Sea-Air CO2 Flux in the Northeastern Part of the Black Sea

A. Orekhova*, E. V. Medvedev, I. N. Mukoseev, A. V. Garmashov

Marine Hydrophysical Institute of RAS, Sevastopol, Russia

* e-mail: natalia.orekhova@mhi-ras.ru

Abstract

Carbon dioxide is one of the green gases and its entry into the atmosphere and further redistribution in the waters of the World Ocean not only plays a significant role in the climate on the Earth, but also affects the characteristics of waters. The research of inland seas, e.g. the Black Sea, makes it possible to study the influence of atmospheric CO2 on the characteristics of waters and to assess the contribution of regional ecosystems to the total budget of the CO2 flux of the World Ocean. The paper presents numerical estimates of the sea–air CO2 flux, analyzes its direction and identifies factors that determine the values of the CO2 flux in the northeastern part of the Black Sea during a cold period. For the analysis, the data obtained during the cruise of R/V Professor Vodyanitsky in December 2022 were used. The values of the sea–air flux of carbon dioxide were calculated taking into account the wind speed and pCO2 gradient between the sea surface and the near sea surface atmosphere. According to the direct measurements of pCO2, the value of the CO2 flux in December 2022 varied widely from ‒0.05 to ‒8.74 mmol·m‒2·day‒1, the average value being ‒2.11 ± 1.79 mmol·m‒2·day‒1. It was established that during the cold season, the CO2 flux was directed from the atmosphere to the sea surface. Thus, the waters of the Crimean coast serve as a stock of atmospheric CO2. Local minima of flux values were observed in the southeastern regions of the Crimean coast. When analyzing the correlation of the CO2 flux with temperature, wind speed and ΔpCO2, the strongest relationship was found with wind speed (‒0.93), while the weakest one was with ΔpCO2 (0.22). Therefore, the intensity of the sea–air CO2 flux was determined by wind speed, while the direction of the flux was determined by ΔpCO2. The temperature contribution manifested as change in the concentration of CO2 in the water column.

Keywords

CO2 flux, Black Sea, carbon dioxide, partial pressure of carbon dioxide, carbon cycle

Acknowledgments

The work was carried out within the framework of grant no. 169-15-2023-002 dated 01.03.2023 of the Federal Service for Hydrometeorology and Environmental Monitoring.

For citation

Orekhova, N.A., Medvedev, E.V., Mukoseev, I.N. and Garmashov, A.V., 2024. Sea-Air CO2 Flux in the Northeastern Part of the Black Sea. Ecological Safety of Coastal and Shelf Zones of Sea, (1), pp. 57–67.

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