The Relation between the Grain Size Composition of the Sediments from the NW Black Sea and their Total Organic Carbon (TOC) Content

Abstract: The relation between the grain size composition TOC (total organic carbon) concentration was examined by linear and non-linear regression analysis of analytical data for more than 500 sediment samples from the NW Black Sea. A significant dependency of the TOC concentration on the percentages of clay and especially the <16 μm fraction (clay plus fine and very fine silt) was identified, the model best fitting the analytical data being exponential. Three groups of sediment samples were identified using the K-means clustering technique, the deep sea sediment samples being clearly singled out

Late Holocene microfaunal and nannofloral assemblages of the NW Black Sea

Abstract. This study describes the fluctuation pattern in Late Holocene microfaunal (i.e. foraminifera and ostracods) and nannofloral assemblages of two cores collected from the Romanian Black Sea shelf, at a water depth of 28 and 66 m, respectively. The lithology of the cores is mainly characterised by blackish muds, alternating with thin, centimetres-thick sand and coquina layers. The microfaunas are dominated by brackish foraminiferal and ostracod assemblages that are still common in the actual Black Sea communities, living nowadays at water salinity lower than 18 ‰. In the shallower water Site EF 08-01, the abundance ratio between Caspian and Mediterranean ostracods is 0.7, while in the deeper water Site BS 08-055, the abundance ratio between Caspian and Mediterranean ostracods is 0.01. These data argue for the dominance of Mediterranean ostracod fauna with lower abundance in shallower environments of the Black Sea and with a very high abundance in the deeper parts of the internal shelf, i.e., at a water depth of 66 m. Based on the calcareous nannoplankton fluctuation, four Nannofloral Intervals were identified, which indicate a gradual salinity increase of the surface waters during the deposition of the Late Holocene Shallow Unit. In the same interval, the benthic microfaunas (ostracods and foraminifers) argue for a more stable salinity environment in the two studied cores from the Black Sea inner shelf

Trace element contamination in the arms of the Danube Delta (Romania/Ukraine): Current state of knowledge and future needs

This paper provides the first critical synopsis of contamination by selected trace elements in the whole Danube Delta (Romania/Ukraine) to: identify general patterns of contamination by trace elements across the Delta, provide recommendations to refine existing monitoring networks and discuss the potential toxicity of trace elements in the whole Delta. Sediment samples were collected between 2004 and 2007 in the three main branches of the Delta (Chilia, Sulina and Sfantu Gheorghe) and in the secondary delta of the Chilia branch. Samples were analyzed for trace elements (Cd, Co, Cr, Cu, Ni, Pb, V, and Zn) and TiO2, Fe2O3, MnO, CaCO3 and total organic carbon. Cluster analysis (CA) and Principal Component Analysis (PCA) showed that levels of Cd, Cu, Pb, and Zn were influenced by anthropogenic activities. At the opposite, concentrations of Cr and Ni largely originated from the weathering of rocks located in the Romanian part of the Danube catchment and naturally rich in these elements. Data analysis using Self- Organizing Maps confirmed the conclusions of CA/PCA and further detected that the contamination tended to be higher in the Chilia and Sulina arms than in the Sfantu Gheorghe arm. The potential ecological risks due to trace element contamination in the Danube Delta could be identified as moderate and localized, provided that the presence of the natural sources of Cr and Ni was properly considered. The available results suggest that monitoring sediment quality at the mouths of Sulina and Sfantu Gheorghe arms is probably enough to get a picture of the sediment quality along their entire lengths. However, a larger network of monitoring points is necessary in the Chilia and secondary Chilia delta to account for the presence of local point sources and for the more complex hydrodynamic of this part of the Danube Delta

A MSFD complementary approach for the assessment of pressures, knowledge and data gaps in Southern European Seas : the PERSEUS experience

PERSEUS project aims to identify the most relevant pressures exerted on the ecosystems of the Southern European Seas (SES), highlighting knowledge and data gaps that endanger the achievement of SES Good Environmental Status (GES) as mandated by the Marine Strategy Framework Directive (MSFD). A complementary approach has been adopted, by a meta-analysis of existing literature on pressure/impact/knowledge gaps summarized in tables related to the MSFD descriptors, discriminating open waters from coastal areas. A comparative assessment of the Initial Assessments (IAs) for five SES countries has been also independently performed. The comparison between meta-analysis results and IAs shows similarities for coastal areas only. Major knowledge gaps have been detected for the biodiversity, marine food web, marine litter and underwater noise descriptors. The meta-analysis also allowed the identification of additional research themes targeting research topics that are requested to the achievement of GES. 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license.peer-reviewe

Upper Holocene Calcareous Nannoplankton of the NW Black Sea.

