Bering and Chukchi Seas. These estimations showed that the 

 maximum of "Chernobyl' s" concentration could not exceed 

 0.07-0.09 Bq /m\ 



Taking into consideration that the real concentrations of 

 Cs'" in the Chukchi and the Bering Seas are 1.6 Bq/ m' 

 (Table 1), then the maximum contribution of "Chernobyl's" 

 Cs'" could not have been more than 6%. 



The results of the vertical distribution of Cs'" in the 

 Chukchi and Bering Seas and the Gulf of Anadyr are given in 

 Figs. 1, 2, and 3. The concentration of Cs'", which is the 

 average value along the whole investigated area, was estimated 

 as 2.4 Bq/m- (a range of 1.6 to 3.7 Bq/m- ), 2.4 Bq/m- for the 

 Chukchi Sea and the Gulf of Anadyr, and 2.3 Bq/m^ for the 

 Bering Sea. The maximum concentration, 3.7 Bq/m\ was 

 determined in the to 40 m layer to the southwest of 

 St. Lawrence Island. 



Fig. 1. Vertical profiles of Cs'" concentrations in the Chukchi Sea (the mean 

 direction of the currents are shown hy the arrows). Numerator = Cs'" 

 budget (Bij/m-), denominator = the average concentration of Cs'" 

 (Bq/m') at that station from the surface to the bottom. 



It is important to note that the vertical distribution of Cs'" 

 in the Bering Sea was homogeneous. The vertical distribution 

 in the Chukchi Sea, however, was characterized by an elevated 

 concentration in the bottom layers (ranging from 2.5 to 

 5.5 Bq/m' and an overall average of 3.1 Bq/m'). 



The maximum gradients for vertical distribution were 

 observed in the western Chukchi Sea — that is, 1 . 1 Bq/m' in the 

 surface layer (0-3 m) and 3.5 Bq/m' at a depth of 40 m. 

 Simultaneously, a correlation in spatial distribution of Cs'" 

 and salinity was observed such that in a direction from the west 

 to the east there was a decrease in the vertical gradients of these 

 parameters and an increase of Cs'" concentrations with an 

 increase in salinity in the upper layers. 



Fig. 2. Vertical profiles of Cs'" concentrations in the Northern Bering Sea. 



Fig. 3. Vertical profiles of Cs'" concentrations in the Gulf of Anadyr. 



Obviously, the flow of surface waters from the west into 

 the Chukchi Sea significantly influenced the distribution of 

 Cs'", especially in the western part of the Chukchi. 



The observed homogeneity of the Cs'" over these areas 

 demonstrated the lack of local inputs of this material. The 

 concentration level was typical for the world oceans and was 

 indicative of global input of Cs'" from the atmosphere over a 

 long period of time. 



328 



