Table 2.

Chemical compositions of ASGM-contaminated and ’control’ soil samples.

Sample	SiO2	Al2O3	Fe2O3	MnO	MgO	CaO	Na2O	K2O	TiO2	S	TOC	IC	Cu	Pb	Zn	As
	(wt%)	(wt%)	(wt%)	(wt%)	(wt%)	(wt%)	(wt%)	(wt%)	(wt%)	(wt%)	(wt%)	(wt%)	(mg/kg)	(mg/kg)	(mg/kg)	(mg/kg)
A-1	49.2	7.36	6.83	2.88	3.24	24.6	0.0001	0.764	0.09	1.47	3.43	4.00	805	6370	11,000	591
A-2	52.8	17.3	6.05	0.70	2.27	13.5	2.96	1.57	0.35	0.31	3.44	1.71	562	1960	2720	121
A-3	52.9	19.1	5.03	0.18	2.22	6.22	3.33	1.75	0.48	0.27	3.61	0.32	416	1230	1220	47
A-4	51.6	21.4	6.7	0.25	2.01	5.79	2.93	2.00	0.47	0.21	5.05	0.35	380	1120	1460	35
A-5	52.8	25.5	7.63	0.08	2.54	4.03	3.64	1.88	0.72	0.07	5.20	0.10	213	68	235	15
A-6	50.6	25.0	7.72	0.09	2.49	5.26	3.73	1.77	0.68	0.04	5.30	0.22	218	78	184	15
A-7	55.2	23.9	7.04	0.04	2.26	4.35	2.81	1.67	0.67	0.06	6.35	0.10	203	74	87	3
A-8	55.1	24.8	7.45	0.08	2.26	3.08	2.69	1.62	0.73	0.06	8.03	0.03	262	87	97	2

∗Note: Operating ASGM site (A-1 and A-2), historic ASGM site (A-3 and A-4) and ‘control’ sites (A-5 to A-8).