Role of Microenvironments andTransition Zones in SubsurfaceReactive Contaminant Transport

Harvey Bolton - Technical Research Manager

Jim Fredrickson – Principal Investigator

Pacific Northwest National Laboratory

PNNL Subsurface Scientific Focus Area

Starting October 2008

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PNNL SFA Science TeamPNNL SFA Science Team

Principal Investigators (2)

John Zachara and Jim Fredrickson

Co-Principal Investigators (9)

Don Baer, Alex Beliaev, Andy Felmy, Allan Konopka, ChongxuanLiu, Kevin Rosso, Tim Scheibe, Liang Shi, Andy Ward

External Collaborators (12)

Steve Conradson (LANL), James Davis (USGS), Scott Fendorf(Stanford), Ken Kemner (ANL), Rob Knight (U CO), Frank Löffler(GA Tech), Melanie Mayes (ORNL), David Richardson (U of EAnglia), Eric Roden (U WI-Madison), Daad Saffarini (U WI-Milwaukee), Roelof Versteeg (INL), Brian Wood (OR State)

geochemistry, microbiology, hydrology, geophysics, spectroscopy,

biochemistry, molecular and multi-scale modeling

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ConceptConceptHanford-inspired subsurface science theme

Hanford Site has long-term concerns and science issues (over 40publications by PNNL staff with acknowledged Hanford Siteimpact)

Close alignment with Hanford 300 Area Integrated Field Challenge,utilization and leveraging of EMSL and other DOE capabilities

Seamless projects integrated across different scales aroundcommon hypotheses

Research sufficiently fundamental for broad application to DOEand other contaminated sites

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Hanford Site Hanford Site –– DOE DOE’’s Largest Legacys Largest LegacyWaste SiteWaste Site

> 1000 contaminated “soil sites”

[cribs, retention basins, disposaltrenches, solid waste burialgrounds]

Pu, 137Cs, 90Sr, U, 99Tc

177 massive storage tanks with 53million gallons of HLW and LLW.67 suspected leakers

137Cs, 90Sr, U, 99Tc, Cr

Over 15 well developedgroundwater plumes

U, Cr, 99Tc, 129I, 90Sr, NO3, CT

200 Area plateau

Columbia River Corridor

4 major canyon complexes

U plant, B plant, REDOX,PUREX

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Contaminant Emphasis

Risk drivers on the Hanford site:

U, 99Tc, 129I, Cr, and CCl4 – environmental mobilityand persistence239,240,241Pu, 137Cs, and 90Sr – lower mobility but highradioactive toxicity

PNNL’s SFA focused on U, 99Tc, and Pu

Polyvalency with complex biogeochemistry

Significant inventory

U = 202,703 kg, 99Tc at 1390 Ci, and Pu at 400 kg

Long term concerns and scientific issues

Important science opportunities

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Research Opportunities at HanfordResearch Opportunities at Hanford

Environmental radiobiogeochemistry

Intermediate duration environmental kinetics (25+y)

Redox chemistry at various scales mediated by ferrousminerals

Deep vadose zone processes

Reactive transport at different scales

Microbiology and biogeochemistry of linkedgroundwater-river systems

Diverse subsurface microbial habitats – vadose,capillary fringe, aquifer, hyporheic etc.

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Microenvironments – DisproportionateInfluence on Chemistry

Biogenic TcO2 Intragrain U(VI) PrecipitatesUO2

2++Na++H4SiO4+1.5H2O = Na[UO2(SiO3OH)](H2O)1.5+3H+

Tc(VII)O4-+4H++3e- =

Tc(IV)O2•nH2O+(2-n)H2O

(McKinley et al. 2006, GCA)

CM

OM

P

OM

(Marshall et al. 2008, Environ. Microbiol.)

