Estimation of Carbon Dioxide Fluxes through the Surface of the Black Sea from Numerical Simulation Results

V. L. Dorofeev, L. I. Sukhikh*

Marine Hydrophysical Institute of RAS, Sevastopol, Russia

* e-mail: l.sukhikh@gmail.com

Abstract

Based on numerical simulation, the paper studies the spatiotemporal distribution of CO2 fluxes through the free surface of the Black Sea. The basic equation for solving this problem is the three-dimensional evolutionary transport–diffusion equation for the concentration of dissolved inorganic carbon. The simulation uses hydrodynamic fields resulting from a previous physical reanalysis as input parameters. A model of the lower level of the Black-Sea ecosystem food chain is used to describe the influence of biological factors on the dissolved carbon dioxide distribution. The concentration and equilibrium partial pressure of dissolved carbon dioxide in the surface layer of the Black Sea were calculated from the numerical simulation results. It is shown that the time dependence of these quantities is highly seasonal. The seawater temperature significantly affects the solubility of carbon dioxide and therefore its fluxes. The equilibrium partial pressure of carbon dioxide averaged over the area of the Black Sea is minimal in January–February and maximal in June–July. Accordingly, in the warm season, the flux of carbon dioxide is directed mainly from the sea to the atmosphere; in the cold season, the sea mainly absorbs carbon dioxide. Biological factors also influence the CO2 content in the sea. Thus, at the beginning of the year, a high concentration of phytoplankton is observed almost throughout the entire Black Sea water area, which is why the absorption of carbon dioxide predominates during photosynthesis. In summer, the release of carbon dioxide predominates due to plankton respiration and oxidation of organic matter. The simulation results are in fairly good agreement with in situ measurements of the partial pressure of dissolved carbon dioxide obtained during scientific cruises.

Keywords

carbonate system, carbon dioxide, partial pressure of carbon dioxide, Black Sea, marine ecosystem, numerical simulation

Acknowledgments

The work was carried out under topic of state assignment of FSBSI FRC MHI FNNN-2023-0001. The authors thank the staff of the Biogeochemistry Department of the FSBSI FRC MHI for providing the results of field data processing.

For citation

Dorofeev, V.L. and Sukhikh, L.I., 2024. Estimation of Carbon Dioxide Fluxes through the Surface of the Black Sea from the Numerical Simulation Results. Ecological Safety of Coastal and Shelf Zones of Sea, (3), pp. 36–48.

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