Table 1.

Composition of fluids used for sorption and temperature experiments. All concentrations are displayed in mg/L, ionic strength (IS) in mmol/L. pH was measured after 24 h equilibration time of fluid with quartz sand at ambient conditions.

	Tap watera	0.01 M NaCl	0.1 M NaCl	1 M NaCl
Na+	12.7	230	2300	23,000
K+	1.9	< 0.004b	< 0.04b	< 0.4b
Ca2+	115
Mg2+	11.1
SiO2	5.7
Cl−	25.8	355	3550	35,500
HCO3−	333	c	c	c
SO42−	49.2
TDSd	558	585	5850	58,500
IS	11	10	100	1000
pHe	6.6	6.9	6.7	5.9

^aComposition according to Stadtwerke Karlsruhe 2022.

^b< 15 mg K₄(Fe(CN)₆)) per kg NaCl as stated by VWR GPR Rectapur.

^cDue to equilibration with atmospheric CO₂ HCO₃⁻ concentration always above 0.

^dAs calculated.

^eAs measured after 24 h equilibration with quartz sand in glass vials.