Expansion of the hydrogen sulfide layer in the Black Sea. The Black Sea: what threats does it pose?
» — sea of hydrogen sulfide in the Black Sea. By the way, this phenomenon makes the Black Sea double by sea - one inside the other. So to speak, nested seas :) Such nested seas are rare in nature. And the enclosed sea of hydrogen sulfide does not occur at all, except in the Black Sea.
The sea of hydrogen sulfide in the Black Sea lies there for a reason and doesn’t bother anyone. If it were so, then, quite possibly, no one would ever know about him. But the sea of hydrogen sulfide periodically manifests itself - and not everyone likes this manifestation. So, imagine the picture - you are relaxing at a resort. And you decide to get up early in the morning to watch the sea sunrise. You get dressed, go to the sea - and see something unimaginable! The entire shore is covered with fish, jellyfish, and some generally unseen animals. It's scary to approach. Corpses, corpses... And the smell of rot in the air.
But if you sit by the shore and look at this miracle, you will notice that the sea inhabitants on the shore occasionally move and twitch. And if you look even longer, you will notice that they are gradually moving back to the sea. And by eight or nine o’clock, when most vacationers go to the sea, the shore is already empty and no longer resembles a worldwide catastrophe.
What happened? A rather rare, but common thing for the Black Sea occurred - a small release of hydrogen sulfide. The smell of which you may have smelled.
Due to the fact that the upper layer of water in the Black Sea is weakly mixed with the lower layer, oxygen rarely reaches the bottom of the sea. And where there is no oxygen, rotting begins. One of the results of rotting is the release hydrogen sulfide.
Well, since the upper, fresher layer of water rarely mixes with the lower, more salty one, this poisonous gas accumulates at the bottom of the Black Sea in huge quantities. And occasionally, when its quantity exceeds imaginable limits, it comes out in the form of huge bubbles.
As the bubble passes through the upper, inhabited layer of the Black Sea, it poisons fish, jellyfish and other living creatures. And they are washed ashore by the sea in an unconscious state. Well, then, when they leave on land, the fish and shrimp run back into the sea.
Measurements have shown that in the center of the Black Sea the hydrogen sulfide zone approaches the surface by about 50 meters; closer to the shores, the depth from where the hydrogen sulfide sea begins increases to 300 meters. As we have already said, in this sense the Black Sea is unique, it the only sea in the world without a hard bottom.
Curious readers may ask: “Why doesn’t a gas that is lighter than water float to the surface right away?” But this is who exactly belongs to the ““ section. Scientists believe that the pressure of the upper layers of water is to blame - 200 meters of water is no joke. And if at least part of this water disappeared, the Black Sea would boil from hydrogen sulfide released in the form of gas.
Why do hydrogen sulfide emissions occur from the depths? For two reasons - excessive growth of the content of this poison and underwater earthquakes. A small displacement of the earth's crust is enough, and the shock wave lifts a huge bubble of gas from the bottom of the sea. So, during the Crimean earthquake of 1927 in Yalta, residents watched the sea burn - hydrogen sulfide, which rose from below, interacted with the air and flared up.
Although, according to other sources, it was not hydrogen sulfide, but methane. And the concentration of hydrogen sulfide in water is so low that it cannot form gas bubbles, boil and poison animals. So it seems like there are no hydrogen sulfide bubbles...
But it is up to scientists to determine what will happen if hydrogen sulfide decides to rise to the surface. We just need to know that there is not a single recorded case where hydrogen sulfide from the bottom of the Black Sea led to the death of people. Or even simple poisoning.
By the way, there is another question that has not yet been solved: “Why is there suddenly a sea of hydrogen sulfide in the Black Sea, but there is no sea of hydrogen sulfide in other seas and oceans?” In fact, there is still debate about the source of hydrogen sulfide in the depths of the Black Sea. Some consider the main source to be the reduction of sulfates by sulfate-reducing bacteria during the decomposition of dead organic matter.
Although in this case another logical question arises: “Where in the Black Sea so many organic matter? To which there is no answer yet. But there is an interesting assumption: for example, one of the hypotheses for the emergence of the Black Sea says that 7500 years ago it was deepest freshwater lake on earth, the level was more than a hundred meters below the modern one. At the end of the Ice Age, the level of the World Ocean rose and the Bosphorus Isthmus was broken. A total of 100 thousand km² were flooded (the most fertile lands, already cultivated people). The flooding of these vast lands may have become the prototype of the myth of the Great Flood. The emergence of the Black Sea, according to this hypothesis, was presumably accompanied by the mass death of the entire freshwater living world of the lake (the same organic matter), the decomposition product of which - hydrogen sulfide - reaches high concentrations on the bottom of the sea
Other scientists adhere to the hydrothermal hypothesis, that is, the release of hydrogen sulfide from cracks on the seabed as a result of volcanic activity. But this version of the development of events does not explain why only the Black Sea received such an honor - to be a double sea.
