In the Chukchi Sea, the -"Th concentration (dissolved + 

 suspended) was lower (0.81 ± 0.08 dpm 1 ') than that in the 

 Bering Sea. The dissolved -'''Th concentration 

 (0.45 ± 0.06 dpm 1') was the same as in the Bering Sea while 

 the particulate -"Th content was lower, amounting to 

 0.35 ± 0.04 dpm 1 '. The value of R in the Chukchi Sea 

 averaged 0.36. 



The average value of accumulation factor of -"Th by 

 particulates in the Bering Sea was 574 ± 63 dpm g ' of dry 

 weight, and 650 ±280 dpm g ' of dry weight in the Chukchi Sea. 



It is evident that there were considerable variations of C^, 

 within relatively homogeneous water masses and with depth at 

 any given station (Table 3). On one hand, it can be due to the 

 differences in the composition of the suspended matter, in 

 particular the organic matter. This is because the Th 

 accumulation factor in organic matter is some orders of 

 magnitude higher than in inorganic matter (Cherry & Shannon, 

 1974; Polikarpov era/., 1976). On the other hand, with highly 

 intensive sedimentation processes, the accumulation factors 

 depend on the length of time the particles remain in suspension. 



TABLE 2 



Results of determinations of -"U and -"Th concentrations 

 in seawater and suspended particulates of the Chukchi Sea. 



TABLE 3 



POM and -"Th concentrations in particulate matter of the Bering and Chukchi Seas. 



227 



