2016 Volume 58 Issue 2 Pages 51-59
To elucidate uptake via the roots and the dynamics of cesium (Cs) in Japanese cedar (Cryptomeria japonica D. Don), we measured the stable cesium (133Cs), rubidium (Rb), and potassium (K) content in the needles and wood of Japanese cedar harvested from four sites: 1) Kawauchi; 2) Kamikawauchi; 3) Otama; and 4) Tadami in Fukushima Prefecture, Japan. The levels of deposition of radiocesium were different among sites. The contents of 133Cs, Rb, and K were higher in current needles and heartwood than in old needles and sapwood, respectively. In addition, 133Cs, Rb, and K content tended to be lower in the small than in the large trees. This result suggests that Cs would be accumulated in heartwood, particularly in mature trees. Proportional relationships were observed between 133Cs in old needles and heartwoods as well as sapwoods. Therefore, 133Cs in wood may be estimated from 133Cs in needles. 133Cs in needles and wood varied among sites, with higher levels observed in Tadami and Kamikawauchi. Exchangeable K in surface soil was slightly lower in Tadami and Kamikawauchi than in Kawauchi and Otama. Soil exchangeable 133Cs was the highest in Tadami. The 133Cs uptake via roots and the dynamics of 133Cs in Japanese cedar may be affected by soil exchangeable K and 133Cs.