2. AIR
Measurements of airborne Sr™ and other isotopes serve one of two purposes, depending on
whether the samples are taken at ground level or in the upper atmosphere. Surface air concentrations do show the presence of radioactivity and, as such, have been useful in meteorological studies. On the other hand they cannot be readily related to deposition since the actual
deposition process is a complex function of local meteorology and particle characteristics.
Upper air collections, particularly in the stratosphere, can be used for the prediction of future
deposition and in material balance studies.
It must be emphasized that none of the air concentrations found are at an activity level
that would in themselves be a direct hazard in inhalation. Hence the measurements are designed purely for obtaining information relating to trajectories and the prediction of future
fallout.
2.1
SURFACE AIR
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a. Naval Research Laboratory Collections.
Samples of airborne dust at the surface are
collected by the Naval Research Laboratory (NRL). These samples are measuredfortotal
fission product activity and in some cases for natural radioactivity. A large number of these
samples were made available to Dr. E. A. Martell at the University of Chicago laboratories,
where they were analyzed for Sr®. These data are reported in Table 12.
The NRL has instituted a program of radiochemical analysis on later samples. These data
are not yet available. Their current network lists the following stations:
Punta Arenas, Chile
Puerto Montt, Chile
Santiago, Chile
Porto Alegre, Brazil
Antofagasta, Chile
Chacaltaya, Bolivia
Huancayo, Peru
Lima, Peru
Iquitos, Peru
Guayaquil, Ecuador
Quito, Ecuador
Bogota, Colombia
Miraflores, Colombia
San Juan, Puerto Rico
Miami, Florida
Columbia, South Carolina
Washington, D. C.
Bedford, Massachusetts
Moosonee, Ontario
Coral Harbour, N.W. Terr.
Thule, Greenland
b. U.S. Public Health Service Collections. The U. S. Public Health Service (USPHS) has
been collecting samples of airborne dust during the test series for the past two years. These
samples are measured in the field for total beta activity, but no radiochemical work has been
done on these samples as yet. The activity collected on a 24-hr sample at the relatively low
flow rates used is not sufficient for radiochemical determination of Srand other isotopes.
The USPHS network has been of value in indicating sites of high airborne activity and possible relation to high fallout deposition. The data have been valuable also in meteorological
interpretation of cloud trajectories following tests. Table 13 shows the locations of stations
in the current network.
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