When you think of the "Black Sea," what comes to mind first? Is it the endless black sea? Or is it the mysterious underwater world? Perhaps, what catches your eye is the dazzling color of the sea and the sky like a sapphire; even the so-called "black water" will be clear when scooped up with both hands.
It turns out that this place, known as "the world's most terrifying inland sea", looks quite "kind" on the surface, so where does its "dangerous character" come from?
1
The Black Sea, an inland sea located between the Eurasian continent, is 1,150 kilometers long from east to west, 611 kilometers wide from north to south, with a total area of about 436,400 square kilometers, making it one of the largest inland seas in the world, with a maximum water depth of 2,210 meters, and the deepest inland sea in the world.
Behind the seemingly normal parameters of the ocean, the Black Sea holds an astonishing secret - its waters have a distinct upper and lower double structure.
200 meters below the surface of the sea is the upper layer of water, which originates from the Bosphorus Strait, which connects the Mediterranean Sea, while below 200 meters of water is the lower layer of water, mainly from the Sea of Marmara.
The formation of this upper and lower layers of sea water dates back to the Paleocene, 65 million years ago.
At that time, due to the movement of the earth's crust, the area of Asia Minor was squeezed and the terrain was uplifted, and the Mediterranean Sea was gradually divided into two parts, thus forming the current Mediterranean Sea and the Black Sea.
Since then, the water level in the Black Sea has gradually decreased, and the salinity has become higher and higher.
Later, earthquakes caused the Black Sea to be intermittently connected to the Mediterranean, and it was not until a major earthquake after the last glacial period that the two were permanently connected.
At the same time, the earthquake also diverted many major European rivers, including the Danube, and diverted large amounts of fresh water into the Black Sea.
As a result, the upper layer of water is mainly supplied by these rivers, and the lower layer of water comes from the ancient saltwater of the Sea of Marmara.
The difference in salinity between the two is enormous, forming a density thermocline at a depth of 200 meters, dividing the Black Sea into two disconnected worlds.
The upper layer of water keeps the water flowing and biologically exchanging with the outside world, and photosynthesis makes it rich in oxygen, which is the "source of vitality" of the Black Sea.
It has rich fishing grounds, a wide variety of marine life, and even a transit point for some migratory fish, where you can see seabirds soaring, fishing boats coming and going, and the water and sky are picturesque.
And below 200 meters, the lower layer of the water is a very different world.
It is isolated from the outside world, with no oxygen input and no biological exchange.
The poisonous gases released by the anaerobic bacteria filled the air like a ghost, and a heavy dead silence enveloped the wilderness.
Occasionally, if a creature strays into this area, it will quickly suffocate to death, leaving no bones left.
It can be described as a "forbidden zone" on the Black Sea, which is not suitable for survival.
Thus, the density cline at a depth of 200 meters becomes the dividing line between light and darkness, life and death, hope and despair in the Black Sea.
2
As mentioned earlier, there is a huge difference in salinity between the two different sources of water in the Black Sea, with the upper layer being relatively light and the lower layer being extremely salty.
They are separated by a boundary layer called a density cline, which does not blend with each other.
The density cline is formed because the density of the upper and lower layers of seawater is too different.
According to measurements, the density of the upper layer of water is generally between 1.0114-1.0135 g/cm3, while the density of the lower layer of water reaches 1.0284-1.0290 g/cm3, which is much higher than that of the upper seawater.
The salinity of such a high-density lower seawater can reach 22-24%, which is a typical high-salinity seawater.
The high salinity results in a very low amount of dissolved oxygen in the lower seawater, with a maximum of no more than 0.3 mg/l.
To make matters worse, there is almost no light here, so there is no photosynthesis to produce oxygen.
As a result, the lower layer of the Black Sea below 200 meters becomes a closed "backwater" zone.
Except for a small number of anaerobic bacteria, few organisms can survive here.
The toxic gases released by these anaerobic bacteria, such as hydrogen sulfide, methane, acetylene, etc., make it a "poisonous soup".
There is also a large amount of undecomposed organic matter in the lower layer of the Black Sea, such as the remains of dead organisms, feces, food scraps, etc.
These organic matter gradually decays and decomposes under the action of anaerobic bacteria and sulfide bacteria, producing foul-smelling and pungent gas, of which hydrogen sulfide has the strongest odor.
Such an environment is a nightmare for any aerobic organism.
If they are lucky, they will suffocate for a short time, and if they are unlucky, they will endure the torture of highly toxic gases.
According to scientific estimates, humans can survive here for a maximum of 10-20 seconds.
However, for some special creatures, it is also a paradise.
Scientists are fascinated by the mysterious phenomenon of life in which creatures in extreme environments have adapted to the conditions of the lower Black Sea, from which they obtain food and energy to thrive.
In the "hellish" environment of the lower layers of the Black Sea, another amazing secret is buried, and that is combustible ice.
This ice-like solid contains a large amount of natural gas, which produces a huge amount of energy once ignited.
The Black Sea contains about 20% of the world's combustible ice reserves, or trillions of cubic meters, which is undoubtedly a huge strategic resource coveted by various countries.
For this huge "oil and gas money", countries are eyeing each other, and you are fighting for it.
At the same time, it has also brought the mysterious and dangerous sea area of the lower Black Sea to the international stage, and this deathly silent place may soon become "lively".
3
Therefore, the ancient Greek navigators named this sea area "Black Sea", which is a metaphor for how much "blacker" it is than other seas.
Later generations of Europeans were full of fear and whimsical ideas, calling the Black Sea "the most terrifying inland sea in the world".
For ancient people, in the face of the unknown and mysterious, there was often instinctive awe and fear.