This distribution can be partly explained by the fact that the Black Sea is structured in such a way that its water exchange with the Mediterranean Sea occurs through the shallow Bosphorus threshold. The Black Sea water, desalinated by the river runoff and therefore lighter, goes into the Sea of Marmara, and towards it, or rather under it, through the Bosphorus threshold, the saltier and heavier Mediterranean water rolls down into the depths of the Black Sea. It turns out to be something like a giant sump, in the depths of which hydrogen sulfide has gradually accumulated over the past six to seven thousand years.
Thus, the average concentration of hydrogen sulfide in the Black Sea is 5.73 mg/l at a depth of 1240 m, and the approximate amount of hydrogen sulfide in the Black Sea is 3.1 billion tons. Some studies in recent years allow us to speak of the Black Sea as a gigantic reservoir of not only hydrogen sulfide, but also methane, most likely also released during the activity of microorganisms, as well as from the bottom of the sea
By the way, this hydrogen sulfide can not only harm or threaten. It can help significantly by improving the energy sector of the Black Sea countries. So, since hydrogen sulfide is a flammable gas, it can be burned and thereby produce energy. Perhaps this is not very justified economically (although when there are thousands of tons of free fuel...), but along with the environmental result, this procedure could well help Ukraine with its gas shortage.
In order to clarify, it is necessary to clarify one more detail: when reading the article, it may seem that at the depths of the Black Sea there is not a solution of hydrogen sulfide in water, but a huge bubble of pure hydrogen sulfide gas, which, for unknown reasons, cannot float to the surface on its own and may explode... In fact, things are simple there hydrogen sulfide solution, i.e. It's just mineral water. The same as in many hydrogen sulfide mineral springs, which bubble up on the surface and do not explode anything around.
So, as you can see, there are many opinions on this matter.
But, nevertheless, the sea of hydrogen sulfide in the Black Sea is a mystery that has not yet been solved. But it shows itself periodically.
Based on materials from http://voda.blox.ua/2008/07/Zagadka-Chernogo-morya.html
Black Sea. It would seem so familiar and absolutely safe. Nothing like this. In its waters, not only are poisonous sea creatures lurking for you, but there is a more serious threat - suffocating toxic fumes.
Dead zone
Not everyone knows that 90% of the Black Sea waters are saturated with hydrogen sulfide. This discovery was made back in 1890 by Russian geologist Nikolai Andrusov. In some places, the hydrogen sulfide layer is located at a distance of 50 meters from the sea surface, and it constantly continues to move upward. Periodically, a liquid lens of “dead” water comes very close to the surface layers, which has a detrimental effect on the inhabitants of the underwater world.
However, there is still life in the hydrogen sulfide cloud, although in the absence of oxygen only certain types of sea worms and anaerobic bacteria that participate in the decomposition of the remains of living organisms can exist here.
Hydrogen sulfide in water is not a unique phenomenon; it is also found in other seas and oceans. But given that the Black Sea is virtually isolated from the World Ocean by the shallow Bosporus and there is practically no normal water exchange, the concentration of hydrogen sulfide here is off the charts.
Sometimes, as a result of storms, hydrogen sulfide vapor escapes, and then in the area where the gas escapes there is a specific smell of rotten eggs. This is fraught with extreme danger. If large amounts of hydrogen sulfide come into contact with air, an explosion may occur. According to experts, the explosion of all the hydrogen sulfide contained in the Black Sea can be comparable to the consequences of the fall of an asteroid weighing half the mass of the Moon.
But something similar has already happened. In the dead of night on September 12, 1927, the Crimean peninsula experienced the full power of an 8-magnitude earthquake. The epicenter was located 25 kilometers south of Yalta, gigantic landslides were recorded, almost the entire crop was lost, and many buildings were destroyed.
As eyewitnesses testified, the vibrations of the earth's surface were accompanied by a disgusting stench and flashes that soared from the surface of the sea to the sky. The pillars of fire, shrouded in smoke, reached several hundred meters in height. This is how the Black Sea burned. Most scientists have no doubt that hydrogen sulfide was to blame.
