Prevention of soil pollution is better than remediation: nip the problem in the bud

Recently, news about the whereabouts of cadmium-contaminated wheat in a county in the north drew widespread attention. The local environmental protection department responded that some farmland was indeed contaminated with cadmium, but the wheat produced had been purchased in a targeted way by the government and did not enter the market. The findings of an investigation into an environmental incident at a school in a certain place in the south were also released to the public recently. Clearly, whether it is agricultural farmland or urban construction land, people's attention to "the environment beneath our feet" is increasing.

China's historical backlog on the soil environment is far greater than that for the atmosphere and water bodies, and soil pollution is a kind of pollution that is hidden yet persistently harmful. Choking smog and discolored river water signal the presence of air and water pollution, but ordinary people find it very hard to tell contaminated land from its appearance. Pollution of agricultural farmland harms human health indirectly through crops, while the problem of "toxic land" in construction land harms the living environment. Therefore, it is highly necessary to maintain a zero-tolerance attitude toward soil pollution incidents.

The attitude must be firm, and the methods must be scientific. In my view, prevention of soil pollution should take priority over remediation, and the most urgent task now is to prevent and control the emergence of new pollution. For uncontaminated soil, we must take preventive measures in advance and mobilize public participation in prevention through policy. At the same time, we should conduct a survey of soil pollution conditions in each area, adopt different measures, and carry out remediation by category, by use, and by stage, gradually reducing the existing stock of pollution, and ultimately ensuring "safety on the tip of the tongue" and "safety beneath our feet."

That prevention is better than remediation does not mean remediation is unimportant. Large-scale soil remediation and treatment is a worldwide challenge, and its complexity and investment far exceed those of air and water. The harder remediation is, the more it highlights the importance of prevention and control. If the pollution sources are not cut off, remediation will yield twice the result with half the effort. Soil pollution is difficult to prevent and control because its capacity for migration and dilution is weak. Fortunately, soil, unlike air and water, is not directly consumed by people. And healthy soil is itself an ecosystem that can reduce and disperse pollution risks. Therefore, soil remediation alone is the most end-of-pipe and last-resort approach to prevention and control.

The introduction of the "Soil Ten Measures" in May this year heralds a shift in China's approach to soil pollution prevention and control, from one-size-fits-all indicator control to comprehensive prevention and control emphasizing risk control. Soil pollution prevention and control should, on the basis of protecting soil, rationally use land by category, rather than seeking to achieve full soil pollution remediation regardless of cost and without regard for science. The environmental risk of soil depends on its use, corresponding to different precise remediation methods. Comprehensive soil remediation regardless of use is beyond reach even in developed countries.

Take heavy metal pollution of farmland as an example. Comprehensive remediation faces many difficulties: some are costly, such as the soil replacement method, which costs over a million yuan per mu to remediate; some take a long time, such as the method of phytoextraction of heavy metals, which requires hundreds of years. In fact, for lightly polluted land, the planting structure can be adjusted to grow trees that do not absorb heavy metals; for especially severely polluted land, risk management and control can be implemented, such as fallowing and retiring farmland or ecological resettlement.

To implement the concept of "prevention first," the first step is to get a clear picture of the soil baseline. Previously, China had carried out several types of special surveys on soil pollution and an overall survey of national soil pollution conditions, gaining a preliminary understanding of the basic situation. However, the precision of the surveys was limited, and the specific distribution of soil pollution, its environmental risks, and its mechanisms of action are not yet fully clear. Therefore, it is necessary to establish a soil environmental quality prevention mechanism and improve the soil environmental supervision system.

Once the baseline is clear, where will the money for remediation come from? The Dajiaoting plot in Beijing is a successful case. This plot was once a major chemical industry hub. After the chemical plants relocated, remediation work began. Multiple enterprises invested nearly 1 billion yuan over three years, remediating an area of more than 1,500 mu, after which towering buildings were built there. Its success lies in the fact that the land had great commercial development value. Although this is an individual case, it shows us that the general principles of pollution prevention and control, "whoever pollutes, remediates; whoever invests, benefits," still apply to soil pollution.

Soil pollution prevention and control requires sustained, long-term effort, a holistic perspective, and the participation of government, enterprises, and the public, and it is necessary to give full play to the roles of both the government and the market. In terms of responsible parties, the main body of "prevention" should be placed on the public and land users, and "remediation" should be placed on remediation enterprises and responsible parties. Whether "prevention" or "remediation," the government must play a leading role and provide a backstop for historical debts whose responsible parties cannot be clearly identified.