446 TRANSURANIC ELEMENTS IN THE ENVIRONMENT 



about 60% as great as those in Alaska, or about proportional to their differences in annual 

 precipitation. However, the estimated '^^Cs deposition at Thule was only 37% of that 

 estimated for Anaktuvuk Pass, which suggests that "dry fallout" must account for an 

 appreciable part of the worldwide fallout deposited on Thule lichen communities. The 

 close agreement between most of the ^^''Cs inventories in the soils and adjacent lichen 

 communities of that region suggested that the two components were balanced by some 

 physical transport mechanism, probably the substantial winds of the region. 



Fallout collections at both Thule and Fairbanks began near the end of a previous 

 major period of fallout deposition that resulted from an extensive series of atmospheric 

 nuclear weapons tests during 1952 to 1958 by Great Britain, Russia, and the United 

 States. Therefore the '^^Cs estimate of 43 mCi/km^ at Anaktuvuk Pass at this time and 

 of 16 mCi/km^ at Thule at the time of sample collection in August 1974 represent 

 conservative deposition estimates. Cornparison of fallout collection data at New York 

 during periods before 1960 and after 1960 suggests that the preceding deposition 

 estimates for the northern Alaska and Greenland areas should be about doubled to 

 account for the total deposition of fallout since the beginning of nuclear weapons testing. 



The estimated deposition of ^^^Cs from fallout in the Thule environs (annual 

 precipitation, 13 cm/yr) determined from ^^ ^Cs concentrations in soil samples (Table 1) 



TABLE 1 ' ^ ^Cs Concentrations and Areal Inventories 



in Soils* of the Thule, Greenland, Environs 



During August 1974 



*Each value is derived from measurement of a 100-g aliquot of dry 

 soil taken from a composite of five 0.01-m^ samples taken along a 

 transect of 0.2 to 0.4 km in the various locations. 



t Refer to Fig. 2. 



ranged from 14.7 to 32.1 nCi/m^ with an average of 21.5 ±2.4 (SE). The maximum value 

 occurred on the southwest side of Saunders Island, where large snowdrifts accumulate 

 during winter periods; the minimum values (<0.01 pCi/g) were obtained in two samples 

 from the windswept headlands at the southern edge of the study area. The validity of this 

 estimate was substantiated by a value of 20.6 nCi/m^ calculated from a 2 3 9,24 0p|j 

 inventory of 0.33 mCi/km^ measured in a large (1-kg) aliquot of 622 cm^ of Thule soils 

 during 1970 and 1971 (Hardy, Krey, and Volchok, 1973) and a ^^^'^'^^Pu/'^ ^Cs ratio 

 of 0.016. Fallout collections at Thule indicated that an additional 0.008 mCi of 

 23 9,240pjj pgj. 3q^2^.g kilometer was deposited between July 1971 and August 1974, 

 bringing the two estimates even closer to agreement. 



