Treatment of Chlorinated Organics with Plants

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Treatment of Chlorinated Organics with Plants

• Joel G. Burken, Assistant Professor
• Department of Civil Engineering
• University of Missouri-Rolla

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Collaborators

• Steve Hirsch, Bill Schneider, Harry Compton
  (Aberdeen)
• John Schumacher (USGS)
• Lee Newman (U. Washington)
• Tom Wood (C. Conn.)

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Outline

• Rationale
• Cl-solvents
• Processes
• Rhizodegradation
• Uptake degradation vol.
• Engineering processes
• Summary

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Chlorinated compounds overview

• Chlorinated solvents
• DNAPLs Moderately soluble VOCs Oxidized
  compounds
• Widely used, many varied sites, large plumes
• PCBs
• Highly immobile, sediment based
• Very persistent

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Phytoremediation of organics

• Uptake - transport to above ground
• Phytodegradation - Direct metabolism
• Volatilization - Direct from plant tissues
• Storage form?
• Rhizodegradation - increased degradation
  binding
• Physical stabilization - less transport leaching

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Rhizodegradation, Cl-Solvents

• Anderson Walton (TCE with grasses)
• Increased mineralization, but insignificant
• Univ. of Washington (Gordon Newman)
• No measured increased TCE degradation(lab)
• Pilot scale some increased Cl-, not major fate
• Carswell AFB
• Reduced redox, Cl-VOC reduced, Cl- increased,
  organic carbon levels increased.

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Rhizodegradation, PCBs

• Mulberry, osage orange, and apple trees
  colonizing PCB-laden lagoon.
• Exudates were high in phenolics, 38mg/g in fine
  root tissues
• Promoted TDO-expression, growth of alcaligenes
  eutrophus

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Phytotransformation

• U. Iowa and U. Washington detected
  trichloroacetic acid, trichloroethanol in cell
  cultures and in plant tissue. Very low levels in
  lab/pilot/field studies
• Very limited 14C incorporation in many studies
  (TCE, PCE, CT, TCB, DCB)
• Overall Not a major fate.
• Genetic engineering approach undertaken to over
  express P-450 in hybrid poplars.

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Phytovolatilization

• Phytovolatilization whereby volatile chemicals
  or their metabolic products are released to the
  atmosphere through plant transpiration
  Schnoor, GWRTAC 2002
• (theory)
• Plants release volatile compounds from leaf
  tissues
• Compounds that reach leaf tissues and have a
  volatile properties (Henrys constant)
• TCE, Nitrobenzene, BTEX (literature)
• Plants have tremendous leaf surface area, which
  is positioned in the mixing zone above ground.

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14C Distribution for Volatiles
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Conjugates
Bound Residues
TCE
Metabolites TCAA
TCE

Rhizosphere -Exudates-Plant/microbes
Bound
CO2
TCE
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VOC findings from earlier laboratory studies

• VOCs which were translocated were volatilized to
  the atmosphere
• Volatilization was a major fate for translocated
  compounds
• Volatilization from plant tissues was higher for
  compounds with a higher henrys constant

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Field Studies Aberdeen MD and Tacoma WA
Ambient Air

• Chlorinated VOCs introduced into root zone or
  contaminated site
• Very low to ND TCE levels detected from leaf bag
  samples, suma canisters, tissue samples,
  FTIR, air samples

Analysis
Continuous Aqueous CT
GW contains TCE, TeCA
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Tree Coring

• Methods D. Vroblesky
• Collect a core sample of the trunk/stem
• Core sample placed into headspace vial
• After equilibration time headspace is analyzed
  via GC
• Partition coefficients are used to determine
  initial concentrations

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TCE Partitioning (Air vs Biomass)
Poplar Core Poplar Cutting
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TeCA partitioning (Air vs Biomass)
Poplar Core Poplar Cutting
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Partition Coefficients
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Wood Water Internal Partitioning

• Trapp et al (2001).
• Mackay and Gschwend (2000), assuming a lignin
  content 20.

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Internal Partitioning

• Partitioning of contaminants between plant
  biomass and transpiration stream
• Partitioning values from experimental
  relationship based upon 12 VOCs and willow
  tissue.
• log Kwood -0.28 (? 0.40) 0.668 (? 0.103) log
  Kow
• (S. Trapp, 2001, Environ. Sci. Technol.)

