34 BIOLOGY OF THE SEAS OF THE U.S.S.R. 



The drift of polar waters 



The direction of the drift bringing masses of surface waters and ice-floes out 

 of the eastern sector of the Arctic basin was charted by the voyage of the Fram 

 and, with greater precision, by the later Soviet expeditions — that of Papanin 

 on drifting ice and by the icebreaker Sedov (1937-39). As was shown by 

 N. Zubov in 1937-39 (Nansen had noted it earlier) the movement of the Arctic 

 basin surface water and of the ice-floes on it is occasioned by the prevailing 

 winds ; the direction the Arctic Ocean's currents corresponds to the direction 

 of the isobars. The Libin-Cherevichny expedition worked in 1941 at 78° 27' 

 to 81° 32' N latitude and 176° 32' to 190° 10' E longitude. 



From the shores of Siberia diluted waters are carried away beyond the zone 

 of the shallows, whence they are caught up by the general westward current to 

 pass between Greenland and Spitsbergen. Two main streams of polar waters 

 and the ice move along the eastern shores of Greenland and through the Davis 

 Strait. 



Water balance 



The attempt to find the main indices of the water balance of the Arctic basin 

 goes back to Nansen. These indices may be given with some approximation 

 as in Table 6. 



Table 6 



Inflow of fresh water into 



Arctic basin km 3 



Fresh water brought by the 

 rivers 4,000 to 5,000 



Surplus rainfall over evapora- 

 tion 



about 2,000 



On account of exchange 

 through the Bering Strait 



about 2,000 



Total about 8,000 to 9 ,000 



The present Arctic basin water balance is probably most unstable. During 

 the Ice Age the Arctic basin waters became greatly diluted, and in the succeed- 

 ing millennia the reverse process of increase of salinity must have gone on. It is 

 clear that the salinity of the Arctic waters always largely depends on the inflow 

 of river water, the amount of ice carried out (two factors greatly affected by 

 seasonal changes) and the nature of the water exchange with the Atlantic 

 Ocean (depending on the bottom topography of the passages connecting the 

 Arctic basin with the Atlantic Ocean). 



