day) at an elevation of 91m.

The flux decreased to 1.2 x 1078 yuCi/(m?

At this highest sampling elevation, the
day) at an elevation of 122 m.
flux on large particles was 1.4 x 1078 yci/ (m2 day).
Thus, the percent
of total americium-241 flux on small particles was 45% at an elevation
of 122 m.
This percent flux on small particles is shown on the right

side of the figure.

Similarly, the americium-241 flux on large particles

was 5 x 107’ yCi/(m? day) at a sampling height of 1.9 m.
At this lowest
sampling elevation, the percent of total americium-241] flux on small
particles was 0.5%.
Americium-241 fluxes on large particles are not
shown between 1.9- and 122-m sampling height since the radiochemical
results were less than radiochemical counting detection limits.

CONCLUSIONS

Both plutonium-239 and americium-241 concentrations were measured for
sampling heights up to 122 m.
Results are reported uCi/em3, uCi/g of

airborne soil, and average fluxes in uCi/(m* day) for both large and

small particles.
The small particles are in the respirable diameter
range.
Since results were determined for heights up to 122 m, these
experimental data are the first to show plutonium-239 and americium241 concentration profiles to those heights.
However, even at a sampling

height of 122 m, the airborne plutonium-239 and americium-241 plumes
were probably not contained.

Some correlation is suggested between americium-241 transport on small
particles and plutonium-239 transport on large particles.
This apparent
correlation needs further validation at other sites and time periods.
Americium-24]1 has been studied even less than plutonium-239 resuspension.
Nevertheless, americium-241 resuspension could become a potential inhalation concern of the future when americium-241 grows in as a daughter of

plutonium-241 at aged plutonium resuspension sources.

In addition to

showing americium-241 transport by resuspension, these data also show
plutonium-239 and americium-241 are transported on both small and large
particles.
Although transport on large particles does not present an
immediate inhalation concern, transuranics transported on large particles
could present a subseauent inhalation concern.
After these large particles are deposited, small particles can be released from the larger host
soil particles (Sehmel, 1978).
If transuranics, these released smail
particles could then be sources for subsequent resuspension in the
inhalation diameter range.
Experimental data are needed to develop and
validate transport models for both respirable and nonrespirable particles

as well as plutonium-239 and americium-241 detachment from large particles.

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