Lop Nur, since it is a moor, means that it must be a beautiful lake before it dries up. As it turns out, it does. Let's take a look at what Lop Nur used to look like.

In 1972, in the satellite released by the United States, the Lop Nur we saw was a "big ear" about 60 kilometers long and 30 kilometers wide. Back then, people didn't know where this place was or how it came to be.

Located in the southeastern part of Xinjiang, it is the lowest place in the eastern part of the Tarim Basin , with an altitude of only about 780 meters. The basin is high in the west and low in the east, so that the snow melted from the Tianshan and Kunlun Mountains converged into the Tarim River, the Kongque River, the Cheerchen River and the Shule River.

These rivers eventually converged to form this historically 3,000-square-kilometer lake, which is also the second largest saltwater lake in China.

In 2010, the scientific expedition project "Retravelling the Road of Pengjiamu Scientific Expedition and Expedition" was successfully concluded. During this expedition, researchers discovered the continuous westward extension of the lake shoreline of East Lake in Lop Nur, and speculated that the area of ​​Lop Nur once exceeded 10,000 square meters. kilometer.

This is equivalent to twice the size of Qinghai Lake, the largest lake in China . And it is comparable in size to the famous Salar de Uyuni in Bolivia's Sky Territory, which was also born in the desert. From this we can imagine what kind of grand scene Lop Nur was in ancient times.

As early as the pre-Qin period, the "Shan Hai Jing" recorded Lop Nur, which was called "Youze" at that time, and Lop Nur was also translated as Lop Nur in Mongolian, which means a lake with many waters.

When Lop Nur was full of water, a mysterious small country, Loulan , even appeared. After Zhang Qian returned from his mission to the Western Regions, he wrote to Emperor Wu of the Han Dynasty: "Loulan, there is a city in Shiyi, and Yanze is near." It can be seen that in this barren area, there was a short-lived civilization because of Lop Nur.

But historically, the area of ​​Lop Nur has been in a state of increase or decrease under the change of natural environment. According to historical records, Lop Nur has been shrinking since the Han Dynasty. Until the Qing Dynasty, it had become a small lake with a length of eight or ninety miles from east to west and a width of two or three miles from north to south.

However, in 1921, the Tarim River was diverted to the east, and after flowing through Lop Nur, the lake water began to gradually increase. In 1950, the area of ​​the Lop Nur lake could reach more than 2,000 square kilometers.

Changes in estimated water area in Lop Nur over the past 10,000 years

The Lop Nur wasteland has also been washed by the river to form a grand canyon that stretches for more than 60 kilometers. The two banks of the river, which were filled with yellow sand, have also begun to become green.

Lop Nur slowly drying up

But by 1960, the lower reaches of the Tarim River began to dry up again, and Lop Nur, which had no river water supply, began to dry up rapidly. By 1972, Lop Nur had completely dried up.

Populus euphratica

The environment around Lop Nur has also been seriously affected. The Populus euphratica, known as the "defender of sand", died in large areas. The Taklimakan Desert also began to turn Lop Nur into a barren desert at a speed of 3-5 meters per year.

Lop Nur reproduces the "lake"

Why did the "lakes" appear in the already dry Lop Nur? It turns out that the lake here is no longer the original lake, and the water in it is not lake water, but brine, which is rich in a large amount of potassium.

In the 1970s and 1980s, scientists have been looking for possible potash mines in Lop Nur. Since China was very potassium-deficient at that time, there was a little hope, and scientists were reluctant to let it go.

In 1995, a scientific research team led by the famous geologist Wang Mili discovered the brine potassium ore buried in the Quaternary salt layer in the "Luobei Sag" in the northeast depression of Lop Nur. The total area of ​​this salt lake reaches 200 square kilometers, and its reserves exceed 250 million tons. It is the largest sulfate-type brine potassium deposit in the world, with a potential value of more than 500 billion yuan.

"Luobei Depression"

To extract the potash ore from the brine layer, it is necessary to extract the potassium-containing brine underneath. So in 2000, a potash company was established in Lop Nur, Xinjiang. After completing the pilot test, the potash mine in Lop Nur will be mined, and the annual output of potassium sulfate can reach 40,000 tons.

Potash mine discovered in Lop Nur

Since a large amount of brine needs to be pumped out of the ground, but the land in the Lop Nur area is extremely permeable, it is impossible to pump the water directly to the ground . Therefore, the potash mining company built a reservoir in the potash mine area and covered the land of the reservoir with a film so that the brine could not easily penetrate into the ground.

With the mining of potash mines in Lop Nur by the Potash Company, these brines have also been extracted to the surface one after another, thus forming large and small artificial lakes. These brine lakes show a wave of light under the sunlight. The sparkling appearance looks no different from the real lake.

Potash mine

What is potash mine? What does it do? How important are these potash mines? Why is it worthwhile for scientists to risk their lives time and time again to go deep into Lop Nur? How did the potash mines in Lop Nur form?

Potash mine

• Potassium salt

Potassium salts include carnallite, magnesium sulfate and potassium chloride, etc., and are the collective name for these natural potassium-containing minerals . Potash mines are generally distributed in the crustal surface or in dry underground brine, with strong solubility and high purity.

