Table 5. The averages of heavy metal pollution rates in the non-metallic mining and smelting areas (%).

Non-metallic mining and smelting activities	Cu	Pb	Zn	Cd	As	Ni	Cr	Hg
Coal exploration	13.80	6.69	7.35	20.14	1.03	1.45	10.66	26.27
Realgar ore	—	—	—	—	53.90	—	—	—
Rare earth mining	66.67	42.97	0.00	100.00	2.86	0.00	0.00	66.00
Oil exploration	0.00	0.00	0.00	96.63	0.00	0.00	0.00	0.00
Total	12.43	10.57	6.70	41.46	3.37	1.11	8.40	37.23