Assessment of Controlling Processes for Field-Scale Uranium
Reactive Transport under Highly Transient Flow Conditions
Rui Ma1*, Chunmiao Zheng2,3, Chongxuan Liu4, Janek Greskowiak5, Henning Prommer6,7,8, and
John M. Zachara4
1
School of Environmental Studies, China University of Geosciences, Wuhan, China
2
3
Department of Geological Sciences, University of Alabama, Tuscaloosa, Alabama
4
5
Center for Water Research, Peking University, Beijing, China
Pacific Northwest National Laboratory, Richland, Washington
Department of Hydrogeology and Landscape Hydrology, University of Oldenburg, Oldenburg,
Germany
6
7
8
CSIRO Land and Water, Perth, Australia
School of Earth and Environment, University of Western Australia, Perth, Australia
National Centre for Groundwater Research and Training, Flinders University, Adelaide,
Australia
Supporting Information
*Corresponding author: phone: +86 (27) 6788-3152; email: rma@cug.edu.cn
School of Environmental Studies, China University of Geosciences, Wuhan 430074, China
Submitted to Water Resources Research
Running Title: Controlling processes for field-scale uranium reactive transport
Dual domain model:
Liu et al. [2008] indicated that the dual domain multi-rate surface complexation model
could better simulate the kinetic uranium reaction in the field-textured column with the sediment
collected from Hanford 300A site. In their study, the multi-rate surface complexation model was
coupled to a dual domain model to account for the impact of sub-facies scale physical and
chemical heterogeneity in field-textured sediment columns on the U(VI) transport:
Mj
NS 
q kj ,m 
Cim
 2 Ci
Ci
m
  m  aij 
  mv
  im (Cim  Ciim )
  m D
2
t

