Table 2.

Soil Quality Classification with threshold values for Pollution Indices.

Class	Qualification	Igeo	EF	CF
0	Unpolluted	Igeo < 1	EF < 2	CF < 1
1	Slightly polluted	1 < Igeo < 2
2	Moderately polluted	2 < Igeo < 3	2 < EF < 5	1 < CF < 3
3	From moderately polluted to strongly polluted	3 < Igeo < 4
4	Strongly polluted	4 < Igeo < 5	5 < EF < 20	3 < CF < 6
5	From strongly polluted to extremely polluted		20 < EF < 40	CF > 6
6	Extremely polluted	Igeo > 5	EF > 40

I_geo, geo accumulation index; EF, enrichment factor; CF, contamination factor ( Adapted from^55,56,62 ).