Variation in the atmospheric concentrations of radioactive lead isotopes with varying meteorological conditions at Kawasaki

Every four hours variations of 212Pb and 214Pb concentrations were observed at Kawasaki, Japan. The variation patterns within 24 hours of the atmospheric concentration of short-lived 241Pb is similar to that of 212Pb concentration. Temporal reductions of atmospheric 212Pb concentration by rainfalls also appeared. The atmospheric 212Pb and 214Pb concentrations decreased increasing wind velocity, implying that the possible turbulence in the lower layer of the atmosphere dilutes the surface air of high concentration with the air at higher layer of lower concentration. The variation in atmospheric concentrations of the short-lived 212Pb and 214Pb, which is formed within the surface air, depends strongly on the local meteorological conditions in a short period. (author)