266 TRANSURANIC ELEMENTS IN THE ENVIRONMENT 



these indicated relationsliips would suggest a threshold wind speed of 5 m/sec for 

 resuspension or whether a smooth curve should be drawn tlirough all data points. 



In other portions of this figure, selected straight lines suggesting wind-speed 

 dependencies are shown only for wind speeds above 5 m/sec. For the 1.1- plus 2.0-fim 

 impactor stages, airborne concentrations increased with wind speed to the 9.3 power. For 

 the 3.3- plus 7-/im impactor stages, airborne concentrations increased with wind speed to 

 the 5.2 power. For total plutonium collection within particle cascade impactors, a range 

 of wind-speed dependency is shown on the right side of the figure. For a sampling height 

 of 0.3 m, air concentrations increased witli wind speed to the 4.4 power. However, at a 

 sampUng height of 1.8 m, airborne concentrations increased with wind speed to the 3.0 

 power. 



These data in Fig. 20 are the first to show that plutonium is resuspended from off-site 

 locations. In addition, airborne plutonium concentrations show a very high wind-speed 

 dependency for this off-site plutonium resuspension. As will be discussed later, tracer 

 wind resuspension rates suggest a wind-speed dependency to the 4.8 power. Tliis is similar 

 to the wind-speed dependency shown by this off-site plutonium resuspension data. 

 However, other data on plutonium resuspension show a different wind-speed dependency. 

 West of the U-Pond on the Hanford reservation, airborne plutonium concentrations 

 increased (Sehmel, 1977c) with wind speed to only the 1.5 power. Reasons for these 

 differences in the wind-speed dependency of on-site vs. off-site plutonium resuspension 

 are unknown. Possibly a threshold wind velocity above which resuspension increases 

 rapidly with wind speed was not exceeded at the U-Pond. 



Nonrespirable airborne plutonium blowing from off site onto the Hanford reservation 

 was also measured. In this case sampling direction was controlled by placing stops that 

 allowed the rotating cowl (Fig. 3) inlet to rotate only with the range of 190 to 260°. 

 Plutonium analysis was for the total nonrespirable solids collection in cowls at each 

 height rather than as a function of particle size, as was done for Rocky Flats (see Figs. 1 1 

 and 13). 



Plutonium-239 concentrations and fluxes for nonrespirable particles blowing from off 

 site near the Hanford Prosser barricade are shown in Table 8. Plutonium concentrations 

 on nonrespirable airborne solids ranged from 1.3 X 10""^ up to 2.1 X 10~^ AtCi/g. These 

 concentrations are similar to those shown in Fig. 15 for airborne nonrespirable particles 

 collected west of tlie U-Pond. 



TABLE 8 Plutonium Transport on Nonrespirable Particles from 

 Off Site near the Prosser Barricade on the Hanford Reservation 



Airborne ^ ^ ' Pu 

 nonrespirable flux, 



/iCi m~' day"' 



2 3 9 



Pu on airborne 



Only for 190 



Sampling to 260° winds, 



height, m (d/min)g~' juCi/g 3 to 11 m/sec For total time in field 



