Prospective decrease in atmospheric radiocarbon

作者：Reidar Nydal, Knut Lövseth · 发表于：Journal of Geophysical Research Atmospheres · 年份：1970 · DOI：10.1029/jc075i012p02271 · 被引用次数：37 · 研究领域：Atmospheric and Environmental Gas Dynamics、Radioactive contamination and transfer、Radioactivity and Radon Measurements

Since 1965 the excess of artificial 14C in the troposphere has been decreasing. The 14C that appears in the atmosphere as radioactive CO2 disappears into the ocean and the terrestrial vegetation. Our calculation in based on a residence time for CO2 in the atmosphere of 4–6 years. The exchange between the atmosphere and the mixed layer of the ocean occurs according to a residence time of 5–10 years. In the mixed layer of the ocean 14C is removed much faster than was earlier expected. It is assumed that 14C in this layer has reached its maximum level (10–15% above normal) and will decrease. With an assumed decrease according to a decrease coefficient of 0.1–0.05 year−1 in the mixed layer, the atmospheric 14C level is calculated for further years according to a two-term exponential function. The calculation predicts that a normal 14C level in the atmosphere will be reached in about 30 years. Further nuclear tests will, of course, change the predicted level.