March 2002
    State of the Science Conference
U.S. Environmental Protection Agency
                Boston, Massachusetts
                    May 1,2000
          United States Environmental Protection Agency
             Office of Research and Development
         National Risk Management Research Laboratory
                   Cincinnati, OH


The U.S. Environmental Protection Agency through its Office of Research and
Development funded and managed the research described here under Con-
tract 68-D7-0001 to Eastern Research Group. It has been subjected to Agency
review and approved for publication. Mention of trade names or commercial
products does not constitute endorsement or recommendation for use.

The U.S. Environmental Protection Agency is charged by Congress with protecting the Nation's land, air, and
water resources. Under a mandate of national environmental laws, the Agency strives to formulate and imple-
ment actions leading to a compatible  balance between human activities and the ability of natural systems to
support and nurture life. To meet this mandate, EPA's research program is providing data and technical support
for solving environmental problems today and building a science  knowledge base necessary to manage our
ecological resources wisely, understand how pollutants affect our health, and prevent or reduce environmental
risks in the future.

The National Risk Management Research Laboratory is the Agency's center for investigation of technological
and management approaches for preventing and reducing risks from pollution that threatens human health and
the environment. The focus of the Laboratory's research program is on methods and their cost-effectiveness for
prevention and control of pollution  to air, land, water, and subsurface resources; protection of water quality in
public water systems; remediation of contaminated sites, sediments and ground water; prevention and control of
indoor air pollution; and  restoration of ecosystems. NRMRL collaborates with both public and private sector
partners to fostertechnologies that reduce the cost of compliance and to anticipate emerging problems. NRMRL's
research provides solutions to environmental problems by: developing and promoting technologies that protect
and improve the environment; advancing scientific and engineering information to support regulatory and policy
decisions; and providing the technical support and information transfer to ensure implementation of environmen-
tal regulations and strategies at the national, state, and community  levels.

This publication has been produced as part of the Laboratory's strategic long-term research plan. It is published
and made available by EPA's Office of Research and Development to assist the user community and to link
researchers with their clients.
                                            E.Timothy Oppelt, Director

                                            National Risk Management Research Laboratory


Many people participated in planning and organizing the Phytoremediation: State
of the Science Conference which was held May 1-2, 2000. The primary con-
tributors for the conference are listed below:

Steven Rock, U.S. Environmental Protection Agency (U.S. EPA), National Risk
Management Research Laboratory (NRMRL), Cincinnati. OH
Steven McCutcheon, U.S. EPA, National Exposure Research Laboratory (NERL),
Athens, GA
Norman Kulujian, U.S. EPA, Office of Research and Development (ORD), Phila-
delphia, PA
Joan Colson, U.S. EPA, NRMRL, Cincinnati, OH
Mitch Lasat, U.S. EPA, Office  of Solid Waste and Emergency Response
(OSWER), Washington, DC
Steven Hirsch, U.S. EPA Region 3,  Philadelphia, PA
Judy Canova, Bureau of Land and Waste Management, South Carolina Depart-
ment of Health and Environmental Control
Jeff Heimerman, U.S. EPA, OSWER, Washington, DC
Linda Fiedler, U.S. EPA, OSWER, Washington, DC

The success of the conference and the preparation of this document are also
due to the efforts of the many speakers and poster presenters.

Eastern Research Group provided logistical support both in advance of and
during the  conference  as well as for the development of this document under
Contract 68-D7-0001.





    Superfund's Viewpoint on Phytoremediation
       Stephen Luftig

    The Science and Practice of Phytoremediation
       Steven McCutcheon

    Interstate Technology Regulatory Cooperation: Making It Easierfor Regula-
       Robert Mueller

    The Future of Phytotechnologies
       Steven Rock

  Fundamental Processes of Plants and Soils

    Transport of Contaminants in Plant and Soil Systems
       Larry  Erickson, Lawrence Davis, Qizhi Zhang,  and  Muralidharan

    Rhizosphere Remediation  of Recalcintrant Soil Contaminants: An Impor-
    tant Component of Long-term Sustained Biosystem Treatment
       John Fletcher

  Brownfields Application and Beneficial Use of Land

    Integrating Remediation Into Landscape Design
       Niall Kirkwood

    Goals For Brownfields Pilots—O'Sullivan Island
       John Podgurski


    Capturing a "Mixed" Contaminant Plume:Tritium Phytoevaporation at Argonne
    National Laboratory
       M. Cristina Negri, Ray Hinchman, and James Wozniak

    Application of Phytoremediation to Remove Cs-137 at Argonne National
    La bo rato ry—West
       Scott Lee

 The Fate of Chlorinated Solvents that Disappear from Planted Systems

   The Role of the Plant and the Rhizosphere in Phytoremediation
      Milton Gordon

   The Case forVolatilization
      William Doucette

   Phytotransformation Pathways and Mass Balance for Chlorinated Alkanes
   and Alkenes
      Valentine Nzengung

 Innovative Solutions for Metals Removal

   Progress in Risk Assessment for Soil Metals, and in-situ Remediation and
   Phytoextraction of Metals from Hazardous Contaminated Soils
      Rufus Chaney

   Phytoextraction: Commercial Considerations
      Michael Blaylock

   ZincHyperaccumulation in Thlaspi caerulescens
      Mitch  M. Lasat

 Plume Control: Simulations and Forecast

   Chasing Subsurface Contaminants
      Joel Burken

   Effect of Woody Plants on Ground-water Hydrology and Contaminant Con-
      James Landmeyer

   Modeling Plume Capture at Argonne National Laboratory—East
      John Quinn

   Phytoremediation Potential of a Chlorinated Solvents Plume in  Central
      Stacy Lewis Hutchinson and James Weaver

 Plume Control: On the Ground Experience

   Phytoremediation at Aberdeen Proving Ground, Maryland: Operation and
   Maintenance, Monitoring and Modeling
      Steven Hirsh

   Phytoremediation Systems Designed to Control Contaminant Migration
      Ari Ferro

   Deep Planting
      Edward Gatliff

   Transpiration: Measurements and Forecasts
      James Vose

Vegetative Covers

   Monitoring Alternative Covers
      Craig  Benson

   Growing a 1000 Year Landfill Cover
      William JodyWaugh

  Tree Covers for Containment and Leachate Recirculation

  EPA Draft Guidance on Final Landfill Covers
      Andrea Mclaughlin and Ken Skahn

Degradation of Organic Compounds in Soils

  Hydrocarbon Treatment Using Grasses
      M. Katherine Banks

  Phytoremediation of Explosives

  Case Study: Union Pacific Railroad
      Felix Flechas

  Phytoremediation in Alaska and Korea
      Charles Reynolds


  Using Excavated Material for the Remediation of Sewage Farm Land in
  Berlin and Brandenburg
      HolgerBb'ken, Reinhart Metz, and Christian Hoffmann

  U.S. and International Activities in Phytoremediation: Industry and Market
      David Glass

  Phytostabilization Practices for Riverbank and Wetland Problems
      Wendi Goldsmith and Bill Morgante

  Field Studies  Examining Rhizosphere-enhanced PCB Degradation in the
  Czech Republic
      Mary Beth Leigh,  John Fletcher, David Nagle, Martina Mackova, and
      Thomas Macek

  Natural Attenuation/Phytoremediation at a Former Sludge Basin
      Paul Olson, Paul Philip, and John Fletcher

  Phytoremediation of Heavy Metals, Metalloids, and Organics: A
  Multidisciplinary Approach
      Elizabeth  Pilon-Smits, Marinus Pilon, and Paul Olson

  Growth and Contaminant Uptake by Hybrid Poplars and Willows in Response
  to Application  of Municipal Landfill Leachate
      Christopher Rog and Jud Isebrands

  Aqueous Phase Phytotreatment of Munitions
      Victor Medina

  Measuring Evapotranspiration in Hybrid Poplars
      Paul Thomas

  Sap Flow Methods to Measure Phytoremediation Water Removal
      Michael van Bavel

  Transport of Methyl Tert-butyl Ether through Alfalfa Plants
      Qizhi Zhang, Lawrence David, and Larry Erickson



       B. Speaker List

       C. Poster Presenter List

       D. Attendee List

                   Superfund's Viewpoint on  Phytoremediation

                                        Stephen D. Luftig
                            Office of Emergency and Remedial Response
                               U.S. Environmental Protection Agency
Steve Luftig is the Director of the U.S. Environmental
Protection Agency's Office of Emergency and Reme-
dial Response. This office manages Federally-funded
emergency response and longer-term cleanup activi-
ties at hazardous waste sites underthe Superfund pro-
gram, and ERA'S implementation of the Federal Oil
Pollution Act. Steve has helped implement wide-reach-
ing reforms that have dramatically increased the pace
of cleanup work, and has received  numerous awards
for innovative management. In 1999, Steve received the
prestigious Presidential Rank Award, given to only a
handful of federal executives each year. In his career
with EPA, he has managed a variety of federal environ-
mental programs both in New York, where he started in
1972, and in Washington, D.C. headquarters, where he
has been since 1990. Steve is a licensed professional
engineer and member of Tau Beta Pi, the National En-
gineering Honor Society. He graduated (Magna Cum
Laude) from the City College of New York, with a Bach-
elor of Engineering (Chemical) Degree, and has a Mas-
ters Degree in Civil  (Sanitary)  Engineering from New
York University.



Stephen Luftig, Director

Office of Emergency and Remedial

   A                      oj^

 Examples of Superfund Environmental
 Response Team Recent Successes
A Portland, OR (TCE polishing and park)
A Leadville, CO (mine tailings in-situ)
A Aberdeen PG, MD  (TCE and restoration projects)
A Naples, UT (gasoline spill - polishing)
A Lovell, WY  (PAHs - polishing)
A Tibbitts Road Site, NH (polishing and site
A Davis Liquid Chemical, RI (polishing and
A Kauffman Minteer, NJ (polishing)
A Sears Property, NJ  (polishing)

Superfund's Viewpoint on Phytoremediation
   Early projects have shown promising results
A Not a panacea - has certain concerns and
   Attractive because it is effective and
   Rarely used alone - can be under certain
   Usually part of a treatment train as a polishing
   Can be both a remediation tool and used for

Superfund's Viewpoint on Phytoremediation
Phyto C%>iisl^ci;;.;.,,,is
   Requires site specific testing and design

A Specific to contaminant concentrations and is
   chemical dependent

   Seasonal/geographical/climatic dependent

   Can take long time - growth rate dependent
   Depth dependent - on root systems
   Seems to work well for small, shallow plumes

      Superfund's Viewpoint on Phytoremediation
Food chain exposure concerns

Attractive nuisance issues

Down time if damage occurs

Need to use Native plants (Executive Order)

Need to manage for invasive aliens (EO)

Superfund's Viewpoint on
Phytoremediation Regulatory Issues
   Few Federal impediments, but must
   comply with NCP

   Nine-criteria drive remedy selection

   ITRC is working on Guidance to
   overcome state regulatory

   Some State ARARs may need to be

   Evapotranspiration caps for landfills

                     The Science and Practice of Phytoremediation
                                     Steven C. McCutcheon, Ph.D., PE
                               US EPA National Exposure Research Laboratory
                                      Ecosystems Research Division
                                             Athens, Georgia
Plenary Session I Phytoremediation: State of the Sci-
ence Conference US Environmental Protection Agency
Boston, Massachusetts May 1, 2000

Dr. Steven C. McCutcheon is an internationally known
expert on water quality, watershed hydrology, hydrody-
namics, sediment transport, cleanup of toxic organic
chemicals and metals, phytoremediation, ecological en-
gineering, and environmental planning. He authored the
1989  book, Water Quality Modeling, Vol. 1, by CRC
press, co-authored in 1999 Hydrodynamics and Trans-
port for Water Quality by Lewis Publishers and CRC
press, and was editor of the American Society of Civil
Engineers, Journal of Environmental Engineering. He
is on the editorial board of Ecological Engineering by
Elsevier, International Journal of Phytoremediation by
CRC, and was on the Board of Hazardous, Toxic, and
Radioactive Waste Practice Periodical, a new journal
by the American Society of Civil Engineers. He is cur-
rently writing and editing Phytoremediation: Scientific
Advances to Manage Contamination  by Organic Com-
pounds for Wiley and Sons. The 1997 EPA Science
Achievement  Award in  Chemistry by the American
Chemical Society and EPA, and 1995 EPA Science
Achievement Award in Waste Management by the As-
sociation for Air and Waste Management and EPA, was
awarded Dr. McCutcheon (with  others) for innovative
advances in permeable barriers to  clean up ground
water  and  development of a new component of
phytoremediation.The 1994 Richard  R.Torrens Award
by the American Society of Civil Engineers (outstand-
ing editor among the 21 editors in the Society), the En-
gineer of the Year in the U.S. Environmental Protection
Agency selected by National Society of Professional
Engineers, and the Young Civil Engineer in Government
in 1984 by the American Society of Civil Engineers have
been given him as well. Consulting experience includes
designing and conducting stream and ground water
quality assessments in Italy, arid lake and harbor water
quality assessments in western and eastern China, and
reviews of basin water quality studies, including review
of plans for the Han River in Korea  prior to the 1988
Olympics. As  a registered engineer  in Louisiana, Dr.
McCutcheon has served  as an expert witness on the
1983 flooding in New Orleans  in a precedent setting
class action. The Detroit District of the Corps of Engi-
neers engaged him as a consultant to testify at a ,401
Water Quality Hearing by the State of Wisconsin. In a
tenure-track position at Clemson, he advised the State
of South Carolina and Home Builders Association on
sediment control regulations, and International Paper
on water quality standards for the Sampit River. He was
involved in the bioremediation cleanup of the EXXON
VALDEZ oil spill in Alaska, and the emergency response
modeling of a chemical spill in the Sacramento River.
Dr. McCutcheon has been involved in risk and expo-
sure assessments at a number of hazardous waste sites
involving  metals and organic chemical contaminated
sediments and soils. As a leader in phytoremediation,
Dr. McCutcheon is at the forefront in developing  new
uses of plants to clean up hazardous waste sites and
control contaminant releases to reduce clean up costs
at U.S. military facilities. He supervised student research
at Clemson University and the University of Georgia in
nonpoint source pollution, forest management to con-
trol  water quality, hydrodynamics, and  estuary water
quality modeling. Dr McCutcheon is known for guiding
university research to meet immediate needs in water
quality management in South Carolina and Oregon. He
developed and wrote guidance forthe US Environmen-
tal Protection Agency on regulating waste loads into
estuaries and streams. Forthe internationally reviewed
Handbook of Hydrology, he is the lead author of the
chapter, Water Quality. He has  authored over 167 ar-
ticles, papers, chapters, books, and reports, including
international  consulting reports. Steve holds the Ph.D.
and M.S. degrees from Vanderbilt, and a B.S. in Civil
Engineering from Auburn University.

Dr. McCutcheon serves on the Florida Bay Science
Oversight Panel for ecosystem restoration by the Na-
tional Park Service, NOAA, USGS, Corps of Engineers,
South Florida Water Management District, and State of
Florida. He has served on four-peer review panels on
South  Florida Ecosystem Management, Circulation
Modeling in  Florida Bay,  and the Florida Bay Model
Evaluation Group. He chaired the peer panel for tem-
perature modeling of the central Platte River to resolve
conflict between the EPA Administrator and Governor
of Nebraska. In addition to service on a hazardous and
radioactive waste management panel advising the De-
partment of Energy forthe National Academies, he has
served on more than 35 other advisory panels for uni-
versities and  government agencies.

This presentation will briefly review terminology, and
define  the types,  benefits,  and  limitations  of
phytoremediation. A review of where phytoremediation
fits  in the scheme of hazardous waste management
serves as a lead into an overview of the scientific ad-
vances  on which the practice of phytoremediation is

Based on the advances and application of

•  phytoaccumulation of metals and other contaminants
•  rhizosphere biodegradation of organic compounds
•  phytodegradation of organic contaminants
•  phytovolatilization of metalloids, metals and some
   organic compounds
•  phytostabilization  of metals and organic contami-
•  rhizofiltration of metals
This presentation defines broadly the application of
phytoremediation as a niche or polishing technology and
when the approach can be used as a primary treat-
ment. Secondary benefits for nonpoint source treatment
in air and water, effluent treatment, erosion control arid
site management, and ecosystem restoration will be put
into context with the general scientific and ecological
engineering knowledge of the art. The fundamental un-
derstanding of plant and rhizosphere biochemistry and
contaminant fate and transport will be contrasted with
the field and pilot studies that represent the current proof
of concepts and proof of principles that justify use of
phytoremediation.The practice is summarized as those
approaches that are ready for application (given the
appropriate pilot and feasibility investigations for spe-
cific sites), promising treatments expected to be tested
soon, and conceivable phytoremediation approaches
that require intensive development. Finally, the intrinsic
strengthens of phytoremediation and future potential for
the technology will be reviewed forthe regulatory appli-
cations in hazardous waste management.

Steven C. McCutcheon, Ph.D.
National Exposure Research
Ecosystems Research Division
Athens, Georgia
 Plenary Session I <;
    State of the ^
        Science Cj.
     Boston, MA *?;
     May 1, 2000
History and Types _,
Phy toremed iat ion
Strengths and Limitations
Rhizosphere bioremediation
Accumulation  of Metals and
Other Compounds
State of  the  Technology

PHYTOREMEDIATION: use of green plants
or vascular plants to clean up or control
hazardous wastes.

Coined in 1991 by Raskin (metals accumulation)

Schnoor et al. (1995) seems to be first
   recognition that plants are very effective in
   degrading organic chemicals for remediation

Growing element of ecological engineering — the
  use of the self-engineering ability of plants
              TYPES OF
   ^^^^^^.•" rf":.' J| :^£L^^^
   lytoaccumulation, phytoextraction,
  lant-assisted bioremediation
  1 lytodegradation or pi  '  '

                                           • J *!••• : "
               F i"*  T V <*l_; --'jfcn •»      '"^JT-"
               BENERlts  OF'-
   If •• ft •
     •„. «Jl-
Plants self-engineer soil and water environment
(moisture, pH, redox, organic matter, nutrients)
Highly evolved enzymes for detoxification, energy
extraction, and nutrient management
Complete break down and recycling of some organic
Cost effective in some cases

     Shallow soils, ground water and streams
     Slower than excavation,  incineration, thermal
     desorption, and chemical oxidation
   C Mass transport limitations like bioremediation
   •v Winter shutdown  - - seasonal rates
   • Phytotoxicity limits to lower concentrations
   ./ Multimedia transfer to air & ground water possible
   • Bioaccumulation and product toxicity not well
     understood for many chemicals
   •• Unfamiliar to many regulatory agencies

 Where Phytoremediation Fits
 Niche technology and polishing step to control
 and treat hazardous waste sites
 Complete technology for some nonpoint source
 pollution (water <& air), <& industrial waste
 Widespread, cost effective treatment of
 moderate to low concentrations
 Long-term treatment and control
 Consistent with erosion control, site
 management, and ecosystem restoration
 Some hot spot treatments possible
Heavy metals: Pb, Ni, Zn, Cd, Cr
Other inorganics: CIO4, Se, Ar, radionuclides
BTEX, PAH, petroleum hydrocarbons, PCB
Munitions (TNT, RDX, HMX), other nitroaromatics
Phosphorus based pesticides and nerve agents
Chlorinated aliphatics (TCE, PCE and others)
Pesticides (atrazine, cyanided compounds, DDT,
methyl bromide)
Nitriles and phenols
Methyl Tetra Butyl Ether (MTBE)

   Isolated and now forecast the plant enzymes
   that degrade organic contaminants
   Conducted mass balance and pathway analyses
   to prove complete degradation and estimate
   potential toxicity of intermediates
   Axenic tissue cultures establish some plant
   and microbial enzymatic processes are
   powerful tools to engineer cleanup and
Biotechnology Tools
 ELISA field kits to
 select native
 to locate oxidative
 and reductive sites
 to better engineer
 created wetlands
 and plantations

    Proof of Principle — Organic

   Field proof of principle for TNT and RDX
   at Iowa AAP (Milan AAP ambiguous)
   Lab proof of principle for pink water and
   Feasibility of intrinsic remediation at
   Joliet AAP
   Lab proof of concept for chlorinated
         Science Advances in
    Rhizosphere Bioremediation
     Isolated and characterized
     microorganisms that degrade PAH/TPH
I,-.£,, • Advanced field management techniques |!
t ;#  for nutrients, water, and plant        ^
?yK  selection                          1
    • Analytical methods to better quantify  |f
 •;"   treatment efficiency and success

        Proof of Principle —
%   Rhizosphere Remediation
Craney Island and Gulf Coast Proof
Principle for PAH/TPH
Field proof of concept for
chlorinated solvents: NW, Hill AFB,
Carswell AFB TX, Cape Canaveral,
(Orlando feasibility expected soon)
Field proof of concept for TNT and
RDX removal at Milan A AP

      and Rhizof iltration Science
         ;W>    •*«'"•' •'•' *?*"
  Botanical prospecting dating to the 1950s in
  the USSR and US
  Cataloged over 400 species of
  hyperaccumulators worldwide
  Field test kits for metal hyperaccumulation
  Uptake and segregation processes using cation
  pumps, ion transporters, Ca blocks, metal
  chelating exudates and transporters,
  phytochelatin peptides, and metallothioneins


 Accumulation and Rhizof iltration:
  Proof of Concept and Principles
     Pb removal at NJ Magic Marker plots
     using surfactants and Boston site
     Heavy metal and radionuclide removal
     from plots at DOE facilities
     Feasibility of radionuclide removal by
     sunflowers in Chernobyl ponds
     Pilot Ur removal from ground water
     at Ashtabula

mf -jPf)? Lffi *s  j£JUf»j. '         .  , -*
s ^ • Discovery that grasses
    speciate Se and transpire
                            e product!
1 ! •  Transgenic Arabidopsis immune to Hg
: '-   poisoning and transpires Hg(0)

   '•  :
Se uptake in Central Valley of California
Se removal from oil refinery waste into San
Francisco Bay wetlands
*  y^t JNK/ %•' ,    ' *, „ - -**^!," A «
\ 1,n < '<       ->l"i  ', ; ,* n'l.'.^sr* \ s .^^-ip^Vfiidrfrf-',

      i $ m                                ;ig

Summary of the Technology Available

 • Control and accumulation of Pb and Ni

 • Treat munitions contaminated water and waste

 • Treat PAH/TPH contaminated soil

 • Control and treat shallow chlorinated solvent

 • Se control in soils and wetlands

 • Radionuclide control and treatment of soil

 • Water balance and leachate control for landfills
         Promising Technology

     Perchlorate treatment

     MTBE control

     Stabilization for Pb, Cu, Zn, Ni in soils

' >#.
Accumulation and disposal of Zn, Cr, Cd
PCB removal from soil
Accumulation of PCP
Pesticides and nerve agent treatment

         What to  Look for in a
     Phytoremediation Strategy
      Indigenous aquatic and terrestrial
      communities that self engineer waste sites
      and unit processes and have dominant       rj
      species with the effective enzymatic      Ei* *
      processes or spur effective rhizosphere
      degradation and do not require energy-
      intensive intervention or co-factor and
      nutrient supplements
      Rapid growing single metal accumulators   f
      carefully using surfactants to overcome   *  j
      soil binding                            j


  Long-Term Promise — continued
             "!'<•   ,1''

             .  ., Laura Carreira, Om
             ' "icbson, Valentine:;
 .-,.,,-•!!,-  >:&€. DOD        Nov.-  -;t^
• itnern ractlmes Command    Air

    Interstate Technology Regulatory Cooperation: Making It Easier for

                                          Robert Mueller
                         New Jersey Department of Environmental Protection
                                        401 E. State Street
                                          P.O. Box 409
                                        Trenton, NJ 08625
Robert Mueller has a B.S. in Psychobiology from Albright
College  and an M.S. in  Environmental Science from
Rutgers University. He has worked as an environmen-
tal scientist for 25 years  in both the public and private

Robert Mueller is currently employed by the New Jer-
sey Department of Environmental Protection as a Re-
search Scientist. He is working in the  Division  of
Science, Research and Technology in the Office of In-
novative Technology and Market Development. His of-
fice is working  within the New Jersey Department of
Environmental Protection (NJDEP) and with other states
to develop methods to share information on innovative
technologies and break  down barriers to the deploy-
ment of these technologies. One such effort is the In-
terstate Technology and Regulatory Cooperation (ITRC).
The ITRC is a group of over 30 states dedicated to this
mission. Mr. Mueller is leading the  phytoremediation
team within the ITRC.

The Interstate Technology & Regulatory Cooperation
(ITRC) Work Group was created through the Western
Governors Association to expedite the use of innova-
tive hazardous waste and remediation technologies.
Currently the ITRC has expanded to include more than
30 states, three federal partners, stakeholders, and two
state associations. In January 1999, the Environmental
Research Institute of the States (ERIS) became the new
host of the ITRC.

    Provides a  forum for states to exchange technical
    Creates a network of state contacts to promote the
    use of innovative technologies;
    Identifies interstate barriers to the deployment of
    Benchmarks state perspectives about innovative
    Develops consensus among state regulators, with
    input from industry and public stakeholders, on tech-
    nical regulatory aspects of using innovative tech-
Through these mechanisms, the ITRC develops guid-
ance documents intended to help regulatory staff con-
duct an expeditious review of the  use of a specified
technology and to help technology developers/vendors
collect performance data that  can be used to support
regulatory approval.

To see if the ITRC has developed any guidance docu-
ments that are useful to you, you may access the ITRC
website at www.itrcweb.org. If you have already identi-
fied a site where one of the ITRC guidance documents
can be used to deploy an innovative technology, please
contact the ITRC State Point of Contact (POCs) for the
state in which the site is located.These POCs are listed
in the website also.

For more information please feel free to contact Mr. Brian
Sogorka, NJ, or RocLer Kennett,  NM, Managing Co-
Directors of the ITRC, orRickTomlinson, ITRC Project
Manager, c/oThe Environmental Council of the States,
444 North Capital Street, Suite 305, Washington DC
20001, (202) 624-3669 (phone), (202) 624-3666 (fax).

          Promoting Innovative
      Environmental Technologies
         Purpose of ITRC
ITRC is a state-led, national coalition of
regulators working with industry and
stakeholders to:
 • improve state permitting processes and

 • speed deployment of technologies
   through interstate ai

       Participating States
        Other Participants
Industry representatives
Public Stakeholders
Federal agencies


                      Host organization

                            Council of States
                         State organizations

                             ™ ! Western Governors'

                                Southern States

                                Energy Board

        Products  & Services
   Regulatory and Technical Guidelines
   Technology Overviewsa
   Case Studies
                         '• i ir<:i •
   Training Courses          *^
   Peer Exchange
   Technology Advocated
        Document  Contents
Site Characterization
-Pre-Treatment Sampling
-Site Modeling
-Exposure Analysis
-Historical Data about Site Use
-Data Requirements
-Analytical Methods

       • Clean-Up Levels
         -Closure Criteria
         -Intended Use
         -Surrounding Community
Performance Data
 -Treatability Studies
 -Test & Demonstration
 -Monitoring for Treatment
 Goal and Fugitive Emissions
 -System Operating
 -Health & Safety
 -Feed Limitations

        Benefits to States
« Access to peers & experts in other regulatory
« Shortened learning curve by obtaining advance
  knowledge of new and used technologies
» Cost-effective involvement in demonstrations
  conducted in other jurisdictions
» Sounding board for problem solving
» Information and technology transfer
* Maximize limited resources
« Personal & professional development
        Benefits to  Industry
» Forum conducive to advancing technology &
» Insight into the regulatory world
» Access to multiple state entities
» Opportunity for broader review of technology
» Unique & cost-effective approach to
  demonstration & deployment of new technology
» Mechanism to identify and integrate regulatory
  performance expectations amongst states

          Benefits to  DOD
» Facilitates interactions between DOD managers
  and state regulators
» Increases consistency of regulatory
  requirements for similar sites in different states
» Can help reduce uncertainties when preparing
  cleanup plans
* Addresses contaminants of concern to DOD
  (heavy metals, VOCs, PAHs, organic
  pesticides, solvents, etc.)
» One technical team is dedicated to UXO, a
  problem unique to DOD
•0-    Benefits to  DOE
* Facilitates interactions between DOE managers
  and state regulators.
« Increases consistency of regulatory requirements
  for similar cleanup problems in different states.
« Can help reduce uncertainties when preparing
  cleanup plans.
* Addresses DOE's remediation needs (metals,
  organics, asbestos, mixed waste).
» One technical team, Radionuclides, is dedicated
  to a problem of particular concern to DOE.

   yv   Benefits to USEPA    *

   Forum to facilitate idea sharing between
   regulators at the federal and state levels.
   Unique & cost-effective approach to
   demonstration & deployment of new
   Mechanism to identify and integrate
   regulatory performance expectations amongst
State Engagement -Points of Contacts

 * Serve as liaisons between states and ITRC

 » Help gain state concurrence on documents

 * Encourage use of ITRC products/services

 « Document use of ITRC documents (38
   examples to date)

 » Record institutional changes resulting from
   ITRC (46  examples to date)

          Technical Teams
Accelerated Site
Enhanced In Situ
Low Temperature Thermal
Metals in Soils
Permeable Reactive Barriers
Plasma Technologies
 ';'-.  Ill  !'

