448 TRANS URANIC ELEMENTS IN THE ENVIRONMENT 



radiographic and microscopic studies of debris, and geometric mean particle diameters of 

 2 to 5.6 //m were reported in snow/ice samples obtained shortly after the accident 

 (Langham, 1970; Gjc^rup, 1970). 



Isotopic ratios in the Thule soil and alluvium samples from uncontaminated sites were 

 in the range of 0.011 to 0.065 for ^^^'^'^^Pu/'^ ''Cs and 0.15 to >1.0 for 

 2 38p^/2 3 9,240p^ jj^g 2 3 8 p^/2 3 9 ,2 4 p^ ^^^-^^ -^ ^-^^^^ communities, by comparlsoH, 



were usually within the range of 0.020 to 0.024, which was reported for global fallout 

 (Harley, 1975). 



Radionuclide concentrations in soil samples collected at the Alaskan sites during 

 summer periods of 1975 and 1976 are shown in Table 3. Inventories of ' "^ ''Cs, expressed 

 as nanocuries per square meter, were generally proportional to average annual rainfall 

 regimes at the three locations. The greatest amounts were in Fairbanks samples, although 

 Fairbanks receives only about three-quarters as much precipitation as Bettles; however, 

 these values were not significantly different (t-test value, 1.54; df, 2;P<0.2 to 0.3), nor 

 were the Anaktuvuk Pass and Bettles values (t value, 1.43; df, 6;P<0.2). Fairbanks 

 values were significantly different from those for Anaktuvuk Pass (t value, 4.01; df, 6; 

 P<0.01). There was a significant difference between the areal inventories of '^''Cs 

 measured at Anaktuvuk Pass in 1975 and 1976 (t value, 1.81; df, 7; P<0.10) but not 

 between those in July and September 1976 (t value, -0.88; df 8; P<0.40). This was 

 apparently due to slightly greater fallout deposition during 1974 and 1975 after the large 

 atmospheric nuclear weapons tests conducted by the People's Republic of China in 1973 

 and 1974 (Carter and Moghissi, 1977). The ^^^'^'^"Pu/' ^ ^Cs ratio was 0.016 in 1975 

 and then decreased to 0.004 to 0.007 at all sites in 1976 as greater amounts of ^^"^Cs 

 were apparently deposited. 



Concentrations and inventories of ^^^'^'*°Pu in Alaskan soils during 1975 and 1976 

 were substantially less than those in Greenland during 1974; in most cases they were 



TABLE 3 Radionuclide Concentrations (Mean ± Standard Error) 



in Soil Samples* Collected at Anaktuvuk Pass, Bettles, and Fairbanks, 



Alaska, During Summer Periods of 1975 and 1976 



*Kach sample consisted ofa 10-g aliquot taken from a 0.1- by 0.1- by 0.05-ni core after drying and 

 sieving to remove rocks greater than 6.35 mm in diameter, 

 t Number of samples. 



