Soil poisoning

The heavy metal pollution of farmland caused by the indiscriminate mining of mineral resources has reached an alarming point

Ah Yue is a minority girl at the Central University for Nationalities. She is from a village in Gejiu, Honghe Prefecture, Yunnan Province. She is the first university student in the village. She said: “I can come to Beijing to study. lucky."

Talking about his hometown, A month is emotionally complicated.

Yunnan Gejiu is called “Sitou” and covers an area of ​​1,587 square kilometers, with a population of 453,300. Tin reserves of more than 900,000 tons, accounting for one-third of the country's total tin reserves, one-sixth of global tin reserves.

Here, all people are closely related to tin.

Ah Yue’s grandfather had worked in the tin mine for more than 30 years. Ah Yue’s father is a local famous Tin artisan craftsman. Ah Yue’s brother is doing tin crafts import and export business, and Ah Yue caressed her 18 years old tin bracelet. , It has been tightly stuck in A month thin wrist.

Tin makes this land an anomaly. The tin mines that can be dug everywhere make the nearby villagers rich and prosperous. The married daughters are decorated with heavy tin ornaments. The locals believe that tin is a treasure given to them by the gods.

However, with accompany with tin is arsenic, which is the main component of the compound.

According to the public papers of the Environmental Remediation Research Center of the Institute of Geographic Sciences and Natural Resources Research of the Chinese Academy of Sciences, the use of arsenic as tin as a subsidiary mineral in China has a low value of utilization. More than 70% of them have become abandoned tailings. As of 2008, at least 1.167 million tons of arsenic in China has been left in the environment. This is equivalent to millions of tons of scattered arsenic in the wilderness, letting rain wash, injecting into rivers and seeping into the soil...

As a result, this land rich in tin is also suffering from arsenic.

Ah Yue’s grandfather died of lung cancer caused by arsenic poisoning. The three uncles of Ah Yue are also old miners. As the same illness has passed away, Ah Yue’s father has left the tin mine. However, he has already suffered from severe arsenic poisoning. Even the strength of Weichai is not good enough to learn later. Live craftsmanship to live on.

Since then, Ah Yue’s hometown has been called “Cancer Village”. The cancer incidence here was once as high as 2%, nearly 100 times the national average, and the average life expectancy was less than 50 years old.

Since the 1990s, the central and local governments have come forward to carry out rectification and rectification work. All tin miners must wear anti-virus and go down. However, the land and groundwater that have been contaminated are difficult to repair, and the heavy history has not passed. It is not only the fathers who have suffered.

Ah Yue’s brother’s vision is very poor. When the sun goes down, he can’t see things. On Ah Yue’s sister, she has a faint spot of poison. Many young people in the village are weak and often sick....

A month's home originally had 12 acres of land, planted tobacco leaves and persimmon trees, each year can have tens of thousands of income. “The tobacco leaves is long gone, who dares to smoke 'smoke' ah? The persimmon on the persimmon tree is yellow and clear, and the nuclear child is black. The mother originally loved to eat persimmons, and I would never eat persimmon in my life. It's up."

The once fertile land could no longer be cultivated. The peasants had no way out. The water and the food had to be bought in the town hundreds of miles away, and more and more people chose to leave their homes.

The reporter asked Ah Yue. After graduation, will she return to work in the township? A month was silent for a long time and whispered, "I don't know."

pain

A similar case does not only appear in Yunnan Gejiu

In 2001, the Huanjiang Maonan Autonomous County in Guangxi Province suffered a flood that had been encountered once in a hundred years. The sudden natural disaster destroyed the homeland. However, the greater pain was after the flood.

The flood washed away the abandoned tailings dam in the upstream, resulting in 246 times more harmful elements in the farmland of more than 10,000 hectares downstream. The basic harvest of the crops was virtually eliminated. The fish and shrimps in the river sections of more than 100 kilometers of the nearby Minjiang River were extirpated, and all the pollution along the river area was polluted. Until 2004, 60% of the farmland was still deserted and deserted. The mayor of Hechi, the lower reaches of the Minjiang River, who had enlisted for enlistment in the army for many years, was not able to pass the medical examination.

