scholarly journals Heavy Metals in the Bottom Sediments of the Black Sea Northwestern Shelf in Recent Years

2021 ◽  
Vol 28 (5) ◽  
Author(s):  
I. V. Korablina ◽  
T. O. Barabashin ◽  
N. I. Katalevsky ◽  
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◽  
...  
Keyword(s):  
Black Sea ◽  
Bottom Sediments ◽  
Seasonal Dynamics ◽  
Iron Content ◽  
Anthropogenic Load ◽  
The Black Sea ◽  
Average Characteristic ◽  
The Earth ◽  
Northwestern Shelf ◽  
Characteristic Concentration

Purpose. The study is aimed at investigating metal accumulation in the 0–2 cm layer of the bottom sediments of the Black Sea northwestern shelf over 2000–2020, and at identifying the sea bottom areas subjected to the increased anthropogenic load through comprehensive assessment of the degree of their pollution taking into account their granulometric composition. Methods and Results. The bottom sediments were sampled annually from the 0–2 cm depth at the same stations. The detected metal concentrations were compared with their content in the Earth crust and the background values. The dynamics and trends of the individual metals’ content in the shelf bottom sediments were assessed for the whole period of observations. The notion of the average characteristic concentration of an element is introduced; the procedure for its calculation is represented. The pollution of bottom sediments was analyzed with the regard for the element average characteristic concentration in the bottom sediments of various granulometric types. Increase in the average content of lead, zinc and chromium was revealed from the beginning of the observation period to 2020. The seasonal dynamics of these elements was found in the whole water area under study (as well as the iron content at some areas). Conclusions. Multiple cases of the lead, manganese and chrome concentrations exceeding their content in the Earth crust were recorded; as for zinc and copper, such cases were few and sporadic. The tendencies in variation of the bottom sediments content were determined: the average long-term values of the lead concentration increased by 1.2 times, those of zinc – by 1.6 times, and those of chrome – by 2 times; the concentrations of iron, manganese and copper remained essentially the same. Seasonal dynamics of the zinc, chromium, lead and iron content was shown. For a number of metals, the cases when their absolute content exceeded their average characteristic concentration in the corresponding type of the bottom sediments had been found. The regions subjected to a multi-faceted anthropogenic load were identified; the areas of possible local inflow of the monitored elements were revealed. The bottom sediments sampled in 2019 were the most polluted.

Significance of Mineralogical and Lithologic-Petrographical Rank in the Ranking of Geological Information

2020 ◽  
Vol 42 (4) ◽  
pp. 33-49
Author(s):  
O.V. CHEPIZHKO ◽  
V.V. YANKO ◽  
V.M. KADURIN ◽  
I.M. NAUMKO ◽  
S.M. SHATALIN
Keyword(s):  
Fluid Flow ◽  
Black Sea ◽  
Bottom Sediments ◽  
Oil And Gas ◽  
Sedimentary Cover ◽  
Geochemical Characteristics ◽  
The Black Sea ◽  
Flow Parameters ◽  
Geochemical Parameters ◽  
Geological Information

For the first time the importance of mineralogical and lithological-petrographical ranks in the line of geological information ranks is substantiated for implementation of long-term forecasts, standard and non-standard approaches to research of physical and geochemical parameters as a basis of creation of complex system of forecast criteria and prospecting indicators of hydrocarbons within the sedimentary cover of Black sea based on the theory of global fluid-flows derivation. These criteria have different sensitivity to the object (hydrocarbon deposits) and are therefore ranked. The ranking determined the following parameters: 1) seismic data within the object, obtained by the method of deep seismic sounding, RWM SDP; 2) parameters of tectono-geodynamic structures; 3) the main characteristics of sedimentary cover and bedrock; 4) geochemical characteristics; 5) parameters of mineral complexes and fluid inclusions in mineral neoformations; 6) the value of the distribution of meiobenthos. Based on modern views of oil and gas geology, structural-tectonic and lithological-facies criteria are among the main ones. The study of the mineralogical component of sediments is made with using mineralogical, thermobarogeochemical and X-ray spectral methods. Fixation of anomalies of fluid flow at the bottom of the Black Sea as to the distribution of abiotic parameters in order to assess the prospects of oil and gas is determined by structural and tectonic features and high permeability of fluid flow; parameters of mineral complexes (minerals, facies) and genetic connections; heterogeneity of geochemical characteristics of bottom sediments; the presence of hydrocarbon inclusions in authigenic minerals of bottom sediments.

