Variability of Equilibrium Partial Pressure of Carbon Dioxide (pCO(2)) and Concentration of Dissolved Inorganic Carbon (TCO2) in the Black Sea Coastal Waters in 2010-2014

Based on direct field measurements of pCO(2) and TCO2 carried out in 2010-2014 in the Black Sea coastal waters, dynamics of inorganic carbon on different time scales is considered. It is shown that the highest variability of both parameters on a small time scale is observed during the seawater spring warming resulting from the upwelling impact. The diurnal variations of the pCO(2) and TCO2 values (in course of the analogous period) demonstrate no pronounced tendencies; they are characterized by significant inter-annual variability. In course of summer and autumn-winter hydrological seasons, the diurnal variation of pCO(2) and TCO2 is insignificant. The minimum values of TCO2 are observed in summer and autumn-winter, whereas the maximum ones - in spring during upwelling. The pCO(2) value in seawater achieves its maximum in late spring and minimum - in late autumn-early winter hydrological season. The results of pCO(2) measurements in a warm season prove the previous notions on the Black Sea waters as a source of CO2 emission to the atmosphere. Carbon dioxide is assumed to be more intensively bound and transformed into the other forms of inorganic carbon in a cold season. Possible reason of this phenomenon can consist in increase of the suspended matter inflow to the water area due to more frequent storms and growth of the terrigenous runoff volume. In cold season, the lower pCO(2) is characteristic of seawater and the higher one - of the atmosphere. Complex character of pCO(2) temporal variability testifies to heterogeneity and different intensity of the factors influencing this value in different seasons.