Experts are seriously puzzled by the problem of accumulating hydrogen sulfide in the surface layers of the Black Sea. Any tectonic shift can lead to the release of a huge amount of toxic substance, and then the consequences can be much more serious than during the Crimean earthquake.
Oceanologist Alexander Gorodnitsky is convinced that such a threat is quite real: “The Black Sea is a seismically active region, there are earthquakes that provoke emissions of gas hydrates - accumulations of methane and other flammable gases compressed under high pressure.”
In an unfavorable scenario, tons of concentrated sulfuric acid will enter the atmosphere: thousands of people will die from suffocation, millions will have to move away from the coast, but even there they will be overtaken by hydrogen sulfide, causing acid rain.
Several years ago, a release of hydrogen sulfide was recorded at the Koblevo resort in the Nikolaev region (Ukraine). There were then more than 100 tons of dead fish on the shore. Engineer Gennady Bugrin, who participated in the liquidation of the consequences of the disaster, warns that such an emergency could happen again at any time and on a larger scale.
Toxic waters
The situation with the ecological situation in the waters of the Black Sea is no better, primarily due to the waste constantly entering them from the Danube, Prut and Dnieper. Industrial enterprises and public utilities shamelessly pour tons of industrial and human waste into rivers, which leads to the gradual extinction of many species of flora and fauna of the Black Sea coastal waters. In Russia, the most polluted marine area is located near the ports of Novorossiysk and Taman.
Together with river water, pesticides, heavy metals, phosphorus, and nitrogen enter the Black Sea, as a result of which phytoplankton multiplies rapidly and the water begins to bloom. And this leads to the destruction of bottom microorganisms, which in turn causes hypoxia and the subsequent death of many inhabitants of the seabed - squid, mussels, oysters, young sturgeon, crabs. According to environmentalists, the area of the kill sometimes exceeds 40 thousand square meters. km.
Of course, all this does not pass without a trace for humans. The head of the Department of Extreme Natural Phenomena and Man-Made Disasters of the Southern Scientific Center, Candidate of Biological Sciences Oleg Stepanyan, warns and reminds that the Black Sea is not a pool with filtered water and you need to choose the right places for swimming, because often even on city beaches you can see sewage being poured into the sea water from nearby cafes and snack bars.
And although, according to Stepanyan, special services monitor the cleanliness of the beaches and the bacterial situation on them, it is important to be vigilant. Especially dangerous in such cases are the sandy and pebble beaches of large resort cities, where the process of self-purification of water is slow.
Deputy coordinator of the public organization “Environmental Watch for the North Caucasus” Dmitry Shevchenko notes that there are such polluted areas in the Black Sea, for example, in Gelendzhik or Anapa bays, that going into the water is simply a health risk.
Today, a constant problem for the Black Sea has become the massive development of green filamentous and lamellar algae, including the so-called sea lettuce (Ulva). Eating such algae is fraught with serious poisoning, since they grow in places overflowing with organic substances coming through wastewater.
Doctors also warn about the possible harm to the body from mussels and rapana caught in the large port waters of Novorossiysk, Tuapse, and Sevastopol. Mussels actively filter poisoned sea water, and rapana are predators that eat them. But if someone still decides to enjoy the Black Sea delicacies, then you should pay attention to the color of their meat. Light yellow or pinkish most likely indicates its suitability for consumption, but blue, black or simply very bright indicates that the mollusks have accumulated heavy metals, petroleum hydrocarbons and other toxicants.
Dangerous inhabitants
In the waters of the Black Sea, of course, there are not as many poisonous inhabitants as in tropical seas, but extreme caution must still be exercised here. First of all, we are talking about large jellyfish with a diameter exceeding 30 centimeters. Under no circumstances should you touch them, as you can get burned by the stinging cells. A “kiss” from such a jellyfish in the throat or chest area can cause respiratory paralysis or heart failure.
In the sandy shallows of the Anapa bank, in the area from the village of Volna to the village of Blagoveshchensky, the stingray is often found, the poisonous spine of which can penetrate even a thick rubber coating and cause a very sensitive wound with subsequent swelling of the damaged part of the body.
The small scorpion fish, or, as it is also called, the sea ruff, also poses a serious danger. She mainly hunts among rocks, and hypothetically you can step on her. The prick of its poisonous thorns will be very painful and the wound will take several weeks to heal.
The sea dragon, although it does not look intimidating, poses no less a threat than a stingray or scorpionfish. Venom glands are located on its first dorsal fin. Fishermen or divers sometimes inadvertently grab a thorn, and as a result, excruciating sharp pain in the wound area and a feverish state accompanied by a rise in temperature. In this case, it will not be possible to do without a doctor.
