Characteristics of State and Evolution of the Black Sea Hydrochemical Structure

A. V. Varenik✉, S. I. Kondratyev, E. V. Medvedev, D. S. Khoruzhiy, N. A. Orekhova

Marine Hydrophysical Institute of RAS, Sevastopol, Russian Federation

✉ e-mail: alla.varenik@mhi-ras.ru

Abstract

Purpose.The purpose of the study is to analyze the features of spatial-temporal and vertical distribution of oxygen, hydrogen sulfide and main nutrients (phosphates, nitrates, ammonium and silica acid), as well as the characteristics of carbonate system in the Black Sea in the modern period .

Methods and Results. The data used in the study were obtained by the scientists of Marine Hydrophysical Institute in the scientific cruises in the Black Sea in 2013–2021 within the economic zone of Russia. During these cruises, more than 200 deep-sea stations were carried out, samples were taken using a cassette of 12 bathometers of the Sea-Bird 911 plus CTD Seabird-Electronics INC device at certain isopycnic surfaces. At the coastal shallow-water stations, samples were taken from the surface and near-bottom horizons. Precipitations were sampled by automatic precipitation collectors at the meteorological stations located on Pavlovsky Cape in Sevastopol and at the Black Sea hydrophysical subsatellite polygon (the Southern coast of Crimea).

Conclusions. The location of upper boundary of the suboxic zone varies from σt = 15.7 kg/m3 to σt = 15.9 kg/m3, that in the depth scale corresponds to the interval of ⁓ 40 m. The vertical distribution of hydrogen sulfide is more of isopycnic character, the boundary of isosulfide 3 µM appearing is located within σt = 16.10–16.15 kg/m3. On the vertical profile of nitrates, their maximum concentration not exceeding 4 µM, is observed within the range σt = 15.2–15.5 kg/m3. It is shown that the content of oxidized nitrogen forms has almost returned to the pre-eutrophication level. The concentration of ammonium ions in the aerobic and suboxic zones predominantly does not exceeds 0.5 µM, the ammonium concentration starts to increase at the depth of isopycne σt = 16.10–16.15 kg/m3, at which hydrogen sulfide appears. The maximum concentrations of ammonium ions (96 ± 5 µM) were noted at the depth 1800 m and below that corresponded to the earlier obtained data. The phosphates vertical distribution is characterized by their minimum (˂ 0.5 µM) content at σt = 15.8 kg/m3 and by their maximum one (not more than 8 µM) at σt = 16.2 kg /m3. The hydrogen sulfide content at the depths exceeding 1750 m in the Black Sea is currently 383 ± 2 µM. The pH value of surface waters was 8.29–8.38 decreasing to 7.67 below ~ 50 m. Total alkalinity varied within the range 3268–3335 µM, below σt = 16 kg/m3 it increased sharply reaching its maximum value ~ 4364 µM in the bottom layer. The results obtained confirm the immutability of the previously established features of the vertical distribution of hydrochemical components and the ranges of their concentration variations. The spatial distribution of nutrients clearly shows a decrease in their concentrations from the coastal areas to the deep-sea ones. One of the largest external sources of nutrients the Black Sea waters is atmospheric precipitations. On the synoptic spatial-temporal scales, they can become the main source of inorganic nitrogen, phosphate and silica entering the sea surface layer.

Keywords

Black Sea, hydrogen sulfide, nutrients distribution, atmospheric deposition, hydrochemical regime

Acknowledgements

The investigation was carried out within the framework of the theme of state assignments FNNN 2021-0004 “Fundamental studies of oceanological processes, which determine state and evolution of marine environment influenced by natural and anthropogenic factors, based on the observation and modeling methods”.

Original russian text

Original Russian Text © The Authors, 2023, published in MORSKOY GIDROFIZICHESKIY ZHURNAL, Vol. 39, Iss. 6, pp. 867–892 (2023)

For citation

Varenik, A.V., Kondratyev, S.I., Medvedev, E.V., Khoruzhiy, D.S. and Orekhova, N.A., 2023. Characteristics of State and Evolution of the Black Sea Hydrochemical Structure. Physical Oceanography, 30(6), pp. 826-850.

