicated that radiocesium deposited to the bark was eluted as dissolved radiocesium.…”

“…Fallen leaves were collected immediately after defoliation in November 2013. Chestnut tree samples were obtained from branches of the canopy at a height of approximately 7 m in February 2014 (Sasaki et al, 2016).…”

Radiocaesium accumulation capacity of epiphytic lichens and adjacent barks collected at the perimeter boundary site of the Fukushima Dai-ichi Nuclear Power Station

“…137 Cs was previously suggested to be absorbed and retained on bark surfaces due to the dead tissues in the outer bark [ 29 ]. In case of the FDNPP accident studies, radiocaesium was also distributed on the outer surface of barks [ Castanea crenata (chestnut tree) and Cryptomeria japonica (Japanese cedar)], sampled within the Fukushima Prefecture [ 47 , 48 ]. In addition, most of the radiocaesium in barks was found in the outer bark of cherry trees (30 years old) [ 48 ].…”