TRANSURANIC AND TRACER SIMULANT RESUSPENSION 259 



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Q- 



D. 

 00 



10 



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CO 



10" 



I I I I I I 



1 1 \ — [Mil 



T — r 



I MIL 



Site A 



Site AB 



Soil sample 

 range- 



7 



J I I I I 1 1 1 



10 100 



PARTICLE DIAMETER, pm 



J I'll 



1000 



Fig. 17 Ratio of ^'^Pu/^^'Pu on nonrespirable airborne soil as a function of particle 

 diameter at Rocky Flats. 



This range (Kiey et al., 1976b) represents surface-soil samples taken between the eastern 

 security fence and beyond the eastern cattle fence to Indiana Avenue. 



At sites AB and B, airborne ^■^^Pu/^^^Pu ratios on nonrespirable particles are over 

 one order of magnitude greater than similar ratios from 5-cm-deep surface-soil samples. 

 These ratios do not appear to be significantly affected by sampling height between 0.3 

 and 10 m above ground level. However, considerations of the data-counting-statistics 

 error bars at sites A and AB tend to indicate liigher '^^^Pu/^^^Pu ratios closer to the 

 ground. 



The ^^^Pu/^^^Pu ratio was determined for all nonrespirable particle diameter ranges 

 at sites A and AB at the 0.3-m sampling height. These results are shown in Fig. 17 along 

 with the total ground-surface-soil sample range. At site A the ^^^Pu/^^^Pu ratio is nearly 

 independent of particle diameter for all particle diameters above 20 iim. It is only for 

 particles less than 20 /nm that the ^^^Pu/^^^Pu ratio is significantly elevated at site A. 

 The ^^^Pu/^^^Pu ratios on nonrespirable particles greater than 20 /Lim at site A are all 

 comparable with ratios in the 5-cm-deep surface-soil samples. This similarity would be 

 expected if there were no preferential '^^^Pu to ^^^Pu separation on soil surface. In 

 contrast to site A, ^^^Pu/^^^Pu ratios for site AB are much different and are 

 significantly elevated for all particle diameters above the surface-soil sample range. 



