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months a third method has been adopted, utilizing pots which
have been located at 21 stations throughout the world but too
few data are available to justify presentation at this time.
It will be noted thet the estimates of fallout obtained by
analyzing soil samples are lower than those obtained by gummed
film collection. ‘The differences cen be seen in Table4fwhich
sumerizes the observetion of both the soil sampling and the
gummed film network by zones.
The estimated world-wide faul-
out of Bens Bese on the gummed film samples ie 22)megacuries
compared to #6 megacuries as estimeted by soil samples.
It is
also noted that the soil data indicate a greater degree of
latitudinal variation thm the gummed film data.
In the latter
case the mean deposition in the North Temperate Zone is relatively
high with respect to the somewhat wniform deposition elsewhere
in the world.
Tne data derived from soil samples likewise
indicate a higher deposition in the North Temperate Zone but
there is less uniformity elsewhere in the world and a North-South
gradient is quite evident.
The reason why the soil samples yield lower values is not
Clear.
The integrated fallout es estimated by soil analyses is
only 55% of the value obtained from the gummed film observation.
As noted earlier it is possible that the Sr-90 is incompletely
renoved from the soil by chenicel analysis and this may accowmt
for some, but certainly not all, of the difference.
The gummed
film tends to yield results which are comparable to the Sr-90
meesurerents of pot samples tut it is possible that both the
[DOE ARCHng