Table 2— TESTS STOP IN DECEMBER 1957
{Units in millicuries per square mile)
(2)
Deposition (12/57)
Stratospheric content (12/57)
Fraction removed per year
(2)
25
14 (28 Mt)
0.1
Stratospheric
nonuniformity factor
25
11.5 (23 Mt)
0.2
1.0
3.0
5.3
19.6
Fallout, maximum from
Sr® now in the stratosphere
25 me/sq. mile
decayed to maximum
Total fallout
Time of maximum
21.6
22.0
27
1963
42
1962
(5.8 yrs.)
(5.2 yrs.)
Table 3—-TESTS CONTINUE AT SAME RATE*
(Units in milicuries per square mile)
A
Tropospheric fallout
to 12/57
B
21
6
21/4
6/4
to 12/57
Stratospheric
4
19
nonuniformity factor
Fraction removed
per year
1.0
3.0
0.1
0.2
Tropospheric
injection rate, mc/sq. mile/year
Stratospheric fallout
Prediction of fallout at equilibrium (about 100 years)
Accumulated tropospheric
Accumulated stratospheric
210
60
144 x1 = 144
160 x 3 = 480
Total accumulated
354
540
*Common assumptions: total fallout = 25 at t = 4 years; stratospheric injection rate = 9 Mt/year or 4.5 mc/sq mile/year.
scribed by Dr. Libby. On the other hand, some local values might be higher owing to smallscale meteorology and soil anomalies and dietary peculiarities.
It appears that, despite wide differences of interpretation of the fallout mechanisms, the
uncertainties of deposited fallout on the ground are smaller—by perhaps an order of magni-
tude—than the conversion of this fallout to Sr** human bone content. The interpretations of
hazard from a given predicted Sr*° bone content allows even larger differences of opinion than
the forecast of how much Sr® will be in man.
7
CONCLUSIONS
The technical conclusions drawn from the discussion are: (1) From evidence of total Sr
fallout and tropospheric fallout, it is found that the stratospheric fallout fraction is markedly
nonuniform and has a peak in the temperate latitudes of the northern hemisphere, (2) A seasonal variation in the rate of fallout is present which is probably due to variations in atmos-
337
ms