Vertical distribution of fission products 226Ra and Pb in the atmosphere

The objective of this work was to examine the vertical distributions in the atmosphere of dust originating from the two kinds of source: fission products introduced into the stratosphere by nuclear explosions, and Ra-226 and lead whose sources are at the earth's surface. The measurements of these substances at heights from 6 to 12 km were carried out in the years 1973 - 1976. A comparison of vertical distributions of these two types of pollutants showed that Ra-226 and lead, are transported from the earth's surface to the upper layers of the atmosphere and are accumulated in the stratospheric region. This transport, and consequently the distributions of concentration, depend upon the tropopause height, the season of the year, and the baric systems. It was also found that in the years 1973 - 1976 the content of these two elements was subject to a steady increase both in the troposphere and stratosphere, in contrast to the content of fission products, whose changes were depending upon the current nuclear explosions. (author)