In 1986, Lake Nyos in Cameroon, a tourist attraction, suddenly "changed its temperament", and more than 1,700 people were "killed" by it in various villages along the coast overnight.
After the incident, the whole world was shocked, and scientists from all over the world rushed to Cameroon to vow to uncover the truth behind this **.
So, what exactly caused more than 1,700 people to die overnight?
The United Republic of Cameroon, located on the northeastern shore of the Gulf of Guinea in Africa, is known as the "African Hub".
The Atlantic coastline makes a 90-degree turn here and turns south to the equatorial region.
According to geological judgment, Cameroon is part of the African plate in terms of geological structure and is located at the edge of the plate, which has caused the situation of many ** and volcanoes in Cameroon.
Cameroon borders the Bay of Biafra on the western side, where the world-famous Cameroonian volcano rises, at 4,070 meters above sea level.
Cameroon Volcano is an active volcano that erupted five times in the 20th century alone, most recently in 1982.
Volcanic eruptions inevitably bring about underground faults, ground ruptures, and volcanic craters, and areas covered by Cameroon's volcanoes, and there are still some places where there are huge cracks, and there are still some places that are "sizzling" and steaming outward.
With the Cameroon volcano as the center, it stretches to the Finandopo volcanic archipelago in the southwest, and then to the Mandala Mountains in the northeast to the south of Lake Chad, forming a complete underground fault layer and a volcanic chain.
The geological changes caused by volcanic eruptions eventually formed one volcanic lake after another, and Lake Neos, a famous tourist attraction in Cameroon, is one of them.
Because Lake Nyos is located near an extinct volcanic crater, the water is warm and crystal clear all year round.
This, combined with Cameroon's hot and humid climate, lush greenery and fresh air, makes Lake Nyos a well-known spa resort.
Residents living near the crater lakes in Cameroon have a very high level of worship for the lake, and the village of the Nios Valley on the shores of Lake Nyos is no exception.
The villagers are convinced that people can live forever in Lake Nyos after death.
Therefore, whenever someone in the village dies or there is a major festival, the villagers always perform a devotional religious ceremony by the lake, singing hymns in a mysterious language.
In places where special powers are believed to have special powers, they also sprinkle a liquid made from herbs and animal blood to honor the souls of their ancestors, which is said to keep them at peace.
When domestic and foreign scientists want to conduct geological expeditions to Cameroon, the villagers also perform similar ceremonies to offer so-called tribute to the lake before the scientists are allowed to use various scientific instruments.
The villagers on the shores of Lake Nyos have the highest respect for this lake, but instead of blessing them with the most sacred lake in their hearts, Lake Nyos exposes the ruthlessness of nature to the villagers in the most cruel way.
On 21 August 1986, Cameroon had entered the rainy season.
On this day, dark clouds were thick over Lake Nyos, and soon heavy rain poured down, and the villagers on the lakeside returned to their homes early to rest.
By evening, the village of the Nyos Valley had fallen into silence and peace.
But at this moment, the surface of Lake Nyos not far away suddenly exploded, and a cylindrical gas gushed out, floating on the surface of the lake like a river of smoke.
Soon, the river drifted slowly along the breeze from the valley towards the village of Nyos Valley, silently circling at a low altitude and drifting 16 kilometers away by the lake.
However, it is such an unremarkable and seemingly ordinary river of smoke that has brought terrible deaths to the village of the Nios Valley.
It was like the scythe of death, leaving only corpses in its path.
Soon, the river of smoke filled the entire village of Nyos Valley, and almost all of the village's 1,200 villagers died.
Many people have fallen asleep before they die, and their lives are quietly taken away in their sleep.
Immediately afterward, the river drifted to two other nearby villages, and after raging again, it slowly disappeared into the world.
The next morning, the Nyos Valley, which had been full of life, was covered in death.
The corpses were strewn all over the field, and the stench was terrible, neither people nor animals, nor ants on the ground, nor vultures on the trees, but none of them survived.
A total of 1,736 villagers and more than 6,000 animals were killed.
Death and the unknown permeated the valley, and the few villagers who survived hurriedly informed the local **.
