Distribution of U and REE on colloids in granitic groundwater and quality-controlled sampling at the Mizunami underground research laboratory

Progress in Earth and Planetary Science

Table 2 Changes in the chemical concentrations of colloid-forming elements (Al, Fe, and TOC), REE, and U in the groundwater

Borehole	Sampling date	Interval volumes	V / V ₀	Al	Fe	TOC	La	Ce	Pr	Nd	Sm	Eu	Gd	Tb	Dy	Ho	Er	Tm	Yb	Lu	U
Borehole	Sampling date	Interval volumes	V / V ₀	[μg/L]	[μg/L]	[mg/L]	[ng/L]	[ng/L]	[ng/L]	[ng/L]	[ng/L]	[ng/L]	[ng/L]	[ng/L]	[ng/L]	[ng/L]	[ng/L]	[ng/L]	[ng/L]	[ng/L]	[ng/L]
09MI20	2012.10.9	0	0	5.3	11	1.8	4.2	7.6	1.1	4.8	1.3	n.d.	2.1	0.6	4.8	1.6	6.2	0.9	5.6	1.0	12
	2012.10.9	155	5	5.8	4.0	1.3	4.0	8.6	1.2	5.9	1.7	n.d.	2.8	0.8	6.9	2.2	8.5	1.2	7.5	1.4	4.2
	2012.10.10	310	10	6.1	3.6	0.8	3.9	8.3	1.2	5.5	1.7	n.d.	2.6	0.6	5.9	1.8	7.2	0.9	6.4	1.1	2.9
	2012.10.11	620	20	7.3	3.4	0.8	4.3	8.9	1.3	6.2	1.8	n.d.	2.7	0.7	6.2	1.9	7.8	1.1	7.0	1.3	3.7
10MI26	2012.10.9	0	0	13	3.3	1.3	3.5	6.3	0.9	4.2	1.1	n.d.	1.9	0.5	4.8	1.5	5.7	0.8	5.3	0.8	11
	2012.10.9	120	5	7.5	3.1	1.2	3.7	6.6	1.0	4.6	1.4	n.d.	2.0	0.6	5.2	1.6	6.2	0.9	5.5	0.9	4.0
	2012.10.10	240	10	5.7	2.8	1.3	4.0	7.6	1.1	5.2	1.4	n.d.	2.4	0.7	5.6	1.8	6.7	1.0	5.7	0.9	4.2
	2012.10.11	480	20	5.3	2.4	1.3	3.8	7.9	1.2	5.0	1.5	n.d.	2.4	0.6	5.8	1.8	7.0	1.0	6.0	1.0	5.3

V/V ₀ indicates the ratio of the total groundwater flow-through volume to the packer volume of the sampling intervals in the boreholes. Ultrafiltration was conducted using 0.2 μm membranes. Groundwater samples were collected during replacement (purging) of the groundwater in the 09MI20 and 10MI26 boreholes.