«  Dense Nonaqueous Phase

»  Enhanced In Situ

»  Phytoremediation

«  Radionuclides

«  Unexploded Ordnance
 Accelerated  Site Characterization
Value:    Offers the potential to reduce the time and
         costs of characterizing a site before a
         cleanup plan is chosen

Products: 2 Technology Overviews
         2 Guidelines on technical requirements for
         - SCAPS - LIF
         - SCAPS - VOCs

Status:    Closed out in 1998

Success:  Document helped TX use SCAPS-LIF at an
         EPA Superfund creosote site

   Enhanced In Situ Bioremediation
 Value:    Usually less expensive and more acceptable
          than aboveground options

 Products'. 4 Guidelines including Natural Attenuation
          of Chlorinated Solvents in Groundwater -
          Principles and Practices.
          Technology Overview
          Case Study
          Offered natural attenuation courses in 1998

 Status:    Team conducting training as requested

 Success:  Courses reached more than 900 regulators
          and 500 consultants
Low Temperature Thermal Desorption

  Value:     Removes hazardous solvents from mixed
           waste, reducing waste volume and lowering
           disposal costs

 Products:  3 Guidelines on technical requirements for
           - petroleum/coal tar/gas plant wastes
           - chlorinated organic s
           - mixed waste and/or mercury

 Status:     Team closed out in 1998

 Success:   Contributed to $100/ton savings for
           treatment in NY

             Metals in Soils
 Value:    Treatment could help avoid costly
          excavation, transportation, disposal at waste
          facility, capping, and monitoring

Products'.  Overviews of three emerging technologies
          - phytoremediation
          - electrokinetics
          - in situ stabilization
          Soil Washing Guideline issued in 1997;
          updated in 1999

Success:   Facilitated community acceptance of soil
          washing and phytoremediation at Ft. Dix, NJ
 Permeable Reactive  Barriers
Value:     Offers potential to restore many types of sites
          to the standards that can't be met by
          conventional groundwater treatments

Products:  3 documents on remediation with PRBs
          - regulatory guidance for (1) chlorinated
          solvents and (2) inorganics and radionuclides
          - design guidance for chlorinated solvents

Status:     Offering training courses in 1999 and 2000

Success:   Process—from design through installation —
          took less than four months in NJ

       Plasma Technologies

 Value:    Thermal treatments that have potential to
          treat hazardous, radioactive, military, and
          medical wastes

Product   Technology Overview

Status:    Team closed out in 1998
Value/   Technology verification programs are
Success:  incorporating state verification needs into
         their programs, making it easier for states to
         approve technologies

Product:  A matrix of data provided by 16 states on the
         elements necessary in a verification program
         to increase knowledge and evaluate
         confidence in the verified technology

Status:   Accumulating examples of verification being
         used to improve technology deployment

 Dense Nonaqueous Phase Liquids
 Value:    If not removed, DNAPLs could contaminate
         groundwater for centuries

Planned  An overview of technologies capable of
Product:  characterizing and treating DNAPLs

Partner:  USEPA's Superfund Innovative Technology
         Evaluation (SITE) program

Status:    New team in 1999
 Enhanced  In Situ Biodenitrification
Value:    May be used to treat contamination caused
         by nitrogen fertilization, concentrated animal
         feeding operations, explosives manufacture,
         wastewater treatment, and UXO

Product:  A technology overview

Status:    New team in 1999

Value:    Offered commercially, but many details still
         need to be studied to explain the process and
         guarantee reliability

Product:  A decision tree to help determine when
         phytoremediation is appropriate

Planned:  Technology overview and regulatory issues
Status:    New team in 1999
 Value:    A concern particularly at DOE sites as a
          result of nuclear weapons production

 Planned  A catalog of state, federal, and international
 Products:  radionuclide organizations and their
          A glossary of radionuclide terms

 Status:    New team in 1999

      Unexploded Ordnance
 Value:    Examining the problem of military
          munitions contaminating federal (DOD) and
          private sites

 Planned  Case studies examining ways to remove
 Product:  Barriers to using innovative UXO
          remediation technologies

 Status:    New team in 1999
Web Site:
Brian Sogorka
Roger Kennett
(505) 845-5933
Project Manager:
Rick Tomlinson
(202) 624-3669
http ://www. itrcweb.org
   NJ Dept. of Environmental Protection
   orka@dep. state, nj .us

   NM Environment Department
Me:  Robert Mueller  bmueller@dep.state.nj.us

The Future of Phytotechnologies
          Steven Rock

Environmental Engineer
Remediation and Containment Branch
Land Remediation and Pollution Control Division
National Risk Management Research Laboratory
U. S.  Environmental Protection Agency
26 West Martin Luther King Dr.
Cincinnati, OH 45268
513-569-7149  rock.steven@epa.gov

Steve Rock manages field projects using phytoextraction, phytodegradation, and hydraulic
control with trees. He is the author of several phyto publications, including acting as team leader
on the EPA's Introduction to Phytoremediation, and a chapter in the Standard Handbook of
Environmental Engineering. He co-chairs the RTDF Action Team on Phytoremediation, and has
three subgroups researching the phytoremediation issues of petroleum hydrocarbons, chlorinated
solvents, and vegetative covers for waste containment. He participates in EPA in-house research,
and provides technical assistance to EPA regional staff on questions of phytoremediation.

           The Future of
          Steve Rock, US EPA
have a
bright future

                      Clearly phyto
                      is a
It is fertile ground
for research or commerce

With experts from many backgrounds
 who are frequently out standing
  Experts who go to great lengths to..,

  ...dig up new information.
In this field you
need to keep
your sense of

                         with living
     Sometimes you just get stumped.
       Phyto - Technologies -
 Using Plants as Engineering Tools
• Phytoremediation:  Cleaning soil or groundwater
• Landfill Cover Systems
• Mine Site Reclamation
• Industrial and Municipal Wastewater Treatment
• Erosion control

  The plants are an essential component of the system.

          Plants as Tools

Deep planted trees to intercept groundwater
Wetlands to enhance degradation
Shallow plantings to enhance degradation
Metals extraction & concentration
Prairie or tree based evapotranspiration covers
          Historical Trend
     1993  1994  1995  1996  1997  1998  1999
              Years 1993-1999


Site Name, State
Former Carswell Air Base, TX
Aberdeen Proving Ground,
French Limited, LA
Edward Sears Site, NJ
Ammunition Army Depot, IA
Fort Wainwright, AK
Kaufman Minter, NJ
Army Ammunition Plant,
Del Monte, HI
Bofors-Nobel, MI
Eastern cottonwood
Hybrid poplar trees
Hybrid poplar trees
Wetland and
terrestrial plants
Felt left willow
Hybrid poplar trees
Hybrid poplar trees
Koa haole
Various trees and
wetland plants
TCE/groundwater at 4- 12 ft
Solvents, hydrocarbons
TCE/groundwater at 8 ft
TNT/soil and pond water
Pesticides/soil and
TNT groundwater
Pesticides/soil and
Residual sludge in waste

Full Scale Installations To Date

    Disadvantages of Planted Systems

    - Vegetation to contamination relationship varies
    - Lack of broadly applicable performance data
    - Seasonally, climatically dependent
Site Specific Design and/or
Treatability S
     = High information cost (one time)
     + Low installation and operating cost

   Show me the DATA!!!
           Sample, sample, sample
But data is not information,
information is not knowledge,
and knowledge is not wisdom...

    One future of phytotechnologies
    is integration.

        Integration of Goals

   Integrate goals i.e.- Region 3 project in
   Pennsylvania in which CAFOs (feed
   lots) send biomass to coal mine
   damaged lands for reforestation and to
   sequester atmospheric carbon.
 Integration of

Superfund site with
pump and treat
supplemented by
upgradient phyto,
wetland enhancement,
and a bike path.

         Integrate Disciplines

    Engineering, soil science,
    agronomics/silviculture, climate change,
    many regulatory aspects, environmentalism,
    and entreprenuership.
Natural Capitalism


Amory Lovins, Paul Hawken, and
Hunter Lovins
Rocky Mtn. Institute rmi.org


             Transport of Contaminants in Plant and Soil Systems

             Larry E. Erickson, Lawrence C. Davis, Qizhi Zhang, and Muralidharan Narayanan
                                      Kansas State University
                                       Manhattan, KS 66506
Larry E. Erickson has a B.S.Ch.E. and a Ph.D. in chemi-
cal engineering from Kansas State University. He has
been a member of the chemical engineering faculty at
Kansas State University since 1964.

Dr. Erickson is presently professor of chemical engi-
neering and director of the Great Plains/Rocky Moun-
tain Hazardous Substance  Research Center. He has
been conducting research on the beneficial effects of
vegetation in contaminated soil since 1991. He is editor
of the Journal of Hazardous Substance Research, an
online journal published by Kansas State University at

Larry E. Erickson
Professor of Chemical Engineering and
Director,  Center for Hazardous Substance  Research
Kansas State University

The transport of contaminants in soil and plant systems
depends  on the properties of the contaminant, aque-
ous phase flow, soil properties, and size and growth of
the plants. There is convective flow of the aqueous phase
in soil, plant roots, and plant stems because of differ-
ences in the pressure of water or matrix potential as a
function of position. Significantly larger quantities of
water are lost to the atmosphere through evapotranspi-
ration when growing plants are present. Contaminants
are transported to the soil surface in plant roots and in
the soil.

Contaminants such as  trichloroethylene (TCE) and
methyl-tert-butyl ether (MTBE) diffuse through the walls
of roots and stems. Volatile compounds such as TCE
diffuse through the gas phase in unsaturated  soil into
the  atmosphere. In  small roots, TCE transported  up-
ward in the aqueous phase may diffuse out through the
walls of the roots into the unsaturated soil and to  the
atmosphere. In large mature trees, TCE has been found
in the xylem in locations where the groundwater is con-
taminated with TCE. The concentration  of TCE de-
creases with height because the TCE diffuses  out
through the plant cells between the xylem and bark of
the trees.

Since MTBE is more soluble in water and less volatile
than TCE, it is transported through the roots into plant
stems of alfalfa. The loss of MTBE through the walls of
the stems appears to be limited by diffusion through the
plant cells in the stem wall. This process has been mod-
eled with a transport model.

The fate and transport of water and contaminants in
soil with growing vegetation has been the subject of
research  in our laboratories for more than nine years.
Since much of the information contained in the oral pre-
sentation is available in other manuscripts and publica-
tions, the primary purpose of this manuscript is to identify
these publications and provide information on the sig-
nificant transport processes which have been observed
in our investigations.

Most of the experimental research has been conducted
using plant growth chambers in a laboratory setting.
These chambers include two identical U-shaped chan-
nels, each 10 cm wide, 35 cm deep, and approximately
180 cm in axial length (Narayanan et al, 1995a and
1995b; Narayanan etal., 1999a)and a six channel sys-
tem (Zhang et al, 1998a; Zhang et al, 1999). Each of
the six channels was 10 cm wide, 110 cm long and 65
cm deep with 60 cm of soil. Measurements have been
made of the contaminant concentration in the inlet and
outlet groundwater, the gas phase leaving the surface,
and at points within the  chambers. Experiments have
been conducted with toluene, phenol, trichloroethylene,
and methyl tert-butyl ether.

Models have been developed and computer simulation
has been used to provide additional information on the
processes that are affecting the fate of the contaminants.

The fate and transport of organic contaminants depends
on the physical and chemical properties of the contami-
nants. In the early work with toluene and phenol, bio-
degradation in the soil appeared to be the primary mode

of disappearance. Toluene degradation appeared to be
limited to aerobic conditions (Davis et al., 1994; Erickson
et al., 1994: Narayanan et al., 1995a; Narayanan et al.,
1998a and 1998b). Phenol may have been biodegraded
anaerobically as well as aerobically. There was no evi-
dence that toluene and  phenol were lost to the atmo-
sphere (Davis et al., 1994).

In the research with trichoroethylene (TCE), biodegra-
dation was observed in the early research (Narayanan
et al., 1995b), but it did  not appear to be significant in
the later research (Narayanan et al., 1999a). Experi-
ments were  conducted  to investigate the diffusion of
TCE in  plant systems (Davis et  al., 1999). Values of
diffusivityofTCEin plants were found to be about 0.1 to
0.3 of the value of the diffusivity of TCE in liquid water.
For small roots, TCE which moves upward with soil water
in plant roots may move out of the  roots near the soil
surface by diffusion. Narayanan et al. (1999a) has shown
that the concentration of TCE is very low at the soil sur-
face because of gas phase diffusion  in unsaturated soil.
With alfalfa plants in TCE contaminated soil, there is
little evidence of TCE moving up into the plant stem;
however, Vroblesky et al.(1999) has shown  that TCE
does  move up into large trees. While the estimated
diffusivity for TCE is similar in the trees, the radial dis-
tances are larger and thus,  the concentrations of TCE
in the xylem are detectable and significant.

Plants impact transport by removing water from the soil.
The gas phase diffusion  in the unsaturated zone varies
with the fraction of gas phase volume. As plants remove
water from the soil, they increase the fraction of gas
phase volume in the surface soil which enhances the
transport of oxygen and volatile  contaminants. When
plants are present the movement of contaminants and
the drying rate following  precipitation are different than
when plants are not present.

When methyl tert-butyl  ether (MTBE)  is the contami-
nant, there is a greater tendency forthe contaminant to
be found in the plant because of the  greater solubility in
water and the lower value of the Henry constant com-
pared to TCE. In our research with MTBE, values of
diffusivity for MTBE in plant stems were  found to be
about two orders of magnitude smaller than those for
MTBE in water (values were about 0.008 to 0.02 of those
for MTBE  in  liquid water) (Zhang et al., 2000; Zhang,

The loss of volatile contaminants to the atmosphere has
been  investigated experimentally and through  model-
ing and simulation (Davis et al, 1994; Davis et al., 1998b;
Narayanan et al, 1999b). If  the contaminant is trans-
formed rapidly in the atmosphere and if the  degrada-
tion products  are  environmentally acceptable,
phytovolatilization may be a desirable process to move
the contaminants from the  soil and groundwater into
the atmosphere. Narayanan et al. (1999b) has shown
that volatile organic concentrations in the atmosphere
are usually well below the threshhold limit values where
health concerns become significant. The rate at which
contaminants are moved from the soil to the atmosphere
is limited by the dissipation of water vapor into the at-
mosphere.Thus, when the contaminant and water move
upward together, the rate is limited by the rate of evapo-
transpiration which is limited  by the dissipation of the
soil water into the air. For example, forTCE in soil water
at a concentration  of 1 mmol/L or 131  mg/L, the corre-
sponding concentration  forTCE in water saturated air
is 0.56 ppm by volume  at 25 C. There is a significant
dilution because of the expectation that all of the tran-
spired water must  be dissipated into the air.

The volume of water that is transpired by plants is sig-
nificant (Davis et al., 1998a). When the roots can find
adequate water, alfalfa,  poplars and willows may use
as much as 2 meters of water in one year (2 cubic meters
per square  meter  of area). Zhang  (1999) has shown
that water  use  in planted  chambers is significantly
greater than that in the  unplanted chamber (Zhang et
al., 1998band 1999).There is significant interest in us-
ing plants as solardriven pumps to contain plumes and
the vegetation as the treatment system. While the de-
gree of treatment depends on the contaminant, it has
been shown that for many contaminants, plants may be
used as part of a pump-and-treat system (Davis et al.,
1998a: Erickson etal., 1997: Narayanan etal., 1999b).

Davis, L. C., Muralidharan N., V. P. Visser, C. Chaffin, W
G. Fateley, L. E. Erickson, and R. M.  Hammaker. "Alfalfa
Plants and  Associated Microorganisms Promote Bio-
degradation Rather than Volatilization of Organic Sub-
stances from Ground Water," in Bioremediation through
Rhizosphere Technology, T.A.Anderson and J. R. Coats,
Eds_, ACS  Symposium  Series, N. 563 Washington D.
C., 112-122, 1994.

Davis L. C., M. K. Banks, A. P. Schwab, M. Narayanan,
L.  E. Erickson,  and  J.  C. Tracy.  "Plant-Based
Bioremediation," in  Bioremediation: Principles and Prac-
tice, Vol. 2. Biodegradation Technology Developments,
S.K.Sikdarand R.L.Irvine, Eds.,TechnomicPubl.Co.,
Lancaster, PA, 183-219,1998a.

Davis L. C., S. Vanderhoof, J. Dana, K. Selk, K. Smith, B.
Goplen, and L. E. Erickson-"Chlorinated Solvent Move-
ment through Plants Monitored by Fourier Transform
Infrared (FT-1R) Spectroscopy," J. of Hazardous Sub-
stance   Research,  Vol.  1, No.4: 1-26.  http://
www.eng.p,.ksu.edu/HSRC, 1998b.

Davis, L. C., Lupher, D.,  and L. E. Erickson. "Effects of
Benzotriazoles on Sunflowers and  Fescue," Proceed-
ings of the 14th Annual Conference on Hazardous Waste
Research,  St.  Louis,  MO,   203-209.   ham://
www.engg.ksu.edu/HSRC, 1999.

Erickson, L. E., M. K. Banks, L. C. Davis, A. P. Schwab,
N. Muralidharan, K. Reilley, and J. C. Tracy. "Using Veg-
etation to Enhance in situ Bioremediation," Environ.
Progress, 13:226-231, 1994.

Erickson, L. E.. "An Overview of Research on the Ben-
eficial Effects of Vegetation in Contaminated Soil.Mn-
nals of the New York Academy of Sciences, 829:30-35,

Narayanan, M., L. D. Davis, J. D. Tracy, L. E. Erickson,
and R. M. Green. "Experimental and Modeling Studies
of the Fate of Organic Contaminants in the Presence of
Alfalfa Plants,"  J.  of Hazardous Material, 41: 229-249,

Narayanan, M., L. D. Davis, and L. E. Erickson. "Fate of
Volatile Chlorinated Organic Compounds in a Labora-
tory Chamber with Alfalfa Plants," J. of Hazardous Ma-
terial, 41: 327-340, 1995b.

Narayanan, M.,  J.C.Tracy, L.C.Davis, and L.E.Erickson.
"Modeling the Fate of Toluene in a Chamberwith Alfalfa
Plants I. Theory and Modeling Concepts," J. of Hazard-
ous  Substance Research, Vol. 1, No.  5.  http://
www.engg.ksu.edu/HSRC, 1998a.

Narayanan, M.,  J.C.Tracy, L.C.Davis, and L.E.Erickson.
"Modeling the Fate of Toluene in a Chamberwith Alfalfa
Plants 2. Numerical Results and Comparison Study," J.
of Hazardous Substance Research, Vol. 1, No. 5. http:/
/www.enpg.ksu.edu/HSRC, 1998b.

Narayanan, M., N. K. Russell, L.  C. Davis and L. E.
Erickson. "Fate and Transport of Trichloroethylene in a
Chamber with  Alfalfa Plants," International  Journal of
Phytoremediation, 1:387-411,1999a.

Narayanan, M., L. E. Erickson, and L. C. Davis. "Simple
Plant-Based Design Strategies for Volatile Organic Pol-
lutants," En vironmental Progress, 18:231-242,1999b.
Vroblesky, D.A., C.T Nietch, and IT. Morris, 1999. "Chlo-
rinated Ethenes from Groundwater in Tree Trunks,"
Environ. Sci. & Technol., 33(3): 510-515.

Zhang, Q., L. C. Davis, and L. E. Erickson. "Effect of
Vegetation on Transport of Groundwater and Nonaque-
ous Phase Liquid Contaminants," J. of Hazardous Sub-
stance   Research,   Vol.   1,   No.  8.   http://
www.en.2g.ksu.edu/HSRC, 1998a.

Zhang, Q., L. C. Davis and L. E. Erickson. Using vegeta-
tion to treat methyl-tert-butyl ether contaminated ground-
water. Proceedings of the 13th Annual  Conference on
Hazardous Waste Research, Snowbird, UT, 272-283.
http://www.engg.ksu.edu/HSRC, 1998b.

Zhang, Q., L. C. Davis and L. E. Erickson, Transport of
methyl tert-butyl  ether (MTBE) through alfalfa plants,
Environ. Sci. & Technol., submitted, 2000.

Zhang, Q., "Phytoremediation Of Methyl Tert-Butyl Ether
(MTBE)  in Groundwater-Experimental and Modeling
Studies," PhD Dissertation, 1999, Kansas State Univer-
sity, Manhattan,  KS.

This research was partially supported by the U.S. EPA
under assistance agreements R-815709, R-819653, R-
825549, and 825550 to the Great Plains/Rocky Moun-
tain Hazardous Substance Research Center. It has not
been submitted to EPA for review and,  therefore, may
not necessarily reflect the views of the  agency and no
official endorsement should be inferred.The Centerfor
Hazardous Substance Research provided partial fund-

Transport of Contaminants
 in Plant and Soil Systems
  Larry E. Erickson, Lawrence C. Davis,
 Qizhi Zhang, and Muralidharan Narayanan

 Kansas State University, Manhattan, KS 66506

      1, Schematic vltv* ulHi* smiallv t*lend«l*np*rinMBtaJ whip.

              Table 2; Mass balance- for contaminant ear-

Jt». ?
                    3t FTIR rstinules of CO2 'B lfe head-
                      space ul' thf chamber i itmiuii'tbiv ).
       I ni null |
                               CO2      (X), du* to
                             wlthfHil <,'   ("nnlaminiinl
                                           I nil i9i.il |




                         — Swiutalian #Hh i, - 0.2S
                         LJ Chamol I
               0.0   01   05  03   0.4  0.5  Ofl   0.7  08  O.fl   1.0
                              i TCf tod in i
Hg    tixpcritncntalJy measured and nuiwcrically simulated TCB cone pro-
       files in the system. Lines A, B, ami I"! are TOE profiles for % = 0.25,
       0,29, and 0,32, respectively. Bxperknemally measured profiles in the
       aqueous phase arc shown as hollow squares and tilled diamonds.

                                 e.wo fljooo  i
             Trichloroethene concentration in tree cores, in
                nanomoles of gas per liter of core water
Trichloroethene concentration in cores along the trunk of tree 7 (bald
cypress). Cores from the northern trunk were not collected in July 1997.
(From Vroblesky et al, Environ. Sci. & Technol., 33: 510 (1999).)
Estimated values of diffusivity for trichloroethylene in trees


Bald Cyprus
Diffusivity cm2/s
1 x 10-6
3 x 10-6
3 x lO-6
3 x lO-6
Source of data
Davis etal.
Davis et al.
Davis et al.
Davis et al.
Davis et al.
Davis et al.
Vroblesky et al.
 Diffusivity of trichloroethylene in water is 1 x 1Q-5 cm2/s.

Comparison of confined and unconfmed gas phase concentrations of
trichloroethylene (TCE) for several different concentrations in
ground water at 25°C and 1  atmosphere.
Concentration in ground water
Concentration in gas phase
TCE in water**
vapor, ppmv
TCE in water**
saturated air, ppmv
 ppmv = parts per million by volume.
 * Confined gas phase concentrations are assumed to be in equilibrium with the liquid
 **Unconfined gas phase concentrations are based on evaporation of water vapor and TCE
 Integrated amount of MTBE lost to the atmosphere over
 time from the soil surface of six channels.
                             Time (days)
~Ch2   0 Ch3

      5  0.30 -
        0.20 -
        0.10 -
                            o Plant #7-31 -1: experiment
                            — Plant #7-31-1: fitting
                              Plant #7-31-2: experiment
                              Plant #7-31-2: fitting
                            * Plant #7-31-3: experiment
                            — Plant #7-31-3: fitting
                    10       20       30       40
                          Distance from soil surface (cm)
MTBE concentration in plant water as a function of stem position from
the soil surface. The points are experimental data and the solid lines are
the exponential fittings of form c = c0exp(-oz). The concentration is
normalized to the inlet concentration (0.844 mM).
0.20 -

o Plant #8-31-1: experiment
— Plant #8-31-1: fitting
Plant #8-31-2' experiment
Plant #8-31 -2: fitting
A Plant #8-31 -3: experiment

                        10        20        30        40
                           Distance from soil surface (cm)
 MTBE concentration in plant water as a function of stem position
 from the soil surface. The points are experimental data and the solid
 lines are the exponential fittings of form c = c0exp(-oz). The
 concentration is normalized to the inlet concentration (0.844 mM).

          0.0     0.2     0.4     0.6     0.8     1.0

              Relative distance from the stem center R (= r/ro)

Concentration distribution within the plant stem as a function of the
                      (-) r~)7
characteristic distance z (= ——)  , with uniform concentration at Z = 0.

Concentration is reduced to the overall concentration at Z = 0.
J. R. Philip (1958) &

D.A.Rose (1981):              l

diffusion between an individual cell and a large
body of solution in which it was placed
                                                   = 0.0631
   Our Results:

   diffusion between a porous plant
   stem and the atmosphere
    MTBE diffusion coefficient D (with

    uniform concentration at Z = 0):
                            x 10"7 (cm2/sec)
= 0.0631

            Relative distance from the stem center R (= r/ro)
Concentration distribution within the plant stem as a function of Z (=
for plant #7-31-1, with non-uniform concentration at Z = 0.
Concentration reduced to the overall concentration at Z = 0.
    Results—for non-uniform starting
                          = 0.0919
   MTBE diffusion coefficient  Z)f:
              O-8 -          O-7 (cm2/sec)

Comparison of Standard Deviations of Two
Model Solutions from the Experimental Data

7-31-1 7-31-2:7-31-3
0.0782 0.0748
0.0524 0.0519
0.0929 0.0771 0.0676
0.0608 0.0373 0.0253

 Mass balance of water and estimated fraction of MTBE
 transpired by plants during the three- months test period.
Channel #,

Total water added
but not
but not
and not
191 |185
but not
Total water added
Evapo transpired
water (ET) (L)
Estimated average
plant uptake of
MTBE (fraction)
Estimated greatest
plant uptake of
MTBE (fraction)
Corrected recovery
Recoverv with
average plant

0 69
191 |185
109 -.37*
0.024 .0.0**
0.056 :0.0**
080 :1.0
0.82 -1.0
 * There was only evaporation of water in this unplanted channel.
 **No plant uptake for this channel.

                                 Ml fi-
           11 D    
     Rhizosphere Remediation of
   Recalcitrant Soil Contaminants:
An Important Component of Long-term
   Sustained Biosystem Treatment

            John Fletcher
      Slide Hard Copy Unavailable

John S. Fletcher

John Fletcher holds a B.S. from Ohio State University, an MS from Arizona State University, and
a Ph.D. in Plant Physiology from Purdue University.  He is a Professor of Botany in the Dept. of
Botany and Microbiology at the University of Oklahoma in Norman, OK. During his 30 year
tenure at the University of Oklahoma he and his graduate students have studied the metabolism
of nonphotosynthetic plant tissues, root uptake of xenobiotics, ecological risk assessment
(including PHYTOTOX and UTAB database development), and rhizosphere remediation of
PCBs and PAHs.  In 1997 Dr. Fletcher received a level 1 Research Award from EPA's Office of
Research Administration for phytotoxicity research he conducted in collaboration with persons at
the EPA Laboratory in Corvallis, Oregon. His current research is focused on rhizosphere
remediation of PAHs at a former industrial sludge basin in Texas and several PCB-contaminated
field sites in the Czech Republic. Both projects are being conducted with the cooperation of
industrial partners. Dr. Fletcher's professional service activities related to environmental issues
include: Plant Editor for the Journal of Environmental Toxicology and Chemistry, member of the
Chemical Manufacture Association's Technical Implementation Panel for Ecological Risk
Assessment Research, and member of EPA's Scientific Advisory Panel for the Federal
Insecticide, Fungicide and Rodenticide Act.