Imagine - you are relaxing at a resort. And you decide to get up early in the morning to watch the sea sunrise. You get dressed, go to the sea - and see something unimaginable. The entire shore is covered with fish, jellyfish, and some generally unseen animals. It's scary to approach. And the smell of rot in the air. But if you sit by the shore and look at this miracle, you will notice that the sea inhabitants on the shore occasionally move and twitch. And if you look even longer, you will notice that they are gradually moving back to the sea. And by eight or nine o’clock, when most vacationers go to the sea, the shore is already empty and does not resemble a global catastrophe.
What happened? A rather rare but common thing for the Black Sea occurred - a small release of hydrogen sulfide. The smell of which you may have smelled.
Due to the fact that the upper layer of water in the Black Sea is weakly mixed with the lower layer, oxygen rarely reaches the bottom of the sea. And where there is no oxygen, rotting begins. One of the results of rotting is the release of hydrogen sulfide. Well, since the upper, fresher layer of water rarely mixes with the lower, more salty one, this poisonous gas accumulates at the bottom of the Black Sea in huge quantities. And occasionally, when its quantity exceeds imaginable limits, it comes out in the form of huge bubbles. Or small bubbles. As the bubble passes through the upper, inhabited layer of the Black Sea, it poisons fish, jellyfish and other living creatures. And they are washed ashore by the sea in an unconscious state. Well, then, when they leave on land, the fish and shrimp run back into the sea.
Scheme of hydrogen sulfide formation in the Black Sea.
Why does gas, which is lighter than water, not float? Scientists believe that the pressure of the upper layers of water is to blame - 200 meters of water is no joke. And if this water suddenly disappeared, the Black Sea would boil from hydrogen sulfide released as gas.
Why do hydrogen sulfide emissions occur from the depths? For two reasons - excessive growth of the content of this poison and underwater earthquakes. A small displacement of the earth's crust is enough, and the shock wave lifts a huge bubble of gas from the bottom of the sea. So, during the Crimean earthquake of 1927 in Yalta, residents watched the sea burn - hydrogen sulfide, which rose from below, interacted with the air and flared up. Although, according to other sources, it was not hydrogen sulfide, but methane. And the concentration of hydrogen sulfide in water is so low that it cannot form gas bubbles, boil and poison animals.
But it is up to scientists to determine what will happen if hydrogen sulfide decides to rise to the surface. We just need to know that there is not a single recorded case where hydrogen sulfide from the bottom of the Black Sea led to the death of people. Or even simple poisoning.
How the Black Sea appeared.
A turbulent geological past befell the region where the Black Sea is now located. It is still impossible to give a complete history of the Black Sea. Little information has yet been accumulated. And yet, basically, the picture of the geological past of the Black Sea does not raise any fundamental objections among any geologists.
Before the beginning of the Tertiary period, that is, at a time distant from us by 30-40 million years, a vast ocean basin stretched across Southern Europe and Central Asia from west to east, which connected with the Atlantic Ocean in the west and with the Pacific Ocean in the east. It was the salt sea of Tethys. By the middle of the Tertiary period, as a result of the uplift and subsidence of the earth's crust, Tethys was separated first from the Pacific Ocean, and then from the Atlantic.
In the Miocene (from 3 to 7 million years ago), significant mountain-building movements occurred, the Alps, Carpathians, Balkans, and Caucasus Mountains appeared. As a result, the Tethys Sea shrinks in size and is divided into a series of brackish basins. One of them - the Sarmatian Sea - stretched from present-day Vienna to the foot of the Tien Shan and included the modern Black, Azov, Caspian and Aral seas. Isolated from the ocean, the Sarmatian Sea gradually became strongly desalinated by the waters of the rivers flowing into it, perhaps even to a greater extent than the modern Caspian Sea. The marine fauna remaining from Tethys partly died out, but it is curious that such typically oceanic animals as whales, sirenians and seals lived in the Sarmatian Sea for a long time. Later they were gone.
At the end of the Miocene and the beginning of the Pliocene (2-3 million years ago), the Sarmatian basin decreases to the size of the Meotic Sea (basin). At this time, a connection with the ocean reappears, the water becomes saltier, and marine species of animals and plants penetrate here.
Meotic Sea.
