An investigation of changes in radionuclide carrier properties

Aerosol samples were taken in Lithuania and in a highly contaminated region in Russia following a forest burning experiment as well as in the middle troposphere (at altitudes of up to 6 km). Physical and chemical properties and sizes of 134,137Cs, 90Sr, 7Be, 32P, 33P, 35S, stable S and P carriers and their changes in the atmosphere were investigated. Active median aerodynamic diameter (AMAD) of the soluble aerosols of 7Be varied in the range 0.03–0.46 μm; 32,33P in the range 0.13–0.30 μm; 35S in the range 0.11–1.94 μm; and 134,137Cs in the range 0.10–0.86 μm. In most cases in the ground level, air insoluble aerosols carrying the cosmogenic radionuclides were larger (1–5 μm) than soluble ones. No coarse insoluble carriers of cosmogenic radionuclides were observed in the samples taken in the middle troposphere. The size of caesium radioisotopes stuck to insoluble particles in all the samples was similar (˜1 μm). By investigating the forest fire products of highly polluted regions following the Chernobyl NPP accident, it has been determined that in these cases, radionuclide carrier transformation processes take place. The forms and sizes of 134,137Cs and 90Sr vary over a wide range (depending on the burning temperature and other conditions). During forest fires not only does atmospheric radioactivity increase, but a great amount (up to 40%) of submicronic (AMAD 0.02–0.39 μm), water soluble 137Cs is formed.