Ecological Safety of Coastal and Shelf Zones of Sea Ecological Safety of Coastal and Shelf Zones of Sea 2413-5577 20260305 Original paper Concentrations of Nutrients in the Pore Waters of the Sevastopol Bay Bottom Sediments Gurov K. I.
Russian Federation
gurovki@gmail.com Varenik A. V.
Russian Federation
alla.varenik@mhi-ras.ru Myslina M. A.
Russian Federation
myslina@mhi-ras.ru Marine Hydrophysical Institute of RAS Sevastopol Russia 30 09 2026 2026 3 76 92 30 03 2026 20 04 2026 30 06 2026 Copyright © 2026, K. I. Gurov, A. V. Varenik, M. A. Myslina 2026 K. I. Gurov, A. V. Varenik, M. A. Myslina https://creativecommons.org/licenses/by-nc/4.0/ https://ecological-safety.ru/en/repository/issues/2026/03/05/

The paper aims to assess features of the spatio-temporal distribution of nutrient concentrations in the pore waters of the upper sediment layer based on modern in situ data. Samples were collected using a DCh 0.025 bottom grab sampler. Pore water was extracted by centrifugation (Elmi CM 6MT centrifuge). Concentrations of inorganic nutrients were determined photometrically using a KFK 3KM spectrophotometer and a Skalar San++ continuous flow autoanalyser (the Netherlands) after filtration (0.45 µm membrane), except for ammonium samples. Ammonium nitrogen was measured by a modified Sagi–Solorzano method. Correlation coefficients and their significance were calculated using the Statistica software. Qualitative and quantitative characteristics of the spatial distribution of nutrient concentrations in pore waters from the upper sediment layer were obtained for samples collected in Sevastopol Bay in 2024. Seasonal variability was revealed, and relationships with station location, sediment type and geochemical properties of the solid phase were established. In the upper sediment layer of Sevastopol Bay, a weakly alkaline reducing environment predominated: pH and Eh values ranged from 7.1 to 7.8 and from 0 to −270 mV, respectively. Over the year, mean concentrations varied within the following ranges: nitrites were 0.23–0.37 µM; nitrates were 0.71–3.61 µM; phosphates were 11.91–25.84 µM; silicic acid was 21.14–297.30 µM; and ammonium was 139.64–543.76 µM. A negative correlation was found between ammonium and phosphate concentrations and Eh (r = −0.8 and −0.7, respectively), while phosphates and silicic acid showed positive correlations with pH (r = 0.7 and 0.6, respectively). The weakly alkaline reducing conditions observed in the sediments of Sevastopol Bay are the main factor controlling elevated ammonium and phosphate concentrations and low nitrate levels. Intra annual dynamics of nutrient concentrations in pore waters are influenced by hydrological parameters (water temperature), hydrodynamic conditions in different parts of the bay (autumn–winter mixing), as well as by additional local inputs of nutrients with stormwater and sewage discharges.

 Sevastopol Bay bottom sediments redox conditions pore waters nutrients nitrates nitrites phosphorus silicon ammonium The work was carried out under the state assignment of MHI RAS on topic No. FNNN-2024-0001 “Fundamental studies of the processes that determine fluxes of matter and energy in the marine environment and at its boundaries, the state and evolution of the physical and biogeochemical structure of marine systems in modern conditions”.

About the authors:

Konstantin I. Gurov, Researcher, Marine Hydrophysical Institute of RAS (2 Kapitanskaya St., Sevastopol, 299011, Russia), PhD (Geogr.), ORCID ID: 0000-0003-3460-9650, ResearcherID: L-7895-2017, Scopus Author ID: 57200248245, gurovki@gmail.com

Alla V. Varenik, Senior Researcher, Marine Hydrophysical Institute of RAS (2 Kapitanskaya St., Sevastopol, 299011, Russia), PhD (Geogr.), ORCID ID: 0000-0001-5033-4576, ResearcherID: H-1880-2014, Scopus Author ID: 56960448000, alla.varenik@mhi-ras.ru

Mariya A. Myslina, Junior Researcher, Marine Hydrophysical Institute of RAS (2 Kapitanskaya St., Sevastopol, 299011, Russia), ORCID ID: 0000-0002-0054-0379, myslina@mhi-ras.ru

Contribution of the authors:

Konstantin I. Gurov – sampling, formulation of the aims and objectives of the study, analysis and synthesis of the research results, preparation of graphic and textual materials, writing of the original draft of the paper

Alla V. Varenik – general scientific supervision of the study, data preparation, discussion of the results of the work, revision of the text

Mariya A. Myslina – data processing, participation in discussion of the paper materials

All the authors have read and approved the final manuscript.

Article text not included.

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