In the Chukchi Sea, the biosedimentation rate and 

 particulate concentration were considerably higher values than 

 those in the Bering Sea and averaged 

 85.0 ± 22.1 mg dry wt m ' d ' and 1.28 + 0.06 g dry wt m \ 

 respectively. Maximum biosedimentation rates for this region 

 occurred below the thermocline. The residence time of the 

 POM in the water column averaged 23 ± 5 days in the Chukchi 

 Sea. The vertical POM profile showed an increased 

 concentration in the 15^0 m layer as compared with the 

 surface waters. The high values of POM and high rates of 

 biosedimentation were evidently due to the phytoplankton 

 bloom observed during the investigation. The bloom achieved 

 red tide proportions at certain stations in the Chukchi Sea. The 

 POM concentrations as a whole matched the spatial distributions 

 of the average biosedimentation rates (Table 6). 



The values of suspended organic matter for the regions 

 investigated, as a whole, repeated the regularities of spatial 

 distribution exhibited by the average biosedimentation rates 

 (Table 6). 



In the Bering Sea, the minimum biosedimentation rates 

 from the upper40-m layer were observed in the Gulf of Anadyr, 



670-950 mg dry wt m ' d ' . The POM fluxes were much higher 

 in the shallow northern Bering Sea, 

 1,630-2,800 mg dry wt m- d ', and in the open sea, 

 2,320- 3,130 mg dry wt m" d '. The average values of the 

 biosedimentation parameters for the upper layer (0-40 m) of 

 the Bering Sea were as follows: the POM flux was 

 1940 ± 410 mg dry wt m- d ', the POM concentration was 

 52.6 ± 2.4 g dry wt m -, and the residence time of POM 

 was 19.5 ± 7.4 days. 



It should be noted that biosedimentation rates vary 

 considerably in different parts of the sea. Near the coasts of the 

 Chukchi Peninsula and Alaska, the sedimentation fluxes from 

 the euphotic layer were the same as in the open and "prestrait" 

 Bering Sea. In the central part of the Chukchi Sea, where the 

 phytoplankton bloom was most intense, the POM flux increased 

 to 5.9 g dry wt m- d '. 



This assessment of biosedimentation in the Bering and 

 Chukchi Seas points to the high intensity of these processes. 

 This is related to high productivity of the region — principally, 

 to the high rate of organic matter formation in the subarctic and 

 arctic zones of the World Ocean in summer. 



TABLE 5 



Biosedimentation parameters in the Chukchi Sea. 



229 