References

  1. Murray, J.W., ed., 1991. Black Sea Oceanography: Results from the 1988 Black Sea Expedition. Deep Sea Research Part A. Oceanographic Research Papers, 38(Suppl. 2), pp. S655-S1266.
  2. Murray J.W., Gilbert P.M. and Pitcher G.C., eds., 2005. Black Sea Oceanography, Harmful Algal Blooms. Oceanography, vol. 18, no. 2. Rockville, Maryland, U.S.: TOS, 262 p.
  3. Konovalov, S.K. and Murray, J.W., 2001. Variations in the Chemistry of the Black Sea on a Time Scale of Decades (1960–1995). Journal of Marine Systems, 31(1-3), pp. 217-243. doi:10.1016/S0924-7963(01)00054-9
  4. Konovalov, S.K. and Eremeev, V.N., 2012. [Regional Features, Stability and Evolution of the Biogeochemical Structure of the Black Sea Waters]. In: V. N. Eremeev and S. K. Konovalov, eds., 2012. [Stability and Evolution of Oceanological Characteristics of the Black Sea Ecosystems]. Sevastopol: ECOSI-Gidrofizika, pp. 273-299 (in Russian).
  5. Krivosheya, V.G., Ovchinnikov, I.M. and Skirta, A.Yu., 2002. [Interannual Variability of the Cold Intermediate Layer Renewal in the Black Sea]. In: A. G. Zatsepin and M. V. Flint, eds., 2002. Multidisciplinary Investigations of the Northeast Part of the Black Sea. Moscow: Nauka, pp. 27-39 (in Russian).
  6. Belokopytov, V.N., 2011. Interannual Variations of the Renewal of Waters of the Cold Intermediate Layer in the Black Sea for the Last Decades. Physical Oceanography, 20(5), pp. 347-355. doi:10.1007/s11110-011-9090-x
  7. Miladinova, S., Stips, A., Garcia-Gorriz, E. and Macias Moy, D., 2018. Formation and Changes of the Black Sea Cold Intermediate Layer. Progress in Oceanography, 167, pp. 11-23. doi:10.1016/j.pocean.2018.07.002
  8. Stevens, C.J., David, T.I. and Storkey, J., 2018. Atmospheric Nitrogen Deposition in Terrestrial Ecosystems: Its Impact on Plant Communities and Consequences across Trophic Levels. Functional Ecology, 32(7), pp. 1757-1769. doi:10.1111/1365-2435.13063
  9. Duce, R.A., LaRoche, J., Altieri, K., Arrigo, K.R., Baker, A.R., Capone, D.G., Cornell, S., Dentener, F., Galloway, J. [et al.], 2008. Impacts of Atmospheric Anthropogenic Nitrogen on the Open Ocean. Science, 320(5878), pp. 893-897. doi:10.1126/science.1150369
  10. Mahowald, N., Lindsay, K., Rothenberg, D., Doney, S.C., Moore, J.K., Thornton, P., Randerson, J.T. and Jones, C.D., 2011. Desert Dust and Anthropogenic Aerosol Interactions in the Community Climate System Model Coupled-Carbon-Climate Model. Biogeosciences, 8(2), pp. 387-414. doi:10.5194/bg-8-387-2011
  11. Yadav, K., Sarma, V.V.S.S., Rao, D.B. and Dileep Kumar, M., 2016. Influence of Atmospheric Dry Deposition of Inorganic Nutrients on Phytoplankton Biomass in the Coastal Bay of Bengal. Marine Chemistry, 187, pp. 25-34. https://doi.org/10.1016/j.marchem.2016.10.004
  12. Doney, S.C., Mahowald, N.M., Lima, I.D., Feely, R.A., Mackenzie, F.T., Lamarque, J.-F. and Rasch, P.J., 2007. Impact of Anthropogenic Atmospheric Nitrogen and Sulfur Deposition on Ocean Acidification and the Inorganic Carbon System. PNAS, 104(37), pp. 14580-14585. doi:10.1073/pnas.0702218104
