Farmland soil remediation is still "poor and white"?

Status quo: at present, the accumulation of reserve or application engineering cases of farmland remediation technology in China is very limited, and there are many problems in the so-called farmland soil remediation demonstration projects, such as non-disclosure of process, non-disclosure of technology, unclear cost and so on. It is of little significance to draw lessons from and popularize.

It is suggested that the state should introduce preferential incentive policies in agriculture, give enterprises longer-term land management rights, and guide and support the cultivation of high-value cash crops or ecological green food to increase soil output per mu of farmland.

Liu Yangsheng, secretary-general of the China Environmental Protection Industry Association's Special Committee on heavy Metal pollution Prevention and soil remediation and a professor of the School of Environment of Peking University, said in an exclusive interview with our reporter a few days ago that he is not worried about the restoration of urban industrial sites, because "the standard is becoming more and more standardized, the technology is more mature, and the market driven by the value of land redevelopment has been formed." In contrast, he is more concerned about the remediation of farmland soil. "among the feedback from enterprises, several voices are the most concentrated: one lack of repair standards, the second lack of project demonstration, and three lack of business models."

It is suggested that the new standard should be changed to the mode of pollutant activity control, and the general survey of relevant basic data should be improved before it is introduced.

At the beginning of this year, when the Ministry of Environmental Protection decided to openly solicit opinions on the revision of the current "soil Environmental quality Standard" to the "soil Environmental quality Standard of Agricultural Land", Liu Yangsheng put forward dozens of specific suggestions. In his view, the "soil Environmental quality Standard" implemented since 1995 has been difficult to meet the current requirements.

Liu Yangsheng believes that, "unlike industrial sites using solidification and stabilization remediation technology can prevent the risk of exposure of pollutants in the environment, farmland is a living body. Plants will change the existing forms of various heavy metal pollutants around their roots in the process of growth. Therefore, there is a phenomenon that the soil in some areas does not exceed the standard, but the grain grown exceeds the standard; in some areas, the soil exceeds the standard value by dozens of times, but the grain is safe. "

He said that this is closely related to the activity of pollutants, "such as chromium, which is difficult to be absorbed by crops under inert conditions." In his own experiments, he also found that in the same soil with excessive heavy metals, the absorption of different crops was also different.

"there are many problems in the total quantity control method in the current standard, and the newly revised standard should be changed to the mode of pollutant activity control." However, Liu Yangsheng also admitted that there are certain difficulties in the specific operation of such means of control. "for example, the acidity and alkalinity of soils in the south and the north are different, and which crops are planted in different types of polluted farmland do not affect food security, and these issues all need to be studied systematically." Therefore, he suggested that the census of relevant basic data should be improved before the introduction of the new standard.

There are no successful cases abroad for reference, but there are common problems in domestic farmland soil remediation demonstration projects, so it is of little significance to learn from and popularize them.

"in foreign countries, no other country has such a large area of heavy metal pollution in farmland like China. Therefore, the real farmland restoration industry has not been formed abroad, and there are no ready-made successful cases for our reference. " Liu Yangsheng pointed out that at present, the accumulation of farmland remediation technology reserves or application engineering cases in China is very limited, and the so-called farmland soil remediation demonstration projects generally have many problems, such as "the process is not disclosed, the technology is not disclosed, and the cost is not clear." it is of little significance to draw lessons from and popularize.

He believes that the basic principles of farmland soil prevention and control should give priority to protection, unpolluted farmland should prevent the threat of pollution, and slightly polluted and heavily polluted farmland soil should adopt differential remediation techniques and programs.

"for less polluted farmland soils, strengthening and popularizing farmland management may be more important than applying remediation agents, and farmers are more likely to accept low-cost solutions." Liu Yangsheng said: "take wheat as an example, the ability of roots and leaves to absorb heavy metals in soil is different during the whole growth process, so if you change the degree of anorexia in farmland soil, such as water, and keep it in an anaerobic environment, the amount of heavy metals absorbed by plants is smaller at this time."

As for the heavily polluted farmland soil, Liu Yangsheng believes that it is urgent to develop relatively mature, stable and low-cost green remediation technology, and pay attention to the resource utilization of soil. "the surface soil has been formed for thousands of years, and soil remediation without considering the utilization of resources is a huge waste of resources."

It is urgent to explore feasible business models, guide the participation of social capital, and suggest that the state should introduce preferential incentive policies in agriculture.

"in the city, the restoration market driven by the value of land redevelopment has been formed, and the industrial contaminated site has been realized through bidding and hanging. Unlike farmland, its output value is lower than the cost of restoration. Therefore, the source of funding for farmland soil remediation is a problem. " Liu Yangsheng said that as the source of farmland pollution is complex, the main body of responsibility is difficult to determine, and farmers are unable to afford the cost of restoration, the funds for restoration at this stage mainly come from the state finance.

"it is also unrealistic to let the state bear it all. at present, it is urgent to explore a feasible business model and guide the participation of social capital. However, all business models involve benefit feedback, and it is unrealistic for companies to invest in repair without a return. " He suggested that the state should introduce preferential incentive policies in agriculture, give enterprises longer-term land management rights, and guide and support the cultivation of high-value cash crops or ecological green food to increase soil output per mu of farmland.

Because it is related to food security, Liu Yangsheng does not approve of easily changing the nature of farmland soil. "the core of the business model can only be taken from the soil and used in the soil," he said. "