PNNL-13501 - Pacific Northwest National Laboratory

[Pb-212]/[Pb-212] final
100
10
1
0.1
0.01
0.001
0.0001
0.001
0.01
0.1
1
10
Flux [Pb-212]/[Pb-212] o
0.0001
0.01 0.1 1 10
Time (hr)
100 1000 10000
Figure 4. Theoretical concentration of 212 Pb versus
transport time over land with several fixed 220 Rn source
terms
should be greater than that over the ocean, therefore, flux
ratios that result in a final [ 214 Pb]/[ 222 Rn]o ratio of less
than one are not generally applicable unless they originate
from a land mass with a significantly higher 222 Rn flux.
Since this work did not examine air movement prior to the
Pacific Coast, these curves have been included in the
Figure 3. Once the data in Figure 2 has been corrected to
Bq/m 3 , this information along with vertical mixing can be
used to calculate the average local 222 Rn flux rates.
Conversely, if the local 222 Rn flux rates are known, then
the measurements can be used to calculate mixing.
Assuming the initial [ 212 Pb]/[ 212 Pb]final