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settled on « fim banis the broad principles of stratospheric movement,
mixing and the mechaniem of the escape of melear debris te the tropoPRLS
The Present Distribution and Amounts of Fallout Radioactivity
Sampling Methods
During the past several years several thousands of samples of fallout material on gwmed paper, in pots, in sell, in water, in milk and
other foodstuffs and in Inman end animal bores and other animal tissues
have been eellested in the United States and from all over the world,
They have been analysed for gross gamma activity, mixed beta gama activ
ity, for strostiu-90, for osalue-137, cerlue~-l, bariwe-1)0, and a
number of other flesion products as well as for induced activities. In
general, we have as much or more fallout on the United States as any-
where in the world outaide of ruclear weapons test sites. Furthermore,
average values of Sr-90 in soils and food supplies in Northern United
States are as high aa are found in other similarly large geographic
areas.
There may, however, be in remote localities areas with greater
average soil content of Sr-9 of which we are as yet unaware.
Likewlse,
we know that in 1956 in one area in Cardigan Wales, where the soil is
extremely lov in caledum (0.3 gna/Kg), bones fron a sheep grazing the
area have shown as high as 170 yyo Sr-90/gm Ca.
Probably the most reliable index of total fallout to date in a
given area ie to be found in analyses of carefully selected soil samples,
By. Iyle Alexander, 7.3. Department of Agrlavlture, has been in charge
ate