  13. Kumari, V.R., Yadav, K., Sarma, V.V.S.S. and Dileep Kumar, M., 2021. Acidification of the Coastal Bay of Bengal by Aerosol Deposition. Journal of Earth System Science, 130, 223. doi:10.1007/s12040-021-01723-x
  14. Boyd, P.W., Mackie, D.S. and Hunter, K.A., 2010. Aerosol Iron Deposition to the Surface Ocean – Modes of Iron Supply and Biological Responses. Marine Chemistry, 120(1-4), pp. 128-143. doi:10.1016/j.marchem.2009.01.008
  15. Goyet, C., Bradshaw, A.L. and Brewer, P.G., 1991. The Carbonate System in the Black Sea. Deep Sea Research Part A. Oceanographic Research Papers, 38(Suppl. 2), pp. S1049-S1068. doi:10.1016/S0198-0149(10)80023-8
  16. Makkaveev, P.N., 1996. Dissolved Inorganic Carbon and Total Alkalinity in Anoxic Waters of the Black Sea. Oceanology, 35(4), pp. 494-499.
  17. Hiscock, W.T. and Millero, F.J., 2006. Alkalinity of the Anoxic Waters in the Western Black Sea. Deep Sea Research Part II: Topical Studies in Oceanography, 53(17-19), pp. 1787-1801. doi:10.1016/j.dsr2.2006.05.020
  18. Kondratev, S.I., Medvedev, E.V. and Konovalov, S.K., 2017. Forecast of Circulation Processes and Propagation of Oil Pollution in the Eastern Black Sea Based on the Regional Complex Model. Physical Oceanography, (4), pp. 35-45. doi:10.22449/1573-160X-2017-4-35-45
  19. Kondratev, S.I. and Vidnichuk, A.V., 2018. Features of the Oxygen and Hydrogen Sulfide Vertical Distribution in the Black Sea Based on the Expedition Data Obtained by Marine Hydrophysical Institute in 1995–2015. Physical Oceanography, 25(5), pp. 390-400. doi:10.22449/0233-7584-2018-5-390-400
  20. Kondratev, S.I. and Vidnichuk, A.V., 2020. Vertical Distribution of Oxygen and Hydrogen Sulphide in the Black Sea in 2016. Vestnik Moskovskogo Universiteta. Seriya 5, Geografiya, (3), pp. 91-99 (in Russian).
  21. Kondratev, S.I. and Khoruzhii, D.S., 2021. Vertical Distribution of Phosphates in the Black Sea Based on the Expeditionary Data, 2016–2019. Physical Oceanography, 28(5), pp. 538-548. doi:10.22449/1573-160X-2021-5-538-548
  22. Kondratev, S.I., Varenik, A.V. and Orekhova, N.A., 2023. Inorganic Forms of Nitrogen in the Deep Part of the Black Sea Based on the Expeditionary Data, 2016–2019. Physical Oceanography, 30(2), pp. 186-201. doi:10.29039/1573-160X-2023-2-186-201
  23. Carpenter, J.H., 1965. The Chesapeake Bay Institute Technique for the Winkler Dissolved Oxygen Method. Limnology and Oceanography, 10(1), pp. 141-143. doi:10.4319/lo.1965.10.1.0141
  24. Solórzano, L., 1969. Determination of Ammonia in Natural Waters by the Phenolhypochlorite Method. Limnology and Oceanography, 14(5), pp. 799-801. doi:10.4319/lo.1969.14.5.0799
  25. Grasshoff, K., Ehrhardt, M. and Kremling, K., eds., 1983. Methods of Seawater Analysis. Weinheim: Verlag Chemie, 419 p.
  26. Ivanov, V.A. and Belokopytov, V.N., 2013. Oceanography of the Black Sea. Sevastopol: ECOSI-Gidrofizika, 210 p.