Experts surveyed once estimated that “poisonous water” will enter the Pearl River system through the Minjiang River and the entire Pearl River Delta will be killed. The pollution will soon spread to millions of acres of land, affecting over 100 million people, and the repair period will exceed 100 years.

In addition to Yunnan, Guangxi, and major metal production areas such as Hunan, Sichuan, and Guizhou, a growing number of heavy metal-contaminated lands have formed around many mining areas.

The Ministry of Land and Resources has publicly stated that China has 12 million tons of food each year polluted by heavy metals and direct economic losses exceed 20 billion yuan. And these foods are sufficient to feed more than 40 million people each year. Similarly, if these foods flow into the market, the consequences will be disastrous.

cover

A scientist who had worked on land pollution research for many years told reporters a meaningful story.

Just a few years ago, the scientist was invited to test the land for heavy metal pollution. After the experimental results came out, the scientists were greatly shocked because the pollution of this famous grain-producing area in China was so serious! The scientist himself handed over the monitoring report to a local senior official. After an ardent thought, the official said: “This situation is indeed very serious and we have always attached great importance. However, we are currently unable to govern, so please do not tell anyone. I read this report."

Through multiple collections, the reporter found a number of academic papers from the Institute of Geographical Sciences and Natural Resources Research Center of the Chinese Academy of Sciences, which have not yet been publicly disclosed in the society.

According to the papers, there are a large number of arsenic wastes in Liannan, Nandan, Guangxi, Nandan, Guangxi, Changning, Hunan, Changde, Hunan, and Zhangzhou, Hunan. As a result, the arsenic content of crops around the mining area exceeds the national standard by several hundred times.

The Xiangjiang River has a total length of 856 kilometers and a drainage area of ​​94,600 square kilometers. This “Mother River” that has irrigated half of Hunan Province now receives a large amount of industrial wastewater, making the total amount of arsenic, cadmium, and lead in the river water account for more than 90% of the province’s total emissions.

The task group also conducted experiments on heavy metal content of crops. The experimental results showed that the content of arsenic, cadmium, nickel, and lead in vegetables along the middle and lower reaches of the Xiangjiang River from the Hengyang to Changsha sections was inconsistent with the national “Contaminant Limits in Food” standard, exceeding the standard. The rates were 95.8%, 68.8%, 10.4% and 95.8%, respectively. These “oversized crops” are not only consumed by local farmers but also transported to more townships and cities.

The paper also mentions that the content of arsenic and zinc in paddy soil is higher than that of vegetable fields. According to scientific experts, the heavy metal content of rice and other paddy fields will be higher due to the stronger adsorption of heavy metals by water.

In 2008, the results of investigations on heavy metal pollution in farmland soils and vegetables in the middle and lower reaches of the Xiangjiang River were all released, but they were only published as scientific research results in academic journals and were not publicly available to receive sufficient attention.

According to the news from the Hunan provincial government portal, in 2010, the national Xiangjiang River Basin heavy metal pollution control project was established. In June, it invested 460 million yuan to build infrastructure. In September, it was supported by special funds from the Ministry of Environmental Protection. “The Xiangjiang sees Qingshui just around the corner. ".

However, according to scientific research scholars, according to the calculation of polluted areas mentioned in the survey papers, the treatment of heavy metal pollution in the Xiangjiang River Basin needs at least 10 billion investment and more than 10 years of recovery cycle.

Then, do these "polluted areas" of food inflow into the market seriously affect food security?

In November 2010, the reporter called the Hunan National Grain Quality Monitoring Center. The wiring personnel said that the detection of heavy metal content in foods is extremely demanding for equipment and technicians. At present, there are few institutions that can make authoritative tests in China. They are not yet relevant. Test items, so can not stand.

On February 16 this year, the reporter called the Hunan Province Grain and Oil Products Quality Monitoring Station again. The responsible person of the station said that the station can do the relevant tests for heavy metal content of grain from the level of equipment and technology. However, “Our company did not do There was no data on the detection of heavy metal content in any area of ​​Hunan."

murderer

How did large-scale soil heavy metal pollution gradually form?

