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



As one moves eastward the waters of the Black, Caspian and Aral Seas 

 undergo a lowering of their saline composition relative to that of the ocean 

 (Table 145). 



Table 145. Comparative saline composition of waters of ocean and Black, Caspian 

 and Aral Seas, expressed in percentages of the total (L. Berg from L. Blinov) 



The increase of sulphates from 10-34 to 40-85 per cent and the decrease of 

 chlorides from 8945 to 58-94 per cent are the most characteristic features of 

 these changes. The change of the salt content of the water of the south-Russian 

 seas is not a simple derivative of the river discharge, although it is controlled 

 by it. Whereas the saline composition of the Caspian Sea salt content can be 

 considered as the 'chemical legacy' of the ocean, exposed for some time to 

 the influence of river discharge and subjected to a complex conversion, the 

 Aral Sea water is by origin metamorphized water of the coastal drainage. 

 This can be shown by a comparison of the salt composition of the water of 

 the Caspian Sea and that of the Volga, in percentages (Table 146) (S. Bruje- 

 vitch, 1937, 1941). 



Table 146 



Salts Ocean Caspian Sea Volga, off Astrakhan 



Na 



К 



Ca 



Mg 



CI 



Br 



so 4 

 co 3 



This fact comes out even more clearly in a comparison of the salt composition 

 of the Aral Sea water with the average ionic discharge over many years 

 of the rivers Amu-Darya and Syr-Darya (Table 147) (O. Alekin, 1947). 