In the Pliocene (1.5-2 million years ago), communication with the ocean again completely ceased, and in place of the salty Meotic Sea, an almost fresh Pontic lake-sea appeared. In it, the future Black and Caspian seas communicate with each other in the place where the North Caucasus is now located. In the Pontic Lake-Sea, marine fauna disappears and brackish-water fauna is formed. Its representatives are still preserved in the Caspian Sea, in the Azov Sea and in the desalinated areas of the Black Sea.
Pontic Sea.
This part of today's Black Sea fauna is united under the name "Pontic relics", or "Caspian fauna", since it is best preserved in the desalinated Caspian Sea. At the end of the Pontic period in the history of the reservoir, as a result of the uplift of the earth's crust in the North Caucasus region, the basin of the Caspian Sea itself gradually separated. Since then, the development of the Caspian Sea, on the one hand, and the Black and Azov Seas, on the other, has followed independent paths, although temporary connections between them still arose.
With the onset of the Quaternary or Ice Age, the salinity and composition of the inhabitants in the future Black Sea continue to change, and its outlines also change. At the end of the Pliocene (less than 1 million years ago), the Pontic lake-sea decreased in size to the boundaries of the Chaudin lake-sea. Heavily desalinated, isolated from the ocean and inhabited by Pontic type fauna. The Sea of Azov at that time, apparently, did not yet exist.
Chaudin lake-sea.
As a result of the melting of ice at the end of the Mindel glaciation (about 400-500 thousand years ago), the Chaudin Sea is filled with meltwater and turns into the Ancient Euxinian basin. In outline it resembled the modern Black and Azov Seas. In the northeast, through the Kuma-Manych depression, it communicated with the Caspian Sea, and in the southwest, through the Bosphorus, with the Sea of Marmara, which was then separated from the Mediterranean and was also experiencing a period of strong desalination. The fauna of the Ancient Euxinian basin was of the Pontic type.
Ancient Euxinian basin.
During the Ris-Würm interglacial (100-150 thousand years ago), a new stage in the history of the Black Sea began: for the first time since Tethys, due to the formation of the Dardanelles Strait, a connection between the future Black Sea and the Mediterranean Sea and the ocean appeared. The so-called Karangat Basin, or Karangat Sea, is formed. Its salinity is higher than that of the modern Black Sea. Various representatives of real marine fauna and flora penetrate into it with ocean waters. They filled most of the reservoir and pushed brackish-water pontic species into desalinated bays, estuaries and river mouths. But this pool has also changed.
Karangat Sea.
18-20 thousand years ago, on the site of the Karangat Sea, there was already the New Euxinian lake-sea. This coincided with the end of the last, Würm, glaciation. The sea was filled with melt water, again isolated from the ocean and greatly desalinated. Once again, the salt-loving oceanic fauna and flora are dying out, and the Pontic species, which survived the difficult Karangat period for them in the estuaries and river mouths, came out of their hiding places and once again populated the entire sea.
New Euxinian Sea.
This went on for about 10 thousand years or a little more, after which the newest phase in the life of the reservoir began - the modern Black Sea was formed. However, the word “modern” in this case does not at all mean identity with today’s sea. Initially (about 7, and according to some authors, even about 5 thousand years ago) a connection was formed with the Mediterranean Sea and the World Ocean through the Bosphorus and the Dardanelles. Then the gradual salinization of the Black Sea began. After another 1-1.5 thousand years, water salinity was created sufficient for the existence of a large number of Mediterranean species. Today, about 80 percent of the fauna of the Black Sea are “newcomers” from the Mediterranean Sea, and the Pontic relics have again retreated into desalinated bays and estuaries, as during the existence of the Karangata Basin.
Analyzing various periods of the history of the Black Sea, we can conclude that the current phase is just an episode between past and future transformations. In the future, the most unexpected changes are possible.
What is the current appearance of the Black Sea? This is a fairly large body of water with an area of 420,325 square kilometers. Its average depth is 1290 meters, and its maximum depth reaches 2212 meters and is located north of Cape Inebolu on the Turkish coast. The calculated volume of water is 547,015 cubic kilometers. The seashores are little indented, with the exception of the northwestern part, where there are a number of bays and bays. There are not many islands in the Black Sea. One of them - Zmeiny - is located about forty kilometers east of the Danube Delta, the other - Schmidt Island (Berezan) - is located near Ochakov and the third, Kefken - not far from the Bosphorus Strait. The area of the largest island, Snake Island, does not exceed one and a half square kilometers.
