Chemical fractionation of radioactive caesium in airborne particles containing bomb fallout, chernobyl fallout and atmospheric material from the sellafield site

Abstract

Airborne particulate material was collected at Didcot (UK) in June 1959, a period of elevated atmospheric 137Cs concentrations due to atmospheric weapons testing; in May 1986, during the peak of Chernobyl deposition; and in 1987, from a location close to the Sellafield reprocessing plant. The samples were selectively extracted chemically in an attempt to identify the different forms of radiocaesium. Approximately 70% of the Chernobyl material was found to be water-soluble, compared to only 8% of the weapons fallout and 50% of the Sellafield material.The results corroborate evidence from elsewhere that Chernobyl radiocaesium was more mobile than weapons fallout. However, the data are not completely conclusive as chemical changes during storage on filters of the weapons fallout material would have had some effect. The initial mobility of the Chernobyl radiocaesium was rapidly reduced as it became locked in certain lake sediments.