t

x

x
j 1 

 k 1
q kj ,m
t
  kj (Q mj  q kj ,m )
Mj
q kj ,im 
Ciim N S 
m
im
  aij 
   (Ci  Ci )
t
j 1 
 k 1 t 
q kj ,im
t
k ,im
  kj (Q im
)
j qj
(S1)
(S2)
(S3)
(S4)
with i=1, 2, .., N; j=1, 2, ...Ns; k=1, 2, .., Mj
whereby C im and C iim are the total aqueous concentrations of chemical component i in the
mobile aqueous phase characterized by mobile porosity  m , and in the immobile aqueous phase
characterized by immobile porosity  im , respectively. In the following discussion, the mobile
and immobile aqueous phases are referred to as mobile and immobile domains. Symbols q kj ,m
and q kj ,im are the concentrations of adsorbed species j at sorption domain k in the mobile and
immobile domains, respectively; Q mj and Q im
j are the sorption extents of adsorbed species j in the
mobile and immobile domains, respectively, and are defined as the theoretical concentration of
adsorbed species j that would be in equilibrium with the aqueous phase compositions;  is the
physical mass transfer coefficient between the mobile and immobile domains; N is the total
number of chemical components.
Transient flow conditions:
The hydrographs for the wells within and near the IFRC site and stage for the Columbia
River were given in Fig. S2(a).Groundwater levels in the wells instrumented within Hanford
aquifer responded rapidly to the fluctuations of the Columbia River stage. This caused the
dynamic change of groundwater flow directions and the magnitudes of hydraulic gradients
determined using the classic three-point approach (Silliman and Frost, 1998) over the duration of
the injection experiment as shown in Fig. S2(b).
The change of Br and U(VI) concentration distributions during the experiment:
There were only three cluster wells instrumented at the study site and most of the Br and
U(VI) concentrations were measured from fully-screened wells. Thus, the 3D images of Br and
U(VI) concentrations cannot be developed. The change of Br and U(VI) concentration
distributions during the experiment were shown in Fig. S3. There are many uranium
concentration spots observed due to the intraborehole flow effect. Mass centers of injected Br
and U(VI) plumes as defined by Br and U(VI) concentrations transported through the central
area of the well field as shown in Fig. S3.
The change of cation concentrations in the models with and without considering cation
exchange reactions:
The main chemical difference between the injection and background water was that Na+
concentration in the injection water was one order of magnitude higher than that in the
background water (Table 1). In the model without considering cation exchange reactions, the
arrival times and peak concentration durations of injected higher Na+ breakthrough curves were
similar to those of Br- and U(VI) breakthrough curves, while Ca2+, Mg2+ and K+ concentrations
varied little during the test since their concentrations in the injected and background waters were
close (Fig. S4). However, when considered cation exchange, the Ca2+ and Mg2+ concentrations in
the model increased at the early period when injected higher Br and lower U(VI) concentration
plumes arrived, and the injected higher Na+ concentrations arrived later than that in the model
without considering cation exchange reactions (Fig. S5). This was caused by the exchange of
aqueous Na+ with adsorbed Ca2+ and Mg2+. During the later experiment period, the Ca2+ and
Mg2+ concentrations began to decrease to the level in the background water , meanwhile the Na+
concentrations started to increase with the peak concentration being lower than that in the model
without considering cation exchange reactions. This indicated that the aqueous Ca2+ and Mg2+
exchanged with adsorbed Na+ . Compared Fig. S4 to Fig. S5, it can be seen that the cation
exchange reactions affected the Ca2+, Mg2+ and Na+ concentrations.
References:
1． Liu, C., S. Shi, and J. M. Zachara (2009), Kinetics of uranium(VI) desorption from contaminated
sediments: effect of geochemical conditions and model evaluation, Environ. Sci. Technol., 43(17),
6560–6566.
2． Liu, C., J. M. Zachara, N. P. Qafoku, and Z. Wang (2008), Scale-dependent desorption of uranium
from contaminated subsurface sediments, Water Resour. Res., 44, W08413, doi:
10.1029/2007WR006478.
3． Dong, W., and S. C. Brooks (2006), Determination of the formation constants of ternary complexes of
uranyl and carbonate with alkaline earth metal (Mg2+, Ca2+, Sr2+, and Ba2+) using anion exchange
method, Environ. Sci. Technol., 40, 4689–4695.
4． Guillaumont, R., T. Fanghänel, J. Fuger, I. Grenthe, V. Neck, D. Palmer, and M. H. Rand (2003),
Update on the Chemical Thermodynamics of Uranium, Neptonium, Plutonium, Americium and
Technetium, Elsevier: Amsterdam.
5． Hanford IFRC team (2010). Multi-Scale Mass Transfer Processes Controlling Natural Attenuation
and Engineered Remediation: An IFRC Focused on Hanford's 300 Area Uranium Plume, Annual
report to the DOE Office of Sciences, Pacific Northwest National Laboratory, Richland, Wash.
6． Silliman, S.E., Frost, C., 1998. Monitoring hydraulic gradient using three-point estimator. J. Environ.
Eng. 124, 517–523.
Table S1. U(VI) aqueous speciation reactions used in the reactive transport models (from Liu et
al., 2008).
Speciation reaction
UO22+ + H2O = UO2OH+ + H+
UO22+ + 2H2O = UO2(OH)2(aq) + 2H+
UO22+ + 3H2O = UO2(OH)3- + 3H+
UO22+ + 4H2O = UO2(OH)42- + 4H+
2UO22+ + H2O = (UO2)2(OH)3+ + H+
2UO22+ + 2H2O = (UO2)2(OH)22+ + 2H+
3UO22+ + 4H2O = (UO2)3(OH)42+ + 4H+
3UO22+ + 5H2O = (UO2)3(OH)5+ + 5H+
3UO22+ + 7H2O = (UO2)3(OH)7- + 7H+
4UO22+ + 7H2O = (UO2)4(OH)7+ + 7H+
UO22+ + CO32- = UO2CO3(aq)
UO22+ + 2CO32- = UO2(CO3)22UO22+ + 3CO32- = UO2(CO3)343UO22+ + 6CO32- = (UO2)3(CO3)662UO22+ + CO32- + 3H2O = (UO2)2(CO3)(OH)3- + 3H+
3UO22+ + CO32-+ 3H2O = (UO2)3O(OH)2(HCO3)+ + 3H+
11UO22+ + 6CO32- + 12H2O = (UO2)11(CO3)6(OH)122- + 12H+
2Ca2+ + UO22+ + 3CO32- = Ca2UO2(CO3)3
Ca2+ + UO22+ + 3CO32- = CaUO2(CO3)32Mg2 ++ UO22++ 3CO32- = MgUO2(CO3)32UO22+ + NO3- = UO2NO3+
a
Log K (I=0)
-5.25
-12.15
-20.25
-32.40
-2.70
-5.62
-11.90
-15.55
-32.20
-21.90
9.94
16.61
21.84
54
-0.855
0.655
36.43
30.70
27.18
26.11
0.30
Guillaumount et al. (2003)
Dong and Brooks (2006)
b
Table S2. Ion exchange reactions used in modeling (from Liu et al., 2009)
Ion exchange reactions
Log K
Ca2+ + 2NaX = CaX2 + 2Na+
1.88
Source
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
b
b
b
a
Mg2+ + 2NaX = MgX2 + 2Na+
1.87
K+ + NaX = KX + Na+
1.32
H+ + NaX = HX + Na+
0.0
Fig. S1. Plan view of the Hanford IFRC site showing the model domain as a rectangle in green
color (a) and IFRC experimental well field (b) (cited from Ma et al., 2011).
Fig. S2. (a) River stage fluctuations and well hydrographs; (b) Groundwater flow direction and
magnitude of hydraulic gradient calculated with three point method (Silliman and Frost, 1998) at
the IFRC site during the experiment.
Fig. S3. The U(VI) and Br concentration contours during the test
Fig. S4. The breakthrough curves of simulated Ca2+, Na+, Mg2+ and K+ concentrations during
uranium tracer test in the model without considering cation exchange reactions.
Fig. S5. The breakthrough curves of simulated Ca2+, Na+, Mg2+ and K+ concentrations during
uranium tracer test in the model with considering cation exchange reactions.