Table 3. Metal Concentrations in Select Aqueous Sources Within or Proximate to the USA (ppm).

(Values reported represent either a range or single value for individual study cited, or a collective range for multiple studies cited).

Metal	Produced Water (Conventional)45,46	Produced Water (Unconventional)47–49*	Seawater50–52	Geothermal Sources39,53	Acid Mine Drainage54
TDS	70,000	120,000 – 300,000	35,000	46,000 – 50,000	13,000
Ag				1.40
Al			0.50	4.20	300.00
As	0.09	1.10	0.01 – 0.02	12.00
Ba	8.00 – 342	1.00 – 3,390	0.02 – 0.05	235	0.01
Cd	0.00 – 0.01
Ce					1.07
Cr	0.02 – 0.03
Cs				14.0
Dy					0.17
Er					0.11
Eu		0.04			0.03
Gd					0.16
Hg	0.01
Ho					0.04
K	200 – 11,600	516 – 1,040	329 – 392	17,500	9.40
La					0.27
Li	7.00 – 400	19.1	0.10 – 0.17	215 −440
Lu					0.02
Mg	100 – 26,000	781 – 1,190	1,290 – 1,320	54.0	504
Mn	0.50 – 7.00	0.68	0.00 – 0.01	1,400 – 1,560	231
Nd					0.49
Ni	0.03 – 0.42	0.02	0.00 – 0.01
Pb	0.00–0.05			102
Pr					0.11
Rb			0.12 – 0.20	135
Sb	0.01			0.40
Sc		0.04			0.03
Sm					0.12
Sr	7.00 – 4,500	237 – 277	8.10 – 13.0	400
Tb					0.03
Tm					0.02
U			0.00 – 0.02		0.85
Y					0.89
Yb					0.10
Zn	0.10 – 26.0		0.00	540	645

^*This reference is the only non-U.S. centric source but is included because of its wealth of information on REEs.