21 Q TRANSURANIC ELEMENTS IN THE ENVIRONMENT 



AIRBORNE RESPIRABLE SOIL CONCENTRATION, pg/m^ 



Fig. 22 Equivalencies between plutonium on airborne soil and airborne plutonium 

 concentrations. 



10~^ to 10^. Nevertheless, two equality assumptions are used in this section to predict 

 airborne radionuclide concentrations. 



Airborne plutonium concentrations can be predicted by assuming both parameters of 

 airborne soil concentration and plutonium concentration per gram on that airborne soil. 

 In this case the equivalency between these two parameters and airborne plutonium 

 concentrations is shown in Fig. 22. As a point of reference, airborne concentrations at 

 Hanford are (Sehmel, 1977b) about 80 )Ug/m^ for wind speeds of 5 m/sec. Hence, in using 

 Fig. 22, a plutonium concentration on airborne soil of approximately 10~^ /aCi/g would 

 be required (assuming a surface contamination depth of 1 cm and a soil density of 2 

 g/cm^) at an airborne soil concentration of 80 jug/m^ to exceed or approach maximum 

 permissible airborne ^^^Pu concentrations. 



As is shown in Tables 2 and 3, there is no experimental basis for adequately 

 predicting plutonium concentration on total airborne soil since airborne soil usually 

 consists of both uncontaminated soil blowing in from off site and the resuspended 

 contaminated soil. At our present state of knowledge, there are only limited data for 

 ratios of plutonium on total airborne soil compared with total surface soil. Moreover, 

 there is no experimental resuspension data to relate plutonium concentrations on 

 respirable surface soils vs. plutonium concentrations on respirable airborne soils. 



Airborne solids concentration levels were estimated from data (Sehmel, 1976b; 

 1977c) shown in Fig. 23. Airborne particle volume distributions were determined at the 

 Hanford area using both an optical particle counter and a cowl-impactor system (Sehmel, 



