The organic matter content of the phaseolin ooze is lower than that of the 

 mussel ooze, although the former lies deeper; this is apparently due to the 

 lesser density of its animal population. The accumulation of organic matter in 

 the still deeper oozes, already in the 

 reduction zone, is conditioned by the 

 absence of organisms which could 

 have used it and by the feeble vertical 

 circulation which would have brought 

 it up into the upper layers of the Sea. 



The first to make a comparison of the 

 salinity of the bottom water with that 

 of the main masses of sea water in 

 former geological periods was S. P. 

 Brujevitch (1952). A sharp decrease in 

 salinity, down to 4% (in chlorine) at a 

 depth of 6 m, was recorded by the exam- 

 ination of cores from the deeper parts 

 of the Black Sea. This, according to 

 Brujevitch, is the salinity of the Novo- 

 Euxine basin of brackish water; he 

 points out that in the open sea there is 

 no change of salinity with depth (Fig. 

 192). The same method was later used 

 by B. Kullenberg (1954) in the Baltic 

 Sea with the same result. 



Benthos remains are almost absent while plankton remains are predominant 

 on the floor of the reduction zone in the deep-water sediments of the Black 

 Sea. The predominant part played by plankton organisms in the formation of 

 organic matter on the deep floor of the Black Sea is also shown by the 

 carbon/nitrogen ratio. While on the shallow floor this ratio is about 4 to 4-5 



24 



22 20 18 16 /4 12 10% 



♦—CALCIUM CARBONATE 



Fig. 192. Alterations in chlorine and 



calcium carbonate content with the 



depth in the sea- bed (Brujevitch). 



