i24 TRANSURANIC ELEMENTS IN THE ENVIRONMENT 



sand filter mingles with that from the uranium recovery A-line and other sources 

 (sampHng point D). 



A total of 121 particles were analyzed from System 1(16 from sampling point 23, 67 

 from point 29, and 38 from point 30) and 417 from System II (125 from sampling 

 point A, 107 from point B, 1 14 from point C, and 71 from point D). These figures do not 

 include 20 particles that contained no elements with atomic numbers greater than 9 and 

 were assumed to be organic. 



Grouping of Data by Enrichment Factors 



The results were expressed in terms of "enrichment factors" (dimensionless ratios of 

 elemental concentrations), which enabled the intercomparison of the compositions of 

 plutonium-bearing particles with other atmospheric aerosols and the intracomparison 

 among particles collected from different sampling points. A definition of enrichment 

 factors and an explanation of their development and application in this work are given in 

 the appendix. 



For a comparison of the chemical composition of the particles collected from 

 Systems I and II with each other and with the average for global crustal aerosol, the 

 particle analyses were grouped according to the level of the enrichment factors. Four 

 groups were established for each element by using the elemental concentration data in 

 Table A.l of the appendix. The first group contained particles with no detectable 

 amounts of the element sought. The second group contained detectable amounts with 

 enrichment factors less than one standard deviation below the geometric mean 

 enrichment factor, EFg/Sg. The third group contained particles with enrichment factors 

 between the lower and upper limits of one standard deviation from the geometric mean 

 enrichment factor, EFg/Sg and EFg X Sg, respectively. The fourth group contained 

 enrichment factors greater than one standard geometric mean enrichment factor, 

 EFg X Sg. The third column of Table 6 gives the percent of the particles analyzed which 

 gave positive analyses for each element. The fourth, fifth, and sixth columns of Table 6 

 contain the percent of those having positive analyses which had enrichment factors less 

 than, between, and more than the lower and upper limits of the geometric standard 

 deviation. 



For a comparison of the chemical composition of particles collected at the various 

 sample points in System II with each other and with global crustal aerosol (Table A.l), 

 this process was repeated, and the results are listed in Table 7. 



Particles with no detectable amounts of an element were not counted with those with 

 enrichment factors less than the lower limit for the geometric standard deviation (s^,) 

 because there can be no zero or negative concentration of enrichment-factor values in 

 log-normal frequency distributions. Thus the size of the three groups is expressed as the 

 percent of the particles giving positive analyses rather than the percent of the total 

 number of particles. 



Particle Evaluation by Size 



In this study particles were selected for analysis on the basis of the number of observed 

 fission -fragment tracks. Since there were many more particles than could be analyzed, 

 those having 3 or 4 tracks were generally passed over in favor of those surrounded by 50 

 or more tracks. The selection of particles for analysis, however, was not biased by 



