inefficient for dry fallout and still provides no measure of
interception on vertical surfaces.
The-intorpretetion_of.icclaied.
sampling points-as-extrapelatéd to -the-entire-vorld-mist -ba
approached withcautionsince the snountof--Strontiui-90-removed+
by rainfallmaydepend onminy-local-characteristics of the rain~
as-will be notedIaterr A major shortcoming of ths past has been
the lack of observing points.
Until recently, routine analysis
of strontia“i90,BStsaSite to one or two places,
—
On the other hand, there has been/extenstve gumed film
network,
But the gumusd film suffers from a series of sharte
comings.
1.
the
With the szall lip surrounding the film, Aater running off
the paper my be considerable,
In fact, in a study by the Armour
Ressarch Foundation, the paper wos found to be only about 10%
efficient for a rainfall of 0.1" in one hour, for soluble substances.
2. Inring dry westher, the gummsd film was found to develop
an electrostatic charge at relative hunidities balow 5%. The
result was a difference in collection efficiency by a factor of
6 between high and low hunidities.
On the other hand, the gumzed film does procuce nunbers which
appear to ba consistent with the pot msthod at 4s few piscespsig
an overall collection efficiency of about LO.
It has been the purpose of this review of collection methods
to enumsrate the likely sources of error in dsterrintng the total —
anount of fallout of Strontiuxr-90 per year. It is ovident that
“Jarge random errors are likely and that there ere orrors whose
magnitude and sense cannot even be estinated, But of those
wicertainties whose sense can be daterrined, it is the present
ths
t -esties
yie
tes-of anmial-fallout mdeinttiali;-by
mitthas Loe he
For example, Libby sssuzes no impaction on
vertical surfaces, no rmmoff or leeching losses for his soil samples,
“>