Assessment of Heavy Metal Pollution Characteristics andEcological Risk in Soils around a Rare Earth Mine in Gannan

Table 2

Criteria for assessment of soil pollution with Nemerow pollution index.

The values of Nemerow pollution index	Pollution class	Pollution levels
PZ ≤ 0.7	I	Clean
0.7 < PZ ≤ 1	II	Moderately clean
1 < PZ ≤ 2	III	Slightly polluted
2 < PZ ≤ 3	IV	Moderately polluted
PZ > 3	V	Heavily polluted