Anthropogenic Impact on the Lithodynamics of the Coastal Zone of the Southern and Western Black Sea Coast (Review)

2021 ◽  
Author(s):  
T. V. Efremova ◽  
Yu. N. Goryachkin ◽  
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Keyword(s):  
Coastal Zone ◽  
Black Sea ◽  
Bottom Sediments ◽  
Anthropogenic Impact ◽  
River Flow ◽  
The Black Sea ◽  
Negative Consequences ◽  
Coastal Zones ◽  
Natural Dynamics ◽  
The Impact

Anthropogenic impact on lithodynamics of the coastal zone changes the natural dynamics of bottom sediments, which leads to increased abrasion and swelling of beaches, activation of landslide processes creating a threat of destruction of the coastal infrastructure. The article aims at providing an overview of the scientific literature on the anthropogenic impact on lithodynamics of the coastal zone of the southern and western coasts of the Black Sea (shores of Romania, Bulgaria and Turkey). The work shows that with all the differences in the natural conditions of the coastal zones of these countries the types of anthropogenic effects they undergo are almost the same. These include: hydrotechnical construction without regard to the impact on the neighbouring coast sections; reduction of solid river flow due to river regulation by reservoirs; construction of capital facilities directly on the beaches; illegal extraction of sand from beaches and river beds; dredging with sale of the extracted material to construction companies; covering of cliffs by various structures; destruction of coastal dunes, etc. The main negative consequences of these actions are reflected in disruption of natural dynamics and shortages of bottom sediments, changes in the coastline, reduced aesthetic attractiveness and accessibility of shores, destruction of coastal ecosystems. The article also provides information on the legislation of these countries regarding environmental management in the coastal zone

scholarly journals Drivers, mechanisms and long-term variability of seasonal hypoxia on the Black Sea northwestern shelf – is there any recovery after eutrophication?

2013 ◽  
Vol 10 (6) ◽  
pp. 3943-3962 ◽  
Author(s):  
A. Capet ◽  
J.-M. Beckers ◽  
M. Grégoire
Keyword(s):  
Organic Matter ◽  
Spatial Distribution ◽  
Interannual Variability ◽  
Black Sea ◽  
Sea Surface ◽  
The Black Sea ◽  
Northwestern Shelf ◽  
Bottom Waters ◽  
Seasonal Hypoxia ◽  
Bottom Hypoxia

