wee eB atl se tet. «aun Plutonium-239 Anomaly in the Troposphere by H. L. Volchok, (HASL) P. W. Krey, (HASL) During the period mid-1968 through mid-1969, some unusual be- havior of Pu-239 relative to Sr-90 has been observed in surface air. For many months and at many surface air sampling stations in the North- ern Hemisphere, the ratio Pu-239/Sr-90 exceeded all values in the stratosphere at comparable times. discussed in this paper, Although a number of possibilities are this apparent enrichment of Pu-239 is not readily explainable. Most of the Pu~239 existing in the world came about by the inter-~ action of enormous neutron fluxes in atomic explosions with the U-238 present in such devices of the weapons. (1,2) or from unfissioned Pu-239 from the cores Much smaller amounts may have been released to the environment by a variety of accidents and incidents on the earth's surface such as airplane crashes at Thule, Spain (3) Greenland, and Palomares, or the recently publicized contamination in the neighborhood of Rocky Flats, Colorado (4). Sr-90 on the other hand has been re- leased to the atmosphere mainly in nuclear explosions as a product of the fission reaction. Since the major production modes of these two radionuclides are very different, their. distribution in the stratos- phere and surface air have been studied for some time. - “oe. . 7. ~ - fem - oe sare eart ren pt ge tt per ge ere >