In the 1960s, a group of Chinese people shouldering the national mission went to Lop Nur, Xinjiang to engage in R&D missions, and successfully achieved "two bombs and one satellite" in Lop Nur. From then on, Lop Nur became famous in China. According to geologists, there were many oases in Lop Nur a long time ago. At least 300 years ago, there were many lakes in Lop Nur, otherwise the ancients would not call this place "berth".
But in the 1970s, Lop Nur gradually dried up, and all the lakes dried up in less than ten years, and the ecological environment in this area entered a state of barren grass. In recent ten years, some lakes have been found in Lop Nur, and the water in these lakes is as clear as the water in shallow water, which makes people wonder why lakes will appear again in Lop Nur, which has been dry for a long time. Is this nature's uncanny workmanship or is there another reason?
What caused Lop Nur to dry up?
After long-term research by scientists, it is found that there are three reasons for the dryness of Lop Nur. First of all, the older the water vapor transported to Lop Nur, the less it will be. Thousands of years ago, there were many lakes in Lop Nur, and the formation of these lakes depended on the water vapor transported from the oceans, such as the Indian Ocean, the eastern coast of China and the Arctic Ocean. But later, the climate of these oceans changed, which led to the decrease of water vapor transported inland.
In addition, Lop Nur is a low-lying land, surrounded by mountains, which keep the water vapor out. In the long run, the climate in Lop Nur becomes very dry. Secondly, people constantly transfer the water in Lop Nur to other places, which leads to the gradual decrease of the lake water reserves in Lop Nur. Lop Nur is located in a relatively arid area in northwest China. People who have lived there since ancient times must have a stable water source if they want to develop agriculture and animal husbandry, and Lop Nur is one of them.
After the founding of New China, the state attached great importance to agricultural production and construction in the western region, so it invested heavily in developing agriculture in Xinjiang. At that time, when people were developing agriculture, they only knew how to use the ready-made Lop Nur, without considering that the lake had dried up, so they kept transferring the lakes of Lop Nur until Lop Nur gradually dried up, and people changed their minds. Moreover, the melting speed of snow and ice in the western region cannot keep up with the disappearance speed of lakes.
Some lakes in Lop Nur depend on the melting of snow and ice on the mountains for water supply. However, the melting speed of snow and ice in western mountainous areas is very slow, which can't keep up with the evaporation of Lop Nur lake and the amount of water taken by human beings, and gradually leads to the drying up of a large number of lakes. According to historical records, the dry up of Lop Nur began in the 1960s, when the lower reaches of Tarim River stopped flowing.
It was not until 1972 that Lop Nur became completely dry in just 12 years. The drought in Lop Nur has had a great impact on the surrounding ecological environment. A large number of herbs withered and died, even Hu Yangshu, known as the "defender of sand prevention", died to pieces. The Taklimakan Desert next to Lop Nur "takes advantage of the situation" and constantly advances to Lop Nur at a speed of 3-5 meters per year. In the end, Lop Nur became a barren desert and was called "the sea of death" by the outside world.
Why is there a lake in Lop Nur, which has been dry for many years?
In fact, the dry up of Lop Nur did not happen in recent decades, and this phenomenon began at the beginning of last century or even in the19th century. It is understood that at the beginning of last century, a few foreign explorers specially heard the name Lop Nur and entered the area for exploration. Half of them went in and never came out again, leaving Lop Nur shrouded in mystery. Since then, Lop Nur has been called the "sea of death", and it is almost difficult for inexperienced people to get out after breaking in.
In recent ten years, Lop Nur once again showed its mysterious characteristics. It was found that some lakes appeared in the barren desert, which looked as beautiful as the shallow sea of Maldives. What's going on here? It turned out that Luo Jia discovered a rich potash mine in Lop Nur, and then invested huge sums of money to develop potash mines. Perhaps you will be curious, what is the relationship between potash mines and the emergence of lakes?
They have a close relationship. The underground potash mine in Lop Nur exists in the form of brine layer. In order to extract potassium from it, underground potassium brine must be extracted first. At that time, China had a large demand for potassium salt, but it could not achieve self-sufficiency and relied on foreign imports for a long time. In order to change this situation, after discovering the huge potassium salt reserves in Lop Nur, the state decided to vigorously develop the potassium salt mines there. Because too much potassium salt is needed, underground brine is continuously pumped out of the ground.
