The Pliocene deposits of the Black Sea Shelf east of the Danube River Delta

2020 ◽  
pp. SP505-2019-102
Author(s):  
Petro F. Gozhik ◽  
Valery E. Rokitsky
Keyword(s):  
Black Sea ◽  
River Delta ◽  
Danube River ◽  
Core Material ◽  
The Black Sea ◽  
Danube Delta ◽  
The Danube River ◽  
Continental Deposits ◽  
Circular Current ◽  
The One

AbstractThis paper provides analysis of the published materials on the occurrences of the Dacian and Cimmerian molluscs in the Danube River valley as well as the results of Pliocene sediments study based on core material of the boreholes drilled at the Black Sea Shelf east of the Danube River Delta.In the early Pontian time, the Dacian Basin was a large sub-basin of Paratethys which, due to an abrupt drop in sea level, separated into the Euxinian, Dacian and Caspian basins. At the end of the Bosphorus time, the discharge of the Dacian Basin waters into the Euxinian Basin formed a wide valley from the Galati-Reni region to the east through the Galati gateway. During the Cimmerian transgression, a vast bay existed on the site of the modern Danube Delta, from which mutual migrations of the Dacian and Cimmerian molluscs took place along the runoff valley. The cessation of runoff occurred during the regressive phase of the Late Cimmerian. The rhythmically bedded thick strata originated during the existence of the runoff valley. These strata were identified as the Pridanubian Formation (Suite). The cryptogenic form of Tulotoma Tulotoma (=Viviparus) ovidii nasonis (Bogachev) is characteristic of the lower and middle parts of the suite. The presence of the Dacian and Cimmerian molluscs in this suite became the basis for the correlation of sediments of the Dacian and Cimmerian regional stages. The Duabian molluscs were registered in the Cimmerian deposits of the Transcaucasus (the Duabian layers), Priazovye and the Kerch–Taman region. The migration of these molluscs took place during the regressive phases due to the circular current in the Euxinian Basin similar to the one existing in the Black Sea today.The Pliocene formation contains marine and continental deposits of the Lower and Upper Pliocene, which are represented by the Pridanubian Formation (Lower and Upper), Cimmerian deposits (non-subdivided Lower and Middle Cimmerian), Lower Kujalnician deposits, Upper Poration deposits, complex of red-coloured palaeosols (the Upper Miocene–Lower Pliocene non-subdivided).The formation of the Pliocene sediments on the Black Sea Shelf, east of the Danube Delta, was controlled by the inter-basin connectivity of the Eastern Paratethys.

High-resolution dataset assessing methane concentrations and modelling the carbon dynamics within Europe's second largest delta, the Danube River Delta

2020 ◽  
Author(s):  
Anna Canning ◽  
Arne Körtzinger
Keyword(s):  
High Resolution ◽  
Dissolved Inorganic Carbon ◽  
Hot Spot ◽  
River Delta ◽  
Danube River ◽  
The Black Sea ◽  
Small Scale ◽  
Spatial And Temporal Variability ◽  
Diel Variation ◽  
The Danube River

<p>Wetlands are known to be significant sources for CH<sub>4</sub>, yet vary between potential sources and sinks for CO<sub>2</sub>. However, in regards to the budgets and processes, they are still considered to have high uncertainties, inconsistencies and a general lack of data overall. One key wetland region in Europe is the Danube River Delta. It is the second largest delta in Europe, consisting of the vastest compact reed bed zone in the world, intertwined with rivers, lakes and channels. It is sourced with water from a drainage basin of 817,000 km<sup>2</sup>, with the Danube River originating in Germany before travelling 2,857 km to the Black Sea. However, considering the potential pollution effects within this terminal zone, as well as the delta being one of the most important wetlands in Europe for its ecological value alone (and therefore fragile), few studies have focused on the dynamics within the carbon cycle. During 2017, three field campaigns across three seasons measured high resolution, small-scale spatial and temporal variability for pCO<sub>2</sub>, CH<sub>4</sub>, O<sub>2</sub> and ancillary parameters within the lakes, rivers and channels with the use of a surface water flow-through package. Given the flexibility of the system, we were able to conduct day-night cycles and extensive mapping transects. We discovered day-night cycles showing significant variation of CH<sub>4</sub> concentrations within the lakes and channels, as well ‘hot spot’ anomalies showing potential ground water sourcing and extreme CH<sub>4</sub> concentrations flowing in from the reed beds. Although reasoning for supersaturation in surface waters are under continuous debate, we conclude a potential reason for such dynamic diel variation within the lake may be due to biomass decomposition and extensive macrophyte concentrations creating a temporarily anoxic zone during the day with mixing during the night, such as previously suggested. On top of this, with the use of discrete data collected from the same water source simultaneously, we were able to model alkalinity, dissolved inorganic carbon and pH to examine both 24 h cycles across lakes and day-night dynamics, giving an in-depth glimpse into the carbonate system. Through the extensive mapping, we successful extracted diel variations for pCO<sub>2</sub> and the carbonate species across the lakes with the use of just day-light data, allowing for spatial and temporal variations to be distinguished. We confirm the boundaries between channels and lakes are intertwined as much as they are with the wetlands, and how small extreme anomalies can only begin to be explained with such high-resolution data, even more so in combination with modelled data.</p>

