f
ya
above 50° In efther hemisphere,
In the latitude bands measured, the total!
Stronttum-90 fallout for
megacurfes,
it
1958 would be estimated as 0.76
Because of the heavy Injections during
1958,
Is not possible to use this as a measure of stratospheric
depletion.
If an extended period free of tests continues,
such rates should be readily determined,
polInted out, however, that
It should be
fhe rate found wovld not
necessarily reflect past rates,
The stratospheric deple-
tion rete is not a basic physical constant, but may be a
function of the characteristics of the tests producing the
stratospheric burden,
It
fs possible to roughly estimate the age of
fisston products by the use of
tsotoptic ratios
such as
the
Sr 89/5490 or pa !4075,9° because of the difference in yleids
and half~lives.
The Ba 140/5-90 ratio is only valuable for
fairfy fresh debris and
Is
measured
in precipitation samples.
The Sr 895-90 ratio has been calculated for the pot stations
In Table 3, and the grouped data are plotted In Fig. 7.
The most obvious features are,
I.
None of the differences between bands are
extremely marked,
2.
The average age of the debris
3.
After the U.S. summer
In
the southern
hemisphere,
age of the debris
tortal band,
Is
is greater
tests, the average
lowest In the equa=
were vee eH
’
7
J
a
if
7
7
7
7
a
southerly, and unfortunately stations are not available
Tt yy
2
i
’
3