210
PERKINS, THOMAS, AND NIELSEN
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1964
1963
1962
Fig. 7—Comparisons of the air concentration of ®Y and !4Sb with
W7Cs. Yttrium-88 and '4Sb are corrected to the time of their probable
injection, Nov. li and Dec. 31, 1962, respectively.
which was followed by an activated charcoal trap for collection of
gaseous radioiodine. These flights were limited to 12,000 feet altitude
because of the type of airplane used, but they served to show that
Significant variations in radionuclide concentrations did exist at these
low altitudes. Figure 8 gives typical profiles of the concentrations of
five radionuclides as a function of altitude showing comparatively high
concentrations at 12,000 ft.
The availability of stratospheric air filters, which were furnished
by Isotopes, Inc,, Westwood, N. J., has made it possible to compare the
air concentrations observed near ground level at our geographical
position with those present in the stratosphere above. In Fig. 9 the
_ ratios of the radionuclide concentrations for stratospheric air to those
of ground-level air are compared for 12 radionuclides. These measurements were made on samples collected during January 1964, It is
interesting that these ratios range from about 1500 to 3000 for all the
radionuclides except *y, '4sb, and '!“Cs. The high stratospheric con-