Plutonium isotopes in surface air of Prague in 1986-2006

摘要

Monitoring of ~(239,240)Pu in surface air of Prague started in 1986 in connection with the Chernobyl accident. Measurable activities of 10-28 μBq m~(-3) were found from 29 April 1986 to 5 May 1986. In the most of the monitoring periods of 1987-1996, activities of ~(239,240)Pu in air were not measurable. Positive values for ~(239,240)Pu and ~(238)Pu in air could be obtained after installation of an aerosol sampler with higher flow-rate in 1997. Activity concentrations of ~(239,240)Pu and ~(238)Pu in Prague air in the most of quarters of 1997-2006 were in the range 0.53-5.06 and <0.16-1.10 nBq m~(-3), respectively. Seasonal fluctuations can be found in content of ~(239,240)Pu in air. Activity ratios of ~(238)Pu/~(239,240)Pu in air are higher than those in top soil, so it can be supposed that ~(238)Pu is coming to air of Prague also from other sources than resuspension of fallout from atmospheric nuclear tests.