Sustained Rhizosphere Remediation of Recalcitrant Contaminants in Soil:
                      Forensic Investigations with Laboratory Confirmation

John S. Fletcher, Dept. of Bot. and Micro., Univ. of Oklahoma, Norman, OK 73019

        A conservative estimate of the volume of PAH contaminated soil in the US (based on
U.S. Dept. of Commerce Reports) is 1 billion ton. Biosystem Treatment relying on the integrated
action of plants and microbes over extended time  periods has the  potential of reducing cleanup
costs by >90%, and lead to pollutant degradation rather than just containment that leaves the
burden  of cleanup for future generations.  The three components of Biosystem Treatment are
plant  evapotranspiration, plant-microbe rhizosphere degradation,  and  natural  attenuation of
groundwater by .microbes.  The least studied and therefore  poorest understood of  these three
components is rhizosphere degradation.
        Rhizosphere research in our laboratory has  addressed the hypothesis:  "Roots of some
plant species enhance the degradation of recalcitrant,  organic soil contaminants (i.e. PCBs  and
PAHs) by releasing cometabolites and facilitating soil aeration, both a result of fine root  turn
over".  Published  results from our laboratory supporting this hypothesis are: (1)  purified natural
plant compounds  (i.e. flavonoids)  stimulate the growth and activity of PCB and PAH degrading
bacteria, (2) flavonoid compounds are present in  mulberry fine roots, (3) flavonoid  compounds
accumulate in aging/dying mulberry roots, (4) over 50% of the fine roots turnover (die) annually.
Demonstration of statistically significant reductions  in  the concentrations of high molecular wt, low
water soluble contaminants  in laboratory pot studies have failed.  This is  attributed to  several
factors: (1) pot-study artifacts (i.e. unnatural root distribution), (2) limited soil-root contact at any
one time, (3) long time (several seasons)  necessary for extensive soil exploration through  fine
root turn over.  For these reasons, the only valid test of rhizosphere remediation of  recalcitrant,
slightly water soluble contaminants (PCBs and high molecular wt PAHs) are long term (15-20 yr)
field studies.  Because of the inability to gain authorization to conduct such a study we resorted to
an alternative, forensic examination of naturally revegetated sites. At a revegetated former sludge
basin  we  have  shown   a  50-90% reduction   of  PAHs  (including  slightly  water  soluble
benzo(a)pyrene) in the 120 cm root zone of 12-16 yr old mulberry trees where over two hundred
PAH degrading bacteria isolates have been recovered.
Currently available laboratory and forensic field data justifies initiation of carefully monitored long-
term Biosystem Treatment projects. During early stages of treatment (first 5 years) the
monitoring should establish that the components of the system (roots and degrading bacteria) are
in place with monitoring shifting to analysis of contaminant disappearance after 5 years. It is
gratifying that a Biosystem Treatment strategy has been adopted at Bofors Nobel Site in
Michigan. The most pressing need to advance the Biosystem Treatment concept is improved
assessment tools  to monitor the biological components of the  integrated system. To that end,
our current research is focused on development of improved field assessment tools. Our
approach is: identify working rhizosphere systems at existing revegetated sites, study the
components of these working systems in the laboratory, develop assessment methods in the
laboratory, and return to the field to validate, and use  the newly developed methods.

              Rhizosphere Remediation of Recalcitrant Soil Contaminants:
         An Important Component of Long-term Sustained Biosystem Treatment

              John S. Fletcher, Department of Botany and Microbiology
                    University of Oklahoma, Norman, OK 73019

       A conservative estimate of the volume of PAH contaminated soil in the US (based
on US Dept; of Commerce Reports) is 1 billion tons with some associated with former
manufactured gas plant sites dating back 150 years. Biosystem Treatment relying on the
integrated action of plants and microbes over extended time periods has the potential of
reducing cleanup costs by > 90%. Furthermore, the end result would be pollutant
degradation rather than just containment, characteristic of capped cells where unfavorable
water and oxygen conditions prevent biological degradation,  thus preserving the waste
and leaving the burden of cleanup for future generations. Three important components of
Biosystem Treatment are plant evapotranspiration, plant/microbe rhizosphere
degradation, and natural attenuation of groundwater by microbes. The least studied and
therefore poorest understood of these components is rhiosphere degradation.
       Underpinning our research approach to phytoremediation is the realization that
although plants in natural ecosystems produce polyaromatic compounds (flavaniods,
coumarins, etc.) in their leaves, stems and roots, these compounds have not accumulated
in the soil to concentrations reflective of their annual production over thousands of years
(Figure 1). There is only a limited understanding of the production and recycling of
carbon associated with naturally occurring polyaromatic compounds in terrestrial
ecosystems (i.e. tannins in oak forests, Figure 1). However, it is apparent that since they
have not accumulated to astronomic amounts over the last millennium, mechanisms do
exist within nature to degrade and recycle carbon present in thousands of naturally
occurring polyaromatic compounds many of whose structures resemble those of
recalcitrant pollutants such as PCBs, and PAHs (Figure 2). The obvious question is, "Will
the biological mechanisms in nature that degrade natural polyaromatic compounds also
degrade recalcitrant organic pollutants (i.e. PCBs and PAHs)?" If so, what soil

ecosystems associated with what plants are most active against pollutants? How should
we introduce and manage these natural, multi-organismic systems to optimize their
degradative properties towards recalcitrant pollutants? All of these questions deserve
attention and should be resolved in order to develop dependable sustained
phytoremediation technology. First however, there is a need for a better understanding of
rhizosphere degradation properties and its relationship to xenobiotic compounds. To that
end, our research has addressed the hypothesis: "Roots of some plant species enhance the
degradation of recalcitrant, organic soil contaminants (i.e. PCBs and PAHs) by releasing
cometabolites and facilitating soil aeration, both a result of fine root turn over".
       The emphasis of our research over the past 15 years has been placed on
understanding the mechanism of rhizosphere degradation of PCBs and PAHs with
secondary attention given to the disappearance of these recalcitrant contaminants from
contaminated soil. The rational for placing emphasis on mechanistic studies was that the
results collected not only served to test the hypothesis but also provided a level of
understanding that is necessary to improve the performance of phytoremediation and
develop monitoring tools to facilitate field implementation, the importance of which is
described later in this summary (Figure 3). Published results from our laboratory
supporting the hypothesis and providing a mechanistic understanding of rhizosphere
degedation are: (1) purified natural plant compounds (i.e. flavaniods) stimulate the
growth and activity of PCB degrading bacteria (Donnelly, etal. 1994); (2) Plant roots
release phenolic compounds that support the growth of PCB degrading bacteria, but all
plant species are not effective (Fletcher and Hegde, 1995; Fletcher etal. 1995, Hegde and
Fletcher, 1996); (3) Flavanoid compounds that support the growth of PAH- degrading
bacteria accumulate in aging/dying fine roots of mulberry (Leigh, etal.  1998); (4) field
studies have shown that fine mulberry roots grow in contact with PAH-contaminated
sludge at 1 meter depths (Olson and Fletcher 1999). The combined interpretation of these
data is that the roots of some plant species are capable of growing to immobile soil
contaminants (PCBs and high mol. wt. PAHs) and deliver cometabolies (i.e. flavaniods)
upon fine root death. These natural cometabolites foster the growth and activity of
degredative microbes. The dead/decayed roots also create soil cavities that facilitate soil
aeration. Thus, in order for roots to foster the degradation of immobile soil contaminants

(PCBs and PAHs) it is not necessary for the water insoluble contaminants to move to the
root, because fine roots (<0.5mm in diameter) grow to the contaminants, and upon root
death serve as soil injectors of bacterial cometabolites and facilitators of soil aeration
(Figure 4). Based on this mechanistic understanding, the performance of rhizosphere
remediation can be improved by increasing both root synthesis of cometabolites and the
rate of fine root turnover.
             Efforts on our part to demonstrate statistically significant reductions in the
concentrations of high molecular wt, low water soluble contaminants in laboratory pot
studies have failed. This is attributed to several factors: (1) pot-study artifacts (i.e.
unnatural root distribution), (2) limited soil-root contact at any one time (<5%), and (3)
long time (several seasons) necessary for extensive soil exploration through fine root tur
over (growth followed by death). For these reasons, it is our contention that long-term
(15-20 year) field studies are the only valid test of rhizosphere remediation of
recalcitrant,  slightly water-soluble contaminants (PCBs and high molecular wt PAHs).
Because of the inability to gain authorization to conduct such a study we resorted to an
alternative, forensic examination of naturally revegetated sites. At a revegetated former
sludge basin we have shown a 50-90% reduction of PAHs (including slightly water
soluble benzo(a)pyrene) in the 120 cm deep root zone of 12-16 yr old mulberry trees
where over two hundred PAH degrading bacteria isolates have been recovered (Olson
and Fletcher, 1999; Olson et.al., 2000.)
             Based on current data available from laboratory mechanistic studies and
forensic field data that have been collected on recalcitrant soil contaminants, we believe
carefully monitored long-term Biosystem Treatment projects (15-20 years) should be
initiated. Because of the long time required for roots to have a statistical  influence on the
degradation of immobile soil contaminants for reasons explained earlier, we propose that
during early stages of treatment (first 5 years) the monitoring should establish that the
components of the system (roots and degrading microorganisms) are in place with
monitoring shifting to analysis of contaminant disappearance after 5 year (Figure 3).
Monitoring the existence and operation of the degratative system instead of the product
of the system (compound disappearance) is a more sensitive way to establishing that slow
but sustained rhizosphere remediation is working. We are in the process of developing

chemical and molecular methods to monitor the existence and function of rhizosphere

degradation in the field. The development of these methods is capitalizing on basic

research that was conducted in our laboratory to understand mechanistic features of the

plant rhizosphere.

              It is gratifying that ideas and phytoremediation data gained at the

University of Oklahoma were instrumental  in designing and promoting the Biosystem

Treatment strategy that has been adopted at Bofors Nobel Superfund site in Michigan.

Implementation of the Biosystem Treatment at Bofors will be an example of capitalizing

on the combined action of plant evapotranspiration, plant-microbe rhizosphere

degradation, and natural attenuation by groundwater microbes for the long-term sustained

treatment of contaminants across space and time, typical of natural ecosystems.


Donnelly, P.K., R.S. Hedge and J.S. Fletcher. 1994. Growth of PCB-degrading bacteria
on compounds from photosynthetic plants. Chemosphere 28:981-988.

Fletcher, J.S., P.K. Donnelly and R.S. Hedge. 1993. Bioremediation of PCB-
contaminated soil with plant-bacteria and plant-fungi systems. 5th International
Conference for Remediation of PCB Contamination. Penn Well Pub. 173-181.

Fletcher, J.S., P.K. Donnelly and R.S. Hedge. 1995. Biostimulation of PCB-degrading
bacteria by compounds released from plant roots. In Bioremediation of Recalcitrant
organics. Battelle Press, Columbus, Ohio. Pp. 131-136.

Fletcher, J.S. and R.S. Hedge.  1995 Release of phenols by perennial plant roots and their
potential importance in bioremediation. Chemosphere 31:3009-3016.

Fletcher, J.S. and J. Shah. 1998. Long-term phytoremediation of organic soil pollutants.
EPA Tech. Trends. EPA 542-N-98-055 No. 29:2-3.

Hedge, R.S.  and J.S. Fletcher.  1996. Influence of plant growth stage and season on the
release of root phenolics by mulberry as related to development of phytoremediation
technology. Chemosphere 32:  2471-2479.

Leigh, M.B., J.S. Fletcher, M.D. Kyle, D.P. Nagle, X.Fu andF.J. Schmitz.1998.
Rhizosphere Phytoremediation: Mulberry root flavones released by root turnover support
growth of PAH-degrading bacteria. MS Thesis, Univ.  of Oklahoma (Manuscript in

Olson, P. and J.S. Fletcher. 1999. Field evaluation of a mulberry tree growing on an
industrial waste site with reference to its potential role in phytoremediation.
Bioremediation Journal 3:27-33.

Olson, P. and J.S. Fletcher. 2000. Ecological recovery at a former industrial sludge basin
and its implications to phytoremediation and ecological risk assessment. Environ. Sci and
Pollution Res. (Accepted).

Olson, P., J.S. Fletcher and P.R. Philip. 2000. Natural attenuation/phytoremediation in the
vadose zone of a former industrial sludge basin. Environ. Sci. and Pollution Res.


                 Integrating Remediation  Into  Landscape Design

                                          Niall Kirkwood
Niall G. Kirkwood is Program Director and Associate
Professor at Harvard University's  Graduate Design
School, where he has taught since 1993. He supervises
research, executive education, curriculum development
and teaching in the areas of landscape technology, land
reclamation, and innovative site engineering. In addi-
tion, he is Director of the recently established Harvard
Center for Environment and Technology.

Prior to his academic appointment, he was in private
practice in the United States and Europe as an archi-
tect, landscape architect and urban designer working
on urban  regeneration projects in Barcelona, London,
Riyadh, Los Angeles, Columbus, Ohio and Manhattan.

Professor Kirkwood's current research focus includes
environmentally disturbed sites in industrial and devel-
oping countries, and landfill and brownfields redevelop-
ment. Current study projects  include the reuse of the
Fresh Kills Landfill,  Staten Island, NY and brownfield
sites in New England, Mexico and Asia. Superfund re-
search at Tar Creek, Ottawa County, Oklahoma is is car-
ried out in collaboration with Harvard Medical School
and the Harvard School of Public Health.
He is a member of the board of The Clean Land Fund,
a non-profit revolving loan fund based in Rhode Island
and serves on the Harvard Committee on the Environ-

The presentation will focus on four topics related to the
application of phytoremediation on Brownfields.

    An overview of the development of phytoremediation
    in relationship to land use and development.

    An introduction to landscape design processes and
    their relationship to the use and application of living
    plant material.

    The application of phytoremediation on Brownfields-
    the issues of context, site and implementation.

    An introduction to the larger urban issues surround-
    ing  Brownfields   and   their  impact   on

              Niall Kirkwood
           Harvard Graduate School of Design

               SESSION IIIA
      | EPA^ Phytorem^diation^
Copyright of the President and Overseers of Harvard College

   > Phytoremediation and Landscape Design
>  What is the Landscape Design Process?
   > Phytoremediation and Brownfields
   > Further Issues in Brownfield Design
           [^i^\J''hytoremediation: State_of the Science Conferenc^Bo^oi^MA May [I

> Regional, City Parks & Community Recreational Open Space

> Commercial/Industrial Parks and Biotechnology Centers

> Housing: Assisted and Private

> 'Green Infrastructure': open space/roads/utility/rail corridors

> Landfill Parks and Golf Courses

> Urban Arboretum, Environ. Education & Growing Centers
             '"EPA~Phytoreiniediation: State of the Science Conference, Boston, MA May 1-2,2000 j

  Site Analysis (site identification, economic and site assessment)

> Conceptual Design (project development and financing)

> Schematic Design and Design Development (project planning)

> Documentation and Bidding

> Implementation (cleanup execution and redevelopment of land)

> Maintenance and Post-Occupancy Evaluation

 (source: AIA. Document B163)


      • Refine Select-a-Plant Chart

      • Use Phytoremediation to go beyond Site Closure
             whole ecosystem approach
             use of native plants & habitat restoration

      • Managing Wildlife Issues: Balance Habitat and Treatment

      • Increase Net Environmental Benefit and Value

> SELECTED CURRENT ISSUES (source: J. Ackerman, VHB 1999)

       • Sustainable Economics- urban planning/'smart growth'

       • Treating Social Malaise- livable

       • Environmental education- 'tools for schools9
        Technology Trends- innovations in assessment &

      1. Anticipated Development (9 months - 3 year)
              phytoremediation system is implemented as part of
              delivery of usable site and construction program.
      2.  Long Term (30 year)
              phytoremediation 'embedded' in evolving interim
              and temporary land-use programs


      phytoremediation derived from agricultural-scale (crops, fields
      and hedgerows) rather than urban scale (bosque, allee, garden)

      relationship of phytoremediation to temporary and interim
      brownfield uses and site programs.

      Brown Cities and Brownfields
      nature, scale, complexity and location of site areas.

         Urban Context
         Existing Site Conditions- soils/groundwater
         Other Engineering Activities not Remediation
         Plant Growth Concerns- microclimate/soils
         Adjacent Community Concerns
         Proposed Site Program
         Implementation Concerns
         Disposal Methods
         Time-line- 2 tracks

                 Goals for Brownfields Pilots - O'Sullivan Island

                                        John Podgurski
John Podgurski is currently the Brownfields Coordina-   remediation. In addition, he has worked in the chemical
tor for EPA-Region I with responsibility for implement-   manufacturing industry as a chemical engineer in re-
ing the EPA's New England brownfields efforts.         search & development and production operations.

John has over fifteen years  of regulatory experience   John has been involved with EPA's brownfields initia-
working  in hazardous waste management and site   tive continuously since its inception in 1995.

 EPA Phytoremediation:
 State of the Science
  May 1-2,2000
What is a brownfidd?
A Estimated Number of Sites
A Distribution
A "Typical" Profile (Urban)
                                               What is a brownfield?
A Vacant or under used
  industrial/commercial facility
A. Redevelopment is complicated by
  real or perceived contamination.
 "Typical" Urban Brownfields
      Parcel Size - Lawrence, MA
                                                          Number of Acres
                          • 0.0-0.5
                          • o.s • 1.0
                          • 1.0-1.5
                          • 2.0 - 2.6
                          • 2.5 - 3.0

                Topical" Urban Brownfields
                    Buildings/parcel - Lawrence, MA
               Some of the "Other" Issues	

              A Location
                • Local property values
                • Existing infrastructure (e.g., utilities, roadways, etc.)
                A Surrounding socio-economic stability
                • Security/safety
              A Existing structures
                • Structural integrity
                * Physical layout/retrofitting
              A Financial encumbrances
 Common Brownfields Issues
A "Pre-decisional" investment
A Site investigation/clean-up costs
A Site investigation/clean-up time frames
A Additional engineering/ design requirements
A Potential delays caused by public concerns
A Process uncertainties
  • undetected contamination
  • ineffective remediation
  • changing regulatory climate and standards
  Phytoremediation and the Urban
  Setting - An Opportunity?	
 A Focus on publicly- vs. privately-controlled sites
 A Part of broader strategy to address multiple public needs
   • Flexibility with Future reuse options
    • open space
    • commercial/industrial
    • residential
   • Exposure reductions
    • "low cost" stabilization option
    • long term (remediation)
   • Aesthetic enhancement
 A Some "economy of scale" possible
 A Potential O&M cost reductions

 Phytoremediation and the Urban
 Setting - Potential Issues	

A Small parcel sizes
A Existing structures/surfaces
A Complicated ownership status
A Difficult growing conditions
  • Soil types/debris
  • Shading
  • Microclimates
Potential Issues (continued)

A Site Security/Vandalism
  • May be located in high crime areas
  • High usage areas
A Equipment access
A Public concerns regarding exposure


       Capturing a "Mixed" Contaminant Plume:
Tritium Phytoevaporation at Argonne National Laboratory

   M. Cristina Negri, Ray Hinchman, and James Wozniak


As  a soil scientist  and agronomist, M. Cristina Negri (University Degree 1981, Dottore in
Agricultural Sciences, 110/110 Cum Laude, University of Milan, Italy) shares the leadership of
the  phytoremediation activities at Argonne National Laboratory (ANL) since 1990. Active or
completed phytoremediation projects at ANL include the deployment of a deep-rooted [30']
groundwater phytoremediation project  for hydraulic control and VOC and tritium remediation;
investigation on the potential for using plants to remove Cs-137 and inorganics from soils at
Argonne-West at the INEEL, Idaho; zinc, lead and arsenic phytoremediation studies; and the
study of plant  systems for the treatment  of salt brines produced in the natural gas and oil
extraction processes.

Other activities include developing a proprietary technology for the decontamination of cesium-
137 contaminated milk from the  Chernobyl area, and the study  and scale-up of a soil washing
technology for the decontamination of a Pu-contaminated DOE  soil. Since 1991 M.C. Negri is
the  appointed  Convener of  a working  group  within CEN  (the European  Standardization
Organization) aimed at creating human and environmental safety standards  for growing media
and soil improvers, both traditional and waste-derived. From 1979 to 1991 M.C. Negri worked in
the  private  industry sector  in Italy.   Her activities  related to the study of chemical and
microbiological aspects and environmental impact of  the recovery of biomass and industrial
Publications available upon request.


 Large green plants have the capability to move significant amounts of soil solution into the plant
 body through  the  roots and evaporate this water out of the leaves as pure water vapor in the
 transpiration process.  It is known that tritium, as tritiated water, is partly directly incorporated in
 biological tissues, and partly transpired by plants as tritiated water vapor.

 An innovative application of  engineered phytoremediation has been deployed at the Argonne
 National Laboratory (ANL) site in Illinois. At this site, tritium is present as a co-contaminant with
 Volatile Organic Compounds  (VOCs) in the groundwater, approximately 30 ft (10 m) deep in the
 glacial subsoil.  In 1999, the U.S. Department of  Energy  (DOE),  through the Accelerated Site
 Technology Deployment (ASTD) Program funded the deployment of a phytoremediation system
 in the 317/319 areas with the objectives of minimizing water infiltration  into the source  soils,
 stabilizing the treated  soil  surface to prevent erosion, runoff,  and downstream sedimentation;
 hydraulically  contain  tritium  and  VOCs  migration  with  the groundwater,  and  continuing
 remediation of the residual VOCs in the plume.

 The  phytoremediation  system  installed  involves the use of high-transpiring,  deep-rooted
 phreatophytes to  provide hydraulic control of the contaminated plume.   While the fate of the
 VOCs in  a phytoremediation  system has  already  been demonstrated in a number of cases,
 this installation is pioneering the use of phytoevaporation for the removal of tritium from the

 A preliminary evaluation conducted by ANL prior to the inception of the project indicated that even
 assuming that all  of the tritium (at the  highest concentration in the plume) were transpired by
 plants, air emissions of tritium would result in an inconsequential exposure for a person at the site
 boundary, and be well  within the National Emission  Standards  for Hazardous Air Pollutants

 Soon after DOE funded  the project, the U.S. EPA and DOE agreed to include this remediation
 technology deployment in the projects evaluated by the EPA Superfund Innovative Technology
 Evaluation (SITE)  Program.   Under  this program, the EPA is independently monitoring and
 evaluating the technology's performance at the ANL-E 317/319 sites, in addition to the scheduled
 monitoring activities conducted by ANL.

- Phytoremediation  at the 317/319 areas at Argonne was deployed in the summer of 1999
 achieving a significant, 33% cost saving over the baseline traditional technology of capping and
 extraction wells. As the plants mature, performance data will validate further predicted cost
 savings on operations and maintenance, as the existing extraction wells will be closed and the
 plants will generate no secondary waste.

 Capturing a "Mixed" Contaminant Plume:  Tritium Phytoevaporation
                  at Argonne National Laboratory's Area 319

                    M. Cristina Negri, Ray R. Hinchman, and James B. Wozniak
                                  Argonne National Laboratory
                                     9700 S. Cass Avenue
                                      Argonne IL 60439


Tritium is a soft (low-energy) beta emitter radionuclide.  As such, it is easily shielded by human skin,
paper,  and approximately 6 mm of air.  It is,  however, hazardous when taken internally via ingestion,
inhalation, and absorption.  It decays to Helium-3 and has a half-life of 12.6 years. As it shares the
chemical and physical properties  of hydrogen,  it is  found as  an environmental concern typically as
tritiated water.  As for most of  the  radionuclide contaminants,  its radiological  hazard exceeds the
chemical hazard and thus levels of environmental concern in terms of radioactivity translate into minute
amounts in terms of mass. Sources and an estimated inventory of tritium are reported in Table 1 (from:

Table 1. Sources and estimated inventory of Tritium.
Natural (cosmic rays, m steady state)
Nuclear test explosions (1945-1975)
Nuclear power and defense industry releases
' Commercial devices (radioluminescent, neutron generating)
3 x 109 Ci (most decayed)
1 x106Ci/year
Tritium is known to be directly incorporated in water and biological tissues.  Its average biological half life
in the human body is 7.5 to 9.5 days.  In plants, it is taken up as tritiated water and subsequently mostly
transpired as tritiated water vapor (IAEA, 1981).  Studies conducted by the University of Heidelberg in
natural ecosystems suggested that heavy plant growth might pull water from the soil at a rate so fast to
considerably  reduce  tritium diffusion and  therefore  isotopic mixing in the groundwater (IAEA, 1967).
A small portion of the tritium is accumulated in plants as cell water or into tissue. Work conducted at the
Maxey Flats Disposal Site concluded that trees could be bioindicators of tritium contamination (Rickard
and Kirby, 1987).  In any case, the accumulation in plants appears to be of short duration (4 to 37 days)
(IAEA, 1981; Fresquez et al. 1995).

Tritium contamination of groundwater is present at the 317/319 areas at Argonne National Laboratory-
East (ANL-E), as a result of past operations.  Low levels of tritium, as well as VOCs, have been detected
in the groundwater in this area. The contaminated plume, approximately 30 ft (10  m) deep  in the glacial
subsoil, is migrating toward the southern boundary of the site through a series of sand layers, into the
adjacent Waterfall Glen Forest Preserve of DuPage County.
                                                                               !_/ *
In 1999, the U.S.  Department of Energy's Office of Environmental Management,  through tfre Accelerated
Site  Technology  Deployment  (ASTD)  Program,  jointly  funded  the  deployment / an innovative
phytoremediation  system in the 317/319  areas  with the  following objectives:  .(1)  minimize water
infiltration into the 317  French Drain area soils, some of which were treated previously by soil mixing,
thermal desorptions and iron addition; (2) stabilize the treated soil surface in the 317 French  Drain area to
prevent erosion, runoff, and downstream sedimentation;  (3) hydraulically contain groundwater  migration
and continue remediation of the  residual VOCs within the source area, and (4)  hydraulically contain the
VOCs and tritium  plume south of the 319 area landfill.

Large green plants are  capable of moving significant amounts of scil solution into the plant  body through
the roots  and evaporate 1his water out of the leaves as pure water vapor in the transpiration process

(Chappell, 1998; Wullschleger et al. 1998). Plants transpire water to move nutrients from the soil solution
through the roots (which function  as a highly dispersed,  fibrous uptake system) to leaves and stems,
where photosynthesis occurs, and to cool the plant. While the use of trees to hydraulically control and
remediate contaminated groundwater plumes at depths in the range of five to more than 30 ft has been
successfully applied at commercial installations (Nyer and  Gatliff, 1996) for the remediation of VOCs and
excess nutrients,  its  application to treat  tritium contaminated  groundwater has never been conducted

Technological Approach and Expected Results

The use  of trees to remediate  and  contain  contaminated groundwater  has  been successfully
demonstrated in treating contaminated groundwater. Applied Natural Sciences, Inc, (ANS) demonstrated
the use of phreatophytic trees (i.e., plants such as poplars and willows that do not rely on precipitation
water but seek water deep in soils) with its TreeMediation* and TreeWell* systems, that use a unique and
patented process to enhance  the aggressive rooting ability  of selected trees to  clean up soil and
groundwater  up to 50 ft deep.  Under a CRADA,  ANL-E  and ANS  researched phytoremediation
applications since 1994.
The 317 and 319 areas are located on the extreme southern end of the ANL-E site, immediately adjacent
to the DuPage County Waterfall Glen  Forest Preserve.  The 317 area is an  active hazardous and
radioactive waste processing and storage area.  In the late 1950s, liquid waste was placed in the unit
known as  the  French Drain.   Since that time, this  waste has migrated into underlying  soil and
groundwater.  The principal environmental concern in the 317 area is the presence of several VOCs in
the soil and groundwater and low levels of tritium in the groundwater beneath and downgradient of the
site.  The 319 landfill and French Drain area are located immediately adjacent to the 317 area.  The
principal  environmental concern in the 319 area is the presence of radioactive materials in the waste
mound, in the leachate in the mound, and in the groundwater downgradient of the landfill. Several interim
actions have already been implemented to reduce the VOC and tritium releases from these areas, as the
result of  the Resource Conservation and Recovery Act (RCRA)  Facility Investigation (RFI) conducted
from December 1994 through September 1996.  Currently, existing mechanical extraction wells remove
approximately 20,000 m3/yr of contaminated groundwater, which are sent to ANL's water treatment plant.
While the VOC contaminants are degraded at this facility, tritium  concentrations are diluted with other
wastewater from the lab and discharged in accordance with regulatory limits.

The hydrogeology at the 317/319 sites is  a complex framework  of glacial tills  interlaced with sands,
gravels, and silts of varying character, thickness, and lateral extent.  The subsurface  is a complex
arrangement of approximately 60 ft  of glacial  geologic  deposits  over  Silurian dolomite bedrock.  The
glacial sequence  is comprised of Lemont drift overlain  by the Wadsworth Formation.  Both  units are
dominated by fine-grained, low-permeability till. Permeable zones of varying character and thickness are
present in each. These materials range from silty sands to sandy, clayey gravels to gravelly sands.  In
some locations, pure silt was encountered.  If deep enough, this silt was saturated, and it is assumed to
play in important role in the flow of groundwater in the  study area. The  permeable zones have a wide
range in shape, their thicknesses range from less than one ft to roughly 15 ft and they have limited lateral
extent (Quinn et al. 2000).

On the basis of a preliminary agronomic assessment, hybrid willow  and hybrid poplar trees were selected
for the system.  In the summer of 1999, a total of approximately 800 trees were planted in three locations:
the 317 French Drain area, south of the 317 French  Drain area and 319 area landfill  (the 317 and
319 Hydraulic Control areas), and in the waste trench  south of  the 319 area  landfill.  Approximately
160 hybrid poplars were planted in the area of interest of tritium contamination.  This system is expected
to prevent the  further generation of contaminated groundwater in the source  area by degrading the
contaminants,  and to prevent the further  migration of  these plumes by removing groundwater from
saturated zones downgradient from the source area.  Figure 1 shows the location of  the plantings.  The

installed  system consists  of plantings of hybrid willows and special deep-rooted hybrid poplars.  The
willows were planted in the source area (317 French Drain area) deeper (16-20 ft) than is normal for
horticultural plantings, but without some of the special modifications used with the deep-planted poplars.

