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In Cameroon, known as the "granary of Central Africa", its northwestern part is covered with many cliffs and plateau lakes, which are not only full of rain, but also have a variety of natural climate formations.
The lake here is a must in the world, and because of the lake, Cameroon has become one of the world's famous tourist destinations.
However, tourists who are addicted to beautiful scenery do not know that there is a lake in Cameroon that the locals smell discolored , Lake Nyos.
The lake once claimed 1,700 lives overnight.
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The former Lake Nyos is also very vibrant, and the villagers here also live in harmony with the wildlife every day at sunrise.
It wasn't until 1986 that a large number of animal carcasses suddenly appeared around this lake, and they fell vertically in the forest.
At first, the locals did not care about such a phenomenon, after all, this is a primeval forest, and it is common for animals to fight each other for food, resulting in death.
But what everyone did not expect was that after the animals died, the death scythe was pointed at them.
In the early morning of August 21, 1986, Lake Nyos suddenly erupted into a terrifying noise, waking up many villagers who were still sleeping.
It is said that at that time, Lake Nyos was boiling like boiling water, and a column of water up to tens of meters high gushed out from the surface of the lake, and the air was filled with a relatively unpleasant gas.
People felt dizzy and weak, everyone's face was still distorted and painful, and some villagers wanted to go to the lake to see what was happening, but because of their physical abnormalities, they fell on the way to check the situation.
Only a small number of people eventually took back a life from the hands of the god of death, and many people never woke up again.
According to preliminary statistics from rescuers, more than 1,700 people died and 3,500 livestock died in villages near Lake Nyos, and the village of Gamneau, the closest to Lake Nyos, was the hardest hit, with only 6 of the 650 villagers surviving.
What exactly does Lake Neos "do"?
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After this large-scale murder broke out, many experts and rescue workers also came here.
Due to the large number of casualties, the Government of Cameroon turned to the international organization for help, which quickly formed a best investigation mission led by George Kling, a professor at the University of Michigan in the United States, and Bill Evans, a scientist at the Geological Survey, to the scene of the incident.
Looking at the scene in front of him, someone made a guess: "Could it be caused by a bomb?" ”
However, as soon as it was proposed, it was rejected by experts, because there was no trace of injury on the dead animals and people, and the corpses were intact.
If it were a bomb, it would not kill people invisibly, and in a small country like Cameroon, it is impossible to have such a devastating bomb.
Is it possible that it is an infectious disease?
The answer is also no, because from the tests of biologists and doctors on the spot, neither the dead animals nor humans have detected highly lethal infectious bacteria or viruses.
The third scenario proposed by experts is food poisoning.
But according to the survivors, there was no dinner in the village before the incident, and the doctors did not detect any toxic substances in the villagers' food, nor did they drink water.
Finally, after some analysis by experts and rescue teams, a surprising idea came up:
Lake Neos may have been the culprit in this mass killing.
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To prove this idea, the experts traveled to Lake Nyos to investigate.
As soon as you reach the lake, you feel a strong sense of suffocation and the foul smell floating in the air, a phenomenon that is instantly captured by keen scientists.
I saw that the surface of Lake Nyos was glowing scarlet, the surrounding trees were washed down by the lake, and all I saw was rocky mud and sewage, and even the lake surface had nearly 1 meter of silt exposed.
Very much like the scene of a volcanic eruption at the bottom of a lake.
Through the survey of the site and the comparison of a large number of data, the geological scientist Bill Evans unsurprisingly found that his party was located near a long-dormant crater, and Lake Nyos was the center of the crater.
However, when scientists began to measure the temperature in the lake and extract samples of the lake water, they found that no volcanic material was extracted from the lake water, and the redness of the lake water was not caused by volcanic eruptions.
What's going on?
After the scientific community had submitted the preliminary study to the Government of Cameroon, the Government decided to drain the waters of Lake Neos to identify the causes.
Because if the problem here is not solved immediately, it means that the area will no longer be inhabited by villagers.
As there is less and less water in the lake, the secrets about Lake Nyos emerge one by one.
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In the gas detection and analysis below 200 meters of Lake Nyos, experts found that the proportion of carbon dioxide was as high as 99.4%, and the rest were only a small amount of argon and one or two other elements, and such a high content of carbon dioxide suddenly surprised everyone present.
Because the carbon dioxide we are familiar with is non-toxic, our breathing will exhale a large amount of carbon dioxide, but because the high concentration of carbon dioxide is filled in the air, the oxygen content will be greatly reduced, resulting in a suffocating space without oxygen, and insufficient oxygen will make people die of lack of oxygen.
So what is the reason for the high concentration of carbon dioxide here?
After expert investigation, it was found that when Lake Nyos was first formed, the carbon dioxide that should have been dissolved in the ground began to seep out little by little, because of the excessive pressure, they could not form bubbles, and could only be dissolved in water.
