Table 2.

Average trace element concentrations for selected elements in world coals [69].

	Brown Coal			Hard Coal
Element	No. Samples	No. Analyses	Average concentrations (ppmw)	No. Samples	No. Analyses	Average concentrations (ppmw)
Ag	63	13,248	0.090 ± 0.020	96	11,799	0.100 ± 0.016
As	66	21,092	7.6 ± 1.3	124	22,466	9.0 ± 0.7
B	65	5,800	56 ± 3	103	13,834	47 ± 3
Be	80	48,001	1.2 ± 0.1	118	114,256	2.0 ± 0.1
Br	27	1,061	4.4 ± 0.8	65	6,807	6.0 ± 0.8
Cd	40	2,251	0.24 ± 0.04	75	15,079	0.20 ± 0.04
Cl	39	1,410	120 ± 20	83	9,981	340 ± 40
Co	95	69,660	4.2 ± 0.3	142	125,023	6.0 ± 0.2
Cr	95	46,136	15 ± 1	141	64,442	17 ± 1
Cs	40	1,808	0.98 ± 0.10	70	11,765	1.1 ± 0.12
Cu	90	69,855	15 ± 1	139	75,121	16 ± 1
F	37	3,149	90 ± 7	77	11,249	82 ± 6
Hg	48	3,623	0.10 ± 0.01	94	34,775	0.10 ± 0.01
I	8	52	2.3 ± 0.4	18	264	1.5 ± 0.3
Mn	82	23,231	100 ± 6	134	29,521	71 ± 5
Mo	80	71,606	2.2 ± 0.2	131	104,901	2.1 ± 0.1
Ni	93	70,560	9.0 ± 0.9	143	135,952	17 ± 1
Pb	78	67,744	6.6 ± 0.4	136	93,983	9.0 ± 0.7
Sb	43	5,220	0.84 ± 0.09	92	13,662	1.00 ± 0.09
Se	39	2,323	1.0 ± 0.15	81	16,478	1.6 ± 0.1
Tl	28	1,588	0.68 ± 0.07	49	6,105	0.58 ± 0.04
V	97	83,964	22 ± 2	139	99,450	28 ± 1
Zn	84	78,908	18 ± 1	137	103,924	28 ± 2