In the 317 and 319 Hydraulic Control areas, poplar trees were planted in boreholes spaced 16 ft apart
drilled down to the contaminated aquifer using ANS's TreeWell® system.  This technology was selected,
in consideration of the hydrogeological setting of the site, to target root growth  in the contaminated
glacial-drift permeable unit approximately  30-ft deep.  The poplars were  planted in  two-ft diameter
caisson  boreholes lined  with  plastic  sleeves  in  order to direct  the  roots exclusively to the main
contaminated  aquifer.  These boreholes were filled with a mixture of topsoil, sand,  peat, and manure to
promote  root growth and tree development. The capillarity of the mixture provides an added benefit of
drawing water to where it is available to the young trees.  All boreholes were also provided with aeration
tubes to ensure a supply  of air to the growing roots.  Figure 2  presents a diagram  of a TreeWell®

Planting  phreatophytic trees at  the capillary fringe in the year 1999 is expected to  provide full hydraulic
control by the year 2003 (see below) and be self sustaining for the full-expected life of  the engineered
plantation. Hybrid poplar and hybrid willow trees typically have a life span of about 40 years. The Path to
Closure  Plan committed ANL-E to have all remedial work at the 317/319 areas completed by October
                                                  '	f-.-fftf" f,"  •>  ^rKC.t-t'~-t
                 Figure 1.  Planting locations at the 317/319 areas.

                                                 ARGONNE 317
                                                 Aff&eA Nrtnnd Science; Inc.
                                                 E.G.GatBft Ph.0., President
                                                       Aprils, 1999
                                                       uifer foerched
                                                 Uty Clay Soil (Aquitard)
                Figure 2. Diagram of a Tree Well ® installation.
ANL-E installed  48 groundwater monitoring wells  on the phytoremediation project site  to track the
performance of the phytoremediation system. Soon after DOE funded the project, the U.S. EPA and DOE
agreed to include this remediation  technology deployment in the projects evaluated by the U.S. EPA
Superfund Innovative Technology Evaluation (SITE) Program. Under this program, the U.S. EPA will
independently monitor and evaluate the technology's performance at the ANL-E 317/319 sites in addition
to the scheduled monitoring  activities conducted by ANL-E.  Monitoring  activities have started  at the
completion of the construction  phase.  Root development will be observed through specially designed
viewing ports (minirhizotrons).

At the end of the remedial process, when a final analysis will verify the absence of the contaminants in
the biomass, the trees will be cut down at ground level, chipped,  and air dried. The roots will be left in
place to decay through natural processes and the chips will be reused on site as mulch for the planting of
native prairie species, in accordance with the planned final restoration  of the area.

Planning Considerations

Preliminary to the implementation of the systern, a modeling study was conducted to assess potential air
emission hazards, according  to existing regulations  (NESHAPS 40 CFR  61  Subpart  H).    Using
maximized assumptions  on  tritium  concentration in  the groundwater and  plant transpiration  rates,
emissions via transpiration were calculated for the four years from the time  of planting to the time of

         canopy closure. Results are reported in Figure 3.  The derived exposure rates to the nearest member of
         the public were calculated as required using the U.S. EPA CAP-88 PC program and resulted in values
         ranging between 6.32x10" mrem/yr in the first year to  2.58 x 10s mrem/yr during year four.  As the
                           Tritium Transpkotttton Rotes at Max Concentration
             Figure 3. Tritium transpiration rates at maximum concentration.

         regulatory standard is 10 mrem/yr, the added exposure was considered inconsequential.  In summary, air
         emission models indicated that even assuming that all of the tritium (at'the highest concentration ever
         found in the plume) were transpired by plants (at the highest transpiration rates), air emissions of tritium
         would be well within the National Emission  Standards for Hazardous Air Pollutants (NESHAPS). At the
         same time, tritium in the groundwater plume would be efficiently controlled.

         To support the deployment of the phytoremediation  system, a groundwater flow model was also
         developed.  Flow modeling was conducted initially to model the natural, transient changes in the flow field
         caused by seasonal changes in recharge to the aquifer.  The  model was calibrated to approximately
         10 years  of water   level  measurements  from site  monitoring  wells.   Anticipated   effects of  the
         phytoremediation system were included.  The model, updated to include the as-built configuration  of the
         phytoremediation system, indicates that the as-built plantation will provide hydraulic containment by the
         fourth year of growth even during the winter months when the trees are dormant (Quinn et al. 2000).

         Cost Savings and Other Advantages

         The conventional, baseline method of remediation of the 317/319 areas originally planned for deployment
         in lieu of phytoremediation included placing an asphalt cap over the VOCs source area and installing
         extraction wells (pump-and-treat) downgradient of the  source areas, from which contaminated water

would be withdrawn and discharged to a lift station, which pumps water to Argonne's waste treatment

The phytoremediation installation was installed with a cost saving of 33% compared to the expected cost
of the baseline approach.  The plant-based system is expected to have lower operating and maintenance
costs also: preliminary evaluations put the cost savings in O&M over the lifetime of the deployment at
40% compared to the baseline approach.  A significant cost saving (as well as a reduction in risks of
spills and worker exposure) is the avoidance of secondary waste (pumped groundwater) and related
treatment.  These cost savings will be demonstrated as the extraction wells are shut  off, expectedly in

In addition to this actual reduction in cost, a number of technical reasons made the  phytoremediation
choice more advantageous versus the baseline technology. As mentioned before, the  subsurface at the
site may be comprised of units of widely  varying lateral  or vertical extent, with gradational or sharp
transitions in permeability.  The fibrous nature of roots allows the trees to penetrate and remediate both
the relatively fast-flowing pore spaces and the  less permeable zones. Fundamentally,  this distinguishes
phytoremediation from  extraction wells,  which remove water mainly from the most permeable aquifer

Phytoremediation was considered more acceptable than the baseline also because of the ability of trees
to actively promote and assist in the degradation of the contaminants at the VOC source area, which the
baseline asphalt cap would not do, with expected reduction  in cleanup times.  The presence of vegetation
was also considered an optimal fit with the planned future land use of the contaminated site and adjacent
areas, as the phytoremediation plantation will contribute to increase soil fertility to host subsequent prairie

Literature Cited

•  Chappell, J. (1998), Phytoremediation of TCE in Groundwater Using Populus, status report prepared
   for the U.S. EPA Technology Innovation Office, available at http://clu-in.org.
•  Fresquez,  P.R., J.B. Biggs, and K.D. Bennett (1995),  Radionuclide Concentrations in  Vegetation at
   Radioactive Waste Disposal Area G During the 1994  Growing Season, LA-12954-MS, Los Alamos
   National Laboratory, June 1995.
•  IAEA (1967), Tritium and Other Environmental Isotopes in the Hydrological Cycle, Technical Reports
   Series No. 73, Vienna, 1967.
•  IAEA (1981), Tritium in Some Typical Ecosystems, Technical Reports Series No. 207, Vienna, 1981.
•  Negri, M.C., R.R.  Hinchman, and E.G. Gatliff,  "Phytoremediation:  Using Green Plants to Cleanup
   Contaminated Soil, Groundwater, and Wastewater," in  Proc. Spectrum '96 Conference, "Nuclear and
   Hazardous Waste Management International Topical Meeting," Seattle, WA, Aug. 18-23, 1996.
•  Nyer,  E.K., and E.G. Gatliff (1996), Phytoremediation, Ground Water Monitoring  and Remediation
•  Quinn, J.J., M.C. Negri, R.R. Hinchman, L.M. Moos, J.B. Wozniak, and E.G. Gatliff (2000), "Predicting
   the  Effect of Deep-rooted Hybrid Poplars on the Groundwater  Flow System at  a  Large-Scale
   Phytoremediation Site," submitted to the InternationalJoumal of Phytoremediation, in press.
•  Rickard W.H.,  and L.J.  Kirby, 'Trees  as  Indicators of Subterranean Water Flow from a  Retired
   Radioactive Waste Disposal Site," Health Physics 52, Vol. 2,1987, 201 -206.
•  Wullschleger S.D.,  F.C. Meinzer, and R.A. Vertessy (1998), "A  Review of Whole-Plant Water Use
   Studies in Trees," Tree Physiology 18, 499-512.

       Capturing a "Mixed" Contaminant
      Plume:  Tritium Phytoevaporation at
           Argonne National Laboratory

                M. Cristina Negri*, Ray R. Hinchman
                      and James B. Wozniak
                   Argonne National Laboratory

                          presented at the
            EPA Phytoremediation: State of the Science Conference
                       Boston, May 1-2,2000
                    "Contact: (630) 252 9662; negri@anl.gov

                      Research Funded by the VS. DOE
                EM-SO, Subsurface Contaminants Focus Area, and EM-40

Argonne National Laboratory, May 2000
       What is Specific to Radionuclides?
       • For practical purposes, plants do not appear to significantly
         discriminate between isotopes
       • Added radiation hazard highlights risks to food chain and
         emphasizes biomass disposal issues
       » Contamination levels of concern for radioactivity convert into
         minute amounts of mass, compared to other inorganic
       * Natural radioactive decay may contribute to the selection of the
         remediation technology, help performance
Argonne National Laboratory, May 2000

             Argonne's Activities in the
        Phytoremediation of Radionuclides
      Deployment of phytoremediation at the 317/319
      area at Argonne-East (VOCs and tritium)
    • Phytoremediation of Cesium-137 contaminated
      soil at Argonne-West (INEEL)
Argonne National Laboratory, May 2000
                Regarding Tritium...

  • A soft (low energy) beta emitter, shielded by skin, paper
    and 6 mm air
  • Hazardous when taken internally (absorbed, ingested,
  * Half life 12.6 years, decays to Helium-3
  • Shares chemical and physical properties of hydrogen
    [e.g., tritiated water (HTO)]
  • Average biological half life in human body 7.5-9.5 days
  • Has a specific activity of 9.61xl09 /tCi/g, so the drinking
    water standard of 20,000 pCi/L equals to 2.08 x 10'12
    g/L (ppbs of a ppb)
Argonne National Laboratory, May 2000

                 Sources of Tritium*
Natural (cosmic rays, steady state)
Nuclear test explosions, 1945-1975
Nuclear power and defense industry
Commercial devices (radioluminescent,
neutron generating)
70 x 106 Ci
8 x 109 Ci
(most decayed)
1-2 x 10b
1 x 106 Ci/year
         * from: www.hfbr.bnl.gov/hfbrweb/hdbll079a.htmlttZZ5
Argonne National Laboratory, May 2000
         Phytoremediation and Tritiated


        • Tritium (3H) is known to be directly incorporated
         in water and biological tissues
        • Plants transpire tritiated water vapor, and plant
         biomass may serve as indicator of tritium
        • High transpiring, deep rooted plants can control
         contaminated groundwater in an engineered plant
Argonne National Laboratory, May 2000

           Fate of Tritium in Engineered

             Phytoremediation Systems

       • Plant uptake with groundwater
          - Transpiration into air with water vapor
             •> Distribution in atmosphere and rapid mixing
               with large volumes of air, decay. Modeling
               needs to establish that risks of airborne radiation
               exposure are acceptable, largely dependent on
               activity concentration and site conditions
          - Accumulation in plant tissue
             •> Mean residence times are 4-37 days
                 - Easily exchangeable (cell water)
                 - Not easily exchangeable (incorporated in

       • Evaporation from soil, seeps...
Argonne National Laboratory, May 2000
          Deployment of TreeMediation®

                    at Argonne-East

        Instead of an asphalt cap and extraction wells,
        approximately 800 trees and a herbaceous cover were
        planted in 1999 to:

        •Achieve hydraulic control of the migrating, 20 to
          30 ft deep plume
        •Improve the degradation of VOCs in soil and

        •Remove tritium from the subsoil

        •Prevent water infiltration and soil erosion.
Argonne National Laboratory, May 2000

          The 317/319 Area at Argonne

       * Former (1940s - 1960s) laboratory waste disposal
         area , approx 2 ha of surface, several SWMUs in the
         area, currently used for waste storage
       «• Soil is contaminated with VOCs, and groundwater
         with VOCs and tritium, baseline technology (asphalt
         cap and extraction wells) was considered less
         advantages - limited predictability and zone of
         influence of wells in glacial subsoil, plus "perpetual"
       «• Currently, extraction wells discharge secondary
         waste to Argonne's treatment plant
Argonne National Laboratory, May 2000
                      317/319 Area
Argonne National Laboratory, May 2000

               The Subsoil at 317/319 Area
  » Complex
    within glacial
    sediments forms a
    hydrologic system
  • Waterbearing
    intervals are in
    sand and gravel
  * Hydrologic system
    is altered by
    perched or
    seasonally wet
    zones and by
    fracturing of
    confining clays by
5  3   5   5   I
Argonne National Laboratory, May 2000
                Remediation Approach

       • Deep-planted, unlined TreeMediation® hybrid
         willows to address VOC source area

       • Deep-planted, TreeWell® engineered hybrid poplars
         to achieve hydraulic control of groundwater

       • Herbaceous cover throughout to minimize water
         infiltration and soil erosion

       • When remediation is complete, trees will be cut
         down, chipped, and used as mulch on site, and native
         prairie vegetation established.
    TreeMediation® and TreeWell® are patents of Applied Natural Sciences, Inc.
Argonne National Laboratory, May 2000

                           Planting Layout
Argonne National Laboratory, May 2000
                   Tree Well® for Groundwater
                      (Hydraulic Control at Depths)
     • Root-engineered plants
       were placed into
       predrilled, 30' deep
     • Impermeable liner
       backfilled with plant
       compatible material
       forces growth into
       contaminated plume,
       excluding perched
       aquifers and
       precipitation water
     • Planting design took into
       account plume velocity
       and winter dormancy
Argonne National Laboratory, May 2000

        Emissions through Transpiration:

                Worst Case Scenario

     • Use maximum concentration EVER found (500 nCi/L)
       — average below 20
     • AH tritium is transpired
     • 160 trees are planted in area of tritium contamination
     • Transpiration rates 2-50 gal/day per tree, April to
     • Derived exposure calculated as required by NESHAP
       standard (40 CFR 61 Subpart H) using U.S. EPA
Argonne National Laboratory, May 2000
    Calculated Emissions via Transpiration
Argonne National Laboratory, May 2000

           Derived Exposure to Nearest
                 Member of Public

       Year 1 (2000): 6.32 x 10'6 mrem/yr

       Year 4 (2003) and subsequent: 2.58 x 10'5 mrem/yr

       NESHAP Standard: 10 mrem/yr

       ANL total for calendar year 1999: 4.3 x 10'3 mrem/yr
Argonne National Laboratory, May 2000
                  Expected Results

     Hydraulic control expected in four years or less

     Tritium is expected to be transpired without significant
     impact on dose to exposed population
    «• Existing extraction wells will be progressively shut off as
     plants grow and achieve hydraulic control
Argonne National Laboratory, May 2000

                Monitoring Performance
                     a combined effort:
        Argonne National Laboratory, U.S. Department of
        Energy (DOE)
        The U.S. EPA, National Risk Management Research
        Laboratory, Superfund Innovative Technologies
        Evaluation (SITE) Program
Argonne National Laboratory, May 2000
              Cost Savings and Other


         Installation achieved 33% cost savings over baseline
         O&M expected >30% cost savings — to be
         demonstrated at plant maturity
         Minimized handling/transportation of secondary
         Accelerated cleanup times
         Potential protection from unforeseen releases from
         other sources in the area
Argonne National Laboratory, May 2000

   Application of Phytoremediation  to Remove  Cs-137  at Argonne Na-
                               tional Laboratory - West
                                          Scott Lee
Scott Lee has a B.S. in civil engineering from North
Dakota State University and a M.S. in environmental
engineering from North Dakota State University. He has
worked as an environmental engineer for Westinghouse
Electric Corporation at the Naval Reactors Facility in
Idaho Falls Idaho, during the cleanup of 57 CERCLA
waste sites.

Scott is currently employed by Argonne National Labo-
ratory-West as an  environmental engineer.  He is in
charge of all 39 CERCLA sites at Argonne National Labo-
ratory-West being remediated underthe Federal Facili-
ties Agreement and Consent Order. He is responsible
for coordinating, developing, and writing all required docu-
ments including the Sampling and Analysis Plan, Re-
medial Investigation Work Plan, Remedial Investigation
and Feasibility Study, Record of Decision, Remedial
Design Remedial Action Work Plan, and the Verification
Sampling Plan. In addition, Scott is managing a two-
year phytoremediation demonstration project as well as
the excavation and disposal activities at these two sites.
A summary of the first year of the phytoremediation
demonstration project at Argonne National Laboratory-
West has been written and will be published in the May/
June issue of Radwaste Solutions magazine.

Summary of WAG 9
CERCLA Activities

~ Listed as NPL site in 1991
  Includes the investigation of 37 WAG 9 waste sites
  Includes the summary of 2 WAG 10 waste sites
  Involved collection and analysis of over 9,400
  contaminant specific samples
  ROD signed 9-27-98
                              Argonne National Laboratory-West

Waste Area Group 9
Contaminants of Concern
       Cesium -137
                                    Argonne National Laboratory-West
   Human Health Risk Calculations
   (present day occupational exposure)
                  Waste Pond
                  (29.2 pCi/g)
Canal (mound)
(30.53 pCi/g)



 37 sites have risks below 1 in 10,000
                                      Argonne National Laboratory-West

 Summary of Comparative Analysis Ranking
 of Remedial Alternative
           Evaluation Criteria
       Alte rnative
                                 3a   4a   4a   4b   5
 Overall Protection of Human Health and the
 Compliance with Applicable and Relevant and
 Appropriate Requirements
 Long-term Effectiveness and Permanence
 Short Term Effectiveness
 Reduction of Toxicity, Mobility, or Volume
 Through Treatment
 Cost (in millions)
meets meets meets meets meets
good good  good good  best

worst good  good good  best
worst good  good good  good
worst worst worst worst best
best best  best  best  good
7.6  5.9   5.9  13.1  2.8
Phytoremediation Obstacles
• Ecological Receptors
   Public Concerns (Homer Simpson)
   Leaching Contaminants
   Noxious Weeds

M ilk! ••]
nt Le
 Design and install irrigation system

 Add additional soil moisture detectors below

Noxious Weeds
  Use of plants found in but not native to Idaho
  More harmful than beneficial
  Eradication must be economically feasible
  Adverse impact must exceed cost of control
                               Argonne I
 Special Controls for Kochia Weed
   Get State approval prior to planting to control
   undesirable weeds
   Harvest before flower
   Establish clear zone around site
   Seed weeds to prevent wind dispersion
                                \rgonne National Laboratory-West




Future Activities

Establish and test three Amaranth species for
   comparison to Kochia (Amaranthus: retroflexus,
   bicolor, and paniculatum)

Compare the Cs-137 uptake for stress and unstressed
   plants prior to harvesting

Use ISSOX (directional sodium germanium detector)
   prior to planting, harvesting, raking, and bailing, Bale
   plant matter
                                     Argonne National Laboratory-West

                 PLANTED SYSTEMS

       The  Role of the Plant and the Rhizosphere in Phytoremediation
   Milton P. Gordon, Sharon Doty, Paul Heilman, Lee A. Newman, Tanya Q.T. Shang, Stuart Strand, Xiaoping
                          Wang and Angela Wilson, University of Washington
Milton P. Gordon received his Ph.D. from the University
of Illinois. He then spent four years as a Post-doctoral
Fellow and as a staff member in the Sloan Kettering
Institute for Cancer Research. This was followed by two
years at the virus laboratory and the University of Cali-
fornia at Berkeley. In 1959 he joined the faculty at the
University of Washington where he is now a Professor
in Biochemistry, Join Professor in Microbiology and in
Ecosystem Sciences in the College of Forest Resources.
Dr. Gordon, together with his colleagues at the Univer-
sity of Washington, is responsible forthe basic discov-
eries underlying  the principals  of plant genetic
engineering using  the  microorganism Agrobacterium
tumefaciens. He is  currently interested in the  use  of
plants to remediate toxic  organic compounds in the
environment, and  together with his colleagues, Drs
Newman and Strand, operate a field site forthe  testing
of various species of trees to determine their ability to
degrade toxic solvents.

The metabolism of trichloroethylene in plants, animals
and bacteria has been  well established. Axenic poplar
cells form  C02,  di  and  trichloroacetic  acids,
trichloroethanol, and insoluble non extractable materi-
als. In a mass balance chamber between75 and 90%
of the TCE taken up by poplar cuttings is transpired
unaltered. In contrast, in an outdoortest plot only about
8% oftheTCE is transpired.The majority ofthe remain-
der of the TCE (70%) is catabolized to chloride ion which
can be recovered from soil. Carbon tetrachloride and
perchloroethylene  were similarly catabolized. The
dismutation of TCE  depends upon the uptake of water
and TCE by trees as irrigation in excess ofthe ability of
the trees to take up water resulted in escape  of unal-
tered TCE. Soil samples from the planted field site did
not convert TCE to  C02 in amounts greater than what
was seen in unplanted soils, indicating no change in
the oxidative metabolism in the soil in the presence of

When tobacco plants containing exogenous cytochrome
P450 2E 1 were studied under hydroponic conditions in
the lab, TCE was converted to trichloroethanol and its
Beta-glucoside although even in this case only a small
fraction (Ca 1 - 5%)  of the TCE was recoverable
trichloroethanol and its glucoside.

The results in our laboratory and field studies indicate a
role forthe  plant in  phytoremediation, but do  not rule
out participation of  rhizopheric organisms  on these or
other sites.

Legends to go with slides

1.   Metabolic pathways of TCE

2.   Apparatus used to determine metabolism of axenic poplar cells

3.   TCE metabolites formed in axenic poplar cells

4.   Formation of CO2 from  axenic cells

5.   Mass balance chamber

6.   Diagram of field site

7.   Field site-1995

8.   Field site-1997

9.   Field site study of TCE

10. Field site study of TCE

11. Apparatus to study transpiration of solvents

12. Chloride ion accumulation in soil of chambers treated with TCE

13. TCE in excess of uptake is not metabolized by soil rhizosphere - note recovery in late 1997

14. Remediation of CC14

15. Remediation of CC14

16. Two year recovery of CC14

17. Remediation of perchloroethylene

18. Formation of trichloroethanol and its B-glucoside in transgenic tobacco plants

19. Personnel


supernatant and axenic cells exposed to TCE  '.

          TCE  Chloral IWcfcfcro-  Diehtoro-  Trfchtot^.
          -     hydrate ethanol    acetic acid acetic acid
                ND4&    NftW    NDlft

Diagnim of a cell



\\vl\ Mith

[ l>trt-rlif>»t ..J »;iu-r

t Ml .it Illill
V\ * M

     I liJJ \ ic'\\
     Sitlc view


Three Year Daily Additions and Recoveries of
             TCE and Metabolites
           •id tied
          - recovered - DO trees
           recovered - tr*es
           recovered -trees


Daily Recovery of Carbon
                    recovered - no trees
                    recovered • trees

            I ivt- TiOH
            <; i MI jut: HUM I IcOif
 The Phyto  Group
Hugh Arnold
Maggie Connor
Sharon Doty
Katrtna Sery
Mi If on Cordon
Paul Heilman
Emily Kenney
Jennifer  Mears
Induiius Muiznieks
 .ee Newman
Tanya Shong
Marietta Sharp
Stefcmfe Stanley
Stuart Strond
Mary Trute
Xiaoping Wong
^ram Wcsfergrec
Rayno Wong


The Case for Volatilization
     William Doucette
   Abstract Unavailable


   William J. Doucette has B.S. and M.S. degrees in Chemistry and a Ph.D. in Water Chemistry         •
from  the University of Wisconsin-Madison.  His research  focuses on the fate of  organic
contaminants in the environment, emphasizing the relationships between molecular structure,         •
physical/chemical  properties  and environmental processes  such as  sorption,  volatilization,
biodegradation, and uptake by biota.  He is currently an Associate Professor in the Department of         _
Civil and Environmental Engineering/Utah Water Research Laboratory, at Utah State University         •
(USU).   Dr. Doucette  also  serves  as  an  Environmental Chemistry Editor for the  journal
Environmental Toxicology and Chemistry. Prior to joining Utah State University, Dr. Doucette         _
worked as  an analytical chemist at the U.S. EPA's Environmental Research  Laboratory in         |
Duluth, MN supporting fish bioconcentration  studies.   Dr.  Doucette was also  a  Senior
Environmental  Chemist at Lilly  Research Laboratories where he directed a variety of studies         _
evaluating the environmental fate of pharmaceuticals.                                                |
   During  the past six years, Dr. Doucette has teamed with crop physiologist Dr. Bruce Bugbee
to investigate the impact of plants on the fate (rhizosphere degradation, uptake, translocation, and         _
volatilization)  of hydrocarbons, PAHs, pentachlorophenol and volatile chlorinated solvents in         |
both laboratory and field studies.













            The Case For
         Bill Doucette & Bruce Bugbce
       Utah Water Rcscarcli Laboratory
         Crop Physiology Laboratory
            Utah Slate University
               Logan, Utah
                                                                              Enhanced rhlzosphers
        Plant uptake of organics

  Root uptake via water or vapor (passive
  diffusion through root membrane)
  Atmospheric deposition onto leaves
  Diffusive transport through air spaces of root
  and shoot tissue (e.g. methane flux through
  wetland plants)
         Quantifying Uptake/Translocation

      • Root Concentration Factor (RCF)
         •Uptake into roots
        -RCF = root conc./external soln. cone.
      • Transpiration Stream Concentration Factor
        -Translocation from roots to shoots
                                                                Brisus cl al.. I9S2
          Cone, inxylem sap
                                                                   Cone, in external solution
                                   Xylem sap
Phytoremediation State of the Science Conference, Omni Park House Hotel,
Boston, MA May 1-2,2000. (doucette@cc.usu.edu)

                                                       Uptake and Phytovolatilization of
                                                            TCE-Literature review
                                                     Schroll ct al. (1994) little root uptake
                                                     Newman et al. (1997) "Measurable"
                                                     transpiration & metabolism
                                                     Schnabel et al. (1997): l-2%uptake shoots
                                                     Burkcn & Schnoor (1998) 21% transpired,
                                                     Davis et al., (1998) TSCFs = 0.1-0.58
        Uptake and Phytovolatilization of
       „„_   TCE-Literature review
       Compton ct al. (1998) TCE detected in
       transpiration gas samples
       Newman et al., (1999) 9% of total TCE loss
       attributed to phytovolatilization
       Nietch et al. (1999) transpiration & diffusive
       Orchard et al. (2000) TSCF = 0.02 -0.22
 Possible Reasons for Differences

Experimental approach & artifacts
Exposure concentration & duration
Plant growth conditions
-Soil vs. hydroponics
-Plant species and age
          Laboratory approaches used to
                determine uptake &

         Static chamber
         Flow-through chamber
Phytoremediation State of the Science Conference, Omni Park House Hotel,
Boston, MA May 1-2, 2000. (doucette@cc.usu.edu)

                                                      Field approaches used to measure
                                                      "Open" bag
                                                      "Sealed" bag
                                                      Flow-through bag or chamber
                                                      Open path FTIR
             Measuring uptake and
       phytovolatilization: considerations

       •>  Humidity build-up
       •  Temperature buildup
       1  Unnatural plant growth conditions
       •  Foliar deposition vs root uptake
       •  Leaks/low recovery
       •  Low concentrations (require trapping)
   USU Lahoratory study-goals

Dual-chamber flow through system
Natural plant environment
High mass recovery
Quantify phytovolatilization
Phytoremediation State of the Science Conference, Omni Park House Hotel,
Boston, MA May 1-2, 2000. (doucette@cc.usu.edu)

                                                                                         TCE + H,0
                                                              (TCIi in shoots*) / (Water Transpin-il)
                                                                    (Exposure Conci'ntralmn)
                                                              *Slored + volatilized
         Study #1
         Mass Balance
           Ippm. 12 d

         Study #2
       Root Zone Aeration
           Ippm, 12 d
         Study #3
                     Key Results

       Mass recoveries (>92%)
       TCE, TCAA, DCAA, & TCEt identified
        -Roots > leaves > stem
       Little or no phytovolatilization
       TSCF ranging from 0.02-0.21
       TSCF independent of exposure cone. (1-70
       ppm) & duration (12-26 days)
Phytoremediation State of the Science Conference, Omni Park House Hotel,
Boston, MA May 1-2, 2000. (doucette@cc.usu.edu)

       10 t 3 1 3 %
        5 t D 6 %
 4 to 7 %
C02 traps:
                                  70 to 75 %
                                                               TSCF Breakdown
Dose Levsl
  1 ppm
  1 ppm
  1 ppm
  1 ppm
  1 ppm
  1 ppm
  1 ppm
 10 ppm
 10 ppm
 10 ppm
 70 ppm
 70 ppm
              Tissue Analysis Results

       • 14C by combustion » extractable 14C.
       • Short-term treatment concentrations:
               Roots > Stems > Leaves
        • Long-term treatment concentrations:
               Roots > Leaves > Steins
Phytoremediation State of the Science Conference, Omni Park House Hotel,
Boston, MA May 1-2, 2000. (doucette@cc.usu.edu)

               Stability Study Results
            Site Location
          11% of the total shoot "C was detected
          in the new leaves that formed after dosing
          No detectable leakage of I4C into root
          zone solution, even after leaf removal.
Air Station
                                                                                  Ordnance Support
                                                                                  Facility (1381)
                                                              Site Description- CCAS Site 1381

                                                         • Small metals cleaning facility from 68-77
                                                         • Shallow aquifer, 2 - 4 ft bgs
                                                         • Sandy soil, little clay or silt material
                                                         • TCE (1-10 mg/L) detected in the S\V corner of
                                                          the site &  in the southern canal
                                                         • Plume size = 2200 ft x 3000 ft
Phytoremediation State of the Science Conference, Omni Park House Hotel,
Boston, MA May 1-2, 2000. (doucette@cc.usu.edu)

Phytoremediation State of the Science Conference, Omni Park House Hotel,
Boston, MA May 1-2, 2000. (doucette@cc.usu.edu)

B 10.000
f 8.000

	 JE- t

                                Plant tissue
Transpiration gas sampling (TCE/PCE)
                                                                        TCE mg/L  sldev  PCE mg/L  stdcev
                                                                            2.^65     1.6    r)
       Extrapolating to the Field

 Plant Uptake = (TSCF)(CTrF)(T)(/)
 TSCF and CTCF arc assumed constant.
 T = Transpiration (200 - 1400 L/m:-yr).
 / = fraction of groundwalcr uptake (0.1-0.5)?
          Directions/Questions for Future
        Improved methods for measuring
        Diurnal, seasonal measurements
        Uniformity of individual trees & canopy
        Precipitation vs groundwattr use
        Can lab measurements be extrapolated to
Phytoremediation State of the Science Conference, Omni Park House Hotel,
Boston, MA May 1-2, 2000. (doucette@cc.usu.edu)

                m LA.X. Want IA Mui'nukv. C Ekuan. M. Rus/a). R. Conollucii, D IXminvs.
               .iif.T. Newnun, RS Crani|ton. RA HaJmioiuj. MO ^'u«, PE NVilman, Dull j
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lonVicrniiniiii-'ihc laic of vuljiilc DPJJIIJL' LiiiitpnuiiN in planted systems. En\-ir<
TtnittilCtwiLWW .HHX-N94.
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h> H>hml PuplarTrtvCmwi H>tlro[\inn.ally HI Riiw-ThriuchPlant Gnimh
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           inu B.CauG, IXitk-r U. Lalumati M, L^nycituLhT, Sclk-uiivrl I.
  initial i» i. J. L'r'iJ'"-'P;Jlll^"'i>s iif tirisinn; «.|iL!iiiti:iits I ruin siit hy aL'ricultural
Phytoremediation State of the Science Conference, Omni Park House Hotel,
Boston,  MA May 1-2,2000. (doucette@cc.usu.edu)

           Phytotransformation Pathways and  Mass  Balances for
                          Chlorinated  Alkanes  and  Alkenes
                         Valentine A. Nzengung, Chuhua Wang and Stacey Box
                             University of Georgia, Athens, Georgia, USA
Valentine Asongu Nzengung has a B.Sc. in geology from
Georgia State University in Atlanta. Upon graduation
from Georgia Tech, he worked at the United States Eco-
systems Research Laboratory in Athens, GA, for two
years before his appointment to a tenure-track faculty
position at the University of Georgia in the fall of 1995.

