Tree-Ring Strontium-90 and Cesium-137 as Potential Indicators of Radioactive Pollution
- Akira Kagawa *a,
- Toru Aokib,
- Naoki Okadac and
- Yukio Katayamad
- a Wood Anatomy and Quality Lab., Forestry and Forest Products Res. Inst., Tsukuba Norin P.O. Box 16, Ibaraki 305-8687, Japan
b Radioisotope Res. Center, Kyoto Univ., Sakyo, Kyoto 606-8502, Japan
c Grad. School of Agriculture, Kyoto Univ., Sakyo, Kyoto 606-8502, Japan
d Div. of Human Environment, The Univ. of Human Environments, Okazaki, Aichi 444-3505, Japan
To examine whether tree rings can be used to detect or assess local historical 90Sr or 137Cs fallout, such as that resulting from the Hiroshima atomic bomb, radial distribution of 90Sr and 137Cs in trees was examined. We studied a gymnosperm [Japanese cedar, Cryptomeria japonica (L. f.) D. Don] and an angiosperm (Japanese persimmon, Diospyros kaki Thunb.) tree species from the vicinity of the atomic bomb hypocenter, and from other locations in Japan. A significant amount of 137Cs was detected in tree rings formed before 1945, indicating lateral migration of Cs. In contrast, the specific activity of 90Sr in the Hiroshima Japanese cedar showed the highest level in 1945, due to relatively immobile characteristics of Sr compared with Cs. Strontium-90 and Sr analyses in tree rings helped identify and distinguish between residual 90Sr activity from the Hiroshima atomic bomb and the atmospheric nuclear testing. This indicates the possibility of detecting or assessing previous local 90Sr pollution through with tree-ring analysis.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © 2002.