scholarly journals Spatio-temporal variations of lateral and atmospheric carbon fluxes from the Danube Delta

2020 ◽  
Author(s):  
Marie-Sophie Maier ◽  
Cristian R. Teodoru ◽  
Bernhard Wehrli
Keyword(s):  
Surface Area ◽  
Black Sea ◽  
Carbon Emissions ◽  
Danube River ◽  
The Black Sea ◽  
Danube Delta ◽  
Carbon Turnover ◽  
Carbon Yield ◽  
River Deltas ◽  
Net Export

Abstract. River deltas with their mosaic of ponds, channels and seasonally inundated areas act as the last continental hotspots of carbon turnover along the land-ocean aquatic continuum. There is increasing evidence for the important role of riparian wetlands in the transformation and emission of terrestrial carbon to the atmosphere. The considerable spatial heterogeneity of river deltas, however, forms a major obstacle for quantifying carbon emissions and their seasonality. While river reaches crossing the delta can serve as reference systems, delta lakes are often dominated by aquatic production and channels act as collection systems for carbon exported from adjacent wetlands. In order to quantify carbon turnover and emissions in the complex mosaic of the Danube Delta, we conducted monthly field campaigns over two years at 19 sites spanning river reaches, channels and lakes. Here we report greenhouse gas fluxes (CO2 and CH4) from the freshwater systems of the Danube Delta and present the first seasonally resolved estimates of its freshwater carbon emissions to the atmosphere. Furthermore, we quantify the lateral carbon transport of the Danube River to the Black Sea. We estimate the delta’s CO2 and CH4 emissions to be 65 GgC yr−1, of which about 8 % are released as CH4. The median CO2 fluxes from river branches, channels and lakes are 25, 93 and 5.8 mmol m−2 yr−1, respectively. Median total CH4 fluxes amount to 0.42, 2.0 and 1.5 mmol m−2 yr−1. While lakes do have the potential to act as CO2 sinks in summer, they are generally the largest emitters of CH4. Small channels showed the largest range in emissions including a CO2 and CH4 hotspot sustained by adjacent wetlands. The channels thereby contribute disproportionately to the delta’s emissions considering their limited surface area. In terms of lateral export, we estimate the net export of the Danube Delta to the Black Sea to about 160 GgC yr−1, which only marginally increases the carbon load from the upstream river catchment (8490 GgC yr−1) by about 2 %. While this contribution of the delta seems small, deltaic carbon yield (45.6 gC m−2 yr−1, net export load/surface area) is about 4-fold higher than the riverine carbon yield from the catchment (10.6 gC m−2 yr−1).

scholarly journals Sedimentary microplastic concentrations from the Romanian Danube River to the Black Sea

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Iulian Pojar ◽  
Adrian Stănică ◽  
Friederike Stock ◽  
Christian Kochleus ◽  
Michael Schultz ◽  
...  
Keyword(s):  
Black Sea ◽  
Danube River ◽  
The Black Sea ◽  
Danube Delta ◽  
Black Sea Coast ◽  
River Danube ◽  
Terrestrial Environments ◽  
Ultimate Fate ◽  
First Time ◽  
Sea Coast

AbstractA multitude of recent studies have detailed microplastic concentrations in aquatic and terrestrial environments, although questions remain over their ultimate fate. At present, few studies have detailed microplastic characteristics and abundance along a freshwater–marine interface, and considerable uncertainties remain over the modelled contribution of terrestrial and riverine microplastic to the world’s oceans. In this article, for the first time, we detail sedimentary microplastic concentrations along a River–Sea transect from the lower reaches of a major continental river, the River Danube, through the Danube Delta, the Black Sea coast to the Romanian and Bulgarian inner shelf of the Black Sea. Our results indicate that isolated areas of the Danube Delta are still relatively pristine, with few microplastic particles in some of the sediments sampled.

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