Valentine Asongu Nzengung is currently an associate
professor of environmental geochemistry and an affili-
ate member of the Advanced Ecology Laboratory.  His
research approach is multidisplinary and focuses on the
development and evaluation of innovative environmen-
tal remediation technologies. The specific technologies
his currently working on include phytoremediation, natu-
ral attenuation, in-situ dethionite treatment barriers for
chlorinated organic solvents, preparation and determi-
nation of the effectiveness of organo-modified clays as
sorbents of hydrophobic organic contaminants. His most
recent discovery involves the use of selected plants
and photoautotrophic microorganisms in decontamina-
tion of perchlorate-contaminated soils and groundwater.
He is also involved in field demonstration and validation
projects at many chlorinated solvent and perchlorate
waste sites. He has published more than twenty research
papers in various environmental research journals and
conference proceedings.

Phytotransformation products of chlorinated alkanes and
alkenes in the rhizosphere, tissues of aquatic plants,
cottonwoods and willows grown hydroponically in a green-
house and in similar trees harvested from a
phytoremediation field site were determined. Using the
results of the identified products, we proposed the pre-
dominant metabolic pathways and estimated mass bal-
ances. Four mechanisms were found to be important in
the removal of the chlorinated aliphatics from water by
aquatic plants, namely: (1) rapid sequestration by parti-
tioning to the lipophilic plant cuticles; (2) phytoreduction
to less chlorinated VOCs; (3) phytooxidation to
chloroethanols, chloroacetic acids and unidentified me-
tabolites; and (4) assimilation into the plant tissues as
non-phytotoxic products. A total mass recovery of bet-
ter than 80% was obtained from the radiolabeled stud-
ies with aquatic plants. Forwoody plants, the predominant
phytoprocesses   included   rhizodegradation,
phytodegradation and phytovolatilization. Mineralization
of chlorinated aliphatics to 14CO2 in the tissues of aquatic
plants and in the rhizosphere of woody plants was con-
firmed. We believe that all of the CO2 formed could not
be accurately quantified since plants utilize CO2 during
photosynthesis. The identification in the plant phase and
in the root zone of metabolites formed by the oxidative
and reductive transformation of the probe chemicals
suggests that more than one pathway requiring different
enzymes may be involved in phyto-transformation reac-
tions. Comparison of metabolites observed in leaf ex-
tracts of mature trees growing over a TCE plume at
Carswell AFB, Fort Worth, Texas; leaves harvested from
younger trees at the field site; and rooted cuttings used
in greenhouse studies provided  evidence  that
Phytotransformation pathways may change with the age
or growth stage of vascular plants.

The  successful   design  and  application  of
phytoremediation treatment  systems at field sites de-
pends on our understanding of the phytoprocess involved
in the attenuation of the specific contaminants. The re-
moval of chlorinated organic solvents (COS) from the
affected environments may be influenced by many fac-
tors, such as physicochemical properties of the organic
solvent, the plant characteristics, the root zone and at-
mospheric conditions. Due to differences in their physi-
ology and geo-environments, the mechanisms by which
aquatic, terrestrial and woody plants metabolize the same
halogenated organic chemicals may vary.

We investigated the plant-mediated metabolic pathways
of six halogenated aliphatics (three halogenated alkanes
and three alkenes) and mass balances for three of the
six compounds. The specific halogenated aliphatics in-
cluded carbontetrachloride (CTC), hexachloroethane
(HCA), tetrabromoethylene (PBE), tetrachloroethylene
(PCE), trichloroethane (TCA), and trichloroethylene
(TCE). The vascular plants used in the studies included
an emergent wetland plant  (Myriophyllum  aquaticum
[parrot feather]), a submergent wetland plant (E/octea
canidensis [waterweed]), and two woody plants (cotton-
woods and willows). The rooted cuttings of cottonwoods

and willows were selected according to their health and
maturity. Duplicate runs were made with cuttings that
came from the same tree and when possible, from the
same branch. This enabled consistency and very little
variation. For comparisons, harvested leaves and roots
from mature cottonwoods and willows growing over a
shallow plume of PCE and TCE were analyzed for me-

Sorption experiments
On arrival at the laboratory, the Elodea to be used for
sorption experiments was heat inactivated (Nzengung
etal., 1999) and 7 g was weighed into 12 serum bottles
and filled with nanopure water (52 ml). The vials were
dosed with different concentrations of PCE or HCA (0,
0.5, 1, 2, 5, and 10 mg/L, respectively) and sealed.  At
the end of the equilibration period of 24 hours, 6 ml of
liquid phase from each bottle were extracted into 6 ml
of hexane and analyzed by GC/ECD. The equilibration
time of 24 h was selected because sorption onto Elodea
by both PCE and HCA was observed to  be very rapid,
with equilibrium attained in about two hours.

Static Batch Transformation
Harvested algae, parrot feather, or Elodea were weighed
into 20 or more 60-mL serum bottles and the remaining
volume was filled with deionized water. Half of the se-
rum bottles were immediately dosed with the compound
of interest and crimped with an aluminum seal and alu-
minum-faced silicon septa. The pH in reactors with live
algae and plant samples was 5.6. Each sample vial and
its corresponding control of dosed liquid without plant
were hand-shaken twice a day for the duration of the
experiment. Headspace was minimized in all bottles.
The solution phase of dosed samples and their corre-
sponding controls were sacrificed for analysis 15 min-
utes after dosing the  bottles and at predetermined time
intervals thereafter. The longest experiments lasted for
30 days and  the shortest for 7  days.  For selected
samples, the entire solution phase was removed with a
gas-tight syringe and the residual plant or algae tissue
extracted with  methanol/acetonitrile (1:1) before analyz-
ing for metabolites. This extraction involved two steps.
In the first step, the residue was first extracted by add-
ing enough methanol-acetonitrile to fill the vial and soni-
cating for 10 minutes, then separating the liquid phase
by centrifugation and analyzing directly by GC/ECD or
LS.  In the second step, the remaining pellets were then
crushed and extracted as above.

Radiolabeled  batch transformation studies were con-
ducted with two different chemicals (14C-PCE and CTC).
The 14C activity present as 14CO2, hydrophilic, extract-
able and unextractable bound fractions was assayed  by
liquid scintillation counting. The excess solution phase
was removed  with a gas-tight syringe and the residual
algae or plant matter extracted by sonicating three times
with 20 ml of a binary solvent (methanol and acetoni-
trile) as described above. The unextracted bound frac-
tion was directly quantified by combusting the remain-
ing pellets in a Packard Model 307 sample  oxidizer
(Packard Instrument Co., Downers Grove, IL). The
evolved 14C02 was trapped and quantified  using a
Beckman LS 6000L liquid scintillation counter.

Hydroponic Bioreactor Studies
A 2.2-liter bioreactor flask with two side ports was used
in the experiment (Nzengung etal. 1999). One port was
connected with a valve and a reservoir for water replen-
ishment and the other port was equipped with a sam-
pling-port. The growth solution was 30% of full strength
Hoagland's solution and was dosed with either saturated
TCE or PCE aqueous solution. Each tree was fastened
into the screwed cap and sealed with dental cement and
acrylic glue. All roots were completely submersed in the
aqueous nutrient media and leaves were outside of the
reactor. The final solution volume was 2000 - 2100 ml
and the headspace was about 10 ml. The roots were
shielded from direct light by shielding the medium-con-
taining  portion of the reactors with aluminum foil. All
studies were conducted in a greenhouse. The volume of
medium was kept constant by adding waterthrough the
replenishment port. A 1 ml aliquot was withdrawn ev-
eryday through the sampling-port and extracted into 6-
18 ml of hexane. The volatile organic compounds
(VOCs) in the hexane phase were measured by GC/
ECD. The experiments were terminated when the PCE
concentration decreased to about 25% of the starting
concentration. The static headspace samples (1 ml)
were taken at the beginning and at the end of the study,
and analyzed on both GC/FID and GC/MS.

For radiolabeled experiments, the upper portion  of the
plant was encased in an inverted 5000 ml Erlenmeyer
flask with 2  ports, one on top and one on bottom. The
flask was secured and sealed in the same manner as
the bottom flask outlined above. The top port was at-
tached to an activated carbon trap to purify the air enter-
ing the  flask. The bottom port was attached to  a series
of traps that were used to capture any products that the
plant had transpired. The first trap was empty  to catch
any transpired waterthat built up during the duration of
the experiment. The second trap contained ethylene gly-
col monomethyl ether, the third trap contained 1M so-
dium hydroxide (NaOH) and the fourth trap contained 10
g of activated carbon. The last trap was connected to a
compressed air cylinder that created a continuous air-
flow through the entire system. Silicone grease was used
to seal  all joints to ensure there was no leakage  at the
numerous connections.

Measurement of Chloroacetic
Following the hexane extraction described above, solid
and aqueous samples were treated with 1M sulfuric acid
and placed in an ultrasonic bath for several hours. Then,
the mixture solution  was extracted using MTBE. The
MTBE extract (2 ml) was mixed with  150 ml
diazomethane saturated MTBE solution prepared in a
Wheaton Generator with 1 gram  1-methyl-3-nitro-1-

nitrosoguanidine and 5 ml of 5M NaOH. The mixture
was placed in an ice bath for 5 minutes, and then at
room temperature for at least 15 minutes (Hales et al.,
1973). Chlorinated acetate methyl esters were measured
on a Shimadzu GC-14A/ECD. The standard solutions of
chloroaceticacid, dichloroaceticacid, and trichloroace-
ticacid were derivertized and measured underthe same

Headspace Measurement of VOCs
A Hewlett-Packard 5890A Gas Chromatograph with FID
was used for VOCs analysis. Exactly 0.5 ml headspace
was manually injected into the injection port maintained
at a temperature of 200°C. A capillary column DB-VRX,
30 m X 0.25 mm I.D., 1.4 urn film (J & WScientific) was
used in the separation of the different VOC components.
The measurement was under helium carrier gas at the
following temperature program: 30°C for 5 minutes; fol-
lowed by temperature increase of 5°C/minute to 60°C
and held for 2 minutes, then increased at 25°C/minute
to 200°C and held for 2 minutes. Data acquisition was
performed on HP 3365 ChemStation. Further VOC quan-
tification was done on a Shimadzu  GC-17A Gas Chro-
matograph with QP-5000 Mass Spectrometer with a
DB-VRX column.

Gas Chromatography Methods
A Hewlett Packard GC-6890 with an electron capture
detector (GC-ECD) was used for quantitative and quali-
tative analysis of the PCE, TCE, and DCE in extracted
aqueous and solid  phase samples. The GC-ECD con-
figuration was a split injection of 1 uL hexane extract
using a Hewlett-Parkard-7863 series automatic injector.
The split injection had a split ratio of 20:1 to maximize
sensitivity. The GC-ECD configuration used was a 32 m
HP-5 Cross-linked 5% methylpolysiloxane phase * 0.32
mm * .25 urn film separation column or a DB-VRX, 30 m
X 0.25 mm I.D., 1.4 urn film). The column temperature
was programmed at 35°C and held for 2 minutes, fol-
lowed by a temperature increase of 5°C/min  to 85°C,
and a subsequent temperature increase of 25°C/min to
160°C which was maintained for 1 minute, resulting in a
total run  time of 16 minutes per a sample. Nitrogen was
used as  the carrier gas with an in-column flow rate of
2.6 mL/min and helium was used as the makeup gas
with a 60 mL/min flow  rate. The inlet was held in the
constant pressure mode at 11.03 Psi. The injector and
detector temperatures were 250°C  and 320°C, respec-
tively. One mg/L of dichlorobenzene samples were ana-
lyzed  as an  external standard. To ensure  accurate
quantitative results, PCE, TCE, and  DCE standards pre-
pared in-house were used to construct calibration curves
each week or whenever GC conditions changed as indi-
cated  by the external standard. Detection limits (GC/
ECD) for TCE and PCE are 1 ppb and 20 ppb  for DCE.

GC/FID  methods were  used in the analysis of VC and
DCE with minimum detection limits of 10 and 5 ppb,
respectively. The temperature program forthe  GC/ECD
and GC/FID methods were similar and both detectors
were operated simultaneously during sample analysis.
Results and Discussions
Aquatic Plants
Sorption experiments with heat-shocked Elodea indicated
that HCA and PCE partitioned strongly to the plant mat-
ter. A partition coefficient of 8 ± 0.3 (SD) mL/g for PCE
and 23 ± 0.7 (SD) mL/g for HCA was estimated. These
coefficients indicate that sequestration is an important
fate process that cannot be ignored. Heat-inactivated
plants were used in sorption studies because viable
plants transformed HCA before the end of the  incuba-
tion time of 24 hrs. Since the plants were heat-treated
and killed in the process, partitioning to the plant mate-
rial ratherthan uptake was assumed.

The transformation products of the probe contaminants
of concern (COCs) identified by GC/ECD and GC/FID
methods (retention time) were confirmed by GC/MS. The
transformation of HCA resulted in pentachloroethane
(PCA) and PCE as the main dehalogenation products,
while relatively small amounts (maximum <500  ug/L) of
TCE and only trace  amounts (<100  ug/L) of 1,1,2,2-
TTCA, and 1,1,2-TCAwere formed. The trace products
are not included in Figure 1 as the data points were not
distinguishable from zero on the plots. Shortly afterthe
samples were dosed with HCA, the concentration of PCA
and PCE increased  rapidly to a maximum within the
first 100 hours before slowly decreasing to below the
GC/ECD detection limit of 5 to 20 ppb. The measured
PCE concentration in solution was generally greaterthan
that of PCA, but did not exceed 30%  of the initial HCA
concentration of 10 mg/L. The corresponding increase
in TCE with decreasing PCE concentration suggests
that  PCE did not just accumulate,  but was  further
reductively dehalogenated to TCE and  other products
not yet identified. The dehalogenation of PCE  to TCE
was  directly confirmed by dosing algae and  aquatic
plants with PCE. Due to the moderate to high aqueous
solubility of PCE and TCE, both chemicals should be
readily taken up, transformed, and bound  by oxidative
enzymes in the algae and aquatic plant tissues.  Neither
DCE nor VC was identified as products in these experi-
ments even though we exhaustively analyzed forthem.
In samples dosed with TCA, TCA appeared to have been
mostly assimilated because its disappearance from so-
lution was not followed by the appearance of reductive
transformation products into solution. It has been shown
elsewhere  that as the number of chlorine substituents
of chlorinated ethenes decreases the  ability to undergo
reductive dehalogenation decreases (Bradley  and
Chapelle, 1996).

The extractable fraction of reductive transformation prod-
ucts decreased with length of time into the experiment.
This  suggests that these metabolites were either oxi-
dized into polar compounds or covalently bound to the
spirogyra and plant tissues.  Interferences from other
compounds in the heterogeneous plant extract have pre-
vented the  complete identification of the hydrophilic
metabolites. The identification of DCAA and TCAA in
axenic Myriophyllum plantlets dosed with HCA is confir-
mation that both reductive and oxidative transformation

                                            Time in Hours
Figurel.    Sorption accompanied by phytotransformation of 10 mg/L HCA by 7 g of Elodea canadensis, includ-
           ing phytoreduction products (PCA, PCE, and TCE) detected by GC/ECD and confirmed by GC/MS
pathways are involved in aquatic plant mediated trans-
formation of HCA. The composition of the identified
metabolites furthersuggests that the phytotransformation
of COCs by aquatic plants and algae involved more than
one pathway, possibly by more than one enzyme (Fig-
ures 2 and 3). Since axenic Myriophyllum and surface
sterilized Elodea metabolized the same COC to the same
products, we concluded that dehalogenase enzyme(s)
mediated the reductive dehalogenation reactions, and
oxidative enzymes (possibly cytochrome  P-450 with
monooxygenase activity, glutathione or laccase) medi-
ated the bound reactions. Other studies (Lamoreauxet
al., 1970) have shown that oxidative enzymes isolated
from green plants were capable of binding  xenobiotics
to plant matter through nucleophilic addition (Kim et al.,

Willows and Cottonwoods.    The rate of TCE and
PCE removal by rooted cuttings of cottonwood and wil-
lows grown hydroponically in a greenhouse increased
with the water uptake of the tree. The highest concen-
tration of PCE and TCE was measured in the roots and
decreased progressively upward (Tables 1,2). No PCE
was measured  in the leaves suggesting that the parent
compound was not accumulated in the foliage because
it was either completely metabolized and/or volatilized.
Generally, PCE was more toxic to the rooted cuttings of
cottonwoods and willows than TCE. PCE was observed
to be toxic to three months old rooted cuttings at initial
solution concentrations of 45 mg/L, but approximately
six months old  rooted cuttings of willows did not show
any observable toxic effects at PCE solution concen-
trations of 60 mg/L.

The parent compounds and metabolites taken up by the
trees are either metabolized or phytovolatilized. The suite
of anaerobic degradation products identified in the
headspace  above the rhizosphere of our  planted
bioreactors (Table 3) in greenhouse studies provided
direct evidence of phytoreduction of PCE and TCE in
the rhizosphere of cottonwoods and willow trees. Our
results are in agreement with those obtained from a field
site in Carswell, Texas, where DCE, VC and higher con-
centrations of dissolved organic carbon have been de-
tected in the root zone of cottonwood and willow trees
growing over a shallow plume of TCE. Previous work
has shown that methanogenic conditions may exist in
the root zones of plants.

We observed TCAA»DCAA>trichloroethanol in plant
tissues from our greenhouse and three years old trees
currently used in phytoremediation of TCE at the Carswell
site.  Meanwhile, DCAA made up 90% of the metabo-
lites identified in leaf tissues of older mature trees grow-
ing over the plume for more  than a  decade. We
hypothesize that the growth stage or age of vascular
plants determines the metabolic pathway of COCs. Also,
the distribution of polar metabolites appears to vary with
the plant species (Tables 1 and 2). The rhizosphere and
headspace gases of trees dosed with either 14C-TCE or
PCE (Table  4) confirmed the mineralization of these
chlorinated organic solvents (COS) to 14CO2. An accu-
rate determination of the mineralized fraction of the par-
ent compounds cannot be achieved because plants
utilize CO2 for photosynthesis.

A transformation pathway that couples phytoreduction
in the rhizosphere, phytotransformation  and assimila-
tion in the plant tissues is proposed to account for the
identified products (Figure 4). Plant enzymes  such as
glutathione-s-transferase and cytochrome P-450 are

       Carbon Tetrachloride
         + 2

         Cl         Cl
          C hloreform
- Cl
                            + OH
                       C  Bound  Residue
                                                              Assimilated Fraction
                               CO2  +  2HC1

Figure 2.   Proposed pathway for aquatic plants and algae mediated transformation of carbon tetrachloride.
believed  to catalyze  the phytoreduction  and
phytooxidation reactions, respectively.

Mass Balances
A mass balance based on GC/ECD quantified products
of 12C-COCs in solution became progressively poorer
with increasing reaction time. This was attributed to the
formation of metabolites not identified by the GC/ECD
method and to the assimilation of the COCs by algae or
aquatic plants. Mass balance estimation based on chlo-
ride in solution from reductive dehalogenation reactions
was poor because of the high background chloride. As
an alternative, we investigated the dehalogenation of
PBE by E/octea and quantified the formation of bromide
on a Dionexlon Chromatograph. After 21 days, 65% of
the initial 10 mg/L PBE was identified as tribromoethylene
(TBE), 30% of total bromide was measured as dissolved
anions in solution giving a mass balance for bromide of
95%. The mass balance for metabolism of 14CTC with
spirogyra after 10 days of incubation showed that CTC
was degraded with 10 - 12% of the initial solute con-
verted to chloroform, and 8% converted to CO2. About
40% of the initial activity was extracted and 45% was
unextracted and considered irreversibly bound to the
spirogyra. It must be noted that the 14CO2 measured in
the solution phase  in batch phytotransformation experi-
            ments with photosynthesizing algae and plants is not
            an accurate estimation of the amount produced in the
            course of metabolism of the solute because plants as-
            similate CO2 during photosynthesis. The bound fraction
            should therefore include a fraction of the 14CO2 assimi-
            lated by the algae or aquatic plant during photosynthe-

            In parallel batches spiked with 12CTC, the extractable
            bound fraction analyzed by GC-ECD and GC/MS after
            48 hours of incubation was identified as chloroform (CF)
            and CTC. The extracted fraction identified as CF and
            CTC decreased with increased incubation time, suggest-
            ing once more that these compounds were sequestered,
            transformed  and  assimilated, but  not simply
            hyperaccumulated. Although greater than 80% of the
            14C-activity was incorporated into the plant biomass (Fig-
            ure 5), not all of it was extractable with organic solvents.
            This suggests that the sequestered fraction may be trans-
            formed and assimilated by the plant tissue (Langebartels
            1986). Kim et al. (1997) recently showed that organic
            chemicals can be incorporated within humic substances
            by oxidative enzymes and rendered nontoxic. In similar
            experiments involving 14C-PCE and spirogyra the mass
            recovery was 95% with <5% mineralization (CO2), 8%
            hydrophilic metabolites, 49-70% activity bound and the

                                                 ci  ci

                                             ci     ci Cl
    Cl.     Cl

    ci"     'ci

                                                   ci  ci
                                                                       Bound Residue
                                                       H Cl
    i    -GI

  Cl      H

                                                + 2e  -
        Cl  Cl
        al    T
      	/-*	/-*
        c  c-ci
        H  H

                                                                             Cl  OH
                                                                         -.  i    i
                                                                         Cl ..... c— c
                                                                           c\     ^
                                                                         (trichloroacetic acid)
                                                                                  Cl   OH
                                                                              ci	i    r
                                                                                /     \
                                                                               H        D
                                                                              (dichloroacetic acid)
                                                 ri       ci

                                                                                 (carbon dioxide)
Figure 3.   Proposed pathway for aquatic plants and algae mediated transformation of hexachloroethane.
Table 1. Distribution of PCE and its metabolites in the rhizosphere and in tissues of
cottonwood trees
PCE (mg/Kg)
TCE (mg/Kg)
TCAA (mg/Kg)
DCAA (mg/Kg)
MCAA (mg/Kg)
Trichloroethanol (mKg)
Lower Stem
Upper Stem

Table 2. Distribution of PCE and its metabolites in the rhizosphere and in tissues of willow trees.
PCE (mg/Kg)
TCE (mg/Kg)
TCAA (mg/Kg)
DCAA (mg/Kg)
MCAA (mg/Kg)
Trichloroethanol (jxg/Kg)
Lower Stem
Upper Stem
Table 3. Summary Results of Rhizosphere Headspace Analysis
Experiment conducted
PCE Cottonwood
PCE Willow
TCE Willow
Metabolites Identified in Headspace above Rhizosphere Media
PCE, PCA, TCE, TCA, DCE, Ethene, Ethane, Methane
PCE, PCA, TCA, DCE, Ethene, Ethane, Methane
TCE, DCE, Ethene, Ethane, Methane
Table 4: Percent Recovery of Parent
Compound and Metabolites in Solution,
Plant and Air Phases
Total %
% Activity
(C02 = 3.4)
% Activity
(CO2 = 3.7%)
rest as dissolved TCE (depending on the reaction time
of the sacrificed sample). The radiolabeled form (14[C]-
HCA) of the chemical was not commercially available at
the time of this study.

For planted cottonwood and willow bioreactors dosed
with 14C-TCE and PCE, 3.4% and 3.7% 14CO2, respec-
tively, was measured in the rhizosphere and little or none
measured in the gases volatilized by the tree leaves
(Table 4). The poor mass balance for experiments per-
formed with woody plants is attributed to losses from
the higher volatilization ofCO2and other highly volatile
less chlorinated products formed in the rhizosphere.

We have identified four predominant phytoprocess in-
volved in aquatic plant mediated transformation of chlo-
rinated alkanes and alkenes. These processes include:
(1) rapid sequestration by partitioning to the lipophilic
plant cuticles;  (2) phyotoreduction to less chlorinated
VOCs; (3) phytooxidation to chloroethanols, chloroacetic
acids and unidentified metabolites; and (4) assimilation
into the plant tissues as non-phytotoxic products. A to-
tal mass recovery of betterthan 80% was obtained from
the radiolabeled studies with  aquatic plants. Data  ob-
tained from greenhouse studies confirmed that  the
mechanisms of removal of COS from water by woody
plants include rhizodegradation, phytodegradation and
phytovolatilization. Mineralization  of halogenated
aliphatics to 14CO2 in the tissues of aquatic plants and in
the rhizosphere of woody plants was confirmed. The
identification of metabolites from oxidative and anaero-
bic transformation reactions in the plant phase and in
the root zone suggests that more than one pathway re-

                                                             	>•   Bound Fraction
HV     V"H
                                                   Cl        H

                                                  2 .2 -dichloroethanol

                                                                               Cl         OH
                                /     \
                                                                              Trichloroacetic Acid

                                                                               Dichloroacetic Acid
                                             Acetic Acid?"
                                                                 H  '
                  /     \
                                                                 Mmiochloroacetic Acid
                                     • Not detected with Willows
                                                                    Carbon Dioxide
Figure 4. Proposed pathway for transformation of TCE and PCE in the root zone (rhizodegradation) and in the
tissues (phytodegradation) of cottonwood and willow trees.

                  >  80
                  O  60
              —0— % CHCL3
              —•$•— % Extracted

              • -A— % Unextracted

                   % in Solution
                                               10          15

                                               Time in Days
Figure 5. Distribution of transformation products of radiolabeled carbon tetrachloride (14C). Mass balance is based
on the quantified products.
quiring different enzymes may be involved  in phyto-
transformation reactions. Comparison  of metabolites
observed in leaf extracts of mature trees growing overa
TCE plume at Carswell AFB, Fort Worth, Texas, leaves
harvested from youngertrees at the field site and rooted
cuttings used in greenhouse studies provided evidence
that phytotransformation pathways may change with the
age orgrowth stage of vascular plants.

Bradley, P. M. and Chapelle, F. H. "Anaerobic mineral-
ization of vinyl chloride in Fe (lll)-reducing aquifersedi-
ments." Environ. Sci. Technol., 30, (6), 2084-2086,1996.

