Table 6- 1 Standard value of soil environmental quality in China (GB15618-1995) Unit: mg/kg.
Note: ① Heavy metals (chromium is mainly trivalent) and arsenic are calculated by elements, which are suitable for soils with cation exchange capacity > 5cmol (+)/kg. If ≤5cmol(+)/kg, the standard value is half of the value in the table; (2) BHC is the total amount of four isomers and DDT is the total amount of four derivatives; (3) Soil environmental quality standards for arsenic in paddy field and chromium in dry land.
According to the application function and protection goal of soil, the standard divides the soil environmental quality into three categories: category I is mainly suitable for the soil in nature reserves (except the original high heavy metal content background), centralized drinking water sources, tea gardens, pastures and other protected areas, and the soil quality basically maintains the natural background level. Class II is mainly suitable for general farmland, vegetable fields, tea gardens, orchards, pastures and other soils, and the soil quality basically does not cause harm and pollution to plants and the environment. Class III is mainly suitable for woodland soil and high background soil with large pollutant capacity and farmland soil near minerals (except vegetable fields), and the soil quality basically does not cause harm and pollution to plants and the environment.
The national soil quality standard consists of three levels: the first level standard is the limit value of soil environmental quality to protect the regional natural ecology and maintain the natural background. The secondary standard is the soil limit to ensure agricultural production and maintain human health. The third-grade standard is the critical value for soil to ensure agricultural and forestry production and normal plant growth.
Corresponding soil quality standards shall be implemented for all kinds of soil: one kind of soil shall implement one kind of standards; Secondary soil should meet the secondary standard; Grade III soil shall meet the Grade III standard.