Distribution of Mercury in the Surface Water of the Black Sea and Its Concentration in Suspended Matter

As a result of sedimentation, suspended particles carry chemical pollution from the surface layer of water into bottom sediments, playing a significant role in waters' self-purification from mercury. For the purpose of establishing the features of mercury distribution in the surface water of coastal and open-sea areas and concentrating it in the suspended matter, mercury concentrations were measured in water sampled in different seasons of the years 2018-2019 from the surface water layer of the Black Sea, and empirical dependencies of the parameters of mercury concentrating by the suspended matter on the seasons and depths of the water areas were determined. It is demonstrated that dissolved mercury forms dominated in the Black Sea during the period under investigation, regardless of the seasons. The concentration of dissolved mercury form in the water of the Black Sea varied from 10.0 to 130.0 ng/L, and the average concentration was 54.9 ng/L. The coefficient of mercury accumulation by suspended matter (K-ss) was determined, which varied within the range (0.01-3.33) . 10(6). The values K-ss > 10(6) provide evidence of the high concentrating capacity of suspended matter in sea water and prevalence of sedimentation over other biogeochemical mechanisms of water self-purification. The formula for calculating the percentage pool of mercury in suspended matter was analysed. The values of the percentage pool of the suspended form of mercury were obtained, ranging from 3.2 to 75 % of the total mercury content in the surface water of the Black Sea for its coastal and open water areas in different seasons of the year.