Kim  J-E. Fernandez  E., and Bollag  J.M. "Enzymatic
coupling of the herbicide bentazon with humus mono-
mers and characterization of reaction products." Environ.
Sci. Technol. 31,2392-2398,1997.
LamoreauxG.L, Shimabukuro R.H., Swanson H.R., and
Frear D.S. "Metabolism of 2-chloro-ethylamino-6-
isopropylamino-s-triazine in excised sorghum sections."
J. Agric. Food Chem. 18,81,1970.

Harms H., Langebartels C. "Standardized plant cell sus-
pension test systems for an ecotoxicologic evaluation
of the metabolic fate ofxenobiotics." Plant Science, 45,

Hales, H.M., Jaouni, T.M. and Babashak, J.F. "Simple
devise for preparing ethereal diazomethane without re-
sorting to codistillation." Analytical Chemistry, 45(13),

Nzengung, Valentine A., L.N. Wolfe, Darrell Rennels and
S.C. McCutcheon. "Use of aquatic plants and algae for
decontamination of waters polluted with chlorinated al-
kanes."  Intern. J. Phytorem.: vol. 1, No. 3, pp. 203 -

  Phyto-transformation Pathways and
 Mass Balance for Chlorinated Alkanes
              and Alkenes
           Valentine A. Nzengung
               Chuhua Wang
                Stacey Box
             Geology Department,

             University of Georgia

          Athens, Georgia 30602
 Uptake of PCE and Water by Cottonwood

   Distribution of PCE Metabolites in
  Rhizosphere and Cottonwood Tissues
Trichloroethanol (ug^
  Percentage of Parent Compound and
Metabolites Recovered in Solution, Plant
           and Air Phases
% Activity
Plant 8.7
Solution 26
(CO2 = 3.4)
(CO2 = 3.7%)
Traps 9-4
Total % Recovery =44 »74

Results of Rhizosphere Headspace Analysis

   PCE cottonwood: PCE, TCE, trans-DCE,
                  ethene, ethane, methane

   •  PCE willow:   PCE, trans-DCE, ethene,
                  ethane, methane

   •  TCE willow:   TCE, trans-DCE, ethene,
                  ethane, methane
     Field site (mature trees + soil+water+TCE)
                  TCE, DCE, VC, methane
   Phytodegradation Products of Trichloroethylene in
                Cottonwood Trees
  	Field Samples Collected January 1999	
Type of
Whip, Leaves
on Trees
Whip, Leaves
on ground
Leaves on trees
Leaves on
1.57 ± 0.06
0.62 ± 0.03
0.26 ±0.13
0.25 ± 0.07
Acid (nig/Kg)
31.3 ± 0.7

   Phy to degradation Products of Trichloroethylene in
   Mature Willows and Cottonwood Trees at Field Site
  	Samples Collected April 1999	
Type of
1A mile East
S. end of Whips
0.07 ± 0.01
0.17 ±0.03
Acid (nig/Kg)
1.34 ± 0.45
1.21 ±0.42
2.32 ± 0.52
Proposed Pathway for Aquatic Plants Mediated Transformation of
HCA Based on Identified Metabolites in Solution and Plant Phases
                                     Bound Residue
                                              q  QH
                                           Cl 	 I  1

   Proposed Pathways for Aquatic Plants Mediated
       Transformation of Carbon Tetrachloride
   Carbon Tetrachloride
      ^  '"•-:
    Cl       Cl
    (10- 12%)

JC .
                                       C Bound Residue
                                         (80-85 % )
                                        Assimilated    Fraction
            CO J 2HC1
Proposed Pathways for Transformation of PCE in Root Zone (Rhizodegradation)

       and in Tissues (Phytodegradation) of Cottonwoods and Willows

               Headspace Bioreactor and Field
              T rans-D C E
                            1 ,1 ,2-T C A
     Not detected with W illows
                                         CO 2
                                        Carbon dioxide

 Proposed Pathways for Transformation of PCE in Root Zone
  (Rhizodegradation) and in Tissues (Phytodegradation) of
            Cottonwoods and Willows

Three primary phyto-processes are important
in phytoremediation of volatile chlorinated
           * Phytovolatilization.
            * Phytodegradation.
            * Rhizodegradation.

In addition, sequestration and assimilation
are important processes for some plants,
especially aquatic plants.


  Phytotransformation of volatile chlorinated
  aliphatics involves multiple pathways.

  Reductive dechlorination and mineralization of
  TCE and PCE occurs mainly in the root zone
  (rhizosphere) of woody plants.

  Oxidative and reductive transformation occurs in
  the tissues of aquatic and terrestrial plants.

Trichloroethanol and trichloroacetic acid were
identified at the highest concentrations in plant
tissues of young trees used in phytoremediation
of TCE and PCE.

In mature or established tree plantations,
dichloroacetic acid was the main metabolite
identified in the plant extract.


In greenhouse studies, evapotranspiration
accounts for majority of the TCE, PCE and
volatile metabolites taken up into the trees.

Does the "age" or growth stage of tree
plantations determine the phyto-transformation
pathway(s) of chlorinated organic solvents?


 Progress in  Risk Assessment for Soil  Metals, and In-situ Remediation
   and Phytoextraction  of Metals  from  Hazardous  Contaminated  Soils

  Rufus L. Chaney1, Sally L. Brown2, Yin-Ming Li3, J. Scott Angle4, Tomasz I. Stuczynski5, W. Lee Daniels6,
       Charles L. Henry2, Grzegorz Siebielec5'1, Minnie Malik1'4, James A. Ryan7 and Harry Compton8.
1 USDA-Agricultural Research Service, Environmental Chemistry Laboratory, Bldg. 007, BARC-West,
 Beltsville, MD 20705. USA. Email: RChaney@asrr.arsusda.gov
2 School of Forest Resources, AR-10, University of Washington, Seattle, WA  98195. USA.
3 Viridian Environmental LLC, Bldg. 007, BARC-West, Beltsville, MD 20705. USA
4 Department of Natural Resource Sciences and Landscape Architecture, University of Maryland, College
 Park, MD 20742. USA
5 Institute of Soil Science and Plant Cultivation, 24-100  PuBawy, Poland.
6 Dept. Crops, Soils and Environ. Sci.,  228 Smyth Hall, Virginia Polytechnic Institute, Blacksburg, VA
 24061. USA.
7 US-EPA, National Risk Management Research Lab, 5995 Center Hill Rd., Cincinnati, OH 45224, USA
8 US-EPA, Emergency Response Team, 2890 Woodbridge Ave, Bldg. 18, Edison, NJ 08837. USA.
Mining and smelting of Pb, Zn and Cd ores have caused
widespread soil contamination  in  many countries. In
locations with severe soil contamination, and strongly
acidic soil or mine waste, ecosystems are devastated.
Research has shown thatZn phytotoxicity, Pb-induced
phosphate deficiency, Cd risk through uptake by rice or
tobacco, and Pb risk to  children,  livestock or wildlife
which  ingest soil are  the common  adverse
environmental  effects at such contaminated sites.
Improved understandings  of soil metal risks to the
environment have been developed which examine risk
to all possible exposed organisms through soil, plants,
animals, or water exposures. This  review summarizes
information about soil Cd risk to food-chains, explaining
that when Cd is present at the usual 0.005-to-0.02 ratio
to Zn in the contaminated soil, only rice and tobacco
allow Cd to be transferred from the soil in amounts which
can harm humans over their lifetime. Zn inhibits plant
uptake of Cd, and inhibits intestinal absorption of Cd,
protecting animals from Cd in most situations. Pb risk
to children or other highly exposed organisms results
from ingestion of the contaminated soil, and absorption
of Pb from the soil into the blood where adverse health
effects occur at 10-to-15 Fg Pb/dL blood. Soil Pb has
much lower bioavailability than water Pb, and if ingested
with food has even lower bioavailability. Research has
shown that if high phosphate levels are added to Pb-
contaminated soils, an extremely insoluble  Pb
compound, chloropyromorphite, is formed in soils from
all known chemical species of Pb which occur in
contaminated soils. It had earlier been learned that
adding adsorbents  such as hydrous  Fe oxides and
phosphate to Pb-contaminated soils inhibited Pb uptake
by crops, and combined with the evidence that these
materials could reduce the bioavailability of soil Pb to
children, feeding tests were conducted with rats and
pigs in several laboratories.  A new approach to
remediation of  severely disturbed  Pb/Zn/Cd-
contaminated soils has been developed which uses
mixtures of limestone  equivalent from  industrial
byproducts such as woodash (to make soil calcareous
and prevent Zn phytotoxicity), phosphate and Fe from
biosolids and byproducts (to precipitate Pb and with
Fe, increase Pb adsorption), organic-N from biosolids
and manures and other beneficial components which
correct the infertility of contaminated and eroded soils.
Composting can stabilize the organic matter and slow
N release to allow higher application of remediation
amendments. Highly effective revegetation has resulted
at four field test locations where this approach was
tested, Palmerton, PA; Katowice, Poland; Bunker Hill,
ID; and  Leadville, CO. All plants tested were readily
grown on the amended soil even with soil  contained
over 1% Zn and 1% Pb. Plant analysis  indicates that
these plants may be consumed safely by wildlife and
livestock, although soil ingestion should be  minimized
at  such sites. Although mining  and  smelting
contamination has caused severe environmental harm
in many locations, this method of soil metal remediation
allows effective and persistent remediation at low cost,
and should  be applied to prevent further dispersal of
the contaminated soil materials at many locations.

The potential use of metal hyperaccumulator plants to
phytoextract soil metals is a new method of remediation
under development. Combining improved cultivars of
these accumulator plants, agronomic  management
practices to maximize yield  and metal accumulation,
burning the  biomass to generate power, and recovery
of metals from the ash appear to offer an  economic
technology compared to soil removal and replacement.

Mining or smelting of Pb-Zn ores generates mine tailings
rich in Pb, Zn, and Cd. Some of these tailings contain
dolomitic limestone, and others contain pyrite which
generates acidity when oxidized. Smelting  of Pb, Zn,

and Cu ores has commonly caused emission of Zn, Cd
and Pb at levels which can cause adverse  effects in
the terrestrial environment. Strongly acidic Zn-rich mine
wastes and smelter contaminated soils cause severe
Zn phytotoxicity (Chaney, 1993), and can prevent all
plants from surviving on  the soil (e.g., Beyer, 1988).
This paper is a summary of the key evidence that such
mine and smelting  wastes cause  phytotoxicity of Zn,
potential Cd risk to humans if rice or tobacco are grown
on the contaminated soil, and Pb risk to children who
may ingest the mine wastes or  contaminated soils or
housedust generated from these contaminated soil
materials. Adverse environmental  effects of these
metals have  resulted in many nations where older
industrial technologies were used in mining orsmelting.

On the other hand, there has been important progress
in  risk assessment methodology for soil metals, and
research on methods to remediate  Zn, Cd, and Pb-
contaminated soils and sediments.  New  practical
approaches for both in situ remediation by addition of
amendments which reverse Zn phytotoxicity and Pb
risk from soil ingestion have been  demonstrated in
recent years. Practical, inexpensive methods are
available to revegetate such contaminated soil materials,
and support vegetation which can be safely consumed
by wildlife, livestock, and humans. Also, phytoextraction
research has illustrated the potential of growing unusual
metal hyperaccumulator  crops on contaminated soils
to  remove some metals,  and  provide biomass power
and an ash which can be recycled to reduce the costs
of remediation.

A full discussion of present-day risk assessment and
soil metal remediation methods would take a book. Thus,
the goal of this paper is to give an overview of these
ideas, with references to full papers and book-chapters
which more fully report the science  which allows the
improved  risk assessment and practical soil  metal
remediation. One of the  most important advances in
soil metal remediation is our development of using
phosphate rich, high Fe biosolids  and composts, and
lime rich woodash and other lime-containing byproducts
to make "Tailor-Made" Remediation Biosolids Mixtures
and  Composts and readily achieve  effective
revegetation and ecosystem restoration at such metal
contaminated sites (see Chaney, Ryan and Brown, 1999;
Stuczynski et al., 1997; Li and Chaney, 1998; Daniels
etal., 1998; 1999; Brown  etal., 1998b; Siebielecetal.,

Improved Risk Assessment for Soil
When present at high enough concentrations, Pb, Zn,
and Cd in soils can cause adverse effects  on plants,
soil organisms, wildlife, livestock and humans through
pathways  which involve  soil ingestion by children or
livestock, ingestion of foods grown on the soil, ingestion
of  animals which ingested plants  which  grew on the
soil, or from leaching of metals to drinking water or
streams where  Zn harms fish  (Table 1).  Extensive
research and evaluation of the literature were conducted
over the last decade to develop quantitative limits for
metals in land-applied biosolids (municipal sewage
sludge), and for characterization of the potential hazards
which a soil could cause (see Chaney and Ryan, 1994;
US-EPA, 1993). And research was conducted to find
methods to amend ortreat contaminated soils to reduce
the risk of soil metals in a persistent manner such that
the hazardous nature would be reversed or remediated.

The formal risk assessment method uses 14 or more
Pathways to estimate the  effect of soil metals on Highly
Exposed Individuals (HEIs) which are humans who live
on the soils, livestock pastured on the soil, crops grown
on the soil, soil organisms in the soil, etc. (Table 1).
Forthe biosolids risk assessment, it was assumed that
1000 t/ha of dry weight of biosolids would be applied
over many years (centuries)  of biosolids use as a
fertilizer or soil conditioner.  In risk assessment for
hazardous soils, the contaminated soil is considered
as is. One important change in the approach to risk
assessment  is the inclusion of valid measurements of
"bioavailability" of soil metals to the HEI organism under
consideration (child, adult, livestock, plant, etc.). And
for the use of field-derived metal transfer coefficients
from soil to plants, soil to livestock, soil to humans,

The importance of using field-derived plant uptake slopes
for the biosolids-amended soil is highly evident from
examination of the literature. First, one needs to consider
the effect of the chemical form of, and recency of metal
salt additions on phytoavailability and bioavailability of
metals added to soils. When metal salts are added to
soil,  or metal salts added to biosolids which are then
mixed with soil,  many errors  can occur (e.g.,
Cunningham etal.,  1975a; 1975b;  1975c). All of these
errors increase plant uptake and bioavailability of added
metals compared to field-contaminated soils.  If pure
metal salts are mixed with soil, it takes a considerable
time for the added metals to reach aquasi-equilibrium
with the  soil (Singh and Jeng,  1993). And other
constituents of a metal source (Fe and Mn oxides,
phosphate, organic matter, etc.) are not applied when
metal salts are used to model the risk of contaminated
soils (Corey et al.,  1987; Logan and Chaney, 1983;
Chaney and  Ryan,  1994). This has caused important
confusion regarding Cd phytoavailability because Fe and
Mn oxides present in biosolids can increase the
selective or  specific metal adsorption ability of the
amended soil, but addition of metal salts cannot have
this effect (Figure 1). Figure  1  shows models of the
patterns of plant uptake of Cd and Zn in relation to soil
Cd and Zn concentrations found in studies of long-term
biosolids application compared to those for metal-salt
treated soils. In Figure 1, all lines start at the linear
slope usually found for added Cd-salts, and represent
equal Cd additions in different forms, to one soil. Curve
A represents the linear response to small additions of
Cd salts found in nearly all studies in the literature. In
curve B, the pattern is of  increasing plant:soil slope at
increasing Cd applications because Zn is also  added,

Table 1. Pathways for risk assessment for potential transfer of biosolids-applied trace contaminants to humans, livestock,
or the environment, and the Highly Exposed Individuals to be protected by a regulation based on the Pathway Analysis
(US-EPA, 1989a, 1993; Chaney and Ryan, 1994). Each Pathway presumes 1000 t dry biosolids ha-1 and/or maximum
allowed annual application of biosolids as N fertilizer.
1 . Biosolids- Soil- Plant- Human
2. Biosolids- Soil- Plant- Human
3. Biosolids- Human
4. Biosolids- 6oil- Plant- Animal- Human
5. Biosolids- Soil- Animal- Human
6. Biosolids- Soil- Plant- Animal
7. Biosolids- Soil- Animal
8. Biosolids- Soil- Plant
9. Biosolids- Soil- Soil Biota
10. Biosolids- Soil- Soil Biota- Predator
1 1 . Biosolids- Soil- Airborne Dust- Human
12. Biosolids- Soil- Surface Water- Human
13. Biosolids- Soil- Air- Human
14. Biosolids- Soil- Groundwater- Human
Highly Exposed Individuals
Individuals with 2.5% of all food produced on amended soils.
Home gardeners with 1000 t ha~1 ; 60% garden foods for lifetime.
Ingested biosolids product; 200 mg d~1.
Farms; 1000 t/ha; 45% of "homegrown" meat.
Farms; 1000 t/ha; 45% of "homegrown" meat.
Livestock feeds; 1000 t/ha; all from amended land.
Grazing Livestock; 1 .5% biosolids in diet.
"Crops"; strongly acidic amended soil (1000 t/ha),
to prevent natural Al and Mn toxicity.
but with limestone
Earthworms, microbes, in amended soil.
Shrews (Sorex araneus L.); 33% earthworms diet,
living on site.
Tractor operator.
Subsistence fishers.
Farm households.
Well water on farms; 100% of supply.
at 100-times the Cd  additions,  and the added Zn
competes for the stronger adsorption sites in the soil.
These first two patterns have been repeatedly observed
in many studies, and are illustrated well by the data in
White and Chaney (1980). In contrast to patterns found
when Cd salts are applied, model slope C in Figure 1 is
for biosolid applied Cd, which causes decreasing slope
toward a plateau with the X axis.  This response is
believed to result from the addition  of adsorbent (Fe,
Mn, Al oxides) for metals along with the metals when
complex biosolids are applied to soils.

Effects of biosolids-applied Cd  in  the long term is the
fundamental question which requires an answer. Does
applied Cd remain plant available or become occluded
in soils and have reduced availability? "Aging" reactions
can  reduce phytoavailability of applied Cd without
occlusion. Several studies have shown substantial
decline  in Cd uptake by cereal crops after biosolids
applications cease in an experiment with repeated
applications (e.g., Chang et al., 1982; Bidwell  and
Dowdy, 1987). Such large reductions in planted uptake
after ceasing biosolids applications have seldom been
observed fordicot crops; part of the effect is known to
result from rapid biodegradation of organic matteradded
in the biosolids. In the studies in which cereals had
much lowered concentrations after applications ceased,
higher than  N-fertilizer application rates were being
applied in a research study. When applications are
limited to regulated N-fertilizer supply for the crop to be
grown, effects on uptake are seldom observed when
high  quality  biosolids  are  utilized.  Further,
phytosiderophores secreted by roots of Poaceae species
may play a  role in the apparent difference  between
cereals and dicots in these responses.

We were able to examine  the  long-term effects of
biosolids applications and salt-Cd additions to a soil in
experiments at Beltsville. Evaluation of Cd uptake by
lettuce grown on a soil amended with a Cd salt or Cd-
rich biosolids in 1976 to 1979, showed that biosolids-
applied Cd had low uptake slopes even when most of
the organic carbon  applied  in the  biosolid was
biodegraded (Brown etal., 1998a). Even though soil pH
declined overtime due to application of N-fertilizers and
normal acidic rainfall, uptake of Cd from the biosolids
plots declined while uptake of Cd from the Cd-salt plots
increased. While on plots where a high quality high Fe
biosolid was applied, no increase in phytoavailability of
Cd was observed.

        c   0
                                                          Cd SOLUBLE SALT
                                                        +Zn SOLUBLE S/
                                                 Cd SOLUBLE SALT
                                                  NOAEL QUALITY BIOSOLIDS
                   INCREASING Cd  ADDED TO  SOIL, kg/ha

Figure 1. Hypothetical models of increasing plant Cd concentration in response to increasing total soil Cd
concentration: A) From addition of a soluble Cd-salt; B) From addition of a soluble Cd-salt with 100 times more Zn
as a soluble Zn-salt; and C) From addition of NOAEL quality biosolids, after organic matter stabilization to
background levels.
In plots on a different soil series where high rates of
high quality alkaline biosolids were applied in 1976, the
high pH and low soil Mn supply allowed the alkaline
biosolids to  induce Mn deficiency by 1990 (Brown et
al.,  1997c). In this study, where the maintained
calcareous pH aided sorption and occlusion of metals
in the high Fe biosolids matrix, the Zn concentration in
diagnostic leaves (of Mn fertilized  treatments  which
regained crop yields) was barely adequate for plant
growth.  This effect, the continued control of metal
phytoavailability even when added organic matter has
been biodegraded, is now understood to result from the
specific metal adsorption of biosolids-applied materials
such as Fe and Mn oxides, and from the quasi-
equilibrium reached in biosolids before application to
the  land. Research has repeatedly confirmed the
existence of slow "aging" reactions  of metals with soil
surfaces and organic matter, and the increasing
occlusion of metals in Fe and Mn oxides (e.g. Bruemmer
et al., 1988; Corey et  al., 1987).  Further, study of
laboratory prepared hydrous Fe oxide fails to observe
the substantial increase in adsorption capacity and
strength when phosphate is present along with the Fe,
Zn, and Cd (Kuo, 1986). This aging response of added
metals is more important for Ni and Zn than for Cd due
                                        to the selectivity of metal adsorption by soil Fe and Mn
                                        surfaces (Singh and Jeng, 1997).

                                        Another clear evidence of biosolids-applied adsorbent
                                        was found in studies by Mahler et al. (1978) in which
                                        paired untreated  and biosolids-amended soils were
                                        collected from long-term biosolids utilization farms at
                                        several locations. The researchers added 0, 5, and 10
                                        mg Cd/kg to each soil to measure the slope of plant
                                        response to added salt-Cd as a bioassay on Cd
                                        phytoavailability, and made both soils calcareous so
                                        that simple difference in soil pH between untreated and
                                        treated soil did not confound the comparison. Figure 2
                                        shows the results for two locations where appreciable
                                        amounts of biosolids and metals had been applied over
                                        time. The Cd uptake slope for freshly added salt-Cd by
                                        Cd accumulator crop Swiss chard on the biosolids-
                                        amended soils was lowerthan forthe non-amended soils.
                                        In general, when unamended and biosolids-amended
                                        soils are compared at equal pH long after biosolids were
                                        applied, their ability to limit solubility and plant uptake
                                        of salt-Cd  and salt-Zn applications are  reduced
                                        compared to non-amended soils. In examining this
                                        sorption  relationship in biosolids-remediated
                                        contaminated soils, Siebielec and Chaney (1999)
                                        reported that high Fe added with a biosolids-compost

        Effect of Biosolids Matrix on  Soil Cd Phytoavailabiity.
         .E   20 H
 A. Control
= B.Sludged

              Total  Cd/Organic Carbon  Ratio in Soil (gig x 10E-4)
Figure 2. Linear response of chard Cd concentration to added salt-Cd on long term biosolids amended or non-amended soils.
Carbon levels in the biosolid-amended soils are no longer above levels in the non-amended soils, and soil pH levels were made
equivalent by making all soils calcareous (based on data from Mahler et al., 1987). Soil A was Merely, and B was Wea.
to a Zn-phytotoxicsoil maintained amorphous Fe oxides
at increased levels in the soil, and reduced Cd and Zn
in soil solution type extractions with 0.01 M Sr(NO

One of the most insidious errors of using metal salts is
the displacement of adsorbed protons from soil cation
binding sites when metals are added, which lowers the
pH of the amended soil; the higherthe metal application,
the greaterthe reduction in soil pH (White et al., 1978).
Thus the researcher sees greater harm at higher metal
concentration, the expected result, but fails to recognize
that the  study was confounded by pH lowering
proportional to metal salt application.

Another serious error in study of biosolids Cd risk is
addition of chloride in one metal salt being tested, which
can substantially increase the plant uptake of Cd due
to  formation  of chloride complexes  which increase
mobility of Cd in soils, and allow a complexed form of
Cdto leak into roots (Mclaughlin etal., 1994). Low soil
pH promotes metal solubility and phytoavailability such
that pH is a almost always more important factor in
                    metal uptake and phytotoxicity than is the amount of
                    metals added.  But high chloride can overwhelm the
                    effect of limestone in reducing phytoavailability of soil
                    Cd (e.g., Li etal., 1997).

                    Another source of error in risk assessment for soil
                    metals is the greenhouse vs. field error illustrated by
                    the work of deVries and Tiller (1978). These researchers
                    compared uptake of metals by lettuce and onion grown
                    on soil-biosolids mixtures at several rates of application,
                    when the  plants were grown  1) in large pots in a
                    greenhouse, 2) in outdoor lysimeters in which the
                    biosolids were incorporated 10 cm deep, and  3) in
                    growers fields in which the biosolids were incorporated
                    10 cm deep. As has been long known, if plants are
                    grown in pots of contaminated  soil,  phytotoxicity and
                    uptake are higher than if grown in the same soil in the
                    field  where the metal rich soil  is present only in the
                    surface soil layer. In pots, the roots cannot escape to
                    subsurface less contaminated soils. Further, some
                    aspect of greenhouse culture which appears related to
                    water use  or salt concentrations in the soil solution

promote metal solubility and uptake by plants. The full
requirement of fertilizer nutrients are usually applied to
pots before starting the  plants, promoting high ionic
strength and hence solubility of soil metals, worse with
smaller than larger pots. Other errors result  from the
temperature of soil in pots in a greenhouse compared
to soils in the field, and watertranspiration in greenhouse
compared to field.

In a similar way, when the bioavailability of metals in
ingested soil is measured by soil feeding studies, Pb
absorption by rats declined when Pb was mixed with
soil (Chaney et al.,  1984; Chaney and Ryan, 1994).
Similar effects  of soil sorption of metals reducing
bioavailability to mammals has been shown for As
(Freeman et al., 1995) and Cd (Schilderman et al., 1997),
and is evident in biosolids feeding tests (e.g., Decker
et al., 1980). Considering the role of adsorption at the
neutral pH of the  small intestine  where most
microelement cations are absorbed by animals, it should
not be a surprise that adsorption of metals on dietary
soil can reduce Pb and other element uptake by animals
in a manner somewhat like the reduction in absorption
by plants (see Freeman et al., 1992; Chaney and Ryan,

Looking at mine wastes and  smelter contamination
processes in relation to these selective soil adsorption
processes, what are the implications for risk assessment
and soil remediation? If high Fe in  biosolids can sorb
metals persistently,  biosolids metals can have low
phytoavailability and bioavailability compared to metal
salts. But smelter-emission contaminated soils will have
received only the more volatile elements emitted by a
smelter stack. Even here, Zn which accompanies
emitted Cd can provide a persistent reduction in potential
plant uptake of Cd by competition at root uptake sites,
and also reduce translocation to plant shoots and storage
tissues (e.g., McKenna et al., 1992b; Chaney et al.,
1999a). Mine wastes may have very high Fe levels from
pyrite in the ore, so Fe would accompany the metals.
But if ore sulfides are allowed to oxidize, soil pH is
lowered severely which greatly increases metal toxicity
risk. We have measured  pH of surface soil in  farmer's
fields which had become covered by  alluvial  deposits
of mine waste where sulfide oxidation lowered pH to <
3. In such a case (often found in Zn-Pb ores  from the
Rocky Mountain area such as Butte, MT and Leadville,
CO), the extreme  acidity is the  key feature  of the
contaminated site. Until this extreme acidity is
neutralized, solubility of Zn will prevent plant survival.

Another important principle of soil  metal risk
assessment is the "Soil-Plant Barrier" to element transfer
to cause food-chain risk to animals. Chaney (1980; 1983)
summarized three  major processes which limit risks
from most elements in soils to animals through the food-
chain Pathway. First, precipitation or adsorption of
metals by soil particles, or in the fibrous  root system
hinders uptake of most elements (Pb, Cr, Sn, Ti, Fe,
Hg, Ag, F, etc.). Second, phytotoxicity of the common
phytotoxic elements  (Zn, Cu,  Ni, Mn, etc.) occurs at
concentration of these  elements in the plant shoots
which do not comprise risk to livestock or humans
chronically exposed to the metals. The third process
involves interactions between  elements which hinder
uptake, translocation or bioavailability of soil metals.
For example, Zn is normally present at 50-200 times
higher concentration than Cd  in Zn-Pb ores. And Zn
metal products are treated to remove most Cd for
separate marketing and to protect the quality of the Zn
in certain industrial applications. When galvanized metal
corrodes, Zn is very high and Cd low such that plant Cd
is  hardly increased when Zn  reaches  severely
phytotoxic concentrations (Jones, 1983). Because Zn
and Cd are commonly absorbed  and translocated at
about the ratio found in the soil the plant is growing on,
and because Zn phytotoxicity occurs at about 400-600
mg Zn/kg dry plant shoots, co-contaminating Zn normally
limits shoot Cd to less than 5-10 mg Cd/kg dry weight.
Coupled with Zn inhibition of Cd absorption by animals,
soil Cd  risk is  alleviated  (see  below) because Zn
phytotoxicity alerts the gardener to the problem.