After the brine is pumped underground, there is a problem. The land in Lop Nur is very permeable, and the brine just pumped will soon penetrate into the land. In order to solve this problem, SDIC built a special reservoir in the potash mining area, and covered the land of the reservoir with film to prevent salt water from infiltrating into the ground again. This method has achieved remarkable results. With a large amount of brine pumped to low-lying areas, artificial lakes, large and small, appeared in Lop Nur.
What is potassium salt? What's the use of potassium salt?
Potassium salt is the general name of natural potassium-containing minerals, including carnallite, magnesium sulfate and potassium chloride. Generally speaking, potassium minerals are distributed in the surface of the earth's crust or dry underground brine, and they are all soluble and of high purity. In the last century, Germany, Russia, Canada, Spain and other countries were important sources of potash fertilizer in the world. Before World War I, Germany almost controlled the global potash market, but now more than a quarter of potash in the international market comes from Canada.
Friends who are familiar with chemical knowledge should know that potash mines are mainly used in the industrial production of potassium compounds and potash fertilizers, of which more than 90% of potash products are used as fertilizers, and almost all the rest are used in industrial production and manufacturing. According to the investigation, 35% of potassium salt is used to produce cleaning agents, 25% of potassium salt is used to produce glass and ceramics in the form of carbonate and nitrate, 20% of potassium salt is used for textile and dyeing, and 13% of potassium salt is used to produce chemicals, which shows that potassium salt is widely used in industrial production.
If the above uses are not closely related to us, then the amount of vegetables and fruits we eat every day is due to potash fertilizer, which is one of the three major fertilizers in China's agriculture. Practice has proved that potassium fertilizer can produce obvious yield-increasing effects on most crops, among which potassium chloride is suitable for rice, wheat, corn, cotton and other crops, and potassium sulfate is suitable for cash crops such as sugarcane, grapes, beets and tea.
How is the potassium salt of Lop Nur formed?
Geologists are also surprised to find that there was a potash mine in Lop Nur at first, and then it was concluded that there was a potash mine in Lop Nur after analysis. The first reason is that Lop Nur was the center of water accumulation in Tarim Basin in ancient times, which provided an excellent geographical environment for the accumulation of potassium salt. It is found that there are more than 100 kinds of minerals containing potassium in nature, and the physical and chemical characteristics of potassium itself make it more stable in flowing liquids such as magma and stagnant water.
In ancient times, rivers originating from Kunlun Mountain, Tianshan Mountain and Altun Mountain finally merged into Lop Nur low-lying areas to form lakes. These flowing waters contained potassium ions, which were deposited after chemical reaction in the lakes and gradually formed potassium salts. The second reason is that the topography of Lop Nur is relatively closed, which is conducive to the accumulation of potassium salts. Geographically, there are Taklimakan Desert in the west of Lop Nur, Kumutage Desert in the south, Kuruk Mountain in the north and Sanlong Dune in the east.
Lop Nur is about 780 meters above sea level, but compared with the surrounding mountains, it is a low-lying land surrounded by surrounding mountains, and it is difficult for potassium salt to flow out after it flows into Lop Nur. The third reason is the arid climate in Lop Nur. Lop Nur is located in the inland of the Asian continent, far from the ocean and surrounded by mountains, which makes the water vapor in the ocean unable to reach, resulting in a long-term dry climate there.
The arid climate makes the water in the shallow water layer and brine layer evaporate, thus a large amount of potassium salt is precipitated at about 10 meter from the surface, which is a relatively easy location for mining.
Won't the geological structure of Lop Nur be destroyed by mining a large number of potash mines?
Lop Nur is currently the largest potash mining base in China, and there are still national mining departments operating there. Moreover, in recent years, the number of lakes in Lop Nur is increasing, and the area of artificial lakes is also expanding, which shows that the brine layer extracted by workers from underground is also increasing. Seeing this, it is estimated that many people will worry that if brine is continuously extracted from the ground, it will not affect the geological structure of Lop Nur and lead to ground collapse.
In fact, mining activities will affect the geological structure of Lop Nur to a certain extent, but the impact is not great, because nature has a certain ability of self-repair. When workers pump the underground salt water layer to the ground, other levels of liquid will flow down from a height to fill the vacant position of the salt water layer. Of course, the person in charge of the National Development and Investment Corporation also said that the exploitation of the potash mine in Lop Nur should be moderate, otherwise it will directly destroy the dynamic balance of the mining area.
If mining is too fast, it will accelerate the rapid depletion of potash mine and eventually become a "dead mine". Dead ore does not mean that all the minerals in it have been mined out, but that improper mining has led to the destruction of the mining area and the inability to continue mining, resulting in the greatest loss, so we need to pay special attention to this problem in the mining process.