  27. Artamonov, Yu.V., Skripaleva, E.A., Fedirko, A.V., Shutov, S.A., Derjushkin, D.V., Shapovalov, R.O., Shapovalov, Yu.I. and Shcherbachenko, S.V., 2020. Waters Circulation in the Northern Part of the Black Sea in Summer – Winter of 2018. Ecological Safety of Coastal and Shelf Zones of Sea, (1), pp. 69-90. doi:10.22449/2413-5577-2020-1-69-90 (in Russian).
  28. Grégoire, M., Beckers, J.M., Friederich, J., Konovalov, S., Kostianoy, A., Nezlin, N., Stanev, E. and Nihoul, J., 2003. Nitrogen Budget on the Shelf and Slope Area of the Black Sea Basin as Inferred from Modeling Experiments. In: A. Yilmaz, ed., 2003. Oceanography of the Eastern Mediterranean and Black Sea. Ankara, Turkey: TUBITAK, pp. 314-321.
  29. Dzhiganshin, G.F., Polonskii, A.B. and Muzyleva, M.A., 2010. Upwelling in the Northwest Part of the Black Sea at the End of the Summer Season and Its Causes. Physical Oceanography, 20(4), pp. 281-293. doi:10.1007/s11110-010-9084-0
  30. Millero, F.J., 2007. The Marine Inorganic Carbon Cycle. Chemical Reviews, 107(2), pp. 308-341. doi:10.1021/cr0503557
  31. Zeebe, R.E. and Wolf-Gladrow, D., 2001. CO2 in Seawater: Equilibrium, Kinetics, Isotopes. Amsterdam: Elsevier, 360 p.
  32. Capet, A., Vandenbulcke, L. and Grégoire, M., 2020. A New Intermittent Regime of Convective Ventilation Threatens the Black Sea Oxygenation Status. Biogeosciences, 17(24), pp. 6507-6525. doi:10.5194/bg-17-6507-2020
  33. Vidnichuk, A.V. and Konovalov, S.K., 2021. Changes in the Oxygen Regime in the Deep Part of the Black Sea in 1980–2019. Physical Oceanography, 28(2), pp. 180-190. doi:10.22449/1573-160X-2021-2-180-190
  34. Tuğrul, S., Murray, J.W., Friederich, G.E. and Salihoğlu, I., 2014. Spatial and Temporal Variability in the Chemical Properties of the Oxic and Suboxic Layers of the Black Sea. Journal of Marine Systems, 135, pp. 29-43. doi:10.1016/j.jmarsys.2013.09.008
  35. McCarthy J.J., Yilmaz, A., Coban-Yildiz, Y. and Nevins, J.L., 2007. Nitrogen Cycling in the Offshore Waters of the Black Sea. Estuarine, Coastal and Shelf Science, 74(3), pp. 493-514. doi:10.1016/j.ecss.2007.05.005
  36. Fuchsman, C.A., Paul, B., Staley, J.T., Yakushev, E.V. and Murray, J.W., 2019. Detection of Transient Denitrification during a High Organic Matter Event in the Black Sea. Global Biogeochemical Cycles, 33(2), pp. 143-162. doi:10.1029/2018GB006032
  37. Murray, J.W., Konovalov, S.K. and Callahan, A., 2003. Nitrogen Reactions in the Suboxic Zone of the Black Sea: New Data and Models. In: A. Yilmaz, ed., 2003. Oceanography of the Eastern Mediterranean and Black Sea. Ankara, Turkey: TUBITAK, pp. 591-602.
  38. Eremeeva, L.V., Romanov, A.S. and Ovsyanyj, E.I., 1995. [Hydro-Chemical Studies in the 33rd Cruise of R/V Professor Kolesnikov]. Sevastopol: MHI, 42 p. (in Russian).
  39. Krastev, A., Shtereva, G., Hristova, O. and Dzhurova, B., 2006. Nutrients in the Western Black Sea Area. Spatial and Vertical Distribution. In: Proceeding of the 1st Biannual Scientific Conference: Black Sea Ecosystem 2005 and Beyond. Istanbul, Turkey, pp. 93-105.

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