Two and a half days later, a Roman Catholic priest and a navigator closest to the valley arrived at the scene, followed by the Cameroonian army, personnel, and medical teams drove into the shores of Lake Nyos.
The horrific scene in front of them shocked everyone present, and the news that "thousands of people died mysteriously overnight on the shores of Lake Nyos" spread quickly around the world like wings.
Scientists from all over the world heard the wind and rushed to the shore of Lake Nyos in Cameroon for the first time, wanting to have a good time.
Through the investigation of the scene and the state of the villagers' remains, scientists agree that they were invaded by some kind of poisonous gas, which is why they died quietly.
I have to say that the experts' ** is very accurate, and the Yanhe River that night is the culprit, so what kind of gas caused such a tragedy?
The first to speculate about the composition of the poison gas was a doctor attending at the hospital in Yaoundé, Cameroon, who assumed that a hydrogen and sulfur compound had poisoned the villagers based on the victim's physical condition.
U.S. Chemical Safety and Health Advisors interviewed some of the villagers who were lucky enough to survive, according to them:"I had a very unpleasant smell, similar to the smell of rotten eggs. ”
Therefore, the consultant was convinced that the gas that poisoned the villagers was hydrogen sulfide.
However, other experts also disagreed.
A researcher from the U.S. Geological Survey argues:"The hydrogen sulfide in the poison gas occupies only a small part, which is simply not enough to cause ** of this scale, so there is another, more lethal gas in the poison gas. ”
After research, he zeroed in on carbon monoxide and carbon dioxide.
Carbon dioxide is the most suspicious because of its heavy mass and collects low-lying areas during circulation, which is consistent with the trajectory of toxic gas flow shown by the survey.
Yasuhiro Yamamoto from the Japan Institute of Medicine agrees.
After arriving in Cameroon, he immediately treated and investigated more than 600 villagers who had been harmed by poison gas.
He found that the victims had a wet lung murmur on their chest and corrosive trauma to their abdomen, indicating that the gas that poisoned them was highly corrosive.
In addition, he learned from the mouths of more than one victim that there was indeed a foul smell at the time of the crime, some said it was like rotten eggs, some said it was like gunpowder after a shot.
Immediately afterwards, Yasuhiro Yamamoto conducted an extraction test on the water of nearby Lake Nyos and found that the water contained very low levels of sulfuric acid and chloride ions.
Combined with various signs, he also believes that there must be a high concentration of carbon dioxide and sulfur dioxide in the poison gas.
Experts have different opinions, but no one can come up with direct and strong evidence to prove their claims.
However, most people agree that the ** of this poisonous gas must be inseparable from Lake Nyos.
Then, as long as the focus of the investigation is on Lake Nyos, I believe that the truth will soon come out.
After obtaining the authorization of the local **, the crowd began to pump water from Lake Nyos.
It turns out that the statement "carbon dioxide is a murderer**" is very true.
Because as the water in Lake Nyos becomes less and less, the carbon dioxide content at the bottom of the lake is also getting higher.
By the time the lake was pumped to the ground, the carbon dioxide content of Lake Nyos had reached a staggering 98%-99%.
Carbon dioxide foam is constantly erupting from the bottom of the lake, making a "sizzle" sound.
Seeing this scene, all experts understood that the real culprit of this accident was carbon dioxide.
It is well known that carbon dioxide can easily squeeze oxygen away due to its heavy mass, so concentrated carbon dioxide is often used in fire extinguishers.
Experts speculate that Lake Nyos** should be similar to this principle.
Carbon dioxide gushes out of the bottom of Lake Nyos and drifts towards the village under the force of the wind, forcing huge amounts of carbon dioxide out of the air.
As a result, all residents can inhale is a high concentration of carbon dioxide gas, which can poison and die.
The "smell of rotten eggs" and "gunpowder smell" in the mouths of the villagers are speculated by experts to be hallucinations caused by the villagers' senses after carbon dioxide invades their brains.
With the emergence of the culprit, the investigation of Lake Nyos** has made significant progress.
But there is a more serious question that remains unresolved: why did the carbon dioxide at the bottom of Lake Nyos suddenly rush to the surface on a large scale?
Where does this carbon dioxide come from?