MR-1

ΔHyaB

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Transition Zones Transition Zones –– Exhibit Chem-Phys-Bio Exhibit Chem-Phys-BioChanges Over Short DistancesChanges Over Short Distances

Ringold FormationRedox Boundary

Columbia RiverHyporheic Zone

(Moser et al. 2003, ES&T)

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Different Scales ~ Different IssuesDifferent Scales ~ Different Issues

0 2 4 6 8 10-4

-3

-2

-1

0

1

(k

)·k2

(Å-2

)

k (Å-1)

Molecular Microscopic Macroscopic Field• Bonding environment

and local structure• Fundamental

mechanisms• Energetics and

structural controls• Solvation effects

• Mineral residence phaseidentity & composition

• Reaction networks andkinetics

• Morphologic and surfaceissues

• Fundamental processcoupling

• Rate processesChemicalMicrobiologicMass transfer

• Advection effects• 1-D scaling issues• Pore scale process

coupling

• Physical heterogeneityWatervelocities/directionsReactants

• Multi-scale mass transfer• Mixing & averaging• Distributed properties• Seasonal issues (temperature, precipitation)

SFA IFC

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SFA/IFC RelationshipSFA/IFC Relationship

IFC Theme: Multiscale mass transfer controls on reactivetransport

Field research with site-specific emphasis

Provides context for significance of microenvironments andtransition zones

Field-scale reactive transport modeling

SFA Theme: Role of microenvironments and transition zones inreactive transport

Laboratory and limited field research with fundamentalemphasis

Microenvironments and transition zones give rise to masstransfer effects important to field-scale transport

Pore-scale reactive transport modeling with upscaling to definefield-scale models and parameters

SFA and IFC efforts are fully complementary across multiple scales

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x60 m

Hanford IFC Field Research

Facies-scale geometry

Pore-scale characterization

SFA Molecular and Pore-Scale Process Research

Pore-scale simulationsUpscaledmodels andparameters

(Geophysical, geological,and geostatisticalcharacterization – SFAand IFC)

• Lab-scale reactive transport

validation

• Utilized in field-scale model

of IFC

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Guiding HypothesesGuiding Hypotheses

Microbial community structure & function determinedby local microscale conditions and mass transferproperties of sediments.

Microenvironments & transition zones will be dominantregions of contaminant reaction.

Diffusion-controlled mass transfer will establish &maintain microenvironments.

Dominant processes within such domains will vary withscale (microns to meters).

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Microbiologic & Geochemical CharacterizationMicrobiologic & Geochemical Characterizationof Deep Borehole Sedimentsof Deep Borehole Sediments

Cultivation-independent analyses

Biomass

Direct microscopic counts

Phospholipid phosphate

% Respiring cells

Phylogenetic / functional diversity andrelative abundance

Census of Bacterial/Archaeal 16S rRNA genesequences (JGI CSP Sanger sequencing +pyrosequencing)

Real time PCR for specific phylogenetic andfunctional groups

Assessment of potential for U or Tcreduction

Amend samples with electron donor

Depend upon natural abundance of Fe(III) orexogenously added ferrihydrite as terminalelectron acceptor (TEA)

Summer 2008 -- ~20 samples across geological formations and transition zones joint w/ IFC

Cultivation-dependent analyses

Enrichment cultures with various TEA's

High-efficiency cultivation strategies

Analysis of metabolic versatility in cultivars

Multivariate statistical analysis ofmicrobial census + geochemical /mineralogical data to generate

hypotheses for field-scale studies

Provide Hanford-relevant microbes formolecular- to pore-

scale research

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Site 1) 300A U seep 7Site 2) 300A U seep 9Site 3) 100HSite 4) 100DSite 5) Locke Is.

Metal-Reducing Bacteria are Common Inhabitants

of Columbia RiverSediments

(J. Tiedje & J. Rodrigues,Michigan State U.)

(Marshall et al.)

