Background levels of 238U and 226Ra in atmospheric aerosols

The 238U and 226Ra contents of small-volume are determined by a chemical analysis technique. Mean activity concentrations of 238U and 226Ra in aerosols over approximately ten years are 0.29 x 10-5 and 0.93*10-5 Bq/m3, respectively. The yearly variation of 238U and 226Ra in aerosols is small. The concentrations of 226Ra are always larger than those of 238U in the same sampling time. The correlation of 238U and 226Ra cannot be recognized (r=0.18). The concentrations of summer samples are greater than those of winter samples for 238U. 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. (author) 11 refs.; 6 figs.; 2 tabs