Studies of Environmental Radioactivity in Cumbria: Part 3. Measurements of Radionuclides in Airborne and Deposited Material

摘要

Six stations sampling airborne particulate and deposited material were established in the Cumbrian coastal region. The measurements were undertaken to study current atmospheric levels and to discriminate between material from nuclear weapon tests, routine atmospheric discharges from the nuclear reprocessing works at Windscale and other sources, e.g. the sea. The results show that samples of both airborne and deposited material contain radionuclide concentrations in excess of those expected from nuclear weapon fallout. For Pu and exp 241 Am isotopes, the excess material comes mainly from a seaward direction. The transfer mechanism is probably resuspension, but the actinide levels are much greater than would be expected from the simple transfer of bulk seawater. For exp 137 Cs, the material in excess of amounts expected from nuclear weapon fallout can be attributed largely to Windscale discharges to air and seaspray containing the bulk seawater concentration of exp 137 Cs. Other fission products present in amounts exceeding nuclear weapon fallout were exp 106 Ru, exp 125 Sb, exp 134 Cs and exp 144 Ce. Tritium was also observed in amounts slightly in excess of nuclear weapon fallout. The highest observed annual average concentration in air for Pu isotopes was 0.2% of the derived air concentration, modified for members of the public, of 2.3 mBq/m exp 3 . (Atomindex citation 12:595355)