In many ancient myths and legends, entering the sea from the sky is something that can only be done by immortals. But in today's advanced technology, we have been able to leave footprints on the moon, and see the edge of the solar system through the "eyes" of the probe. God has already done it, but entering the sea is not enough.

In today's oceans, only about 20% of the area has been unlocked by humans . We often say that water is the source of life, so the ocean composed of water must contain secrets related to the origin of life.

A large number of studies have proved that there are indeed many creatures in the ocean that we have never seen before, and they have also brought us many unsolved mysteries.

deep sea creatures

Deep sea exploration difficulty

However, this place, which hides many mysteries of life, is not friendly to humans. First of all, the pressure on the seabed is very high , which is also the most important factor. When a human dives below 20 meters of the sea surface, they will feel a huge sense of oppression , and then they feel that it is difficult to breathe as if their lungs are being held by something. If they dive further, they are likely to die of suffocation because they cannot breathe in oxygen.

deep dive

Second, the sun's rays cannot penetrate deep into the ocean floor . In 2012, China's manned submersible "Jiaolong" dived into the deepest trench known on earth, the Mariana Trench, which is 7,062 meters deep , and found that it was a deep darkness.

Except for some small organisms and minerals collected by the Jiaolong probe, there is no sign of life. In fact, at a distance of about 200 meters from the sea surface, the sunlight penetrating the water layer can no longer be felt, which leads to the permanently dark and cold environment of the deep sea layer.

"Dragon" goes to sea

Finally, the unknownness of seabed creatures is too strong . According to physics, in the sea water 4000 meters above the surface, there is no life, because the pressure in this place will crush everything.

But the Jiaolong told us that even at a depth of 7,000 meters, there are still creatures alive. At present, we have no way of knowing whether the creatures living on the seabed will pose a threat to human beings. If they do exist, how should we face it?

In this way, it is almost impossible for humans to dive into the Mariana Trench, which is tens of thousands of meters deep, for detection.

However, scientists have found objects related to humans in the Mariana Trench as deep as 10,928 meters. Instead of rejoicing at the discovery, scientists were a little bit outraged over shock because it was the last thing they wanted to see.

deep sea submersible

Explore the Mariana Trench

As the deepest trench on earth, the Mariana Trench has always been very mysterious in people's eyes. But because of the instinctive fear of the unknown, at first, except for the scientists who conducted research and exploration, most people kept a distance from the Mariana Trench.

The Mariana Trench is located in the northeastern part of the Philippines and sinks into the Pacific Ocean. According to scientists' speculation, this trench was formed during plate movement a long time ago and has existed for 60 million years . Because it is located in an extremely unstable area of ​​plate tectonics, there are frequent volcanic eruptions and earthquakes, and the ecological environment is very harsh.

The history of human exploration of the Mariana Trench began in 1875, when the British Royal Navy first discovered the existence of the trench.

From 1957 to 1995, Britain, Russia, and Japan all successively carried out depth measurements of the Mariana Trench. The largest measured data is the Russian "Vitaz", which has a depth of 11,034 meters . Russia calls this detection point "Mariana Depression" .

However, no one has measured this data again after that, so it is considered a miscalculation. The most accurate data comes from the Japanese exploration vessel "Touhou" , which measured the deepest depth of the Mariana Trench at 10,911 meters . The deepest bottom is called the "Challenger Abyss" .

After that, various countries tried to dive into the Challenger Abyss and go to the mysterious seabed to find out. The first to try and succeed were U.S. Navy Lieutenants Donald Walsh and Jacques Picard .

It was January 23, 1960, and they drove the Trieste to the Challenger Deep for the first time in the world. When they looked at the submarine's corrected data, they found that the depth was 10,916 meters. In this place, the two of them accidentally found a 30-centimeter-long plaice, in addition to flounder and shrimp.

Interestingly, the first person to enter the Challenger Abyss alone was not a professional diver, but director James Cameron from Canada .

He dived to a depth of 10,898 meters. In addition to collecting marine life and seawater samples, he also recorded the appearance of the Challenger Abyss with the lens. This may be the "occupational disease" of the director.

China's exploration of the Mariana Trench is not far behind. In 2016, China's self-developed "Haidou" unmanned submersible dived to a depth of 10,767 meters , and helped researchers observe several colorful coral forests growing in the southern part of the Mariana Trench.

On November 10, 2020, China's manned submersible "Striver" dived in the Mariana Trench, reaching a depth of 10,909 meters , breaking the record of China's manned deep dive and creating the first deep dive. The world record for taking 3 people to Challenger Deep at one time.

"The Fighter"

The harm of plastic bags to the earth

In April 2019, American explorer Viktor Veskovo dived into the Challenger Deep, breaking the maximum depth of human diving with a data of 10,928 meters .

Here, he discovered a plethora of new species, including jellyfish, fish, shrimp, and more, as well as sightings of the bottom of the ocean that no one had ever seen before, all of which exhilarated him. But more disturbing and worrying for Viktor Veskovo, he found plastic bags and colored candy wrappers on the seabed.

