Bomb-Produced 14 C in Tree Rings
The 14 C content in 1961–1967 and 1970–1983 tree rings of a spruce grown in Dailing, China (47°N, 129°E) was measured by liquid scintillation. As a result of USSR bomb tests at Novaya Zemlya (72°N, 53°E), Δ 14 C values rose dramatically from 250‰ in 1961 to a maximum 909‰ in 1964, and then gradually...
| Published in: | Radiocarbon |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Cambridge University Press (CUP)
1992
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1017/s0033822200064043 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033822200064043 |
| Summary: | The 14 C content in 1961–1967 and 1970–1983 tree rings of a spruce grown in Dailing, China (47°N, 129°E) was measured by liquid scintillation. As a result of USSR bomb tests at Novaya Zemlya (72°N, 53°E), Δ 14 C values rose dramatically from 250‰ in 1961 to a maximum 909‰ in 1964, and then gradually decreased to 238‰ in 1983. We compared Δ 14 C values in the rings of an oak tree grown at 43°N, 74°W and that of a pine grown at 49°N, 9°E, and atmospheric Δ 14 C values in both northern and southern hemispheres. We observe that: 1) annual tree rings grown in the same latitude zone have the same Δ 14 C values, reflecting rapid longitudinal mixing of the atmosphere; 2) atmospheric 14 C concentrations reached a global equilibrium distribution at the end of 1968, and tree ring 14 C content reflects atmospheric 14 C concentration; 3) 1976–1982 rings of the Dailing spruce show excessive 14 C, likely due to the effect of 1976 and 1980 Chinese bomb tests; 4) Δ 14 C decreases exponentially, halving every 17 yr. |
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