The Black Sea exchanges waters with two other seas: through the Kerch Strait in the northeast with the Azov Strait and through the Bosphorus Strait in the southwest with the Marmara Strait. The length of the Kerch Strait is 45 kilometers, the smallest width is about 4 kilometers and the depth is 7 meters. The length of the Bosphorus Strait is 33 kilometers, the smallest width is 550 meters, and the smallest depth is about 30 meters. Thus, the Black Sea exchanges water with its neighbors at the very surface, and not throughout its depth.
In general, they say that the bottom of the Black Sea resembles a plate in its relief - it is deep and smooth with shallow edges along the periphery.
Blue? Blue? Green? We can safely say that the Black Sea is not “the bluest in the world.” The color of the water in the Red Sea is much bluer than in the Black Sea, and the bluest is the Sargasso Sea. What determines the color of sea water? Some people think it depends on the color of the sky. This is not entirely true. The color of water depends on how seawater and its impurities scatter sunlight. The more impurities, sand and other suspended particles in the water, the greener the water. The saltier and purer the water, the bluer it is. Many large rivers flow into the Black Sea, which desalinate the water and carry with them many different suspended solids, so the water in it is rather greenish-blue, and near the coast it is rather green.
In addition.
Black Sea. It would seem so familiar and absolutely safe. Nothing like this. In its waters, not only are poisonous sea creatures lurking for you, but there is a more serious threat - suffocating toxic fumes.
Dead zone
Not everyone knows that 90% of the Black Sea waters are saturated with hydrogen sulfide. This discovery was made back in 1890 by Russian geologist Nikolai Andrusov. In some places, the hydrogen sulfide layer is located at a distance of 50 meters from the sea surface, and it constantly continues to move upward. Periodically, a liquid lens of “dead” water comes very close to the surface layers, which has a detrimental effect on the inhabitants of the underwater world.
However, there is still life in the hydrogen sulfide cloud, although in the absence of oxygen only certain types of sea worms and anaerobic bacteria that participate in the decomposition of the remains of living organisms can exist here.
Hydrogen sulfide in water is not a unique phenomenon; it is also found in other seas and oceans. But given that the Black Sea is virtually isolated from the World Ocean by the shallow Bosporus and there is practically no normal water exchange, the concentration of hydrogen sulfide here is off the charts.
Sometimes, as a result of storms, hydrogen sulfide vapor escapes, and then in the area where the gas escapes there is a specific smell of rotten eggs. This is fraught with extreme danger. If large amounts of hydrogen sulfide come into contact with air, an explosion may occur. According to experts, the explosion of all the hydrogen sulfide contained in the Black Sea can be comparable to the consequences of the fall of an asteroid weighing half the mass of the Moon.
But something similar has already happened. In the dead of night on September 12, 1927, the Crimean peninsula experienced the full power of an 8-magnitude earthquake. The epicenter was located 25 kilometers south of Yalta, gigantic landslides were recorded, almost the entire crop was lost, and many buildings were destroyed.
As eyewitnesses testified, the vibrations of the earth's surface were accompanied by a disgusting stench and flashes that soared from the surface of the sea to the sky. The pillars of fire, shrouded in smoke, reached several hundred meters in height. This is how the Black Sea burned. Most scientists have no doubt that hydrogen sulfide was to blame.
Experts are seriously puzzled by the problem of accumulating hydrogen sulfide in the surface layers of the Black Sea. Any tectonic shift can lead to the release of a huge amount of toxic substance, and then the consequences can be much more serious than during the Crimean earthquake.
Oceanologist Alexander Gorodnitsky is convinced that such a threat is quite real: “The Black Sea is a seismically active region, there are earthquakes that provoke emissions of gas hydrates - accumulations of methane and other flammable gases compressed under high pressure.”
In an unfavorable scenario, tons of concentrated sulfuric acid will enter the atmosphere: thousands of people will die from suffocation, millions will have to move away from the coast, but even there they will be overtaken by hydrogen sulfide, causing acid rain.
Several years ago, a release of hydrogen sulfide was recorded at the Koblevo resort in the Nikolaev region (Ukraine). There were then more than 100 tons of dead fish on the shore. Engineer Gennady Bugrin, who participated in the liquidation of the consequences of the disaster, warns that such an emergency could happen again at any time and on a larger scale.
Toxic waters
The situation with the ecological situation in the waters of the Black Sea is no better, primarily due to the waste constantly entering them from the Danube, Prut and Dnieper. Industrial enterprises and public utilities shamelessly pour tons of industrial and human waste into rivers, which leads to the gradual extinction of many species of flora and fauna of the Black Sea coastal waters. In Russia, the most polluted marine area is located near the ports of Novorossiysk and Taman.
