452 TRANSURANJC ELEMENTS IN THE ENVIRONMENT 



TABLE 6 Estimated Inventories of "^Pu, "^'^^"Pu, ^^ ' Am, and * ^ ''Cs in 

 Areal Samples of Alaskan Lichen Communities During Summers of 1968—1976 



^Number of samples. 



at the P<0.05 level. Subsequent statistical analyses for four common fallout 

 radionuclides were performed using the untransformed data in a two-tailed t test which 

 allowed separate variance estimates (Nie et al., 1975), and the log-transformed data were 

 tested by Kruskal-Wallis and Kolmogorov- Smirnov procedures (Hollander and Wolfe, 

 1973) (Table 8). The upper 6 cm usually contained significantly greater concentrations of 

 ^^Sr, '^^Cs, "^Pu, and 239,240p^ ^^^^ ^^g j^^^j. 6 cm, except for ^°Sr during 1970. 

 Cesium-137 showed the greatest differences in concentrations in the layers, apparently 

 owing to its greater mobility and concentration in the more rapidly photosynthesizing 

 upper portion of the lichens (Moser, 1977). These data are consistent with similar studies 

 in Sweden (Holm and Persson, 1975) in which Cladonia alpestris carpets were 

 fractionated into several vertical layers. Considering the variation of radionuclide 

 depositions, sampling, and analytical differences, the values reported for the ^■'^Pu and 

 2 3 9,2 4 0pj^j concentrations in lichen samples from central Sweden are similar to those 

 from northern Alaska. 



Concentration ratios of ^^^Pu, ^^^'^'*'^Pu. and ^^''Cs in Greenland and Alaska 

 (lichens/soil) (shown in Table 9) were generally consistent; the exception occurred in 

 ■^^^Pu measured in Greenland samples. The values for the plutonium isotopes were 

 considerably higher than the values in the range of 10~^ to 10"'* reported for most 

 Temperate Zone plants (Francis, 1973). Resuspension of radionuclides from soil to 

 lichens was assumed to be a strong possibility in the Greenland sites and very minor in 