Luo Zhongwei, a researcher at the Institute of Industrial Economics of the Chinese Academy of Social Sciences who has conducted in-depth research on the mining market for many years, believes that since the mid-1980s, the practice in China has been “large mines are opened, small mines have been opened, and water flows quickly”. policy.

"The result is that the local government has the right to examine and approve the development of small and medium-sized mineral resources, and the situation of 'all-in-one' private mining is formed." Luo Zhongwei believes that it is precisely because of the confusion of mining rights that China's mining industry has been concentrating for many years. Insufficient degree, backward mining process, lack of overall planning "three shortcomings."

It is understood that among the proven reserves of minerals in China, the proportion of symbiotic associated deposits accounts for more than 80%, but only 2% of the total utilization of mines is above 70%, and 75% of the total utilization of minerals is less than 2.5%. In other words, the vast majority of mines in China are just for the development of a very small number of ores and will destroy and abandon more mineral resources.

Some media have reported that most of the mines in Huanjiang, Guangxi Province have no stone plowing sites and tailings ponds, and a large amount of waste stones and tailings are piled on the mountains. This not only occupies the arable land that can be used, but is also easily formed during the rainstorm. Debris flow, the most frightening thing is that harmful ingredients in the tailings gradually spread to a larger area along with the rain, the hazards occur at all times.

Another "" is exposed slag.

In Gejiu, Yunnan, smelters and electroplating factories are very dense. The processing of the ore can be used to increase the price. At the same time, a large amount of slag is produced and discarded near mines and mines.

It is understood that in the Zhuyeshan section of the old ore field in Gejiu, Yunnan, more than 100,000 tons of arsenic slag has been exposed and accumulated in the wilderness for several decades. In order to prevent the pollution of farmland caused by arsenic residues, farmers have piled up an earth dam around the arsenic residue. However, arsenic still entered the groundwater system through rainwater. According to tests, the arsenic content of crops near the mine section exceeded 100 times.

Arsenic slag is only one of the "five poisons" of heavy metal pollution. Others are heavy metal residues such as mercury, cadmium, lead and chromium. According to statistics, as of 2005, China has accumulatively produced more than 6 million tons of chromium slag, of which only 2 million tons were disposed of. The total number of “5 slags” is even more difficult to calculate.

Another source of pollution is the sewage discharged by chemical companies.

In addition, excessive use of chemical fertilizers by farmers can rapidly increase the heavy metal content of the soil.

Salvation

In Dengjiatang Township, Suxian District, Zhangzhou City, Hunan Province, the green grass covered the entire farmland. At first glance, it was thought that it was a green rice. On this land that has been heavily polluted by heavy metals and cannot be cultivated, the grass called “soil cleaner” grows lush.

According to Chen Tongbin, director of the Center for the Restoration of Environmental Research at the Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, the ability of barnyardgrass to absorb arsenic in the soil is 200,000 times that of ordinary plants. In three to five years, this land will be absorbed by barnyardgrass. It can be “restoring health” and the farmland that has been repaired in Quzhou has been restored to farming.

Now, weeds have been rooted in Chenzhou, Hunan, Gejiu, Yunnan, and Huanjiang, Guangxi. Especially in Huanjiang, Guangxi, weeds have been planted to a size of 1,000 to 2,000 acres and have become the largest area of ​​arsenic polluted farmland in the world. project.

The "Allied comrades-in-arms" of Zhaicao and the Southeastern Sedum are plants planted in Guangdong to specially repair cadmium-poisoned farmland. Now Southeast Sedum also has more than 100 acres of experimental sites in the country.

In the northwest, on the 300-mu saline-alkali land, bamboo willows, known as “drug addiction and detoxification expert”, are cultivated. It not only is cold-tolerant, drought-tolerant, resistant to alfalfa, and resistant to saline and alkaline. It can also absorb municipal sewage and eliminate nitrogen, phosphorus and potassium. Heavy metals in the soil.

According to Chen Tongbin, the phytoremediation approach is closer to the natural ecology, and it is currently the best choice from the aspects of economic input, repair cycle and avoidance of secondary pollution.

However, the implementation of the phytoremediation method did not go smoothly. Take Gejiu in Yunnan as an example. Currently, the remediation area is less than 100 mu and the polluted area is over 200,000 mu.