Together with river water, pesticides, heavy metals, phosphorus, and nitrogen enter the Black Sea, as a result of which phytoplankton multiplies rapidly and the water begins to bloom. And this leads to the destruction of bottom microorganisms, which in turn causes hypoxia and the subsequent death of many inhabitants of the seabed - squid, mussels, oysters, young sturgeon, crabs. According to environmentalists, the area of the kill sometimes exceeds 40 thousand square meters. km.
Of course, all this does not pass without a trace for humans. The head of the Department of Extreme Natural Phenomena and Man-Made Disasters of the Southern Scientific Center, Candidate of Biological Sciences Oleg Stepanyan, warns and reminds that the Black Sea is not a pool with filtered water and you need to choose the right places for swimming, because often even on city beaches you can see sewage being poured into the sea water from nearby cafes and snack bars.
And although, according to Stepanyan, special services monitor the cleanliness of the beaches and the bacterial situation on them, it is important to be vigilant. Especially dangerous in such cases are the sandy and pebble beaches of large resort cities, where the process of self-purification of water is slow.
Deputy coordinator of the public organization “Environmental Watch for the North Caucasus” Dmitry Shevchenko notes that there are such polluted areas in the Black Sea, for example, in Gelendzhik or Anapa bays, that going into the water is simply a health risk.
Today, a constant problem for the Black Sea has become the massive development of green filamentous and lamellar algae, including the so-called sea lettuce (Ulva). Eating such algae is fraught with serious poisoning, since they grow in places overflowing with organic substances coming through wastewater.
Doctors also warn about the possible harm to the body from mussels and rapana caught in the large port waters of Novorossiysk, Tuapse, and Sevastopol. Mussels actively filter poisoned sea water, and rapana are predators that eat them. But if someone still decides to enjoy the Black Sea delicacies, then you should pay attention to the color of their meat. Light yellow or pinkish most likely indicates its suitability for consumption, but blue, black or simply very bright indicates that the mollusks have accumulated heavy metals, petroleum hydrocarbons and other toxicants.
Dangerous inhabitants
In the waters of the Black Sea, of course, there are not as many poisonous inhabitants as in tropical seas, but extreme caution must still be exercised here. First of all, we are talking about large jellyfish with a diameter exceeding 30 centimeters. Under no circumstances should you touch them, as you can get burned by the stinging cells. A “kiss” from such a jellyfish in the throat or chest area can cause respiratory paralysis or heart failure.
In the sandy shallows of the Anapa bank, in the area from the village of Volna to the village of Blagoveshchensky, the stingray is often found, the poisonous spine of which can penetrate even a thick rubber coating and cause a very sensitive wound with subsequent swelling of the damaged part of the body.
The small scorpion fish, or, as it is also called, the sea ruff, also poses a serious danger. She mainly hunts among rocks, and hypothetically you can step on her. The prick of its poisonous thorns will be very painful and the wound will take several weeks to heal.
The sea dragon, although it does not look intimidating, poses no less a threat than a stingray or scorpionfish. Venom glands are located on its first dorsal fin. Fishermen or divers sometimes inadvertently grab a thorn, and as a result, excruciating sharp pain in the wound area and a feverish state accompanied by a rise in temperature. In this case, it will not be possible to do without a doctor.
This is perhaps the most famous fact about the Black Sea. Almost all of its life is concentrated in the surface, 100-meter layer of the Black Sea. Deeper - to depths of over 2 kilometers, only a few species of bacteria are found; there are no animals or plants there, because there is no oxygen in the water. These bacteria, living in the water column and at the bottom, decompose the remains falling from the surface (there is even such a term - corpse rain), and release hydrogen sulfide. Its source is sulfur-containing amino acids that are part of proteins.
Seawater sulfates, used by some types of bacteria to oxidize organic matter instead of oxygen, also serve as a source of sulfur (to a lesser extent). Hydrogen sulfide is a poison for animals and plants - it paralyzes cellular respiration in mitochondria.
Hydrogen sulfide is found in soft sediments at the bottom of all seas - oxygen penetrates there very slowly from the water, and the processes of bacterial decay and chemosynthesis with the release of hydrogen sulfide proceed intensively, which is why hydrogen sulfide accumulates in the ground. Dive deeper, where the waves do not stir up the soil, dig the bottom with your palm, and you will see that yellow sand, multi-colored shell rock or gray silt already a few centimeters from the surface have the same black color.
