Total suspended matter distribution features in the north-eastern part of the Black Sea in spring-summer period of 2021

The results of hydrological and hydrooptical measurements carried out in the spring (April 22–May 17) and summer (July 29–August 10) 2021 in the north-eastern part of the Black Sea during cruises 116th and 117th of the R/V Professor Vodyanitsky are presented. It is shown that in spring, when there was an intensive rivers run-off, the area with a high content of total suspended matter was a strip up to 40 km wide, stretched along the coast of the Krasnodar Krai. In summer, when the river run-off was weakened, the maximum values of the total suspended matter concentration were noted in a relatively narrow coastal strip no more than 20 km wide. Maximum turbidity was noted in the surface layer in spring and in summer it descended into the layer of seasonal thermocline, halocline and pycnocline. The consistency of the horizontal distributions of the total suspended matter concentration and temperature had a significant level deeper than the seasonal thermocline – in the spring in the layer from 20 to 35 m, in the summer in the layer from 15 to 70 m, while a direct correlation was observed, i.e. at these depths, warmer waters were characterized by increased turbidity. The maximum level of consistency between the horizontal fields of the total suspended matter concentration, salinity and density in spring was observed in the upper 20–25 m layer, while the correlation was inverse, i.e. at these depths, less saline and denser waters were characterized by increased turbidity, which is explained by intensive river run-off. In summer, the nature of the correlation was preserved, and the best consistency of the horizontal fields of the total suspended matter concentration, salinity and density was observed in the surface 10-m layer and deeper than the seasonal halocline and pycnocline in the 20–40 m layer.