HRCR-5 (seep 9)

UOUO22

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Molecular-Pore Scale ResearchMolecular-Pore Scale Research

Identify & characterizereactive molecules

In vitrokinetic behavior

Interfacial properties& in vivo reactivity

Biogeochemistry Grand Challenge

4x10-6

3

2

1

0

[Pro

tein

] (M

)

3.02.01.00.0

Time (s)

(C)

a

b

c

Homogeneouselectron transfer to

Fe(III)-NTAE (V) vs NHE

0

1

MtrC

i

MRB w/ hematitenanoparticles

outermembrane cytochrome

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Electronic couplingcalculations

7 to 14 Å

0, 45 and 90°

NWChemSpin unrestricted Hartree-FockFe Ahlrichs VTZ; C,O,N,H 6-31G*

Orientation/Distance Effects on ElectronOrientation/Distance Effects on ElectronTransfer RatesTransfer Rates

-8

-6

-4

-2

0

2

4

6

6 7 8 9 10 11 12 13 14 15

Distance (A)

ln (

VA

B/c

m-1

)

orientation #1 orientation #2 orientation #3

Bis-His heme

Iron Terminated (001)Hematite Surface

Hematite(Fe2O3)

(Kerisit & Rosso 2007, J. Chem. Phys. )

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Microscopic Speciation ControlsMicroscopic Speciation ControlsMacroscopic Release Behavior of UMacroscopic Release Behavior of U

Metatorbernite (uranyl copper phosphate) in grain coatings

Copper UraniumBSE Calcium

NPP2 - 4

--- 139 mg/kg ---

PORE VOLUME V/V0

0 150 300 450 600 750 900 1050 1200 1350 1500 1650

U(V

I)a

q

t

ti

μl L

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

input solution U(VI) concentration

0 μmol L-1

166 h SF

242 h SF

144 h SF

173 h SF

175 h SF

307 h SF

237 h SF

SGW 3, pH = 8.85

138 h SF

SGW 2, pH = 8.05

792 h SF

pH = 7.55

2.2 cm

300 A sediments containprecipitated U

Speciation modeldeveloped from EXAFS,S-XRD, and TEM/EPM

Column study integratesmultiple pore-scaleprocesses

Column study to investigate mass-transfer controlleddissolution

(Catalano et al. 2006, Arai et a;. 2007, Zachara et al. 2008)

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NMR Pulse Gradient Spin Echo (PGSE)NMR Pulse Gradient Spin Echo (PGSE)Measurements of HMeasurements of H22O Self-Diffusion inO Self-Diffusion in

Intragrain FracturesIntragrain Fractures300 MHz EMSL NMR

Measures magnetic moment under field gradient (G) todetermine self diffusion during t

Determines ensemble of molecular random movementsof 1H-associated with diffusion

Data allows calculation of diffusion factors for reactivemineral grains

Basis for pore-scale transport models

(Liu et al. 2007, WRR)

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Synchrotron X-ray Spectroscopy &Synchrotron X-ray Spectroscopy &Microscopy (APS)Microscopy (APS)

(Marshall et al. 2006, PLoS Biology)

X-ray microscopy, Kemner et al.

R (A)

-1 0 1 2 3 4 5

Tf

Mit

d

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

MR-1 + Tc(VII) + HFO

CN32 + Tc(VII) + HFO

2PC-C + Tc(VII) + HFO

PCA + Tc(VII) + HFO

Tc(IV) + HFO

Tc(IV) standard

Tc-O(ts)

Tc-Fe (ss)

Tc-Tc (ss)

Tc-O (fs)

heterogeneous

reduction

signature

Tc EXAFS, S. Heald

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SFA Implementation (FY09-10)SFA Implementation (FY09-10)

Microbial ecology investigations of unconfined aquifer in 300A &biogeochemical studies (U and Tc) w/new MRB isolates

Molecular/microscopic studies of MRB isolates & derivedbiomolecules in model mineral-water systems

Molecular speciation & biogeochemical reaction studies of Pu inZ crib sediments and model systems

Competitive interfacial redox reactions of O2 and Tc(VII) inHanford Fe2+-containing minerals and 200A deep vadosesediments

Pore-scale reaction networks, macroscopic transport behavior,and coupled kinetic transport models in 300A sediments

Geophysical imaging & measurements of different types forfacies and transition zone delineation in 300A U plume

Initial/Transition Science Themes