We observed this by descending deeper than 40 meters - where the gurnard walked along the bottom with its “paws” and exposed black silt under the gray surface (chapter “Life on Underwater Rocks”). Black is the color of sulfides - salts that hydrogen sulfide, like a weak acid, forms with metals. Therefore, shells in hydrogen sulfide turn black, and any metal object turns black. One of the legends about the origin of the name “Black Sea” is connected with this: they say that people came up with it when they lowered a metal weight on a rope into the sea to measure the depth. They brought him to the surface - he became completely black. Perhaps that's how it was. But the hypothesis that the name “Black” reflects the impression of Mediterranean travelers about our sea during a winter storm seems more plausible.
Hydrogen sulfide is often present in the weakly mixed bottom layer of water in other seas, especially in deep enclosed bays, but the Black Sea is the only one where such a gigantic mass of water is saturated with this substance. The reason here is that, despite a relatively small area, the Black Sea has great depth; The underwater slopes of the coasts are steep - as a result, water exchange between deep and surface waters is insufficient - oxygen does not penetrate deep into the sea. In other words, the Black Sea does not mix well.
Oxygen penetrates into water through the surface of the sea - from the air; and also - it is formed in the upper illuminated layer of water (photic zone) during photosynthesis of plankton algae. In order for oxygen to reach the depths, the sea must mix - due to waves and vertical currents. And in the Black Sea, the water mixes very weakly; It takes hundreds of years for water from the surface to reach the bottom.
The surface layer of the Black Sea water – to a depth of approximately 100 meters – is predominantly of river origin. At the same time, saltier (and therefore heavier) water from the Sea of Marmara enters the depths of the sea - it flows along the bottom of the Bosphorus Strait (Lower Bosphorus Current) and sinks deeper. Therefore, the salinity of the bottom layers of the Black Sea water reaches 30‰ (grams of salt per liter of water).
The change in water properties with depth is not smooth: from the surface to 50-100 meters, salinity changes quickly - from 17 to 21‰, and then further - to the bottom - it increases evenly. The density of water also changes according to salinity.
The temperature at the sea surface is always determined by the air temperature. And the temperature of the deep waters of the Black Sea is 8-9 o C all year round. From the surface to a depth of 50-100 meters, the temperature, like salinity, changes quickly - and then remains constant until the very bottom.
These are the two masses of Black Sea water: superficial– desalinated, lighter and closer in temperature to air (in summer it is warmer than deep waters, and in winter it is colder); And deep– saltier and heavier, with a constant temperature.
The layer of water from 50 to 100 meters is called the boundary layer - this is the boundary between two masses of Black Sea water, the boundary that prevents mixing. Its more accurate name is the cold boundary layer: it is always colder than deep waters, since, cooling to 5-6 o C in winter, it does not have time to warm up during the summer. The layer of water in which its temperature changes sharply is called a thermocline; a layer of rapid changes in salinity - halocline, water density - pycnocline. All these sharp changes in the properties of water in the Black Sea are concentrated in the boundary layer region.
Stratification (stratification) of Black Sea water by salinity, density and temperature prevents vertical mixing of the sea and enrichment of the depths with oxygen. In addition, all the rapidly developing Black Sea life breathes - planktonic crustaceans, jellyfish, crabs, fish, dolphins breathe, even the algae themselves breathe - they consume oxygen.
When living organisms die, their remains become food for saprotrophic bacteria. Bacterial decomposition of dead organic matter (rotting) uses oxygen. With depth, decomposition begins to dominate the processes of creating living matter by planktonic algae, and oxygen consumption during respiration and decay becomes more intense than its production during photosynthesis. Therefore, the further from the surface of the sea, the less oxygen remains in the water. In the aphotic zone of the sea (where sunlight does not penetrate), under the cold intermediate layer - below a depth of 100 meters, oxygen is no longer produced, but only consumed; It does not penetrate here due to mixing - this is prevented by the stratification of waters.
As a result, there is only enough oxygen for animal and plant life in the upper 150 meters of the Black Sea. Its concentration decreases with depth, and the bulk of life in the sea - the biomass of the Black Sea - is concentrated above 100 meters depth. , This is how it turns out that 90% of the water mass of the Black Sea is almost lifeless. But in any other sea or ocean, almost all life is concentrated in the upper, 100-200-meter layer of water. True, due to the lack of oxygen and the presence of hydrogen sulfide in the water, there is no deep-sea fauna in the Black Sea
this reduces its biodiversity even further, in addition to the effects of low salinity. For example, there are no predatory fish of the deep with huge toothy mouths, in front of which luminous baits are hung.
