Effect of reducing groundwater on the retardation of redox-sensitive radionuclides

Table 7 Measured iron concentrations (μg/L) in 0.2-μm filtrate in different treatments

Test ID	Alluvium/J-13			Devitrified tuff/J-13		Zeolitic tuff/TCU			Carbonate/LCA
	J-13 Control	Blank	Sorption	Blank	Sorption	Control	Blank	Sorption	Control	Blank	Sorption
A	ND^a	1038 ± 1520	ND	1414 ± 221	557 ± 435	ND	27,752 ± 5,894	26,328 ± 4,882	ND	ND	106 ± 36
B	ND	703 ± 957	15.0 ± 5.7	98.5 ± 7.2	260 ± 347	ND	5,545 ± 4,139	4,465 ± 3,050	ND	6.94 ± 5.00	12.4 ± 21.6
C	160 ± 118	219 ± 32.7	32.1 ± 20.4	639 ± 634	108 ± 46.3	ND	123	3,539 ± 3,136	ND	16.0 ± 10.2	6.47 ± 11.6
D^b	891 ± 1193	90.0 ± 60.4	5.65 ± 4.65	230 ± 86	279 ± 149	958 ± 1,371	2,185 ± 1,624	1,307 ± 1,330	187 ± 224	ND	171 ± 254
E	ND	865 ± 489	9.84 ± 13.7	199 ± 74.0	82.5 ± 20.8	ND	4,734 ± 491	5,475 ± 4,227	27.3 ± 17.7	ND	33.5 ± 5.56

^a ND: not detected; below the detection limit of about 5 μg/L.
^b"11 ppm" FeCl₂ was added into both background and tracer sorption solutions used in Test D. Measured Fe²⁺ concentrations in the control samples are in the range of 0.2 to 1 ppm, which is consistent with the excepted dissolved Fe²⁺ concentrations from Geochemist's Workbench; the Fe²⁺ in solution is controlled by the solubility of FeCO₃ and/or Fe(OH)₂.

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