| Autor: |
Noriyuki Momoshima, E.A. Bondietti |
| Rok vydání: |
1994 |
| Předmět: |
|
| Zdroj: |
Journal of Environmental Radioactivity. 22:93-109 |
| ISSN: |
0265-931X |
| DOI: |
10.1016/0265-931x(94)90016-7 |
| Popis: |
The distributions of 90 Sr and 137 Cs in tree trunks were measured for eight species. The concentration of 137 Cs was relatively uniform in the wood xylem and did not show any correlation with the temporal record of cumulative deposition of fallout in the northern hemisphere, indicating that 137 Cs was mobile in the wood xylem. The distributions of 90 Sr were classified into three groups. All of the gymnosperms—red spruce, eastern hemlock and white pine—showed a maximum 90 Sr specific activity in rings formed in the 1960s and the overall distribution was closely associated with the temporal record of the cumulative deposition of fallout. Three of five angiosperms—hickory, elm and American beech—showed similar distributions to the gymnosperms except that the maximum 90 Sr specific activity corresponded to the 1970s. The other two angiosperms—yellow poplar and sugar maple—did not show any correlation with the cumulative fallout deposition. The radial distribution of 90 Sr in gymnosperms was simulated considering a steady-state cycling of 90 Sr in the forest ecosystem. The model suggested that a few per cent of stable Sr are replaced annually in the nutrient pool of gymnosperms. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