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Core Water vs. Bulk Solution
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Undergraduate research project data
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Tree Coring

• Samples are collected from trees across the site
• Samples are also collected vertically
• CT Carbon tetrachloride
• TCE Trichloroethylene
• TeCA 1,1,2,2- Tetrachloroethane

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Petarcik Field Site Tacoma, WA

• Carbon tetrachloride is dosed to hybrid poplar
  planted in HDPE lined basins
• 3 years of dosing, over 90 CT (and TCE in
  previous cell) is removed
• Only traces detected in leaf-transpiration gas
  sampling
• Slight metabolites detected, but lt1

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Petarcik Field Site Vertical sampling
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Petarcik Field Site Vertical sampling
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Petarcik Field Site Vertical sampling
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Petarcik Field Site Vertical sampling
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Aberdeen Proving GroundsJ-Field Site
Phytoremediation project
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September 2000 field sampling
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April 2001 data, J-Field Site
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Lab Studies
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Diffusion Trap
Air Flow
Activated Carbon
Needle
Glass Tubing
Teflon seal
Poplar cutting
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Results of Diffusion Trap Analysis
TCE dosing at 500 ppm until day 28 n 2, S.D.
shown.
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Total diffusion mass vs. influent
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Field Scale Diffusion Trap
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Activated Carbon Traps
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SPME Analysis
SPME analysis by John Schneider, Argonne National
Labs
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Spatial analysis of core TCE concentrations w/
groundwater
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Spatial analysis of core TeCA concentrations w/
groundwater
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Mass Removal Estimation

• TCE TeCA
• Avg Co 0.22 (0.05 0.88) 1.32 (0.31-5.33)
  ppm
• Avg. Transpiration 116 l/treeday
• Total Site 183 trees
• Volume treated 3.6 106 L/year
• Total Mass Removal through volatilization
  0.85 (0.2 3.6) 5.3 (1.2 21) kg/yr

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Overall plan

• Complete sampling planned ?
• Transpiration
• Trans. Gas
• Leaf tissues
• Core samples
• GW and soil
• Vadose zone

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Potential site investigation/monitoring tool
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Core Water vs. Bulk Solution
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OU1RIVERFRONT SITE
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OU1 RIVERFRONT SITE Tree core recon.
Missouri River

• 30 feet alluvium
• GW 17-25 feet
• 60 Trees cored
• 7 Residences
• PCE in 29 trees
• 0.1 7,600 ug/L
• Screen out
• Dry cleaner- Bulk tank area- Old Auto dealer

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Lagoon
Dry cleaner

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OU1 RIVERFRONT SITE 1999-2001 well installation

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Based on tree-cores - 17 Direct-push holes -
7 alluvial wells - GW 17 25 ft deep

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Were engineers.

• Can we improve the system by engineering the
  processes?

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Engineering the Processes

• Modifying the plant-microbe symbiotic
  relationship to achieve optimal goal.
• Germida Siciliano used innocula to increase the
  degradation of TPH,
• Alvarez et al. showed 1,4 dioxane degradation was
  increased with the addition of a degrading
  strain,
• Crowley and Wood both modified root colonizers
  for degradation of Dichlorobenzene and TCE
  respectively

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Enhanced Rhizodegradation
Find Prevalent Rhizobacteria
Incorporate constitutive, TCE degrading enzymes
and GFP expressing enzymes
Put them back
Find viable recombinants
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Genetic Stability of P. fluorescens 2-79TOM
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In-situ degradation
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Degradation of TCE, Poplar Rhizosphere
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GFP in Phytoremediation

• Green Fluorescent Protein (GFP). The gene gfp
  originally found in the jellyfish, Aequorea
  victoria codes for GFP.
• Incorporated into root colonizing bacteria,
  offering a visual marker system to study growth
  and survival

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Generation of GFP-recombinants
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Growth on poplar roots
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Transport of recombinants
Water Table was lowered 1 m over a 4 month period
Day 1
Root growth Day 1-61
Day 61
Root growth Day 61-122
Day 122
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Initial Screening, 4 months




Non inoculated
Pb5gfp2-2
Rhizobium 35645gfp2-1 (root colonizing strain
from ATCC)
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Why poplar?

• where willows occur naturally, one can search
  for water in these places
• -Vitrivius, Roman architect, 100 AD
• - Phreatophyte
• Latin for Tree Well

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Why poplar? High water use, controlled genetics,
fast growing, many
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Summary

• VOCs tested are translocated from the
  contaminated groundwater
• Concentrations are decreasing along the
  transpiration pathway
• No metabolite accumulation has been observed (low
  levels detected)
• Concentrations in tree cores do resemble
  groundwater concentrations, not predict

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Summary

• Native Rhizodegradation is not a reliable process
  for chlorinated solvents,
• Exudates from selected plants have been shown to
  foster PCB degradation,
• Engineered strains of rhizosphere colonizing
  organisms are can thrive in and be transported by
  plant roots,
• Results indicate the specificity of GEM/Plant
  symbiosis greatly impacts potential for
  recombinant survival.