112) showed small differences in content. Volumetric content 

 was 0. 1 87 cmVm' and 0.09 cmVm' at 200 m. and 0.218 cm Vm' 

 and 0.04 cmVm' at 2,450 ni. The values are typical of deep 

 waters of the Pacific (Kopelevich, 1981). The Secchi depth 

 varied from 10 m (Station 132; most turbid surface waters) to 

 15 m (Stations 108, 111). 



Conclusions 



Before stating main conclusions, it should be noted that 

 primary hydrooptic characteristics of the Bering and Chukchi 

 Seas were investigated for the first time. 



The northern Bering and Chukchi Seas were discussed in 

 terms of their transmittance and spatial variability in cross- 

 sectional transects. 



1. The transmittance of waters in this study decreases with 

 the increase of latitude. The results of instrument-assisted 

 measurements correspond to visual observations of Hb depths 

 at which a standard white disk disappears ( 1 2-22 m in the Gulf 

 of Anadyr. 7- 1 6 m in the northern Bering Sea, and 4- 1 m in 

 the Chukchi Sea). The relationship between H^:, and the average 

 value of attenuation index (ehs) may be expressed by the 

 relationship ,, 45 



H. 



(Eh.) 



2. The zonal distribution of average transmittance reflects 

 the dynamics of northern seas. It can be utilized to detect 

 cyclonic eddies and to assess areas where waters have different 

 conditions of formation. 



3. Increased turbidity of water is accompanied by a higher 

 rate of fine fraction particulates growth. 



4. Waters with different qualitative composition of 

 particulates display distinct angular and integral characteristics 

 of light scattering. This feature enables optical properties of 

 such waters to be used as an indicator in regionalizing the 

 waters by their productivity . It is also helpful when investigating 

 the dynamics of currents. It is shown that diatom particulates 

 in potentially hioactive waters of the cross current increases 

 with latitude. These waters are carried to the Chukchi Sea 

 through the eastern portion of the Bering Strait. In the western 

 portion, it was heavily turbid low-productivity water with 

 relatively high content of fine fraction. 



5. The waters in the Gulf of Anadyr and divergence zone 

 in the Chukchi Sea are characterized by high productivity. 

 They show similar values of angular and integral light scattering 

 that are specific for diatomic particulates. This signifies the 

 ability of biological particulates for intensive development in 

 the Bering Sea (where beneficial conditions exist). It may also 

 show affinities between the dynamic processes occurring in 

 both the productive zones. 



6. In waters with predominant content of diatom particulates 

 (identifiable as a specific combination of angular and integral 

 characteristics of light scattering ). the chart of zonal distribution 

 of average transmittance correctly reflects ( in qualitative temis) 

 the spatial distribution of chlorophyll content. 



7. In high productivity waters of the Chukchi Sea, the 

 relationship between chlorophyll concentration and attenuation 

 index will be Chi c/,,,, = 20e,n,+7. 



151 



