if:
~= bb -
vs
meacurements on tne stvor.tium-C9,otcontium-93 ratio, as shown
by vain samples coliected monthly at vaziouw. piaces ail over tue
world, are plotted toyether with the values predicted by the
simple uniform theocy for 40° Latztude and for pure
ctratospheric faliout.
fccording to the model, stratospheric
fal.out i: the principle type sccusring throughout most of the
Southern Hemirphere and in certdin parts of the Morther: Hemisphere
which happen not to have been in the path. of txroposphevic
aeprvis.
The theoretical caicuiation i made by taking the
various contzibutions to the stratospheric ceservoir and
muitiptying by their caiculated strontium-v9 to strontium-92
ratios (new deoris is taken as naving a ratio of 18) ana the
nhaif-iife of stroncium-sc9 is taken as being 54 days with, of
course, strontium-9)'s haif-life being 28 years).
In thi.
manner the expected 3289 j 5299 ratio of faitout from the
Vtcvatosphere is calcuiated.
It hac a fluctuating value due to
injections from weagone tests but it rapidiy settles down at all
times prior to Octover 1958 to something Like 5 to 13 units.
The tropospheric debris on the other nand having a mean
iy
esidence time of only one month has a much higher strontium-39
co strontium-9) satio.
Ir makings the ca.zculation for the tota1
expected faliout at any given position the amount of tropospheric
depcris is caicuiated oy the cules siven previously and the
averaze taken.
Similac caiculation. are done with barium-149
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