More than 300 million cubic meters of gas have been formed in the slow accumulation over a long period of time, and the deeper the lake water of Lake Nyos, the more gases are dissolved.
Under normal circumstances, the surface water temperature of the lake in winter drops much faster than the bottom water, and the water temperature of the bottom lake is relatively warm.
Because the density of the bottom water is lower than the density of the surface water, the bottom lake water will rise to form a water cycle, so that the dissolved carbon dioxide will also be released.
Under the perennial sunlight of Lake Nyos, which is located at the equator, the temperature of the surface layer of the lake has always been very high, but the temperature of the lake at the bottom is relatively low, so that the water cycle cannot be formed, and the dissolved carbon dioxide has nowhere to be released, which has led to its higher and higher content.
To put it simply, it is to compare Lake Nyos to the sparkling water we often drink, and the bottle cap of the sparkling water is the pressure of the lake, which breaks the water balance in the lake under the agitation and circulates the water at the bottom of the lake.
Carbon dioxide is quickly released without the shackles of pressure, and under this continuous reaction, more lake water is driven, directly forming a large fountain.
The high concentration of carbon dioxide released forms a super anesthetic after mixing with the air, and as long as a little inhalation will make people unconscious, or even suffocate, the effect is extremely fast.
Normally, although there will still be a large number of bubbles discharged from the lake, it will never cause explosive exhaust, unless there is an external force that disturbs the water temperature balance of the upper and lower lakes, causing it to reverse the flow.
However, there was no volcanic eruption on the day of the 21st, and what external forces disturbed the water temperature balance in the upper and lower layers of the lake?
Experts believe that it was the rainy season, and the surface of Lake Nyos stored a large amount of cold water, and carbon dioxide slowly dissolved in the warm water layer.
Days of rain have left the lake in a number of landslides and mudslides. The stones and silt in the mudslide quickly poured into the bottom of Lake Nyos due to gravity, and broke the water temperature balance between the upper and lower layers of the lake, directly causing a large amount of carbon dioxide to erupt instantaneously, thus causing this turbulent explosion.
This problem has been solved, and a new question has emerged, why does the water of Lake Nyos change from turquoise to scarlet? Is it because the concentration of carbon dioxide is too high that the lake water changes color?
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The concentration of carbon dioxide in the lake does not determine the color of the lake, just like the Coke sparkling water we often drink, which is black, because of the addition of edible coloring agents. The carbon dioxide concentration in Sprite sparkling water has nearly reached its peak, but it has not changed the original transparent color of the drink.
So whether the concentration of carbon dioxide is more or less does not determine the color of the water.
Some experts speculate that the concentration of carbon dioxide reaches the top level, causing some red algae to be produced in the water. However, after the identification and analysis of water quality testers, there is no red algae in the lake.
With more detailed analysis by inspectors, it was found that the lake water contained iron ions.
After the investigation of geological experts, it was found that there is a small rhombite next to Lake Nyos, because the location is very close to the lake, most likely because the huge impact of the lake water hit the surface of the iron ore, so that the iron element returned to the lake of Lake Nyos with the flow of water.
But it is also possible that the volcano at the bottom of the lake has exploded before, and the carbon dioxide, sulfur dioxide and other harmful gases produced by the explosion have caused the churning of the lake to rise to the surface of the lake in an instant to contact with the air, causing it to be oxidized, and forming a shocking scarlet object floating on the surface of the lake.
At this point, the real culprit of the "African Killing Lake Incident" that shocked the world finally surfaced.
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In order to successfully release the harmful toxic gases and a large amount of carbon dioxide accumulated in the lake, scientists suggest that the "diversion method" be adopted to release the harmful gases at the bottom of the lake in order to achieve the effect of "exhaust gas and anti-spray".
After many explorations, attempts and experiments, the scientists finally inserted two exhaust pipes hundreds of meters long into the lake to regularly discharge its harmful toxic gases.
A few years later, with the advancement of science and technology, the Cameroonian government replaced the two exhaust pipes that were hundreds of meters long and installed a siphon device on Lake Nyos.
Through the siphon device, part of the water and harmful gases at the bottom of the lake are used, so that the water column generated at a speed of hundreds of kilometers per hour soars into the air, up to more than 50 meters, and the excess gas is released to prevent the "Killing Lake" from erupting again, endangering human life.
At the same time, an early warning system has been installed at the lake's edge to monitor the situation at the bottom of the lake. If there is a tendency for a sudden eruption of gas and exceeds the warning line, the early warning system will sound an alarm to inform nearby villagers to evacuate immediately.
Today's Lake Nyos is no longer the "killing lake" that people once talked about, and its surroundings have also returned to the appearance of green mountains and rivers, birds and flowers.
But this scenic place has lost the previous fireworks because of this great disaster, and it has not only become a taboo for Cameroonians, but also a place where they are unwilling to set foot in death, and it is also a place where Cameroonians have infinite grief for their relatives and friends.