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



rotation of the current, (3) the cooling of the surface layers, (4) the warming 

 up of the deep layers, (5) the internal waves, (6) turbulence and diffusion.' 

 Wodjanitzky thinks it possible, as a first approximation, to divide the Black 

 Sea water vertically into five zones — three main and two intermediate ones 

 (Fig. 189). 'In the first zone,' he writes, 'the water rises in the centre, there is a 

 horizontal movement towards the periphery, and a sinking down there — a 

 thermal convection. A turbulent mixing (internal waves) takes place in the 

 second zone. In the third there is a rise in the centre, a horizontal movement 

 away from the centre and a sinking down at the periphery. There is some tur- 

 bulent mixing with internal waves in the fourth zone. There is some thermal 

 convection and a feeble movement away from the periphery in the fifth zone.' 

 This problem cannot be solved without taking into consideration the water 

 balance through the Bosporus, and Wodjanitzky makes the following com- 

 putation : if the annual inflow of Sea of Marmora waters is 200 km 3 (S 36% ) 

 and the outflow is 360 km 3 (S 12% ) and if the salinity is taken into considera- 

 tion in both cases (the salinity of the Sea before it became connected with the 

 Dardanelles being 12% , and the period lasting 6,000 years), the salinity bal- 

 ance of the basin can be represented in the manner indicated in Table 155 and 

 Fig. 190. 



Table 155 



If this rate of change* in the water balance through the Bosporus is main- 

 tained, there is no salinity increase at present and a certain equilibrium has 

 been established. As a result of his computations Wodjanitzky (1948) draws 

 the conclusion that a vertical mixing of the Black Sea waters takes place at all 

 levels and that the deep waters may be lifted to the upper, inhabited layer of 

 the Sea in 100 to 130 years. 



Nitrogen and phosphorus compounds 



P. Danilchenko and N. Chigirin (1930) have shown that in the depth of the 

 Black Sea the nitrates, like the sulphates, go through ' a process of reduction 

 with the formation of ammonia and free nitrogen (denitrification.) 'The 



* In \9A2-A6 there appeared a series of articles by F. Illyott and O. Ilgaz, attempting 

 to prove that the Bosporus discharge current takes with it the reverse current waters, 

 and that this current does not actually reach the Black Sea. The opinions of these authors 

 were not accepted. 



