The paper studies dynamics of carbonate system parameters during the spring-summer coccolithophores bloom using data on temperature, salinity, carbonate system parameters (CO₂, pH and alkalinity) and backscattering index (b_bp(550), m⁻¹) for the northern Black Sea surface waters during the 127th and 131st cruises of R/V Professor Vodyanitsky. Within the studied periods (June 2023, May-June 2024) coccolithophores concentrations exceeded 1.00 million cells/L, while high pCO₂ (mean 486 ± 18 μatm) was also observed. The surface water layer was oversaturated with CO₂ compared to the atmosphere, with a mean water CO₂ supersaturation of 14% (58 μatm). However, no pronounced relationship was found between coccolith concentrations and pCO₂, pH and alkalinity values, which may indicate a non-core contribution of the bloom to CO₂ concentrations in the surface waters. It was found that even during the coccolithophores blooming period, temperature is the key factor determining the surface waters pCO₂. The spatial distribution of suspended matter concentration represented by coccoliths was determined by water dynamics and current structure in the Black Sea.
About the authors:
Natalia A. Orekhova, Head of Laboratory for Monitoring and Research of Greenhouse Gas and Oxygen Fluxes in the Marine Environment, Marine Hydrophysical Institute of RAS (2 Kapitanskaya St., Sevastopol, 299011, Russian Federation), PhD (Geogr.), ORCID ID: 0000-0002-1387-970X, ResearcherID: I-1755-2017, Scopus Author ID: 35784884700, natalia.orekhova@mhi-ras.ru
Elena N. Korchemkina, Senior Research Associate, Marine Hydrophysical Institute of RAS (2 Kapitanskaya Str., Sevastopol, 299011, Russian Federation), PhD (Phys.-Math.), ORCID ID: 0000-0003-0526-4083, ResearcherID: I-1595-2015, Scopus Author ID: 23004799100, korchemkina@mhi-ras.ru
Eugene V. Medvedev, Junior Research Associate, Marine Hydrophysical Institute of RAS (2 Kapitanskaya St., Sevastopol, 299011, Russian Federation), ORCID ID: 0000-0003-0624-5319, ResearcherID: C-7016-2016, eugenemedvedev@mhi-ras.ru
Igor N. Mukoseev, Senior Research Associate, Marine Hydrophysical Institute of RAS (2 Kapitanskaya St., Sevastopol, 299011, Russian Federation), ORCID ID: 0009-0000-3485-1004, igor.mukos@gmail.com
Contribution of the authors:
Natalia A. Orekhova – concept statement, study tasks statement, analysis and summary of the study results
Elena N. Korchemkina – concept statement, analysis and summary of the study results, preparation of the article text
Eugene V. Medvedev – participation in discussion of the results, analysis and summary of the study results, preparation of the article text
Igor N. Mukoseev – preparation of the article materials
All the authors have read and approved the final manuscript.