The dataset for the chronology of the sedimentation in the Danube abyssal fan which records the major episodes of the late-Holocene Black Sea evolution.

Anoxic marine sediments at the confluence with large rivers are key archives for monitoring the anthropogenic impact in the environment and asses the carbon sink character of oxygen deprived waters. This data article describes the analysis methodology and the results of the deep-sea sediments sampled from the NW part of the Black Sea, using the 14C dating, stable carbon isotopes, C/N ratio, metallic traces and 210Pb and 137Cs radioactivity. For this purpose, 26 sediment samples were taken from the MN183-3 sampling point (43.925.917 N, 30.758.911 E, 658 m water depth) using a Mark II-400-type multicorer. The samples were collected during the two weeks Mare Nigrum (MN) #183 marine expedition, which took place at the beginning of September 2018, in the Romanian section of the Black Sea shelf and continental slope. These analyses were employed in the construction of a Bayesian high-resolution sedimentation model, reported in M.Ilie et al. (2022).

Tensor-train approximation of the chemical master equation and its application for parameter inference.

In this work, we perform Bayesian inference tasks for the chemical master equation in the tensor-train format. The tensor-train approximation has been proven to be very efficient in representing high-dimensional data arising from the explicit representation of the chemical master equation solution. An additional advantage of representing the probability mass function in the tensor-train format is that parametric dependency can be easily incorporated by introducing a tensor product basis expansion in the parameter space. Time is treated as an additional dimension of the tensor and a linear system is derived to solve the chemical master equation in time. We exemplify the tensor-train method by performing inference tasks such as smoothing and parameter inference using the tensor-train framework. A very high compression ratio is observed for storing the probability mass function of the solution. Since all linear algebra operations are performed in the tensor-train format, a significant reduction in the computational time is observed as well.

Freshwater lake to salt-water sea causing widespread hydrate dissociation in the Black Sea.

Gas hydrates, a solid established by water and gas molecules, are widespread along the continental margins of the world. Their dynamics have mainly been regarded through the lens of temperature-pressure conditions. A fluctuation in one of these parameters may cause destabilization of gas hydrate-bearing sediments below the seafloor with implications in ocean acidification and eventually in global warming. Here we show throughout an example of the Black Sea, the world's most isolated sea, evidence that extensive gas hydrate dissociation may occur in the future due to recent salinity changes of the sea water. Recent and forthcoming salt diffusion within the sediment will destabilize gas hydrates by reducing the extension and thickness of their thermodynamic stability zone in a region covering at least 2800 square kilometers which focus seepages at the observed sites. We suspect this process to occur in other world regions (e.g., Caspian Sea, Sea of Marmara).

First observations on the abundance and composition of floating debris in the North-western Black Sea.

The occurrence of marine litter in the Black Sea region is poorly known and even less data have been reported on the abundance of floating debris. Here we present results from a ship-based visual survey carried out in the North-Western part of the Black Sea, providing the first preliminary data on the characteristics of floating debris in Romanian waters. High litter densities peaking to 135.9 items/km(2) were found in the study area (mean 30.9 ± 7.4 items/km(2)). Probably due to the proximity of the Danube delta, natural debris were on average, much more abundant than anthropogenic litter in most surveyed locations (mean 141.4 ± 47.1 items/km(2), max 1131.3 items/km(2)). Most of the 225 objects we sighted consisted of pieces of wood and other riparian debris (75.5%), however plastic items remained undoubtedly the most abundant type of litter, representing 89.1% of all sighted man-made items. The Black Sea is not exempt from the global invasion of floating debris, however data are still lacking and a basin-wide survey is urgently needed to identify accumulation areas and develop regionally effective solutions to the problem of marine litter.