Abstract. The investigations focused on two profiles from the Black Sea, placed in front of the Portiţa Mouth and in the south-eastern part of the Sahalin Island. Up to 40 m water depth, the samples from the Portiţa profile contain only reworked Mesozoic and Cenozoic calcareous nannoplankton taxa. In the same profile, the bloom of the calcareous nannoplankton species Emiliania huxleyi, together with abundant benthic foraminiferal taxa, were recorded in the first 11 cm of sediments, at below 40 m water depth. All the samples collected in the SE of Sahalin Island contain only Mesozoic and Cenozoic reworked calcareous nannoplankton taxa; no marine assemblages in situ were remarked

The National Institute of Research and Development for Marine Geology and Geoecology – GeoEcoMar: Twenty years of scientific activity

The National Institute of Research and Developmentfor Marine Geology and Geoecology – GeoEcoMar was created in 1996 according to the Governmental Decision 1315/25.11.1996, by reorganizing the Romanian Centre for Marine Geology and Geo-ecology CRGGM (founded in 1993). Presently the National Institute of Marine Geology and Geoecology - GeoEcoMar is the Romanian pole of excellence for research in marine, coastal and fluvial geology, geophysics and geo-ecology, as well as an international reference centre for Marine and Earth Sciences in the Black Sea region. In the last twenty years, GeoEcoMar has experienced a continuous scientific and financial growth, both at national and international levels. Since 1996 an “institute of national interest” due to its technical potential and scientific performances, GeoEcoMar`s main objective is to perform complex and multidisciplinary researches of sea – delta – river macro-systems, having as key focus the Black Sea – Danube Delta – Danube River system

Maps of the topography of water surface levels in the Danube Delta, between the main branches

Within the project “Hydrological Monitoring of Wetland Areas Using SAR Techniques (Hydro-SAR)”, concluded by the TERRASIGNA (Romania) with the European Space Agency (ESA), the task of GeoEcoMar was to track and check the correlation of data provided by InSAR techniques with ground observations and measurements in the Danube Delta. Activities in the field and laboratory enabled elaboration of maps of vector fields for the water flow directions on the Danube Delta territory, based on the relief of the water surface levels at 450, 400, 350, 300, 250, 200, 150, 100, 50 and 0 cm, measured at Tulcea hydrologic station. In order to elaborate the maps of water surface levels, the altimetric stability of hydrometric gauges from the Danube Delta territorry was checked by establishing the Earth crust subsidence in each gauge location. Interpretation of recorded data shows a relative low subsidence rate for the location of the hydrometric gauge in Tulcea (observations recorded for the period 1858-2013) selected as hydrometric reference point, with the origin of the zero of the gauge situated at 0.57 m altitude relative to the Black Sea – Sulina reference system. The paper presents isoline maps of the water surface levels on the surface of the Danube Delta between the main distributaries (Chilia – Sulina – Sf. Gheorghe), for the above mentioned water surface levels

Danube River: sedimentological, mineralogical and geochemical characteristics of the bottom sediments

Abstract. For a better understanding of the recent pollution in the lower Romanian sector of the Danube and its relations with human activities, yearly investigations have been carried out on 50 cross sections, between km 1072 - Bazias and the Danube mouths, using R/V Istros. The field activity was performed on three main sections, each with different geological, morphological and hydrological features: Iron Gates I and II dam lakes, km 845 – Mile 44, and the Danube Delta area. Physical and chemical investigations were performed on bottom sediment and surface water samples. Biological samples were collected and investigated as well. The 2005 results allowed an assessment of the Danubian aquatic environment, the comparison of present and previously collected data and the identification of significantly sensitive areas. Mitigation strategies according to the EU requirements are proposed

The interplay between tectonics, sediment dynamics and gateways evolution in the Danube system from the Pannonian Basin to the western Black Sea

Understanding the natural evolution of a river–delta–sea system is important to develop a strong scientific basis for efficient integrated management plans. The distribution of sediment fluxes is linked with the natural connection between sediment source areas situated in uplifting mountain chains and deposition in plains, deltas and, ultimately, in the capturing oceans and seas. The Danube River–western Black Sea is one of the most active European systems in terms of sediment re-distribution that poses significant societal challenges. We aim to derive the tectonic and sedimentological background of human-induced changes in this system and discuss their interplay. This is obtained by analysing the tectonic and associated vertical movements, the evolution of relevant basins and the key events affecting sediment routing and deposition. The analysis of the main source and sink areas is focused in particular on the Miocene evolution of the Carpatho-Balkanides, Dinarides and their sedimentary basins including the western Black Sea. The vertical movements of mountains chains created the main moments of basin connectivity observed in the Danube system. Their timing and effects are observed in sediments deposited in the vicinity of gateways, such as the transition between the Pannonian/Transylvanian and Dacian basins and between the Dacian Basin and western Black Sea. The results demonstrate the importance of understanding threshold conditions driving rapid basins connectivity changes superposed over the longer time scale of tectonic-induced vertical movements associated with background erosion and sedimentation. The spatial and temporal scale of such processes is contrastingly different and challenging. The long-term patterns interact with recent or anthropogenic induced modifications in the natural system and may result in rapid changes at threshold conditions that can be quantified and predicted. Their understanding is critical because of frequent occurrence during orogenic evolution, as commonly observed in the Mediterranean area and discussed elsewhere