The Soil-Plant Barrier fails to provide complete protection
for only a few elements, Se and Mo which are widely
known to poison  ruminant livestock, and Cd  under
circumstances which separate Cd from Zn (Table 2).
The Soil-Plant Barrier for Co could also theoretically
fail because  ruminant  livestock  cannot tolerate the
concentrations of Co (injury to ruminant livestock beg ins
at approximately 10 mg Co/kg dry forage) which can be
reached in plants when  Co is phytotoxic (25 mg/kg or
higher in plant shoots). Cd risks to humans is discussed
below. Se is not only a risk to livestock, but can harm
humans who consume only foods locally grown on
contaminated soils (Yang etal., 1984).

Another case where livestock and wildlife can be harmed
by metals is the case in  which high emissions of Zn or
other elements from  a smelter cause  extensive
contamination on the surface  of plants by deposition
from the aerosol source. In this case, plants can reach
much higher concentrations without phytotoxicity than
possible by root uptake if the metals were in the  soil.
For elements which have low uptake slopes, or for which
phytotoxicity protects the food-chain (e.g. Zn, Cu, Pb,
As, F, Fe), deposition can cause plant metals to reach
levels which can poison sensitive livestock (e.g., Chaney
et  al., 1988).  Zn on forages has  killed  young horses
(foals) at many Zn smelter locations because apparently
healthy plants can contain over 1000 mg Zn/kg, but if
the Zn had been absorbed by roots, visible signs of Zn
phytotoxicity would have occurred by 500 mg Zn/kg
shoots.  Different livestock are sensitive to  different
metals, for example ruminants are sensitive to induced
Cu deficiency and Pb, As and F toxicity, while young
horses are especially sensitive to excessive ingested

Another aspect of soil metal risk has received much
attention in recent years, the potential for soil metals to
harm  soil organisms. However, our experience  has
indicated that metal-sensitive  plants such as lettuce

Table 2. Maximum tolerable levels of dietary minerals for domestic livestock in comparison with
levels in forages.

As, inorg.
Level in Plant Foliage*
mg/kg dry foliage
1 5-1 50
1 5-1 50
25-1 00
50-1 00
500-1 500
Maximum Levels Chronically Tolerated6
mg/kg dry diet
ABased on literature summarized in Chaney (1983).
BBased on NRC (1980). Continuous long-term feeding of minerals at the maximum tolerable
levels may cause adverse effects. Levels in parentheses were estimated (by NRC) by
extrapolating between animal species.
cMaximum levels tolerated were based on Cd or Pb in liver, kidney, and bone in foods for
humans rather than simple tolerance by the animals.
and white clover are visibly harmed at soil metal
concentrations below those  required to harm soil
microbes or earthworms, etc. (Chaney, 1993; Ibekwe
etal., 1998). Further, the errors from adding metal salts
are potentially much more important for soil organisms
than for plants because the organisms are present at
the moment when soluble  metals are mixed with the
soil. And many ecotoxicology studies use artificial soils
with addition  of metal salts,  and cause  much more
severe toxicity to earthworms  and soil microbes than
found with biosolids or stack emissions cause soil
contamination with Pb, Zn, and Cd (e.g., Spurgeon and
Hopkins, 1996). Concerns about harm to the rhizobium
for white clover from biosolids-applied Zn have been
clarified by comparisons of the toxicity of Zn and Cd to
the rhizobium, compared to toxicity to the plants (Ibekwe
et al.,  1996; 1997a; 1997b; 1998; Angle and  Chaney,
1995; Angle etal., 1993). If nodules are formed before
testing metal toxicity, Zn and Cd had no effect on N
fixation before yield of the plant had been sharply reduced
by metal phytotoxicity. And testing of microbial metal
tolerance with  controlled chemical activity of Zn  and
Cd showed that the microbes were much more tolerant
of these elements than were plants. The most sensitive
step appears to be the rhizobium infection of root hair
process rather than survival of the microbes in soil.
Even  arguments about microbial genetic diversity in
relation to soil  metal enrichment appear to result from
study of highly contaminated biosolids, or unusual soils,
since  Ibekwe  et al. (1997b) found that  low soil  pH
reduced  survival of white clover rhizobium on both
control and metal rich soils, and the rhizobium survived
with good diversity when soil pH was  maintained  at
levels needed to produce legumes. We have observed
nodulated white and red clover growing on  soils with
very high levels of Zn (> 3000) if pH is maintained and

phosphate is supplied at levels required for legume
production  (see  below discussion of ecosystem

Soil Cd Risk Assessment
Although great concern has been expressed about Cd
poisoning of humans from smelter emissions and mine
wastes, research has now clarified the situations where
such Cd food-chain poisoning may occur. Cd is
important regarding chronic toxicity — acute toxicity is
prevented by regulations to limit chronic toxicity of Cd
emissions  and  discharges.  In  mammals,  Cd
accumulates over one's lifetime in the proximal tubules
of the kidney cortex; if a toxic concentration is reached,
a renal proximal tubular dysfunction will occur (this is
not "kidney failure" as this term is commonly used).
Ordinarily, kidney Cd accumulates in humans until about
age 50, and then starts to decline overtime. If one has
ingested insufficient bioavailable Cd overthat 50 years,
no disease  results.  Smoking cigarettes commonly
doubles kidney cortex Cd for persons who smoke one
pack per day, compared to non-smokers, because Cd
enters the mainstream smoke and is well absorbed in
the lung (e.g., Elinderetal., 1976). Average non-smokers
today have only 10-15 mg Cd/kg fresh weight of kidney
cortex, far lower  than the 200 mg/kg fresh weight
required for the  tubular dysfunction of sensitive
individuals in the population.

Because soil Cd  (from  dispersed mine  and smelter
wastes) caused human disease in Japan and China
(Kobayashi,  1978; Tsuchiya et al.,  1978; Cai et  al.,
1990),  and aerosol Cd in the workplace has harmed
industrial workers  at many factories which used pure
Cd salts such as Cd-Ni battery manufacturing, much
research  has been conducted to improve our
understanding of Cd risk to humans.  In the case of soil
Cd, agronomy is very important is understanding  the
risk to humans, not just toxicology  and medicine
(Chaney et al., 1999a). Although soil Cd caused human
Cd disease in subsistence rice farmers, much higher
soil Cd had no adverse effects on persons exposed to
Zn+Cd rich soil and dust, garden foods orwestern grains
(Shipham, UK—Strehlowand Barltrop, 1988; Stolberg,
Germany — Ewers et al., 1993; Palmerton, PA, USA
— Sarasua et al.,  1995). Because of the chemistry of
flooded soils, ZnS is formed and persists for some time
after a  flooded rice soil is drained, but CdS is quickly
transformed to more phytoavailable forms, and pH drops
making the soil Cd more phytoavailable. Rice growers
drain their fields at the  start of flowering to optimize
yield of grain. Cd absorbed by rice during grain filling is
readily translocated to grain while Zn is not increased
in grain even though the soil had 100 times more Zn
than Cd, similar to western soil contamination cases
(e.g., Takijima and Katsumi, 1973). Further, polished
rice grain contains insufficient Fe, Zn and Ca to supply
the amounts needed for humans (Chaney et al., 1999a).
Subsistence rice farm families are commonly Fe and
Zn deficient if they do not obtain adequate Fe and Zn
from other dietary sources. And deficiency in Fe, Zn,
and Ca promote Cd absorption in the human intestine
(Fox, 1988; Foxetal., 1984), promoting risk from Cd in
rice grain. One of the first experimental findings which
illustrated that rice Cd risk was qualitatively different
from other foods was a study of New Zealand oyster
fisherpersons who consumed up to 500 jj,g Cd/day in
high Cd oysters, but had no evidence of renal tubular
dysfunction from these high levels of Cd, as high as
the Japanese rice consumers who had a high incidence
of renal tubulardysfunction (Sharmaetal. 1983) Further
examination of these oyster consumers revealed that
their kidney Cd was hardly increased by oyster-Cd, but
responded strongly to smoking (Sharma et al., 1983;
McKenzie-Parnell and Eynon, 1987; McKenzie-Parnell
et al., 1988). Many other errors have  resulted when
toxicologists tried  to predict Cd risk on the basis  of
injected Cd, or adding Cd salts  to purified diets. And in
interpretation of diagnostic information of secretion on
low molecularweight proteins in  urine by normal humans
compared to persons which suffer frank tubular disease
from dietary Cd (see Chaney et al., 1999a).

Wheat and vegetables have been  found to have very
different soil-plant-animal relationships for Cd and Zn
compared to rice.  These crops are  grown in aerobic
soils where both Cd and Zn are plant available during
growth, andZn inhibits both uptake of Cd from soil, and
transport of root Cd to edible tissues of the plant. And
Zn  is translocated  to  all plant tissues where Cd
accumulates so it is simultaneously present with Cd in
any foods and in  the intestine (Table 3) (see also
McKenna et al., 1992a). Although  corn is  also a poor
source of bioavailable Fe, when western crops are grown
in soils enriched in both Zn and Cd, corn grain has
increased Zn levels  somewhat proportional to the
increased Cd, and the Zn in the such corn grain satisfies
the human Zn requirement and inhibits absorption of Cd
in the intestine much more effectively than found for
rice grown on such contaminated soils.

It is difficult to overstate the importance of Zn in a crop
in inhibiting animal absorption of  Cd from that crop. Table
3 shows the accumulation ofCdandZn by Swiss chard
(Beta vulgaris L. var. c/c/a) grown  on soil treated with
normal  chemical  fertilizers vs. different biosolids
products used as  fertilizer. For one of the biosolids,
chard leaf Cd was increased by 5-fold in the strongly
acidic soil, butZn had a corresponding increase. Guinea
pigs were fed the chard at a high fraction  of diet for a
long period, yet there was no significant increase in Cd
in kidney or liver.  In this  situation,  although the soil
contains significantly increased  levels of Cd, it has zero
bioavailability to the guinea pigs.

When  livestock are fed crops grown on Zn+Cd-
contaminated soils, Cd is very poorly absorbed by cows,
sheep, pigs and chickens. The  usual 100 Zn:1 Cd ratio
prevents accumulation of Cd in  animal tissues used for
food, and strongly limits accumulation in  kidney and
liver. For example, in the feeding study of Kienholz et
al. (1979) in which  3 or 10% biosolids were mixed with
cattle diets and fed for 90 days,  the fraction of ingested
Cd which remained in the carcass including liver and

kidney was < 0.1%. Thus animal agriculture usually
prevents Cd risk in humans who consume "homegrown"
meat. When high quality biosolids with low Cd:Zn ratio
are used on land, no increase was found in kidney or
liver Cd (Decker etal., 1980). When biosolids with high
Cd levels and high Cd:Zn ratios were fed to cattle, kidney
and liver Cd levels were significantly increased (e.g.,
Johnson etal., 1981). A rare exception to this rule that
Zn  prevents food-chain transfer of Cd is found in
Australia  and New Zealand where  "cape weed"
selectively accumulates Cd relative to Zn on pasture
soils.  The  soils had become somewhat Cd enriched
due to use of high Cd (and high Cd:Zn ratio) phosphate-
fertilizers. Capeweed could thus increase Cd transfer
to sheep liver and kidney, which prevents sale of these
organs in Europe for animals over 2 years of age (it is
likely that even this Cd does not comprise risk because
of Zn supplied in liver and kidney along with Cd; market
rejection of such  liver and kidney is  based on  Cd
concentration alone, ignoring interactions which affect
bioavailability of food Cd).

Soil Lead Risk From Ingested Soils.
Study of soil contamination by automotive and industrial
Pb  emissions clearly showed that aerosol  Pb
accumulated in plant leaves when air Pb was high in
previous years. But high soil Pb concentrations increase
Pb levels in most crops weakly. As other sources of Pb
to soils were considered, an important role of house
paint  Pb in contaminating soils near painted  walls
became evident (see Chaney et al., 1984; Chaney and
Ryan,  1994). We have measured up  to 5% Pb in
houseside soil in a remote rural home. Because of these
multiple soil Pb contamination sources, a number of
scientists studied uptake of Pb by garden crops which
a family might grow in a home vegetable garden. A few
crop types do respond to increasing soil Pb with
appreciable uptake, particularly the low growing leafy
vegetables such as lettuce. Potatoes and other root
vegetables which can carry soil particles on their "skins"
can bring higher Pb from contaminated gardens.

However,  as Pb risk  to children was increasingly
recognized, and found to  occur  at lower blood  Pb
concentrations than  previously considered  toxic
(Centers for Disease Control, 1985), the ingestion of
soil and housedust by young children became recognized
as the predominant route of soil Pb riskto children rather
than plant  uptake from contaminated soils. Pb risk is
complex, and children become Pb poisoned from drinking
water pipes with acidic water, from Pb-rich glazes on
pottery, from ingestion of paint chips, from Pb in  the
solder which closed food cans for many decades, etc.
Each of these sources can cause "undue Pb absorption"
in 1-7-year-old children such that over 5%  of the
population exceeds 10 Fg Pb/dL whole  blood. Above
this level, sensitive children begin to show evidence of
some Pb health effects on hearing and balance, and as
Pb rises more and more above this level, populations
of children show lower IQ  levels (ATSDR, 1988). If
housedust is enriched to high levels of Pb from paint or
smelter sources, high  blood Pb is commonly found,
while mine wastes which cause equivalent increase in
Pb ingestion cause little  increase in  blood Pb (e.g.,
Steele et al., 1990). Thus the source of Pb contamination
of soil may influence the risk of this  Pb. Many
researchers believe this results because different
sources  of Pb have  either different solubility or
bioavailability,  or physical mobility to children. One
source of confusion about risk from soil Pb results from
the use of fasted animals in study of Pb risk. When Pb-
acetate is administered to fasted animals, it remains
essentially 100% soluble  and bioavailable  upon
ingestion. But when food in present in the stomach and
intestine, humans absorb as low as 1% of  diet Pb
compared to 60-80% absorbed when human adults are
tested in the fasted condition (e.g, James etal., 1987).
Soil acts somewhat like food by buffering pH and binding
Pb. Thus the risk from soil  Pb may  be qualitatively
different from Pb in paint dust or smelter emissions
where little adsorbent accompanies the Pb (see  Chaney
and Ryan, 1994).

High soil Pb is found at many locations  in  most
countries. As  noted  above, housepaint is  a very
common source of high soil  Pb. And leaded gasoline
caused high soil Pb near heavily trafficked roads. Pb
smelters, including  secondary Pb smelters such as
battery recycling factories, cause extensive dispersal
of highly bioavailable PbO in  communities if housing is
near to smelter stacks. Mine wastes have  often
increased soil  Pb, but have lower bioavailability as
shown in many tests.

The first approach to protection  of children from
excessive soil Pb was soil removal and replacement
by clean soil.  For urban homes, soil  removal and
replacement is quite expensive. And studies have shown
that in most cases soil Pb concentration is much higher
nearthe foundation of domiciles. Paint residues  fall onto
the soil. And automotive and  stack  emission Pb in
particulates are collected on the surfaces of houses by
surface tension, and then washed onto the soil. Over
time these Pb sources are altered to forms controlled
by soil chemistry,  adsorbed  Pb on Fe  oxides, or
pyromorphite (e.g., Cotter-Howells and Thornton, 1991;
Zhang, Ryan and Yang, 1998).

An important aspect of soil Pb risk was  identified during
a large US-EPA study  evaluating removal  and
replacement of Pb-contaminated soil  around houses.
In these studies, part of the children were assigned to
soil replacement immediately after characterization of
population blood Pb, while other children were assigned
to have their soil replacement one year later, after
characterization of blood Pb in the two  populations one
yearafterthe initial measurements (about 9-10 months
after soil replacement). In the Boston, MA, study, the
soils replaced averaged about 1950 mg Pb/kg, but blood
Pb was only slightly (but significantly) reduced due to
the independent effect of soil  removal and replacement
(Weitzman etal., 1993). Many other studies of children
exposed to soil and housepaint Pb have affirmed that
soil Pb has lower risk than paint Pb, which we believe

Table 3. Bioavailability of Cd in biosolids-fertilized Swiss chard fed at 28% of diet to Guinea pigs for 80
days (Chaney et al., 1 978b).

High Metal Biosolids
Blue Plains Digested
Blue Plains Compost
Soil Cd
Soil pH

Cd in
Zn in
Cd in
Cd in
ng/g dry weight
14.9 a
14.5 a
14.5 a
15.8 a
3.1 at
2.7 a
2.7 a
3.6 a
JMeans followed by different letters are significantly different at P < 0.05).
should at least partially be attributed to the adsorption
of Pb by soil particles in the digestive tract. Pbin house
paint is the principle Pb risk to children today, not the
Pb in contaminated soils.

Guidance for Beneficial Utilization of
Biosolids and Biosolids Composts.
With the development of the 40 CFR 503 Rule for land
application of biosolids, a risk-based estimation  of
allowable cumulative biosolids element applications was
provided (US-EPA, 1993; Chaney and Ryan, 1993; Ryan
and Chaney, 1993). This rule included the "Alternative
Pollutant Limit" (APL) which allowed marketing of higher
quality products. This reflects the increasing evidence
that regulation of biosolids quality would provide more
protection than regulation only of the cumulative
application of elements in biosolids. This pattern results
from the adsorption or precipitation of these elements
by the mineral constituents of the biosolid, as discussed

Table 4 shows the limits of the 503 Rule, the USDA "No
Observed Adverse Effect Level" (NOAEL) biosolids
limits, and concentrations we consider "attainable" by
good pretreatment of industrial wastes, and reduction
of corrosivity of drinking water.  Because these  lower
levels of trace elements can commonly be attained by
good practices, some want to require that all biosolids
and composts be regulated at the lower "attainable"
levels. We find this argument un-persuasive. The APL
and cumulative metal application limits of the 503 Rule
are protective  under  the very conservative risk
assessment model, 1000 t/ha, for highly exposed
individual with lifetime  exposure at this  cumulative
application rate. On the other hand, we feel it appropriate
to advise biosolids generators  and composters that
lower concentrations of these elements can be readily
attained if they work at it.  Higher quality products will
create higher demand in the market, and bring in higher
economic return for the marketed products. We view
this as best practice, but not needed  to  achieve the
protections expected by citizens which are the basis of
the 503 Rule.

In the case of "yard debris" or "green wastes" composts,
lower element levels can be attained than found in
biosolids and biosolids composts. And composts
prepared from pre-separated Municipal Solid Waste
(MSW) can contain lower concentrations than found in
biosolids  composts (Epstein, et al., 1992). Pre-
composting separation of glass, metal and plastic from
other MSW constituents minimizes concentrations of
elements in the compost products, but there is little
evidence that this difference is so  great that only pre-
separation should be allowed for MSW composting. Pre-
separation of MSW compostable fraction is most
important  for removal of glass,  plastic, and metal
particles which reduce acceptability to consumers.

Further, without inclusion of biosolids or manures in yard
debris or  MSW-composts, they are  poor nutrient
sources, and have little value as fertilizers or in
remediation  of contaminated soils. Although some
individuals may believe it  important to impose tight
regulations on contaminants in these different kinds of
composts, to require each to be as clean as possible,
risk assessment  should continue to be the basis of
regulations (as recommended by Hornick et al., 1983).
Labeling of composition, including nutrient value and
trace element levels in relation to the US-EPA limits,
will provide consumers the basis for choice of soil
amendments. Composting or heat drying can provide
the pathogen kill needed for biosolids and  livestock
manure, and yard debris composts, to be safely used
on lawns and gardens where humans will have exposure.
Perspective on risk of elements in these many compost
type consumer products is  needed when considering
development of restrictive regulations. IftheCd and Pb
in high quality biosolids composts  and MSW compost
products cause no increase in human or environmental
risk, similar to other commercial organic amendments
including yard debris composts, there is no legitimate
basis for claiming such products have different Cd or
Pb  risk. The  high Fe and phosphate of high  quality

Table 4. Limits of the 40 CFR 503 biosolids Regulation (EPA, 1993) vs USDA recommended biosolid quality
for long-term use on farmland, and attainable quality biosolids and composts. Deletion of Cr limits from the 503
Rule is discussed by Chaney, Ryan and Brown (1997).

Ceiling 99th
=APL, mg/kg
Percentile of NOAEL(1993)

Attainable Quality
<1 500-2000
biosolids products can provide a solution for soil Pb
environmental risks as noted above, not add to Pb risk
of children.

In situ Remediation or Inactivation of Soil
An alternative to soil replacement to reduce soil Pb risk
to children  has been  developed, the use of soil
amendments to precipitate soil Pb, or otherwise reduce
the bioavailability of soil Pb based  on animal feeding
tests. These strategies are complementary, in that high
phosphate can hasten formation of chloro-pyromorphite
[Pb5(PO4)3CI] an extremely insoluble Pb mineral, and
mixtures of Fe and phosphate can increase the Pb-
adsorption capacity of a soil, to reduce bioavailability
in the intestine  by stronger binding to ingested soil
particles. Some very elegant work by Ma, Ryan, Logan,
and cooperators (Ma  et al., 1993; Zhang et al., 1997;
1998; 1999a; 1999b) showed that pyromorphite can be
formed from  all chemical species of Pb found in soils,
and that different Pb chemical species react at different
rates. Both Pb and phosphate have limited solubility at
normal soil pH, which tends to slow the reaction. But
when phosphate amended soil enters the acidic
stomach, the pH condition favors  rapid formation of

The  use of biosolids  to  reduce soil Pb bioavailability
was developed based on studies of Pb absorption by
livestock which were exposed to, or fed, biosolids with
different levels of Pb (e.g., Decker etal., 1980), and on
the reduction in Pb uptake by lettuce when soils were
amended with composted biosolids (Sterrett  et al.,
1996). These feeding studies were conducted to evaluate
risks to livestock and wildlife of Pb in biosolids. As
summarized by Chaney and Ryan (1994), until biosolids
exceed 300 mg Pb/kg, there was no net retention of Pb
by test animals. For some biosolids with stronger Pb
adsorption ability, even higher Pb concentration in the
biosolid, fed at 3-10% of dry diet, had no effect on blood
or bone Pb. Both mechanisms could be at play in this
case because biosolids are rich in P, and when Fe is
added during wastewater treatment to improved
phosphate  removal, the biosolid has  even higher P
levels along with high Fe (up to 10% compared to typical
levels of 1-2% Fe in dry digested biosolids in the absence
of Fe additions  during sewage processing). In a
comparison of different  biosolids  processing
technologies effect on the ability of the  biosolids
products to inactivate soil Pb, Brown et al. (1997b) found
that all products from one treatment works could reduce
Pb bioavailability, but those higher in Feand phosphate
were most effective. Any products to be used where
children might be exposed to the soil must be treated
to kill pathogens; and high rates of application are
desired to achieve a high reduction in  bioavailability with
a single treatment.  So composted biosolids rich in Fe
are favored for remediation of soil Pb around houses.
Such composted materials are also very effective in
alleviating soil compaction, and Zn phytotoxicity in

acidic urban soils, and improve soil physical properties
and soil fertility. Thus lawn grasses usually grow very
well  on compost-amended  urban soils, providing a
physical barrierto soil ingestion by children.

Because application of composted biosolids rich in Fe
and P substantially reduced  Pb uptake by lettuce and
other plants (Sterrettetal., 1996), and the Pb in biosolids
had very low bioavailability when ingested by beef cattle
(Decker et al., 1980), we tested the incorporation of
different biosolids products to reduce the bioavailability
of soil Pb to mammals (see Chaney and  Ryan, 1994;
Brown et al.,  1997b). To date our cooperators have
conducted 3  separate studies in  which soil Pb
bioavailability was reduced 50% or more (within 30 days
of mixing)  by incorporation of 10% biosolids in a high
Pb urban soil, or smelter contaminated soil.

Remediation and Ecosystem Restoration
using Tailor-Made Biosolids Mixtures and
With the finding that adding high  Fe and phosphate to
soils reduced Pb uptake by crops, and reduced soil Pb
bioavailability to animals which  ingested the soil, we
considered using such biosolids plus other byproducts
or "wastes" to achieve a comprehensive remediation of
the usually barren soils surrounding long term Zn or Pb
smelters. Such soils often contain 1% Zn, 100 mg Cd/
kg, and 100-30,000 mg Pb/kg (e.g., Chaney et al., 1988;
Brown et al., 1998). Smelters often emitted SO2 in large
amounts, which caused local soil  acidification nearthe
smelter as sulfuric acid was formed. In the case of mine
wastes, if the mine tailings contain high levels of pyrite
(FeS), when the tailings become aerobic the sulfide was
oxidized generating sulfuric acid. Soil pH could be
lowered below 2, causing severe phytotoxicity from
many metals  (Zn, Cd, Al, Mn). And when tailings or
smelter emissions are rich in Pb, part of the soil Pb is
converted  to pyromorphite, greatly reducing the plant
availability of native soil phosphate. Even if these soils
are limed to pH 5.5-6, if high  Zn levels are present the
soil can remain severely Zn-phytotoxic. Low P availability
due to the  presence of Pb interacts adversely with high
soil Zn because high Zn shortens roots thereby reducing
P uptake ability of roots. The combination of soil acidity,
high  soil Zn, high soil Pb and low  soil phosphate make
a very difficult soil  condition to  remediate. One can
revegetate such soils only  if one remediates the P
deficiency, the Zn phytotoxicity,  and the potential for
acid generation overtime.

Considering this combination, we initially tested use of
high  Fe,  calcareous, biosolids compost from
Washington,  DC,  to remediate the severely Zn
phytotoxicsoilatPalmerton, PA (Li and Chaney, 1997;
Li et al., 2000). Accumulated soil Zn made survival of
Kentucky  bluegrass difficult, and many  homes were
surrounded by barren soils; homeowners even gave up
on trying to grow grasses and covered their soil with
mulch. In  tests we conducted, the application  of
limestone to reach pH 6.5 or  higher, along with normal
application of N, P, and K fertilizers to establish lawns,
allowed grasses to germinate and start to grow.  But
when the plants were stressed by cold, heat, ordrought,
the lawn grasses died. We found that the highly  Zn-
resistant 'Merlin' red fescue performed well with  this
intermediate pH and phosphate levels, but tall fescue
and bluegrass simply died on the control fertilized soil,
orthe limestone plus fertilizer treatment (Li et al., 2000).
With the application of 224 t/ha of composted high Fe
biosolids which contained 30% limestone equivalent,
the soil immediately became calcareous (and had  lots
of pH buffering capacity), and high phosphate status
(Li et al., 2000). Further investigation of these soils by
Siebielec and Chaney (1999) revealed that the higher
Fe in the biosolids-compost-amended soil increased
metal adsorption, lowering  soil  solution  Zn and Cd
concentrations betterthan limestone addition alone. This
same compost was highly effective in reducing soil Pb
bioavailability to rats in several feeding studies (see
Chaney and Ryan, 1994; Brown etal., 1997b).

Not all biosolids contain high limestone equivalent, or
high Fe levels. But there are many industrial, urban,
and agricultural byproducts which can provide the Fe
and limestone equivalentto make a remediation product.
Composts have a special value for application in cities
where children would be exposed to the amended soil
because composting  kills  pathogens in biosolids.
Composts are also preferred when contaminated stream
side soils are to be remediated. Chaney, Walker, Brown,
et al. noted that one could combine different manures
and  byproducts to make  a  mixture  which aided
remediation of metal contaminated soils. The mixture
needs to contain  limestone equivalent,  phosphate,
adsorbent, and slow release organic N, as well as
microbes in order to achieve effective remediation of
soil Pb, Zn, and Cd. This approach has been called
"Tailor-Made Remediation  Biosolids Mixtures and
Composts" to stress that if one searches one's region,
one can find different wastes or byproducts which have
little value for commercial use or are disposed in landfills
at substantial cost, but which when combined and
applied to metal contaminated soils, can inactivate soil
Pb, prevent Zn phytotoxicity, improve soil fertility and
physical properties, and supply energy, nutrients and
inoculum for soil  microbial populations. Limestone
equivalent can come from wood ash, from lime wastes,
from sugar beet waste lime, from fly ash and other
alkaline byproducts if the levels of other contaminants
in the  byproduct  would not  prevent use of these
materials on cropland. These materials usually contain
levels of Zn, Cd, As, and some other elements higher
than found in background soils, but not at levels which
would cause risk through plant uptake on home gardens,
orthrough soil ingestion.

Using such mixtures has been shown to provide a "one-
shot" persistent remediation and revegetation of metal
contaminated sites such as Palmerton,  PA (Li and
Chaney, 1998), Katowice, Poland (Stuczynski et al.,
1997; Daniels etal., 1998), and Kellogg, ID (Brown et
al., 1999), where mine wastes and smelter emissions

killed ecosystems. Plants growing on the remediated
sites contain levels of Zn and other elements which are
safe for lifetime consumption by livestock or wildlife.
Further, in the work to establish a demonstration
experiment at Kellogg, ID, Henry, Brown et al. (1998b)
found that certain biosolids spreading equipment was
highly effective in applying a mixture of biosolids, wood
ash, and logyard debris to strongly sloping barren soils
on Bunker Hill. Non-composted mixtures are considered
appropriate for such remediation because composting
provides a value-added product which needs to  cost
more than a simple mixture of biosolids plus byproducts.
Compost would be preferred to control N-mineralization
so that higher cumulative rates of application can be
made to improve the likelihood of full remediation of the
contaminated soil, although including cellulosic
byproducts in the Tailor-Made mixture can limit soil
nitrate leaching potential.

