SPATIO-TEMPORAL FEATURES OF THE NUTRIENTS DYNAMICS IN THE NORTHEASTERN BLACK SEA
Spatio-temporal dynamics of nutrients in the deep and coastal waters of the Black Sea for the long- term period of 1996-2018 was investigated. The research was carried out in the spring (March-April-May) and summer-autumn (August-September) periods of the year. Samples were collected at a standard depth down to 200 m. It has been shown that in the deep-water area of the Black Sea, seasonal dynamics of nutrients and their distribution extremes are closely related to biological and hydrological processes in the water column. During upwelling phenomena, supplementing of the active layer with mineral nitrogen and phosphorus is observed. Accumulation of organic forms of nitrogen- and phosphorus-containing compounds during a photosynthetic process is accompanied by depletion of their mineral constituent. The dynamics of biogenic compounds in the coastal part of the sea are much less susceptible to seasonal variation. The main feature of the vertical distribution of biogenic substances in coastal waters is their highest concentration in the surface layer. Among the dynamic factors in the coastal zone, upwelling is of great importance. Detailed analysis of multi-year data from two periods (1960-1970 and 1996-2018) showed the identity of the vertical distribution of nitrogen and phosphorus concentrations in the deep sea with an increase in the portion of the organic component in the active layer in the modern period in comparison with 1960-1970.