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| A Critical View on the Status Quo of the Farmland Soil Environmental Quality in China: Discussion and Suggestion of Relevant Issues on Report on the national general survey of soil contamination |
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| KeyWord:report on the national general survey on soil contamination; soil pollution; soil environmental quality; heavy metal; management method by loading capacity |
| Author Name | Affiliation | | WANG Yu-jun | Key Lab of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | LIU Cun | Key Lab of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | ZHOU Dong-mei | Key Lab of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | CHEN Huai-man | Key Lab of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China |
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| Abstract: |
| The Report on the national general survey of soil contamination was a reflection of the reality and appearance of the survey′s samples and methodologies conducted by the Ministry of Environmental Protection and the Ministry of Land and Resources. Since the soil samples were collected from the de facto survey area about 6.3 million km2, the conclusion drawn from the analytical results of such large sample size was fairly representative of the current status of China′s soil ; while there was an apparent lack of necessary in-depth analysis of the formation of data. Thus an objective and rational viewpoint on the description of the status quo of the soil environment quality is needed. In the first part of this article, we discussed the standards, the key factor to identify whether the heavy metal levels in farmland exceed the national standards, the problems about soil samples collected from high background areas and the traceability analysis of contaminants where the levels of contaminants exceed the standards. Based on our discussion, the following opinions were put forward: （1）The evaluation standards need to be clarified, as in terms of heavy metals in the cultivated land, the choice of standards is affected by many factors, which is closely related to the type of soil and crops. （2）The corresponding content of heavy metal in agricultural products where the soil samples were collected need to be evaluated, since the heavy metal content in the edible part of the agricultural products is the key indicator to determine the impact of heavy metals in the soil. Lacking the corresponding data, it cannot determine whether the soil is contaminated or not. （3）Soils with high background levels of heavy metals should not be classified as the contaminated soil. According to the definition of soil contamination, such area does not have the characteristic feature of contamination, as the high background values of heavy metals in the area come from the natural parent materials or the soil formation processes. It should be generally attributed to the environmental exceptions, and in the term of soil utilization, it should belong to the category of "science of soil adaptability". （4） The sources of soil pollution where the standards were exceeded should be carefully screened. When the Cd content in soil increased 40% or 50%, the possible Cd input from external sources should be considered from the viewpoint of material balance. The loading capacity of soil for contaminants was suggested to be adopted as guideline principle in the management of soil environmental quality, and its advantage and feasibility was discussed in the second part of the article. For the consideration of general soil management, it is advantageous to transit from a single standard to composite standards, which takes into account the sustainability of natural soil quality and sustainable utilization of soil resources. Regarding the contaminated soil, the incorporation of the concept of loading capacity will be beneficial for determining the remediation criteria. In the economic assessment of the pollution compensation, the compensated utilization and the restoring capacity could be quantified according to the capacity consumed by exogenous substances. It will also help to assess the liability and implement the protection measures in identifying the legal responsibility subject of soil pollution. The procedure of calculating the loading capacity of soil for contaminants is practical and feasible, and thus it is recommended to be incorporated in the future management of soil environmental quality. |
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