Variability of Equilibrium Partial Pressure of Carbon Dioxide (pCO₂) and Concentration of Dissolved Inorganic Carbon (TCO₂) in the Black Sea Coastal Waters in 2010 – 2014

Abstract

Based on direct field measurements of pCO₂ 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 pCO₂ 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 pCO₂ 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 pCO₂ value in seawater achieves its maximum in late spring and minimum – in late autumn–early winter hydrological season. The results of pCO₂ 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 pCO₂ is characteristic of seawater and the higher one – of the atmosphere. Complex character of pCO₂ temporal variability testifies to heterogeneity and different intensity of the factors influencing this value in different seasons.

Keywords

equilibrium partial pressure of carbon dioxide (pCO₂), total dissolved inorganic carbon (TCO₂), diurnal variation of pCO₂ and TCO₂, inter-diurnal changes of pCO₂ and TCO₂, seasonal variations of pCO₂ and TCO₂, the Black Sea coastal waters, upwelling.

DOI: 10.22449/1573-160X-2016-4-34-46

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