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Table 2 Modelled diffusion data for the different tracers and comparison with laboratory results

From: Exploring diffusion and sorption processes at the Mont Terri rock laboratory (Switzerland): lessons learned from 20 years of field research

Tracer Parameter D e (10−11 m2/s)
K d (L/kg)
In-situ test FM-Ca,b In-situ test DIb,c In-situ test DI-A1*d In-situ test DI-Be In-situ test DI-A2*f,g,h In-situ test
DRi
Lab data
diffusion
Lab data
batch sorption
HTO D e par
anisotropy ratio
ε
6.8
1, assumed
0.12
5
7, assumed
0.15
5.4–6.5
nc or 6.5
0.17–0.20
4–5i
nc or 4 (lab value)
0.15–0.16 i
6.0
nc
0.15
5.4
5.1
0.164
5.4–5.7o,k,l,m
~4
0.10–0.17j,l,m
 
I D e par
anisotropy ratio
ε
2.5
1, assumed
0.05
1–1.5
4.4, assumed
0.07–0.125
1.2–2.0
nc or 6.25
0.09–0.15
0.83–1.2i
nc or 4 (lab value)
0.08–0.09
3.0
nc
0.08
1.6
3.8
0.08
1.44l,m
1.7 (36Cl)j,l,m
~4 (36Cl)
0.058–0.082l,m
 
Br D e par
anisotropy ratio
ε
     3.0
nc
0.10
2.6 1.7–4.5n, 1.6m
0.078–0.15m,n
 
22Na+ D e par
anisotropy ratio
   7.2–8.2
nc or 8
   7.7
5.1
7.2–9.4o,k,l,m
4–6.7
 
α    0.45–0.62    0.5 0.33 o  
K d    0.12–0.20    0.15 0.09–0.24 o, m 0.15–0.21 o
85Sr2+ D e par
anisotropy ratio
     7.0
nc
  6.5e, 7.5m  
α      2.4   1.9–2.0d  
K d      1.0   0.64–0.75d, 1.4e, 1.7m 1.3o
Cs+, 137Cs+, 134Cs+ D e par
anisotropy ratio
   30   20.0 (Freundlich)
20–40 (ion exch.)
Nc
33(−82)(stable) 26n, 18r (134Cs+, low conc.), 23n (Cs+, stable 1 mM)
2.2–8.7
 
Freundlich isotherm    S = 0.186C 0.53   S = 0.186C 0.53 3-site ion exchange S = 0.45C 0.65 n
3-site ion exchangem
S = 0.85C 0.63n
S = 0.372C 0.53p
3-site exchange siteq
60Co2+ D e par
anisotropy ratio
     2–20
Nc
   
α      115–918    
K d      50–400    420n
  1. Effective diffusion coefficients (parallel to bedding), anisotropy ratios (D e,par /D e,perp.), porosities and sorption parameters. Temperatures for the in-situ and laboratory experiments were about 16 °C and 22–25 °C, respectively. According to published activation energies (20 kJ/mol, Van Loon et al. 2005b), D 16C should be about 0.78D 25C
  2. * Modelling using PHREEQC implementing laboratory–based parameters also obtained satisfactory results (Wersin et al. 2010)
  3. nc: not considered (only diffusion parallel to bedding taken into account)
  4. aGómez-Hernández and Guardiola-Albert (2004), bTevissen and Soler (2003), cPalut et al. (2003), dWersin et al. (2006), eSoler et al. (2008), fWersin et al. (2008), gWersin et al. (2010), hSoler et al. (2013) imodelling in progress, jVan Loon et al. (2004a), kVan Loon and Soler (2003), Van Loon et al. (2004a), lNagra (2014), mAppelo et al. (2010), nunpublished results, oVan Loon et al. (2005a), pLauber et al. (2000), qVan Loon et al. (2009), rVan Loon and Müller (2014)