Recent 14C Activity in the Atmosphere, 14Clean Air

Abstract

Although the Chernobyl accident caused increased 14C levels in certain areas, it has been difficult to prove that it had any effect in two areas of Sweden and one on Svalbard (Spitsbergen), where the precipitation and wind conditions were such that the y-active fall-out was negligible. Knowledge of the steady regional decrease and annual variations at high latitudes, where the pollution from fossil fuel is less than in central Europe, is essential for global studies of the CO2 cycle. The present 14C excess is a net effect of the 14C supply, mainly from tests of nuclear weapons, and dilution, by 14C-free, fossil-fuel consumption. In Sweden, at these northern latitudes, the 14C excess is steadily slightly higher than for "clean air" in central Europe. Annual variations are also smaller in Sweden and Svalbard than in central Europe. The normal 14C excess on Svalbard is slightly less than in Sweden. Detailed results, especially from autumn 1984 to autumn 1987, are given for atmospheric CO2 collected in northern Sweden (Abisko) and on Svalbard (Kapp Linne) and for some atmospheric samples and plant material collected ca 50km east of Uppsala, very close to heavily polluted areas.