Purpose. The purpose of the work is to analyze the suspended matter (SM) flux in the deep part of the Black Sea, assess its variability and investigate the transformation of its composition under anaerobic conditions based on the data collected in 2021–2022.

Methods and Results. The data were obtained by means of sediment traps installed at five horizons along the transect between Cape Chersonesus and Bosphorus Strait in the Black Sea. The automatic deep-sea sedimentation observatory (AGOS) was installed during the 119^th cruise of the R/V Professor Vodyanitsky and retrieved during the 124^th cruise in 2022. The research covered all the seasons in 2021–2022. To collect the material, two types of traps were incorporated into AGOS: to determine the SM vertical distribution and to study its seasonal variation. The processing of the data was conducted using a uniform methodology, which included filtration, drying, gravimetric analysis for the calculation of suspended particulate matter fluxes, as well as determination of the organic and inorganic carbon contents by the coulometric titration method in the laboratory of Marine Hydrophysical Institute of RAS. The study yielded data on the vertical distribution of SM flux and its seasonal variation. The distribution patterns of SM, as well as the organic and inorganic carbon involved in its composition, were revealed.

Conclusions. The dynamics of SM and carbon fluxes are determined by different physical and biogeochemical processes. The SM fluxes are distributed unevenly across depth and change seasonally throughout the year. An analysis of the integral trap data shows that the SM fluxes exhibit variability across different depths, with a range of 62–99 mg·m⁻²·day⁻¹. At depths of 218 and 1568 m, the intensity is at its maximum. Its decrease depends on various biogeochemical processes, including dissolution, oxidation and mineralization. The increase in SM fluxes can be attributed to both deep-sea currents and physical and chemical sorption processes. The seasonal changes in SM flow are represented by two peaks: the maximum occurs during the period July – September, while the minimum occurs in March. Carbon concentration in SM exhibits fluctuations with depth and across seasonal cycles, which are mainly shaped by biological processes. The discrepancy between the peaks of the coccolithophore bloom at the surface and the maximum values of the inorganic carbon flux recorded by the trap can be explained by the sedimentation rates.