If these two issues are not clarified, there will be more similar tragedies on the shores of Lake Nyos in the future.
Analysis of water samples from the bottom of Lake Nyos shows that the carbon dioxide is slowly released from deep in the earth's crust to the bottom of the lake.
Experts in France believe that it is the hot volcanic magma within the earth's mantle that transports this carbon dioxide to the bottom of the lake.
Due to the unique location of Lake Nyos, where there is very much activity underground, experts suggest that it is possible to produce and transport carbon dioxide.
So, what caused the massive eruption of this carbon dioxide, which had been deposited deep at the bottom of the lake until now?
Volcanologists in Italy believe that it was the underground magma riots that brought the **, and the high concentration of carbon dioxide gushed out.
However, more experts believe that this is due to the accumulation of carbon dioxide at the bottom of Lake Nyos, which ferments with various substances, and then breeds more carbon dioxide gas, which fuses with hydrogen sulfide and hydrogen cyanide gas at the bottom of the lake.
In this way, the gas at the bottom of Lake Nyos seems to be a time bomb, as long as there is any opportunity such as **, volcanic eruption, storm, etc., the gas at the bottom of the lake will be **.
In addition, experts also mentioned the possibility of the convergence of hot and cold water layers in the lake.
When hot and cold water are combined, foaming carbon dioxide gas is carried into the water and air.
The area where Lake Nyos is located is kept at a constant temperature all year round, and the warm water layer in the lake is like a big lid on top of the cold water layer.
The cold aquifer below absorbs carbon dioxide until it reaches a tipping point, which happens at the bottom of the lake**.
Under the impact of gas pressure, a high concentration of carbon dioxide gas is ejected from the surface of the lake.
This phenomenon is not uncommon in tropical lakes, and its causes are strong winds and storms.
According to the local meteorological observatory, it did rain heavily on the day of Lake Nyos**, which seems to have triggered a carbon dioxide eruption.
From the point of view of experts, the occurrence of Lake Nyos ** is inseparable from the carbon dioxide "bomb" at the bottom of the lake itself, and of course it is also due to the stormy weather of the day.
So, how to deal with this situation?
Will Lake Nyos be back to its former peace and quiet?
After in-depth research, American chemist William Evans finally came up with a method - the gas lift offset method.
That is, the carbon dioxide gas from the ground is drawn out of the bottom of the lake, thus counteracting the continuous supply of carbon dioxide produced at the bottom of the lake.
In June 2001, the first phase of the "exhaust blowout prevention" project of Lake Nyos was officially launched in Lake Nyos.
Experts inserted a 200-meter-long air pipe into the lake, and a 50-meter-high column of air erupted at once, rising and falling as the lake rose.
It is understood that 90% of this gas column is a high-concentration gas at the bottom of the lake, of which carbon dioxide accounts for the main component, and the remaining 10% is ordinary lake water.
Experts say:"The natural siphon installed this time can discharge 20 million cubic meters of carbon dioxide gas from Lake Nyos every year. ”
On June 16, Cameroon's Minister of Science, Technology and Research Nlund announced that the first phase of the project had been completed and had been a complete success.
According to reports, in order to fully offset the annual carbon dioxide produced at the bottom of Lake Nyos, several similar siphon devices need to be arranged.
It is planned that once the pipes and installations are in place, 300 million cubic meters of carbon dioxide will be discharged from the bottom of Lake Nyos within 5-10 years, thus calming the bottom of the lake.
Today, the exhaust system of Lake Nyos has been installed for a long time, and there has been no similar incident in Lake Nyos since**.
The valley of Lake Nyos has returned to its former comfort and calm, but the villages by the lake have moved away from their original locations, after all, the ** incident back then was too appalling, and no one wanted bad luck to befall them.
It is worth mentioning that this is not the first case of carbon dioxide eruption at Lake Nyos.
Not far from Lake Aynun, there was a small carbon dioxide eruption in 1984.
In addition, there are also many similar volcanic lakes with potential safety hazards in the world's major volcanic belts.
In the future, I only hope that all countries and relevant departments can take Lake Nyos as a warning and solve the hidden dangers of volcanic lakes in their respective fields as soon as possible.