Plutonium Isotopes in Ground-Level Air in Northern Germany Since 1990

The activity concentrations, ratios and seasonal fluctuations of plutonium isotopes in ground-level air in Northern Germany are reported for the years 1990 to 1997. The ^239+240Pu activity concentrations (a) measured on quarterly samples lie in a range 0.4 nBq/m³<a<4 nBq/m³. The ²³⁸Pu activity concentrations are lesser by up to a factor of 0.1 (0.1 nBq/m³<a<0.8 nBq/m³). The total activity concentration shows a typical seasonal fluctuation in the time period under review. In a few quarterly samples the activity ratio of a(²³⁸Pu)/a(^239+240Pu) is significantly increased.