www.sciencemag.org/cgi/content/full/314/5799/638/DC1

Supporting Online Material for

Colloid Transport of Plutonium in the Far-Field of the Mayak Production Association, Russia

Alexander P. Novikov, Stepan N. Kalmykov, Satoshi Utsunomiya, Rodney C. Ewing,* François Horreard, Susan B. Clark, Vladimir V. Tkachev, Boris F. Myasoedov

*To whom correspondence should be addressed. E-mail: rodewing@umich.edu

Published 27 October, Science 314, 638 (2006)

DOI: 10.1126/science.1131307

This PDF file includes:

Materials and Methods Figs. S1 to S3 Table S1 References

Supporting Online Material

“Colloid Transport of Plutonium in the Far-field of the Mayak Production

Association, Russia” by Alexander P. Novikov, Stepan N. Kalmykov,

Satoshi Utsunomiya, Rodney C. Ewing, François Horreard, Susan B. Clark,

Vladimir V. Tkachev, Boris F. Myasoedov

METHODS

Groundwater samples were extracted from the well by an in-situ pump at the rate of

2-2.5 m3/hour. The samples were collected in glass bottles previously purified by

washing with nitric acid (high purity) and deionized water. The equipment was purged by

nitrogen before taking samples. Conductivity, pH and Eh were measured immediately

after the sampling, and samples were taken after the measured values became constant.

Samples were transported to the laboratory immediately after sampling in order to

conduct micro- and ultrafiltration and further measurements. The aliquots of solutions

were taken from each sample for the analysis of major and trace elements and

radionuclides.

Successive micro- and ultrafiltrations were performed in nitrogen atmosphere to

avoid changes in Eh values and carbonate concentration. The samples were filtered

through 200 nm, 50 nm (nucleopore filters, Dubna, Russia), 15 nm (Vladipor, Russia), 10

kD (~1.5nm) and 3 kD (1 nm) (Millipore) micro- and ultrafilters. Aliquots of each filtrate

and filters were used for further analysis.

Major and trace elements and radionuclide analysis

A piece of each filter (about 50 % of the total filter mass) was dissolved in

concentrated nitric acid upon boiling. The concentrations of major and trace elements

were determined using atomic absorption spectroscopy, ion chromatography and

inductively coupled plasma mass spectrometry (ICP-MS). The concentrations of actinides

were determined using gamma-spectrometry with HPGe-detector, liquid scintillation

spectrometry, alpha spectrometry with passivated ion planar silicon detectors (PIPS) and

ICP-MS after appropriate chemical separation procedures (S1).

Actinide redox speciation

The total concentration of actinides in the groundwater samples was too low to use

spectroscopic methods, such as X-ray absorption spectroscopy for actinide redox

speciation. Therefore the solvent extraction method with tenoyl-trifluoroacetone (TTA)

as an extractant (S2) and extraction with supported liquid membrane with di-2-ethylhehyl

phosphoric acid (HDEHP) (S3) were used. In order to achieve the complete extraction of

actinides and to desorb the actinides from colloids, the samples were acidified to pH of 1.

SEM and TEM analysis

Filters were placed in high purity acetone and ultasonicated for a minute in order to

remove the colloidal matter from the filter. The colloid suspension was placed onto

holey-carbon film supported by a copper grid. Transmission electron microscopy (TEM)

was conducted using JEOL JEM2010F field emission gun TEM. High resolution (HR)

TEM, selected area electron diffraction (SAED), HAADF-STEM (high-angle annular

dark-field scanning TEM) and energy dispersive X-ray analysis (EDX) were conducted

using 200 keV electron beam to characterize the sample (S4). The beam diameter of 0.5

nm was used for EDX analysis. The copper signal is from the supporting Cu-grid.

SIMS analysis

The colloidal material was taken from the filters in the same manner as for TEM. For

SIMS measurements an aliquot of suspension was dropped on silicon chips and air-dried.

All analyses were performed by a Nano-SIMS50 (Cameca, France) using 16keV O-

primary ions, and detecting positive secondary ions. Mass resolution was set at M/dM

=2000 for all data. The images were acquired by scanning the primary beam over the

samples and detecting the emitted secondary ions in parallel. Uranium was detected in the

form of UO+ ions in order to get a relatively intense signal without any isobaric

interferences. Iron was followed as 54Fe+, as the 56Fe+ signal was too intense. For the

same reason, 44Ca+ was measured instead of 40Ca+. Manganese and aluminum were

measured as 55Mn+ and 27Al+.

2 4 6 8 10 12-20

-15

-10

-5

0

pH

log

a N

p4+

NpO2+

NpO2(CO3)23-

NpO2(CO3)35-

NpO2CO3-

NpO2

10oC

Near source

2 4 6 8 10 12-20

-15

-10

-5

0

pH

log

a N

p4+

Np3+

NpO2+

3-

NpO2(CO3)35-

NpO2CO3

NpO2(CO3)2-

NpO2

10oC

Well 1/69

Fig. S1. Stability diagrams of Np species in the solution calculated using the conditions at well #41/77 (near source) and well 1/69 (3.9 km). The calculation was carried out using Geochemist's Workbench incorporating thermodynamic database of "thermo.com.v8.r6+". Thespecies in plain and italic text represent the solid and the aqueous species, respsectively.

44Ca

238U16O

54Fe

10 micron 10 micron

10 micron

238U16O 55Mn

20 micron 20 micron

Fig. S2. Nano-SIMS elemental maps of colloids from well 1/69. The contrast is enhanced for the trace elements. (A), Uranium adsorped onto an aggregate of amorphous hydrous Fe oxides. (B),Uranium adsorbed onto rancieite, (Ca,Mn)Mn4O93H2O.

A

B

0 2 4 6 8 10 12–20

–15

–10

–5

0

pH

log

a P

u4+

Pu(CO3)2+

Pu(OH)4(aq)

PuO 2

Pu(CO3)2 PuO2

Well# 1/69Near source

25 Co

Figure S3. Stability diagram for Pu carbonate species. The thermodynamic data were based on (26). In the case of calculations that include other carbonate species; Pu(CO3)32-, Pu(CO3)44-, and Pu(CO3)56- , these species were dominant over the species indicated in this diagram.

Table S1. Oxidation state of actinides in the groundwaters from Mayak region, as percentage.

* Am(III) was analyzed to control performance of liquid membranes

Well index

Distance (km)

Depth (m) U(IV) U(VI) Np(IV) Np(V) Pu(III) Pu(IV) Pu(V) Pu(VI) Am(III)*

63/68 1.10 20 0 100 0 100 0 100 0 0 100 65/68 1.75 60 0 100 0 100 0 54 37 9 100 9/68 2.15 60 0 100 0 100 0 90 10 0 100

176/94 2.50 63 0 100 0 100 0 100 0 0 100 1/69 3.2 44 0 100 0 100 0 79 21 0 100

14/68 3.9 100 0 100 8 92 0 72 28 0 100

References cited in supporting material

S1. B. F. Mayasoedov, A. P. Novikov, F. I. Pavlotskaya, Radiochemistry 40, 461

(1998).

S2. A. Saito, G. R. Choppin, Anal. Chem. 55, 2454 (1983).

S3. B. F. Myasoedov, A. P. Novikov, Evaluation of speciation technology.

Workshop Proc. Tokai-mura, Japan, p25–37 (1999).

S4. S. Utsunomiya, R. C. Ewing, Environ. Sci. Technol. 37, 786 (2003).