Abstract. The Black Sea northwestern shelf (NWS) is a shallow eutrophic area in which the seasonal stratification of the water column isolates the bottom waters from the atmosphere. This prevents ventilation from counterbalancing the large consumption of oxygen due to respiration in the bottom waters and in the sediments, and sets the stage for the development of seasonal hypoxia. A three-dimensional (3-D) coupled physical–biogeochemical model is used to investigate the dynamics of bottom hypoxia in the Black Sea NWS, first at seasonal and then at interannual scales (1981–2009), and to differentiate its driving factors (climatic versus eutrophication). Model skills are evaluated by a quantitative comparison of the model results to 14 123 in situ oxygen measurements available in the NOAA World Ocean and the Black Sea Commission databases, using different error metrics. This validation exercise shows that the model is able to represent the seasonal and interannual variability of the oxygen concentration and of the occurrence of hypoxia, as well as the spatial distribution of oxygen-depleted waters. During the period 1981–2009, each year exhibits seasonal bottom hypoxia at the end of summer. This phenomenon essentially covers the northern part of the NWS – which receives large inputs of nutrients from the Danube, Dniester and Dnieper rivers – and extends, during the years of severe hypoxia, towards the Romanian bay of Constanta. An index H which merges the aspects of the spatial and temporal extension of the hypoxic event is proposed to quantify, for each year, the intensity of hypoxia as an environmental stressor. In order to explain the interannual variability of H and to disentangle its drivers, we analyze the long time series of model results by means of a stepwise multiple linear regression. This statistical model gives a general relationship that links the intensity of hypoxia to eutrophication and climate-related variables. A total of 82% of the interannual variability of H is explained by the combination of four predictors: the annual riverine nitrate load (N), the sea surface temperature in the month preceding stratification (Ts), the amount of semi-labile organic matter accumulated in the sediments (C) and the sea surface temperature during late summer (Tf). Partial regression indicates that the climatic impact on hypoxia is almost as important as that of eutrophication. Accumulation of organic matter in the sediments introduces an important inertia in the recovery process after eutrophication, with a typical timescale of 9.3 yr. Seasonal fluctuations and the heterogeneous spatial distribution complicate the monitoring of bottom hypoxia, leading to contradictory conclusions when the interpretation is done from different sets of data. In particular, it appears that the recovery reported in the literature after 1995 was overestimated due to the use of observations concentrated in areas and months not typically affected by hypoxia. This stresses the urgent need for a dedicated monitoring effort in the Black Sea NWS focused on the areas and months concerned by recurrent hypoxic events.

Nutrient distribution in the Bosphorus and surrounding areas

2002 ◽  
Vol 46 (8) ◽  
pp. 59-66 ◽  
Author(s):  
E. Okuş ◽  
A. Aslan-Yilmaz ◽  
A. Yüksek ◽  
S. Taş ◽  
V. Tüfekçi
Keyword(s):  
Chlorophyll A ◽  
Black Sea ◽  
Nutrient Dynamics ◽  
Lower Layer ◽  
Water Quality Monitoring ◽  
Nutrient Concentrations ◽  
The Black Sea ◽  
Sea Of Marmara ◽  
Nutrient Distribution ◽  
Northwestern Shelf

As part of a five years monitoring project “Water Quality Monitoring of the Strait of Istanbul”, February-December 1999 nutrient dynamics of the Black Sea-the Sea of Marmara transect are studied to evaluate the effect of discharges given by deep disposals. Through a one-year study, upper layer nutrient concentrations were generally under the effect of northwestern-shelf Black Sea originated waters. This effect was strictly observed in July, when the upper layer flow was the thickest. On the other hand, partly in November but especially in December the northwestern-shelf Black Sea originated water flow was a minimum resulting in similar concentrations in both layers. Nutrient fluctuations also affected the chlorophyll a and POC concentrations as parameters of productivity. The nutrient concentrations decreased with the effect of spring bloom and highest chlorophyll a values were detected in November at Strait stations that did not match to the Sea of Marmara values. This fact represents the time-scale difference between the Black Sea and the Sea of Marmara. On the contrary, high nutrient concentrations in the lower layer (especially inorganic phosphate), and therefore low N:P ratios reflect the effect of deep discharge. Vertical mixing caused by meteorological conditions of the shallow station (M3) under the effect of surface discharges resulted in homogenous distribution of nutrients. Nutrient concentrations of the stations affected by deep discharge showed that the two-layer stratification of the system did not permit the discharge mix to the upper layer.

scholarly journals The configuration of the Pontus Euxinus in Ptolemy's Geography

2020 ◽  
Vol 11 (1) ◽  
pp. 31-51
Author(s):  
Dmitry A. Shcheglov
Keyword(s):  
Black Sea ◽  
The Black Sea ◽  
North East ◽  
The Earth ◽  
Open Sea ◽  
Straight Line ◽  
Key Points ◽  
Similarities And Differences ◽  
Types Of Information ◽  
Constituent Elements

