Risk from Inhalation of the Long-Lived Radionuclides Uranium, Thorium, and Fallout Plutonium in the Atmosphere - Aerosols: Measurement, Dosimetry, and Health Effects - page 562

TABLE 22.5
Particle Size Distribution of U and Pu in Air at ANL

Particulate
Concentration
( μ g m −3 )

Air Concentration ( μ Bq m −3 ) Mass Concentration (mBq g −1 )

Particle Size
Range ( μ m)

Particulate
Weight (g)

U Pu U Pu

>7 0.440 19.3 1.07 (37.2%) 0.036 (2.5%) 55.5 (14.5%) 1.81 (1.3%)

3.3-7 0.169 7.4 0.67 (23.3%) 0.044 (3.1%) 89.9 (23.5%) 5.92 (4.1%)

2.0-3.3 0.097 4.3 0.59 (36.4%) 0.11 (7.8%) 139.1 (36.4%) 25.9 (18.1%)

1.1-2.0 0.102 4.5 0.41 (14.3%) 0.28 (19.7%) 91.0 (23.8%) 61.4 (42.9%)

<1.1 0.445 19.5 0.13 (4.5%) 0.96 (67.0%) 6.7 (1.8%) 48.1 (33.6%)

Total 1.253 55.0 2.87 1.43

Source: Adapted from Golchert, N.A. and Sedlet, J., Resuspension studies on fallout level plutonium, in Selected
Environmental Plutonium Research Reports of the Nevada Applied Ecology Group, Report NVO-192, 1978.

Air concentrations at ANL

2

U
Th
Pu

1.5

1

0.5

0

1970 1975 1980 1985 1990 1995 2000

Year

FIGURE 22.2 U, Th, and Pu in ANL aerosol samples.

U and Th, and the fallout actinide, Pu, at the same location collected on a monthly basis is a rare
database. Figure 22.2 displays the annual average TSP in air concentrations for U, Th, and Pu at
the ANL off-site location. Even with this gross depiction it is evident that, in the absence of atmo-
spheric weapons testing, fallout Pu rapidly decreased below that level of the natural emitters. The
graph also shows the impact of local sources (coal-ired power plants) on the U air concentration
and the subsequent decline due to the enforcement of clean air act requirements. The annual means
mask the features of the monthly and seasonal variations measured at this site. Fallout derived Pu
concentrations followed the well-known spring rise pattern, while the U and Th air concentrations
rose in the winter, a direct result of the heating pattern in the area. The data also showed that the
combined air concentrations of U and Th were greater than Pu from 1973 through 2002. The record
is incomplete at ANL, but Pu in air measurements in New York City, the same latitude band as
Argonne, IL, from 1963 through 1973 shows that >92% of the Pu was deposited during this period.
The data obtained for the New York City site and the ANL off-site location were in good agree-
ment for the years of mutual collections. Another interesting thing concerning the ANL off-site
data and the USEPA ERAMS data is that the Chicago, IL, U in air concentration of 2.4 μBq m −3
is close to the national average of 2.1 μBq m −3 of air but a factor of 5-10 greater than the ANL
off-site data. This comparison of a single site with measurements of naturally occurring and a