95% of the world's potash product is used as fertilizer, and the remaining 5% is used in industry. Among them, potassium fertilizers, including potassium chloride and potassium sulfate, are acidic fertilizers and are one of the three indispensable fertilizers for Chinese agriculture. It has obvious effect on increasing the yield of crops.

"Golden Rice"

Among them, potassium chloride is suitable for rice, corn and other crops, and sulfuric acid fertilizer is suitable for economic crops such as sugar cane, grapes, and sugar beets.

In industrial manufacturing, 35% of potassium salts are used in the production of detergents, 25% are used in glass and ceramics, this part of potassium is generally in the form of carbonates and nitrates, and 20% of potassium salts are used in textiles and ceramics. Dyeing, and the rest is used in the production of chemicals. It can be seen that in industrial manufacturing, potassium salts also have a very wide range of applications.

Industrial Potassium Consumption Structure

• Formation of Lop Nor Potash Mine

So how did this important salt lake form? The large lakes in the eastern part of the Tarim Basin in the early days had a wide range and were dominated by freshwater lakes. The flowing water originating from Kunlun Mountains, Tianshan Mountains and Altun Mountains is rich in potassium ions, so it converges to Lop Nur and becomes a salty lake.

As potassium ions chemically react in the lake, thin, dispersed gypsum appears. Under the influence of neotectonic movement, the northern part of Lop Nur was elevated, and the originally unified Lop Nur was gradually divided, forming a secondary salt-forming basin.

Among them , the Luobei Sag is the largest salt-forming basin, and a large amount of glauberite deposits have appeared. Finally, as secondary basins such as the Luobei Sag slowly evolved into salt lakes, a large amount of salt minerals such as halite and polyhalite were deposited.

From the plan view, the Luobei depression looks like an upside-down gourd, and the interior presents a pan-shaped basin that is deep in the north and shallow in the south. buried in the brine layer.

• The value of Lop Nor potassium salt

According to relevant data, China's annual demand for potassium chloride is as high as 12 million tons, while the world's potassium chloride demand is only 60 million tons. Therefore, before finding potash resources, China has been relying on imported potash for a long time, which is very passive.

Before the discovery of the Lop Nur potash deposit , China's potash fertilizer production was only over 2.3 million tons, and the annual import was nearly 9 million tons. The Lop Nur potash deposit is the second breakthrough in China's search for potash mines, which has effectively alleviated 80% of China's external dependence on potash fertilizers.

Potash deposit

Before the successful exploitation of the Lop Nur potash mine, China had always been at a disadvantage in international negotiations and had no say in price. However, with the mining of potash in Lop Nur, the purchase price of potash fertilizer in China is 10-20 US dollars lower than the price of India per ton.

The price of potash has finally been reduced, which has also greatly relieved the pressure on farmers.

Potash mine

In addition, during the mining of Lop Nur potash mine, the "Mountain and Deep Basin Migration Theory" and "Two-stage Potassium Formation Theory" were also proposed and improved, which played an important role in guiding the exploration and mining of Lop Nur potash mine. Under the guidance of many theories, we also have a more accurate understanding of the formation of the Lop Nur potash mine .

Nowadays, not only a potash company has been established in the Lop Nur area, but also with the development of potash resources, the population is constantly pouring in. In 2004, Lop Nur Town was successfully established in Ruoqiang County . The entire town covers an area of ​​50,000 square kilometers, which is almost the same as the total area of ​​Ningxia Hui Autonomous Region. It can be called "the largest town in China".

Ruoqiang County

Now there is an enterprise stationed in the town. In this desolate area, there is a scene of heavy traffic, the discovery and mining of the Lop Nur potash mine, and the original "sea of ​​death" has gradually become a "sea of ​​hope". ocean".

• Influence of Mining Lop Nur Potash Mine

How long will this "sea of ​​hope" last? Will it wait until the potash mines here are mined and die again? In the case of large-scale mining of potash, will it cause secondary damage to the geological structure of Lop Nur ?

Potash factory

As more and more companies are stationed, it means that the mining intensity of Lop Nur potash mine is increasing, and the area of ​​artificial lakes is also expanding. If the underground brine is continuously pumped out, will the geological structure of Lop Nur be damaged or even collapsed?

In fact, under the self-healing power of nature, as long as human beings do not recklessly exploit it, then when we extract underground brine, there will be other bottom liquids left from high places to fill the vacancies of brine.

Distribution of global potassium resources and reserves

Although China's proven potash resource reserves are not large at present, it cannot meet the demand for potash fertilizer in agriculture. But despite this, we maintain a disciplined development principle for these scarce resources.

Wang Xiaofeng, Secretary-General of China Inorganic Salt Industry Association, put forward strategic thinking on the development of China's potash fertilizer industry according to the development of China's potash. He believes that the current mining should prevent the over-exploitation of domestic potassium resources and avoid problems such as waste of resources, inability to keep up with comprehensive utilization and short service life of production equipment.

"Potassium Development"

In fact, no matter what kind of resource, we ask for it from nature. Moreover, many resources are non-renewable, so for a certain resource, we should not only focus on its economic benefits, but ignore the consequences of mining resources.