Glass of water.

Although the phytoremediation method is already very “affordable,” the cost of repairing a ton of contaminated soil is already less than 200 yuan, but the huge amount of repaired area makes the total amount of investment amazing. For example, Chen Tongbin said that the contaminated land in Guangxi's Huanjiang River amounts to 10,000 mu. If it is to be completely restored, the total investment will be at least tens of millions to 100 million yuan, which is not a small amount for local finances.

In Hechi City, Guangxi, weeds have been intercropped with mulberry or sugarcane, ramie and other economic crops, so that the farmers have good economic income while contaminated land is being restored.

However, Chen Tongbin still emphasizes that not all restoration areas can achieve the balance of economic benefits. Soil remediation still requires government guidance and subsidies. Otherwise, the scale of rehabilitation will be difficult to expand.

In addition, breeding seedlings is not easy. The ultra-rich plants found so far are generally wild plants, and their seedling breeding has great technical difficulties. It is even more difficult to realize large-scale seedlings. Therefore, the method used today is to replant the first greenhouse and then transplant it into the repair area. Undoubtedly will increase the cost and difficulty of operation.

Moreover, arsenic-rich hyperaccumulators resembling grasses are mostly concentrated in the south of the Huaihe River in China and rarely found in the north of the Huaihe River, which greatly limits the scope of the phytoremediation method.

For the local villagers, the most painful thing is that the repair period of three to five years is too long. They are kept by the field that cannot be cultivated. They can do nothing but wait.

The cruel reality is that many polluted areas can't wait to adopt the phytoremediation method and instead choose the "local soil method."

The “land and soil method” is also called the physical restoration method. In short, the contaminated soil is buried deeper than 25 cm below the roots of rice. It takes millions of dollars to repair an acre of polluted land by this method. And contaminated soil is still there, and it will even continue to expand. However, because the method of repair is simple and takes little time, this method of drinking thirst is widely used.

Solution

“Only by tightening access, unifying management, and clarifying supervision can we rationally develop mineral resources and contain heavy metal pollution in the soil.” Luo Zhongwei’s viewpoint has also been recognized by Chen Tongbin. “Unreasonable exploitation of minerals is the cause of soil. The most important reason for heavy metal pollution is that it has managed to control the largest problem of soil heavy metal pollution.

Luo Zhongwei believes that China's mining management legislation is relatively weak, and many interventions and out-of-government policies are important causes of unclear ownership of rights and responsibilities. Second, China has not formed a unified mining management system. In terms of management, China implements the distribution of the rights of the central government and the local government as the subsidiary. However, because the central and local governments at different levels have different concerns about resources and different interests, there are occasions where there are policies and countermeasures, and even there are deviations and distortions in the implementation of laws and regulations.

Luo Zhongwei believes that it is necessary to abolish the right of local governments to apply for mining approval, explicitly prohibit local governments from participating in mining companies, and establish a coordination mechanism for the interests of mining.

In addition, in the supervision of the mining industry, Luo Zhongwei suggested that the establishment of a special government department in charge of supervision over the mining industry is imminent.

“Although mining management involves many departments and interests, adjustments and reforms face difficulties, but the cost of life also forces all parties concerned to remain unchanged, and national policies and special governance are constantly being strengthened. It is not difficult to solve the stalemate.” Luo Zhongwei Express optimism.

In the results of the 2010 national special environmental campaign announced recently, as of September 30, a total of 11,510 heavy metal emission companies were investigated, 584 were closed down, and 148 key heavy metal regulatory areas were identified in 14 provinces (autonomous regions and municipalities). , 19 provinces (autonomous regions and municipalities) have identified 1,149 key regulatory companies, and their remediation efforts and regulatory effects are unprecedented.

In 2011, the preparation of the "Comprehensive Control Plan for Heavy Metal Pollution Prevention (2010-2015)" led by the Ministry of Environmental Protection has also been basically completed. The time for publication is just around the corner. The “special fund for prevention and control of heavy metal pollution” set up by the state has also been raised. Increasing financial input will directly translate into “ineffective salvation”.

Everyone is looking forward to the real solution to the problem of the deadlock that surrounds the land, encircling life, and enveloping all humanity.

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