Sampling sites	Background Concentrations	Igeo values and classes
Sampling sites	Background Concentrations	Cu	Zn	Pb	Cd	Ni
1	World average shale	0.13^a	0.14^a	0.27^a	0.73^a	0.05^a
2		0.32^a	0.85^a	0.29^a	0.86^a	0.06^a
3		0.19^a	0.51^a	0.41^a	0.76^a	0.09^a
4		0.06^a	0.14^a	0.10^a	0.39^a	0.10^a
5		0.17^a	0.52^a	0.61^a	1.90^b	0.07^a
6		0.07^a	0.26^a	0.33^a	0.84^a	0.04^a
1	Present study	0.59^a	0.20^a	2.07^c	0.38^a	0.27^a
2		1.48^b	1.21^b	2.22^c	0.45^a	0.62^a
3		0.87^a	0.73^a	3.15^d	0.39^a	0.55^a
4		0.28^a	0.20^a	0.79^a	0.20^a	0.20^a
5		0.78^a	0.74^a	4.75^e	0.46^a	0.40^a
6		0.32^a	0.37^a	2.56^c	0.43^a	0.24^a