The strange environment and ecosystem of the Black Sea was undoubtedly a huge mystery to mankind at that time.
Greek navigators were so frightened by the dark waters of the Black Sea that they gave it the nickname "Black Sea".
The name itself has a certain negative connotation, and later Europeans even more fanciful on this basis, describing it as "extraordinarily terrifying".
In fact, this sense of horror mainly comes from the cultural background of the Middle Ages and the early modern period.
In Europe under the influence of Christian civilization, there is a deep dualistic concept of "light" and "darkness".
Everything that is unknown can easily be associated with "evil" and "devil", as was evident in the Inquisition of the Middle Ages.
Therefore, the mysterious and imprisoned environment of the Black Sea is naturally imagined as the product of "demons".
In particular, the sight of the lower sea being lightless and oxygen-free and filled with deadly poisonous gases has fueled this association.
Many travelers even claim that there is some kind of "black magic" here, and those who seek it have disappeared inexplicably.
This horror reached its peak in the 14th century, when the plague spread widely in Europe, claiming about one-third of the population.
People were terrified, but there was nothing they could do.
This led to the theory that the Bubonic Plague originated in the Black Sea region of the East, caused by some unknown evil creature, or was related to local spiritism.
Despite these unfounded speculations, the hysterical populace still chooses to believe that they have even organized a campaign to eliminate "witches" and infidels.
This psychology of panic and discrimination has also been perpetuated in later literature and legends.
4
Despite its mysterious and terrifying name, the Black Sea has always played an extremely important strategic role in the history of Eurasia.
As early as the Greco-Roman period, the Black Sea was an important shipping route connecting the East and the West.
Large quantities of goods from Asia Minor and the Middle East would pass through here to transport them to various parts of Europe, providing raw materials and markets for the commercial trade of ancient Greece.
Later, Rome expanded its influence to the northern shores of the Black Sea, mainly for the purpose of controlling trade networks.
After the Middle Ages, the South Russian steppe became the focus of contention among various nomadic peoples.
The Xiongnu, Avars, Khazars, Kipchaks, and others successively established their own regimes on the northern shore of the Black Sea.
Not only did they control the north-south communications, but they also raided Byzantium and Eastern Europe through the Black Sea.
From the 15th century onwards, the focus of Russia's southward expansion was also on the Black Sea region.
The fall of Constantinople in 1453 gave rise to the rise of the Ottoman Turkish Empire, which separated Russia from the Mediterranean.
So Russia was determined to retake the Crimean peninsula and acquire its own Black Sea Fleet.
After centuries of wars with Turkey and Poland, Russia finally took substantial control of the northern shores of the Black Sea in the second half of the 18th century.
This laid the foundation for Russia to become a regional hegemon.
And in the 90s of the 20th century, with the collapse of the Soviet Union and the end of the Yugoslav civil war, the political landscape and economic ties in the Black Sea region changed dramatically.
Newly independent states such as Turkey, Ukraine, and Georgia joined one after another, and the original balance of power was upset.
In recent years, with the increasing economic strength of Eastern European and Central Asian countries and the advancement of the "Belt and Road" initiative, the Black Sea has gradually become the "pearl" of the hub of Eurasia.
This has brought unprecedented development opportunities to neighboring countries, and at the same time, the Black Sea itself has become the focus of great power competition.
In particular, after discovering that the Black Sea contains rich oil and gas resources, Turkey and Russia have stepped up competition and exploitation.
This has made the already complex regional situation even worse, and it has also made us see the shadow of the great power game.
Clearly, even in today's age of technological advancement, the importance of the Black Sea region has not diminished.
We have reason to believe that in the future, it will appear in the center of the stage of world history with a new attitude.
5
However, compared to the geopolitical importance of the Black Sea, its unique and fragile ecological environment is more undervalued.
This ancient inland sea has evolved over millions of years to form a complex and precious biosphere, but at the same time, the Black Sea ecosystem is facing unprecedented environmental pressures.
In recent years, there has been a significant increase in pollutants from rivers entering the sea, and the eutrophication of seawater has become increasingly serious, which has led to frequent seasonal blooms and large-scale hypoxic zones on the sea surface.
The spread of invasive alien species has also broken the original balance of the biological chain, and some local rare species are in danger of extinction.
One of the most worrying is the deterioration of the environment in the lower seas, where there is a lack of oxygen and light, and the ecological environment is extremely fragile.
Any disturbance could destabilize the junction of upper and lower seawaters, leading to the release of large quantities of toxic gases, which would not only pollute and acidify seawater, but also endanger the air environment of coastal countries.
To this end, the Black Sea Rim countries have launched a joint initiative to develop policies and regulations to protect this fragile ecosystem.
For example, restricting industrial and resource development activities in critical sea areas to reduce the amount of pollutants entering the sea.
In fisheries, the use of fishing tools and methods that may damage the structure of water bodies is strictly restricted.
But that's not enough.
The fundamental protection of the Black Sea is to respect and follow its unique natural laws.
The significance of its existence is not only to provide resources and benefits for human beings, but also to show the mystery of vitality and self-organization, and enlighten our thinking.
Perhaps one day, advances in technology will allow us to control the workings of the Black Sea, but for now, humility and caution are the only attitudes we should have.
Resources
Eurasian Black Sea. China Natural Science Net. [2012-11-22].
Surface Area—Black Sea Geography. University of Delaware College of Marine Studies. 2003 [2006-12-02].
Maximum Depth—Europa – Gateway of the European Union Website. Environment and Enlargement – The Black Sea： Facts and Figures. [2012-11-22].
The Three Hundred Years' War between Tsarist Russia and Turkey: Russia's Expansion into the Black Sea (4). China.com. 2013-09-10