Abstract. This article aims to explain how Ptolemy could have constructed a map of the Pontus Euxinus (Black Sea), as described in his Geography, under the assumption that his sources were similar to those that have come down to us. The method employed is based on the comparison of Ptolemy's data with corresponding information from other ancient sources, revealing the most conspicuous similarities and differences between them. Three types of information are considered as possible “constituent elements” of Ptolemy's map: latitudes, coastline lengths, and straight-line distances. It is argued that the latitudes Ptolemy used for the key points determining the overall shape of the Pontus (Byzantium, Trapezus, the mouth of the Borysthenes and the Cimmerian Bosporus, the mouth of the Tanais, etc.) were most likely inherited from earlier geographers (Eratosthenes, Hipparchus, and Marinus). In exactly the same way, Ptolemy's data on the circumference of the Pontus and the length of the coastal stretches between the key points (from the Thracian Bosporus to Cape Karambis, Sinope, Trapezus, and the mouth of the Phasis, etc.) closely correlate with the corresponding estimates reported by other geographers (Eratosthenes, Artemidorus, Strabo, Pliny, Arrian, and Pseudo-Arrian), which implies that Ptolemy drew on similar coastline length information. The shortening of Ptolemy's west coast of the Pontus (from the Thracian Bosporus to the mouth of the Borysthenes) relative to the corresponding distances reported by other sources is explained by his underestimation of the circumference of the Earth. The lengthening of Ptolemy's north-east Pontus coast (from the Cimmerian Bosporus to the mouth of the Phasis) can, in part, be accounted for by his attempt to incorporate the straight-line distances across the open sea reported by Pliny. Overall, Ptolemy's configuration of the Black Sea can be satisfactorily explained as a result of fitting contradictory pieces of information together that were inherited from earlier geographical traditions.

Organic Matter of Bottom Sediments of the Crimean and Caucasian Coasts (Azov and Black Seas)

2021 ◽  
Author(s):  
E. A. Tikhonova ◽  
Keyword(s):  
Organic Matter ◽  
Black Sea ◽  
Bottom Sediments ◽  
Petroleum Hydrocarbons ◽  
Water Area ◽  
The Black Sea ◽  
Pollution Level ◽  
Sea Of Azov ◽  
The Caucasus ◽  
The Sea Of Azov

As part of the 113th cruise of the R/V “Professor Vodyanitsky”, research was conducted on organic pollution of bottom sediments in the coastal areas of Crimea and the Caucasus, as well as the water area in front of the Kerch Strait. Concentration of chloroformextractable substances was determined by the weight method and that of petroleum hydrocarbons was determined using infrared spectrometry. Both in 2020 and 2016 (the 83d cruise of the R/V “Professor Vodyanitsky”), properties of the bottom sediments of the Crimean and Caucasian coasts were typical of the marine soils of this region. This indicates that the studied water areas are generally in good condition. In accordance with the regional classification of bottom sediment pollution, the maximum concentrations of chloroform-extractable substances obtained for both the Black Sea and the Sea of Azov coast indicate pollution level III (23% of analysed samples). These values were found in bottom sediments in the Sevastopol water area (225 mg·100 g-1), in the coastal area of Cape Tarkhankut (120 mg·100 g-1) and Karadag (120 mg·100 g-1), the southern part of the Sea of Azov (125 mg·100 g-1) and Tuapse (110 mg·100 g-1). The content of chloroform-extractable substances in bottom sediments off the Black Sea coast of the Caucasus and the Sea of Azov coast is slightly lower than that off the Crimean coast. Pollution level II is assigned to bottom sediments in 46 % of the samples, with an average concentration of 72 mg·100 g-1 of air-dry solids. The rest (31 %) of the studied area was classified as conditionally clean (pollution level I, i. e. less than 50 mg·100 g-1). There has been a slight increase in the concentration of petroleum hydrocarbons in the bottom sediments of both the Black Sea and the Sea of Azov and their share in the total amount of chloroformextractable substances. In general, the level of pollution of bottom sediments by organic matter remained unchanged if compared with previous years, in particular with the data from 2016

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