A 'killing lake' emerges in Africa, killing 1,700 people overnight.

The "killing lake" incident in Africa occurred in Lake Nios in northwestern Cameroon, also known as the Lake Nios disaster.

According to statistics, 1,746 people died in this disaster, and more than 300 people were hospitalized. Although some people were lucky to survive, they suffered from life-long diseases and even paralysis. The death of livestock is also shocking, as high as 3,500.

The entire disaster spread over a wide range, with the lake as the center extending to the surrounding area. The deceased was found in a village 23 kilometers from the lake, and a dead cow was found 100 meters above the lake. A village closest to Lake Nios with only 4 survivors.

What happened on August 21, 1986?

Survivor's Surreal Horror Experience

For the villagers living near Lake Nios, it was a scene that will never be forgotten.

At about 9 o'clock in the evening, a family living above the lake heard a rumbling sound similar to a landslide, and then saw a strange white fog rising from the lake. At that time, the family's father didn't care too much, just told the child to get off. It rained, and then I went to sleep, and then I felt suffocation in my sleep.

The family near the lake also felt the same way. In addition to hearing the rumbling sound, they also smelled a smell similar to rotten eggs. With a gust of wind blowing, the person instantly fainted like a dead man.

After dawn, the vicinity of the lake was also unusually quiet, with no insects or birds chirping.

Some survivors woke up a day later, and the scene around them was horrific.

All the living things around are dead, the children are dead, the family is dead, the neighbors are dead, the hundreds of cattle they raised are dead, the chickens are dead, and even the flies that like to surround the corpse are dead.

The most terrifying thing is that the people who died died in the places where they would appear at this point in their daily life, such as beds and by the fire in the doorway. This means they died on the spot.

killer of lake nyos disaster

For a period of time after the disaster, people were unable to explain the cause of the disaster.

Some people say it is a curse, because there is a story about the "source of death" of Lake Nyos in this area, and it is believed that the lake is inhabited by "evil forces"; others say it may be caused by poisonous gas or infectious diseases. But these were all overturned one by one, because after the investigators entered the area, they did not get sick, ruling out the possibility of infectious diseases, and only animals died in this area, and there was no problem with plants, which also ruled out the possibility of poisonous gas. factor.

It wasn't until a few months after the incident that scientists discovered the "murderer" in the lake.

Scientists analyzed a bottle of water brought from the bottom of the lake and found that there was a lot of carbon dioxide in the water. Combined with many clues at the disaster site, it is believed that the initiator is carbon dioxide, and it is a very high concentration of carbon dioxide.

Carbon dioxide itself is known to be non-toxic. It exists in the air, the content is only 0.03%%, but if the content is relatively high, when it reaches 10%, there will be symptoms of uncomfortable breathing, dizziness or even coma, and if it reaches 30%, carbon dioxide poisoning will occur, and it will take a few seconds. You can fall to the ground and die.

Based on available clues and descriptions of survivors, scientists simulated the entire incident.

It is estimated that about 100,000 to 300,000 tons of carbon dioxide were released instantaneously at that time, and these carbon dioxide came from the lake water. At that time, someone saw a foamy water column about 100 meters high in Lake Nios, and it also set off at least 25 meters. high waves. After the carbon dioxide was instantly ejected, the lake level dropped by 1 meter, and the trees around the lake were also swept down by this energy.

The density of carbon dioxide is greater than that of air. After being injected into the air, it rapidly drops to replace the oxygen in the original air, causing the oxygen to rise and carbon dioxide to deposit at the bottom. And all living things on the ground that live on oxygen are suffocated to death.

At that time, the high concentration of carbon dioxide sank to the ground in a very short time, and then spread to the surrounding at a speed of 20-50 km/h. People could not beat the speed of carbon dioxide at all. As long as they touched it, they would fall to the ground within a few seconds. die.

Where does all this carbon dioxide come from?

Generally speaking, the carbon dioxide in the water mainly comes from the air, but Lake Nios is special. The water in the lake is very deep, with an average depth of 200 meters, and the deepest can reach 500 meters. The bottom of the lake is a volcano, which is a A volcanic lake.

Because of the relationship between volcanoes, a large amount of carbon dioxide will enter the lake water. Volcano experts have estimated that about 5 million cubic meters of carbon dioxide enter the lake water every year.

The amount of carbon dioxide dissolved in water is limited. At one atmospheric pressure and 25°C, the solubility of carbon dioxide is 0.144g/100g of water, which means that after the carbon dioxide in the water is saturated, no matter how much gas there is, it will become bubbles from the water. overflow.

But if it is under pressure, the amount of water dissolved in carbon dioxide will be greatly increased.

This is like the carbonated drinks we often drink. When sealed, it can lock most of the carbon dioxide gas. Once the bottle is opened, it is equivalent to decompression and the gas will overflow.

In addition, low temperature can also increase the solubility of gas, and iced carbohydrate drinks are more powerful than those at room temperature, which is the reason.

Lake Nios is very deep. The deeper the water, the greater the pressure and the lower the temperature. It has both high pressure and low temperature conditions, and the solubility of carbon dioxide is very large.

Carbon dioxide overflows from the bottom of the lake, and the gas bubbles continue to rise upward, and the bubbles get smaller as they go up, and eventually dissolve and disappear at a certain depth in the lake. From overflowing, rising, and finally being absorbed, as long as the carbon dioxide overflowing from the bottom of the lake continues, and the dissolution of carbon dioxide in the lake water does not reach saturation, the entire process will continue to repeat.

Slowly, a huge amount of gas accumulated in the lake water, estimated to be about one billion tons of carbon dioxide.

A seemingly mundane act, like unscrewing the cap of a soda bottle, could upset this balance and trigger a jet of carbon dioxide at the bottom of the lake.

Hot topic: What would happen if a person fell into Lake Nyos?

What turned up the carbon dioxide in the lake water?

If there is just too much carbon dioxide and it cannot be dissolved in the water, then the carbon dioxide will turn into bubbles and overflow the water surface, so it will not cause such a big disaster.

In the Lake Nios disaster, a large amount of carbon dioxide gushed out at the same time, and there is still no accurate answer as to what external force stirred the lake water.

The more popular guess is that the volcanic eruption at the bottom of the lake stirred up the seemingly calm lake water.

The smell of gunpowder and rotten eggs smelled by survivors may be sulfide, which often appears during volcanic eruptions. At the same time, the water in the lake after the disaster turned orange-red. Scientists believe that the volcanic eruption brought out the siderite at the bottom of the lake. , oxidized to form red iron oxide.

There are also a few people who believe that it was caused by a landslide that caused a huge wave of 25 meters.

at last

In 2001, in order to prevent the same thing from happening again, researchers erected a pipeline in the middle of the lake to release and dilute the carbon dioxide gas at the bottom of the lake.

However, a single pipe does not ensure the safety of the lake, and 5 million cubic meters of carbon dioxide are still poured into the lake every year. "Degassing" at this rate would require at least 30 years of carbon dioxide release to be safe.

However, there were still villagers living nearby at that time, the concentration of carbon dioxide emission should not be too high, and the funds were not enough. Ten years later, in 2011, two more degassing columns were added.