Atlantic Ocean - Black SeaThe Black Sea is an inland sea between southeastern Europe and Anatolia that is part of the Atlantic Ocean by way of the Mediterranean Sea. It is connected to the Mediterranean by the Bosporus and the Sea of Marmara, and to the Sea of Azov by the Strait of Kerch. There is a inflow of seawater through the Bosporus at a rate of 200 km³ per year. There is an inflow of freshwater from the surrounding areas, especially central and middle-eastern Europe at a rate of 320 km³ per year. The most important river entering the Black Sea is the Danube. The Black Sea has an area of 436,400 km², with a maximum depth of 2200 metres. The countries that border the Black Sea are Turkey, Bulgaria, Romania, Ukraine, Russia, and Georgia. Important cities along the coastline include Istanbul, Burgas, Varna, Constanţa, Odessa, Sevastopol, Yalta, Kerch, Novorossiysk, Sochi, Sukhumi, Poti, Batumi, Trabzon, Samsun and Zonguldak.
The Black Sea forms an enclosed basin, located between south-eastern Europe and Asia Minor. The basin was formed during the Miocene orogenies which uplifted the mountain ranges and divided the ancient Tethys Ocean into several brackish (water that is saltier than fresh water, but not as salty as seawater) basins, including the Sarmatic Sea. The Caspian, Azov, Aral and Black Seas are the remnants of this evaporated basin. The basin is divided into two sub-basins by a curve that bulges out and extends south from the Crimean peninsula. The north-west of the basin is characterized by a relatively large shelf up to 190 km wide, which has a quite shallow apron with gradients between 1:40 and 1:1000. The southern edge around Turkey and the eastern edge around Georgia however, are typified by a shelf that rarely exceeds 20km in width and an apron that has numerous submarine canyons and channel extensions. The Euxine abyssal plain in the centre of the Black Sea reaches a maximum depth of 2,206 metres just south of Yalta on the Crimean peninsula. The basin is connected to the Mediterranean Sea via the Turkish Straits in the southwest, which include the Bosporus and Dardanelles straits and the Sea of Marmara. The Black Sea is connected to the Sea of Azov in the north-east via the Kerch straits. The Black Sea is the world’s largest water-layered basin where the deep waters do not mix with the upper layers of water that get oxygen from the atmosphere. As a result, over 90% of the deeper Black Sea volume is water depleted of oxygen. The upper layers of the Black Sea are generally cooler, less dense and less salty than the deeper waters, as they are fed by large flowing water input systems, whereas the deep waters originate from the warm, salty waters of the Mediterranean. This influx of dense water from Mediterranean is balanced by an outflow of fresher Black Sea surface water into the Marmara Sea, maintaining the building up of layers and salinity levels. Sea Surface Temperature of the surface waters varies seasonally from 8°C to 30°C. Directly beneath the surface waters the Cold Intermediate Layer (CIL) is found. This layer is composed of cool, salty surface waters, which are the result of localised atmospheric cooling and decreased flowing water input during the winter months. During periods of high surface productivity, short-lived algal blooms cause organic rich layers known as sapropels (dark-coloured sediments that are rich in organic matter) to occur. It has also been reported that there is an annual phytoplankton bloom. The Black Sea has one sub-sea called the Azov Sea, find out more about it HERE! |
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