[Retracted] Chemical Characteristics of Coil Heavy Metal Elements and Ecological Security Risks Caused by Fertilization

Table 1

Classification standard of potential ecological risk of soil heavy metals.

Potential ecological risk coefficient,	Potential ecological risk index,	Pollution degree
<40	<150	Mild ecological pollution
40 ≤  < 80	150 ≤  < 300	Moderate ecological pollution
80 ≤  < 160	300 ≤  < 600	Intensive ecological pollution
160 ≤  < 320	≥600	Very intense ecological pollution
≥320	—	Extremely intense ecological pollution