BACKGROUND LEVELS OF U-238 AND RA-226 IN ATMOSPHERIC AEROSOLS

The U-238 and Ra-226 contents of small-volume aerosols are determined by a chemical analysis technique. Mean activity concentrations of U-238 and (226)R, in aerosols over approximately ten years are 0.29.10(-5) and 0.93.10(-5) Bq/m(3), respectively. The yearly variation of U-238 and (226)R, in aerosols is small. The concentrations of Ra-226 are always larger than those of U-238 in the same sampling time. The correlation of U-238 and Ra-226 cannot be recogonized (r=0.18). The concentrations of summer samples are greater than those of winter samples far U-238. One of the causes of seasonal difference may be due to the fact that the components of aerosols are different according to soil size, soil components, weathering states, etc.