Vertical light attenuation in the northwestern shelf of the Black Sea in the spring period: direct measurements, modeling, and satellite data

2018 ◽  
Author(s):  
Alexandr A. Latushkin ◽  
Vyacheslav V. Suslin ◽  
Oleg O. Martynov
Keyword(s):  
Black Sea ◽  
Satellite Data ◽  
Light Attenuation ◽  
The Black Sea ◽  
Spring Period ◽  
Northwestern Shelf ◽  
Direct Measurements

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.

Investigation of coastal morphological changes due to river basin characteristics by means of remote sensing and GIS techniques

2003 ◽  
Vol 48 (10) ◽  
pp. 135-142 ◽  
Author(s):  
D.Z. Seker ◽  
C. Goksel ◽  
S. Kabdasli ◽  
N. Musaoglu ◽  
S. Kaya
Keyword(s):  
Black Sea ◽  
Satellite Data ◽  
Satellite Images ◽  
Sandy Beach ◽  
Morphological Changes ◽  
Remote Sensing And Gis ◽  
The Black Sea ◽  
Black Sea Coast ◽  
Delta Formation ◽  
Bathymetric Changes

The Riva River is located on the Anatolian (Asian) side of Istanbul by the Black Sea coast, with a wonderful sandy beach and delta formation which has been selected as the study area. The Riva is the largest river in this region, which flows into the Black Sea and also gives its’ name to the area. The river carries some amount of sediments to the Black Sea. These particles cause considerable changes not only in the bed bathymetry and coastal boundaries of the river but also along the coastline of the Black Sea. The aim of this study is to determine these variations by means of satellite data and GIS. In the study, satellite images dated 1975, 1984, 1992 and 2001 have been used. At the end of the study, the possibility of observing bathymetric changes in front of the coastline by means of satellite data has been investigated and results were evaluated and visualised by means of GIS.

Promising Hydrocarbon Prospects in the Paleogene Formations of the Black Sea Northwestern Shelf, Ukraine

2008 ◽  
Author(s):  
I.V. Nedosekova ◽  
I.V. Karpenko ◽  
G.S. Starchenko ◽  
I.V. Karpenko ◽  
G.S. Starchenko
Keyword(s):  
Black Sea ◽  
The Black Sea ◽  
Northwestern Shelf
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