Human waste can be seen in the deepest parts of the ocean, which is enough to show how huge the amount of waste humans dump into the ocean. These pieces of candy paper and a few plastic bags are just the tip of the iceberg. It is ironic to say that, in areas where humans themselves cannot easily set foot, the garbage created by humans can wreak havoc at will .

Plastic has the advantages of low cost and strong plasticity. In our daily life, plastic products are widely used, and can be seen almost everywhere, such as plastic bags, man-made fibers, mobile phone computer shells and so on.

However, plastic also has a very fatal disadvantage, that is, it is difficult to degrade in the natural environment. Scientists speculate that if we want to wait for plastic to degrade naturally, it will take at least hundreds of years, and even thousands of years.

When we discard a large amount of plastic waste at will, it will cause serious environmental pollution problems. It has now been named after the color of this pollution - "white pollution" .

According to statistics, since plastics were developed in the 1850s, humans have produced at least 9.5 billion tons of plastic. And now that human society is developing faster and faster, until a suitable substitute for plastic is found, the production rate of plastic will only increase rather than decrease. Some predict that by 2025, the annual production of plastics may exceed 600 million tons.

Of this plastic produced by humans, only 9% is recycled. The remaining 91 percent was either burned, buried in the soil, or dumped into the sea .

Undersea plastic waste captured by submersible

All these treatments have an indelible negative impact on the natural environment. When plastic is burned, it produces a lot of toxic gases, which can greatly harm the health of humans and other living things, and may cause air pollution.

The plastic buried in the soil cannot be degraded for a long time, and bacteria are easy to breed on it, thereby polluting the groundwater. Plastics entering water sources such as rivers, lakes and seas will pollute the water quality. If animals eat plastics by mistake, they are likely to block their throats or digestive tracts, because they cannot eat and starve to death.

There have been news reports that there are a large number of plastic bags in the stomachs of dead seabirds, and the "Marine Pollution Bulletin" also released a data that the proportion of plastic in the nests of five species of seabirds on Lyddy Island in Scotland is 24.5% to 24.5%. 80% . That's what plastic pollution in the oceans does. However, the impact of plastic pollution on marine life goes far beyond that.

For marine life, the most dangerous thing is not the natural enemies, but the plastic garbage that floats and gathers. In addition to eating these white garbage by mistake, they are also likely to be trapped inside and cannot escape, and can only wait for the natural enemies to come. Prey, or starve to death.

With the development of industry, there is now a new pollutant: microplastics . Because the particles are so small, many marine creatures swallow them as food.

To date, scientists have found microplastics in more than 100 marine organisms , including those at the bottom of the Mariana Trench. It is hard to imagine that human pollution to the environment has reached the deepest sea area.

Find alternatives to plastic

Today, countries around the world have begun to implement the "plastic restriction order", restricting the production of plastic products, advocating the use of cotton bags or non-woven bags, and replacing plastic products in various industries with other degradable materials. Can these seemingly decisive measures actually achieve the desired effect?

The British Environmental Protection Agency conducted an experiment in 2011 and concluded that the carbon emission of non-woven bags after disposal is much higher than that of plastic bags .

According to calculations, a non-woven bag needs to be used at least 11 times to offset the pollution caused by it . That is to say, the pollution caused by discarding a non-woven bag is similar to discarding 11 disposable plastic bags.

Plastic straws are often used in the catering industry. After the plastic restriction order was implemented, they were replaced by paper straws. However, due to the poor taste in use, most customers were dissatisfied. Since then, some milk tea shops have replaced straws with PLA (polylactic acid) straws. This material looks similar to plastic, but it is degradable and seems to be a perfect substitute for plastic.

No matter what you do, people will first look at the cost, after all, one of the reasons why plastic is so widely used is its low cost. The unit price of PLA's raw materials is 25,000 to 30,000 yuan per ton, while the unit price of polyethylene for making plastics will basically not exceed 10,000 yuan per ton.

Some people may say that the more expensive it is, the more expensive it is. Isn't PLA degradable? It is not unacceptable to spend more money and reduce environmental pollution.

In fact, although PLA is degradable, the degradation rate in the natural environment is far less optimistic than we thought. It has been reported that if you throw a PLA bottle into the sea, it will take hundreds of years to break down .

The Central South University of Forestry Science and Technology also conducted an experiment in which PLA plastic was buried in simulated natural soil. After 12 months of re-testing, it was found that its quality only decreased by 0.23%.

However, the study also says that PLA can be decomposed in industrial composting facilities, where it can be heated to a temperature high enough to accelerate the decomposition of PLA by microorganisms.

However, this is not applicable in the real environment, because there is currently no special facility that can accumulate PLA to decompose it. If a reasonable method of disposing of waste PLA products is not found, it is likely to cause new pollution.

But there is still a problem here, that is, the degradable material will be converted into carbon dioxide and methane after being decomposed by microorganisms, both of which will increase the greenhouse effect, which is another thorny environmental problem for humans.

In this way, human society will pay a corresponding price for the unrestrained development of the past few decades. On the road of environmental protection and sustainable development, there are still many hurdles waiting for us to overcome.