Individuals need to  show considerable creativity  in
searching for  byproducts from many sources, near to
the site where remediation would be conducted, to find
a cost-effective combination of remediation agents and
fertilizers, control the rate of N mineralization to protect
groundwaterand preserve the remediation, and support
the growth of plants adapted to the region. When
revegetation is desired "out of normal season" for planting
a site,  one can use large-seeded cereals, and then
overseed with more expensive but more tender native
grasses, legumes, etc.

Another aspect of the combination of limestone
equivalent with biodegradable organic matter in the
Tailor-Made Remediation Mixture is the formation  of
chemical forms of Ca and Mg which move down the
soil profile and neutralize subsurface acidity. This effect
was reported by several researchers, and confirmed for
four kinds of biosolids or composts in a long term field
study by Brown et al. (1997a). The less well aerobically
stabilized the  organic matter of the product, the more
extensive was the leaching of limestone equivalent down
the soil profile.  In the absence of this benefit  of
biodegrading organic matter, surface-applied limestone
slowly neutralizes soil depth by diffusion of Ca and Mg
between soil particles and replacement by dissolution
of the limestone material.  It is possible that the  high
surface area  of amorphous byproduct limestone
materials aids in the reaction rate as well.

Although the focus of this paper is on Pb-Zn-Cd mining
and smelting contamination of soils and remediation of
soil metals risks, many of the same principles apply to
As contamination  (Chappell  et al., 1997). Risk
assessment for soil As  must  consider bioavailability,
chemical speciation, etc., and high Fe additions  may
reduce risks of soil As.

Web Site With Photographs and Data
From  Studies of the Use of Tailor-made
Biosolids Mixtures to Remediate Zn-Pb-
Cd-Contaminated Soils.
Readers may find more details about the soil remediation
research described above at a web site prepared by
cooperators C.L. Henry and S.L. Brown at the University
of Washington; the files contain color photographs and
details  of several studies in which  Tailor-Made
remediation methods were used to remediate severely
phytotoxic  soils  at smelter  and  mine waste
contaminated sites in the western US. The addresses
for these sites are: http://faculty.washington.edu/clh/
bunker.html  (Bunker Hill, Kellogg,  ID); http://
faculty.washington.edu/clh/leadville.html (adjacent to
Arkansas River downstream of Leadville, CO); and http:/
/faculty.washington.edu/clh/wet.html (Page swamp
wetland site near Kellogg, ID).

Phytoextraction of Soil Metals.
Phytoextraction uses plants to remove  metals from
soils. Several approaches have been studied. We have
been working to develop the method which uses natural
metal hyperaccumulator plant species. These rare plants
are selected by evolution on mineralized soils where
they have an advantage over plants which exclude
metals because the metals can help the plant reduce
the effect of  chewing insects and plant disease
organisms on its  ability  to reproduce.  Table 5  lists
hyperaccumulators species for several trace elements,
which achieve over 1% metal in plant shoots when grown
in soils where the plants evolved. Phytoextraction can
be  a "green" technology for  soil remediation, but
commercial systems are still in development.

Our research  team has developed effective metal
hyperaccumulator plants for Ni+Co, and for Zn+Cd
(Brown etal., 1994; Lietal., 1997; Chaneyetal., 1999b).
Table   6  illustrates  the  important   role  of
hyperaccumulation and hypertolerance of metal by these
plants in the annual rate of removal of metals from the
soil. Normal plant species such as corn (Zea mays L.)
do not remove appreciable amounts of metals even when
suffering phytotoxicity from the metal they accumulate
from phytotoxic soils. Thlaspicaerulescens, on the other
hand, has poorer yield than corn, but hyperaccumulated
2.5% Zn in field tests. Further, Li et al.  (1997) have
examined Zn and Cd accumulation from a field test plot
by a number of genotypes of this species collected at
different  locations in  Europe, and found substantial
variation in Cd hyperaccumulation in the presence of
the normal 1 g Cd:100 gZn. All strains accumulated 1-
2% Zn, but differed in Cd hyperaccumulation (Figure
3).  These remarkable genotypes offer an  effective
technology for phytoextraction of Cd from soils with little
Zn contamination,  not possible with the 'Prayon' strain
of T. caerulescens used  in most research on Thlaspi
(Chaney et al. 1999b). And require only the same
nutrients as  crop  plants  to achieve this remarkable
metal uptake and tolerance. Because lower soil pH
increases solubility of Zn and Cd, Thlaspicaerulescens
accumulates higherZn and Cd concentrations if soil pH
is lowered by agronomic management practices. We
believe that cultivars of T. caerulescens could be bred
to combine higheryields, and the Super-Cd-accumulator
trait, and be used to quickly clean up soils where rice or

Table 5. Examples of plant species which hyperaccumulate Zn, Ni, Se, Cu,
Co, or Mn to over 1 % of their shoot dry matter in field collected samples (about
100-times higher than levels tolerated by normal crop plants).
Plant Species
Max. Metal
in Leaves
1 1 ,500
N. Caledonia
N. Caledonia
Reeves &
Brooks, 1983b
Lietal., 1997
Brooks et al.
Kersten et al.,
Brooks, 1977
Beath et al.,
Brooks et al.
1lngrouille and Smirnoff (1986) summarize consideration of names for Thlaspi
species; many species and subspecies were named by collectors over many
years(Reeves and Brooks, 1983a; 1983b; Reeves, 1988).
tobacco can cause human health effects. In this case,
the value of Cd in the crop would not affect the need to
produce the crop to decontaminate a  soil; rather,
phytoremediation services and the value of Zn in the
crop would need to pay forthe costs of crop production
and processing. Phytoextraction with T. caerulescens
cultivars would be remarkably less expensive than soil
removal, and offers the only practical solution for Cd-
contaminated soils  which  comprise  risk  to
humans.Genetic engineering is being used to develop
new plants for phytoremediation.  One successful
example is the transfer of microbial mercuric reduction
genes to higher plants, which allows the plants to reduce
soil mercuric  ion to mercury metal which can  be
evaporated from the soil and reduce risk (Rugh et al.,
1996). Methylated mercury is the dangerous form of Hg
in  the environment; it is lipophilic and  biomagnified
especially in aquatic food-chains. Plants with both the
methyl mercury hydrolase and mercuric ion reductase
have been  developed by Rugh et al.  (1996). Other
fundamental aspects of developing phytoextraction
technologies are summarized by Chaney et al. (1997;

Some   researchers  have  criticized   use  of
hyperaccumulator plants because many have small
biomass yield (e.g., Thlaspi caerulescens where a good
yield is 5 t/ha-year). Some stress that crop plants can
accumulate 1000 mg Zn/kg  in  some cases with little
yield reduction, and compare Zn accumulation by T.
caerulescens under the conditions which kill the crop
plants. In our view, this is not a valid comparison. One
must characterize how high metals can reach when each
crop is managed to attain maximum levels without yield
reduction. Corn, oat, and Indian mustard have only
normal metal tolerance, and are greatly reduced in yield
with 500 mg Zn/kg. If Thlaspi can accumulate 25-100
time more shoot Zn than corn under valid comparison
conditions (Table 4), it seems obvious that plant species
with normal  metal  tolerance offer little value  for

Unfortunately,  natural plants  do not accumulate
concentrations of plant Pb needed to achieve significant
phytoextraction of soil Pb (Chaney etal., 1999b). Some
researches have shown that if one applies strong
chelating agents such as  EDTA,  soil Pb can  be
dissolved, and the root membranes weakened enough
to promote uptake of PbEDTA with the water moving
into roots (Blaylocketal., 1997; Huang etal., 1997; Wu
et al., 1999). Transpiration carries the PbEDTA from
soil into plant shoots (Vassil et al., 1998). When high
Pb levels are reached, the crop plants tested to date
are not tolerant of the accumulated Pb, and growth

Concerns have been raised about application of EDTA
to soils to achieve chelator-induced  phytoextraction
because of the experience the Department of Energy
had with  leaching of chelated radionuclides at their

Table 6. Estimated removal of Zn and Cd in crop biomass of a forage crop (corn), compared
to an existing Zn+Cd hyperaccumulator or an improved Phytoextraction cultivar. Presume
the soil contains 5,000 mg Zn/kg and 50 mg Cd/kg dry weight (or 10,000 kg Zn/ha@15 cm)
and 50 ppm Cd (or 100 kg Cd/ha@15 cm). Crop is presumed to have 10% ash of the dry

Corn, Normal
Corn, Zn-Toxic

Corn, Normal
Corn, Zn-toxic
Super-Cd Thlaspi
Super-Cd CROP
Zn in Shoots
% of Soil
Cd in Shoots
% of Soil
Zn in Ash
Cd in Ash
facilities (Means et al.,  1978). Soil-applied chelators
dissolve metals based  on the activity of soil  metals
and the selectivity of metal binding by the chelator. Non-
target elements can be dissolved and leach down soil
profiles if fields are irrigated, or in humid regions.

Chelator-induced phytoextraction may not work for all
metals or all crops. Robinson et al. (1999) tested  NTA
and  EDTA with Berkheya coddii, a  South African
accumulator of Ni, and found that added chelating agents
actually inhibited uptake by the  plants. Perhaps the
special property of Indian mustard which allowed high
accumulation of PbEDTA does not commonly occur in
other species.

However,  if such a chelate-induced  phytoextraction
technology were practiced with the soil over a plastic
linerto prevent leaching of the EDTA chelates into the
subsurface soil, it might be an effective technology.
But with the need for liner and EDTA in large quantity,
the method is expensive compared to the use of natural
hyperaccumulators as is possible with Zn and Cd,  or Ni
and Co. Because of discussions about chelate-induced
phytoextraction, we calculated the cost of applying
EDTA at rates found to optimize Pb uptake in the work
by Blaylock et al. (1977) and Huang et al. (1997), 10
mmol/kg soil. The price of technical grade EDTA ($1.957
pound) was obtained from a major US manufacturer in
early 2000. Assuming 15 cm depth of soil Pb
contamination, one application of EDTA at 10 mmol/kg
soil costs $30,000/ha. Thus this method is  very
expensive as well  as comprising risk to ground  water
contamination if liners are not used. With the highly
effective in situ inactivation of soil Pb noted above,  it
seems clear that inactivation  of soil Pb is the  more
desirable approach for remediation of soil Pb.

Some  have  criticized  phytoextraction  using
hyperaccumulator plants based on presumed risk to
wildlife which might ingest the crop. Because the crop
is  usually always high in  metals  which it can
hyperaccumulate,  the assumption was that animals
would be at risk whereverthis technology was practiced.
However, field observation of livestock in areas where

                     1   6    8   11   12   14  15  16  17   18   19  20  21
Figure 3. Variation of Thlaspi caerulescens genotypes in shoot Cd:Zn ratio; all accumulated 10,000-20,000 mg Zn/kg, but Cd
transported to shoots reach very high levels in selected genotypes (Li et al., 1996).
hyperaccumulators occur naturally indicates that sheep,
goats and cattle avoid the Alyssum and Thlaspi metal
hyperaccumulators. The seeds of these  species are
small, and comprise little feed value. Further, it is very
unlikely such animals will choose to ingest only a diet
of hyperaccumulator plants considering the avoidance
of metal rich leaves in the studies of Boyd and Martens
(1994) and Boyd and Moar (1999). Chronic exposure to
intrinsic plant metals  has never been reported,  and
would be a valuable topic of study to settle whether
wildlife or livestock may be at risk from fields of farmed
hyperaccumulator crops. In general,  birds  and large
mammals have large ranges, and would be unlikely to
consume much hyperaccumulator plant biomass unless
it were attractive (not found in practice).  Small mammals
such as field mice or other herbivore wildlife with a small
range could live within a phytoextraction field, and would
be expected to be harmed by the plant metals if they
consumed only those plant tissues. Whether field mice
would avoid these plants as found for sheep and goats
is unknown at this time.

Mechanisms Used  by Natural
Hyperaccumulators or Metal-Tolerant
Plants in Storage and Tolerance of Metals
Research on both natural metal hyperaccumulators, and
evolved metal tolerant plant species or ecotypes has
shown that tolerance relies on vacuolar storage of
metals rather than formation of chelates with soluble
ligands, especially those containing P (phytate) or S
(phytochelatins, ormetallothioneins). The work on Silene
vulgaris by Verkleij, Schat, Ernst, et al., has illustrated
this relationship very strongly (Schat and Kalff, 1992;
Harmensetal., 1993; Chardonnens et al.,  1999). And
studies on hyperaccumulators have shown this vacuolar
storage to  play a very significant  role  in  natural
hyperaccumulators (Lasat et al., 1998;  Kiipper et al.
1999; Verkleij  et al., 1998). Also, attempts to use
protoplast fusion to build plants with  higher biomass
but natural hyperaccumulation ability  have proved
unsuccessful (Brewer etal., 1999)

Phytoextraction With Hyperaccumulator
Offers Great Promise for Soil Remediation
Metal hyperaccumulation by plants offers  a new cost
effective approach forsoil remediation. Further, the crop
can be harvested as a biomass crop, air dried like "hay",
and burned in a biomass power generator. For metals
which have commercial value, the ash is a high grade
ore, very different from the traditional metal ores of
commerce. ForZn and Cd, the value of biomass energy
and metals for recycling appears to be a profitable
opportunity (MacDougall et al., 1997),  and for more
valuable metals, hyperaccumulation may be more cost
effective than mining technologies. Phytoextraction and
phytomining technologies require extensive research

and development. One is essentially domesticating a
new crop, a difficult task. Cost effective  metal
phytoextraction  is sufficiently promising that several
research teams are working to develop practical
phytoextraction systems (improved plant cultivars, and
agronomic management practices needed for cost
effective metal hyperaccumulation) (see Chaney et al.,

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effects on soil populations and heavy metal tolerance
of Rhizobium meliloti, nodulation, and growth of alfalfa.
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Angle, J.S., R.L. Chaney and D. Rhee. 1993. Bacterial
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Blaylock, M.J., D.E. Salt, S. Dushenkov, O. Zakharova,
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Boyd, R.S. and S.N. Martens.  1994.  Nickel
hyperaccumulated by Thlaspi montanumvar. montanum
is acutely toxic to an insect herbivore. Oikos 70:21-25.

Boyd, R.S. and W.J. Moar. 1999. The defensive function
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Spodoptera exigua (Lepidoptera: Noctuidae) to
hyperaccumulator and accumulator species of
Streptanthus (Brassicaceae). Oecol. 118:218-224.

Brewer, E.P., J.A. Saunders, J.S. Angle, R.L. Chaney
and M.S. Mclntosh. 1999. Somatic hybridization between
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Brooks, R.R., R.S.  Morrison, R.D. Reeves and F.
Malaisse. 1978. Copper and  cobalt in African species
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1981. Studies on manganese-accumulating Alyxia from
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Brown,  S.L., J.S. Angle and R.L. Chaney. 1997c.
Correction of limed-biosolid induced manganese
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Brown, S.L., R.L. Chaney, J.S. Angle and A.J.M. Baker.
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Brown, S.L., R.L. Chaney, J.S. Angle and J.A. Ryan.
1998a. The phytoavailability of cadmium to lettuce in
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Brown, S.L., R.L. Chaney, C.A. Lloyd and J.S. Angle.
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Brown, S.L., Q. Xue, R.L. Chaney and J.G. Hallfrisch.
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Brown, S.L., C.L. Henry, R.L. Chaney and H. Compton.
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Cai, S., Y. Lin, H. Zhineng,  Z. Xianzu, Y. Zhaolu, X.
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Chaney, R.L.,  J.A. Ryan and  S.L. Brown. 1997.
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Chaney, R.L., G.S.  Stoewsand, C.A. Bache and D.J.
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metal absorption by winter wheat following termination
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Cunningham, J.D., D.R. Keeney and J.A. Ryan. 1975c.
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Ibekwe, A.M., J.S. Angle, R.L. Chaney and P. van
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Ibekwe, A.M., J.S. Angle, R.L. Chaney and P. van
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Ibekwe, A.M., J.S. Angle, R.L. Chaney and P. van
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Li, Y.-M., R.L. Chaney,  J.S. Angle, K.-Y. Chen, B.A.
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Li, Y.-M., R.L. Chaney and A.A. Schneiter. 1995. Effect
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Li, Y.-M., R.L. Chaney, G. Siebielec and B.A. Kershner.
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                   Phytoextraction:  Commercial  Considerations

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                                  Edenspace Systems Corporation
                                     11720 Sunrise Valley Drive
Dr. Michael J. Blaylock holds a Ph.D. in soil chemistry
from the University of Maryland and BS and MS de-
grees in agronomy from Brigham Young University. His
research activities have focused on rhizosphere pro-
cesses affecting trace element and heavy metal uptake
by plants.  Dr. Blaylock has worked for the past eight
years evaluating and developing strategies to address
heavy metal and radionuclide contamination of soils. Dr.
Blaylock is an internationally recognized  expert in the
development of phytoextraction of metal-contaminated

Dr. Blaylock is currently the Director of Ag Research
and Development at Edenspace Systems Corporation
where he  leads Edenspace's research,  analysis and
development team. He has conducted or managed nu-
merous phytoremediation projects at government and
industrial sites including brownfields, the EPA SITE pro-
gram, firing ranges within the Department of Defense,
RCRA Corrective Action sites, former nuclear weapons
development complexes within the Department of En-
ergy, and a "Big Three" auto manufacturer. His research
has led to five company-filed patents  and more than
sixteen peer-reviewed publications.
Phytoextraction of metal-contaminated soils has
emerged as an attractive alternative to traditional soil
remediation methods such as excavation and disposal.
The ability to use phytoextraction as a remediation tool
requires plants capable of accumulating sufficient metal
concentrations in their harvestable biomass coupled with
biomass yield rates that facilitate a significant quantity
of metal removal from the soil to achieve site goals. The
successful application of this technology, however, re-
quires an understanding of site-specific conditions and
key parameters that influence performance. The site
assessment process routinely includes an evaluation
of soil  conditions, contaminant distribution and
bioavailability, remediation goals, and agronomic and
phytometric analyses that allow a determination of ap-
propriate practices (crop selection, soil amendments
and conditioners, and agronomic practices) to ensure

To improve the performance and applicability of the tech-
nology, phytoextraction of metal-contaminated soils can
be integrated with compatible ex situ  and in situ tech-
nologies such as particle size separation and electroki-
netic processes. Recent advances in the technology
have expanded the applicability to soils with particulate
contaminants, contamination below the root zone of
plants, and the use of perennial crop plants and grasses.
Current applications of the technology at firing ranges
and RCRA Corrective Action sites will be presented and
discussed  to  demonstrate  the  versatility  of
phytoremediation to address  metal-contaminated soils.

     Phytoextraction: Commercial
          Michael J. Blaylock, Ph.D.
       Edenspace Systems Corporation
             Reston, Virginia
PHYTOREMEDIATION: Using plants to remove
      pollutants from the environment.

   PHYTOREMEDIATION  Removal of pollutants from the
   PHYTOEXTRACTION  Metal accumulating plants to remove
   toxic metals from soil
   RHIZOFILTRATION Hydroponic plants to remove toxic metals
   from polluted waters
   PHYTOSTABLIZATION Contaminant-tolerant plants to reduce
   mobility and prevent further contamination
   Site Challenges for Phytoextraction

• High total metal concentrations
• Mixed contaminants
• Contaminants below the effective root zone
• Unfavorable water table or drainage conditions
• Particulate/insoluble contaminant sources

     Phytoextraction's Place in the
          Remediation Tool Box
 Many sites contain inorganic contaminants that are
 only treated through a combination of technologies.
 The combination of phytoextraction with soil
 washing (particle size separation) and stabilization
 increases the number of sites amenable to

Integrate conventional remediation with innovative
Use strengths of compatible technologies to
overcome site challenges

         Compatible Technologies
 Soil washing/particle size separation
 Excavation - ex situ treatment
           Phytoextraction Process

Site investigation and assessment
Site applicability or treatability study
Development of agronomic practices
Irrigation and water management
Implementation (planting, cultivation, and harvesting)
Monitoring and analysis
Biomass treatment

            Treatability Study
 Soil characterization
  - Physical
  - Chemical
 Contaminant bioavailability and partitioning
          Case Study: Simsbury CT

• Surface soil lead
• Groundwater concerns
• Address teachable lead as well as total lead
• On-going site use and activities


     Summary of Results - Simsbury
• Areas exceeding total lead concentration goals
  were reduced.
• Average lead concentrations from all crops of
  Brassica juncea exceeded 1000 mg/kg.
• SPLP teachable lead decreased from an average of
  0.85 in April 1998 to 0.08 mg/L in October 1999.

     Case Study - DaimlerChrysler
•  Three-acre ex situ site remediation
•  Elevated lead concentrations below the root zone
•  One year clean-up target

 Excavate subsurface soils for ex situ placement
 Two crops (Brassica juncea, sunflower)
 Dispose of soil exceeding total  lead regulatory goal
 at the conclusion of one season
                                                  S3\| f«Sj, (fc^i rf% «/"& v»| •^
                                                    *~rt In pa I,

September 21,1999 - DaimlerChrysler presented a
1999 Environmental Excellence award to the
Detroit Forge Phytoremediation Project Team
Attended by more than 150 DaimlerChrysler
environmental professionals from throughout the
world, the annual meeting recognized seven top
environmental projects
The award recognized that the team's innovative
use of phytoremediation saved DaimlerChrysler
more than $1,000,000 compared to alternative
remediation techniques

                Zinc Hyperaccumulation in Thlaspi caerulescens

                                           Mitch M. Lasat
                                    AAAS-Environmental Fellow
                     U.S. EPA (5102 G), 401 M Street, S.W., Washington, D.C. 20460
                                   E-mail: lasat. mitch @ epa.gov
Research  presented here is aimed at elucidating the
mechanisms that underlie the accumulation of extraor-
dinarily high levels of Zn in Thlaspi caerulescens leaves
(up to 3%  of the dry weight). Physiological studies fo-
cused on the use of radiotracer flux techniques (65Zn)
to characterize zinc transport and compartmentation in
the root, and Zn translocation and accumulation in the
shoot of T. caerulescens in comparison with a related
Zn nonaccumulator, T. arvense. Results indicated that
Zn transport was stimulated at a number of sites in T.
caerulescens including Zn influx into root and leaf cells
and Zn loading into vascular tissues. Stimulation of Zn
influx into the root cells of T. caerulescens was hypoth-
esized to be due to an increased abundance of Zn trans-
porters at the root cell plasma membrane. In addition, a
compartmentation analysis showed that Zn was seques-
tered in the vacuole of T. arvense root cells, and this
mechanism retarded Zn  translocation to the shoot in
this nonaccumulatorspecies. Molecular studies focused
on the cloning and characterization of Zn transporter
genes in T. caerulescens. Complementation of a yeast
Zn transport defective mutant with  a T. caerulescens
cDNA library resulted in the recovery of a cDNA, ZNTI,
that encodes a Zn transporter. Sequence analysis of
ZNTI indicated that it is a member of a recently discov-
ered micronutrient transport gene family which includes
Fe transporter, IRTI and ZIP Zn transporters. Northern
analysis of ZNTI indicated that enhanced Zn transport
in T. caerulescens results from a constitutively high ex-
pression of the ZNTI  gene in roots and shoots. In T
arvense, ZNTI is expressed at far lower levels and this
expression is stimulated  by the imposition of Zn defi-

A recent EPA analysis of approximately 1,000 superfund
sites with RODs indicated that more than 600 were con-
taminated  with toxic metals. A similar study indicated
that more  than 70% of investigated Brownfields were
contaminated with toxic metals. These results indicate
that soil contamination with toxic metals is a significant
environmental problem.
Metal-contaminated soils are notoriously hard to clean.
Current technologies  resort to  soil excavation and
landfilling, or separation of contaminants by chemical,
physical or electrochemical methods. However, at many
sites, the high cost associated with the use of conven-
tional engineering methods can  be  prohibitive. It has
been estimated that cleanup of U.S. sites contaminated
with heavy metals alone can cost up to $1.7 billion, while
the cost of cleaning mixtures of heavy metals and or-
ganics was estimated at $35.4 billion (Salt et al. 1995).
Because of the high cost, there is a need for less-ex-
pensive remediative technologies. Phytoremediation is
emerging as a cost-effective alternative. Several analy-
ses have demonstrated that the cost of phytoextraction
is only a fraction of that associated with conventional
engineering approaches (Glass,  1999). Furthermore,
because it remediates the soil in situ phytoextraction
avoids dramatic landscape disruption, and preserves
the ecosystem.

The concept of using plants to clean up contaminated
environments is not new. About 300  years ago, plants
were proposed to be used in the treatment of wastewa-
ter (Hartman, 1975). Subsequent research has led to
the identification of plants capable of removing a vari-
ety of toxic metals. Thus, at the end of the XIX century,
Thlaspi caerulescens and Viola calaminaria were docu-
mented to accumulate high levels of metals in the leaves
(Baumann, 1885). In 1935, Byers reported  that plants
of the genus Astragalus were capable of accumulating
up to 0.6 % selenium  in  shoot biomass. One decade
later, Minguzzi and Vergnano (1948) identified plants
capable of accumulating up to 1% Ni in shoots. More
recently, tolerance and  high Zn accumulation in Thlaspi
caerulescens has been reported (Rascio, 1977).

The  idea of using plants to  extract  metals from con-
taminated soil was  reintroduced and developed by
Utsunamyia (1980) and Chaney (1983), and the first
field trial on Zn and Cd  phytoextraction was conducted
in    1991  (Baker   et  al.).   Identification   of
hyperaccumulators, species capable of accumulating
extraordinarily high  metal levels, demonstrates that

plants have the genetic potential to extract metals from
the  rhizosphere.  Unfortunately,  the  use  of
hyperaccumulator species for metal extraction is lim-
ited by plants' small size and slow growth (Ebbs et al.,
1997).  In an effort to make metal phytoremediation a
commercial reality, Brown et al.  (1995) proposed the
transfer of genes that confer the hyperaccumulating
phenotype to plants with higher potential for shoot bio-
mass production. Progress toward this goal, however,
is hindered by a lack of understanding of the basic physi-
ological, biochemical and molecular mechanisms in-
volved  in metal hyperaccumulation.

In this  paper, we present and discuss results of a re-
cent investigation into fundamental aspects of the physi-
ology and molecular biology of Zn hyperaccumulation
in  Thlaspi caerulescens.  This species  is a Zn
hyperaccumulator, capable of accumulating up to 40,000
ppm Zn in shoots without showing toxicity symptoms
(Chaney et al., 1999). This is remarkable considering
that for most common nonaccumulator plants optimal
Zn concentration is < 100 ppm  (Mengel and  Kirkby,
1987).  Thus, T. caerulescens represents a very inter-
esting  experimental system for studying the  mecha-
nisms  of metal hyperaccumulation as  they relate to
phytoremediation. As a reference, we used T.arvense,
a related Zn nonaccumulator species.

To test whether T. caerulescens has a greater potential
for Zn  accumulation compared to its nonaccumulator
relative, T.arvense, we grew the two species in the same
solution and analyzed Zn content of roots and shoots.
Results shown in Table 1 indicate different patterns of
Zn accumulation in the two Thlaspi species; whereas
most Zn was accumulated in roots of T arvense, the
metal was preferentially accumulated in the shoots of
the hyperaccumulator T. caerulescens. Interestingly, T.
caerulescens showed  no injury even at Zn levels as
high  as 100 jj,M. However, severe chlorosis was mea-
sured in leaves of T. arvense grown in 25 jj,M Zn. To
investigate in more details the difference in Zn accumu-
lation between the two Thlaspi species, we conducted
short-, and long-term  radiotracer ( 65Zn) flux experi-
ments. In short-term  (3 hours) uptake studies, we mea-
sured unidirectional  Zn influx into roots. In  long-term
(96 hours) experiments, we measured the net Zn accu-
mulation in roots, which  is the result of Zn influx and
other Zn transport processes such as translocation to
shoot, and efflux from the  root back into the external
solution. In short-term uptake  studies, approximately
twice as much Zn was accumulated  in roots of T.
caerulescens compared with T. arvense. These results
indicate that T. caerulescens has a greater capacity for
unidirectional Zn transport into the root cells. To our
surprise, however, in long-term uptake studies, more
Zn was accumulated in the roots of T arvense com-
pared with T caerulescens. As expected, at the end of
the 96-h-long  uptake experiment, significantly more Zn
was  accumulated (translocated) in the shoots of T.
caerulescens compared with T. arvense confirming find-
ings shown in Table 1. Alteration of Zn transport at sev-
eral sites may be responsible  for the inhibition of Zn
translocation from roots to  shoots of T. arvense. Mea-
surements ofZn concentration in the root sap indicated
that significantly more  Zn was loaded  in the vascular
tissues of T. caerulescens, suggesting that in T.arvense
Zn is prevented from reaching roots vascular tissues
(Lasatetal., 1998).To investigate the mechanism of Zn
sequestration in T.arvense roots, we conducted an efflux
(compartmentation) experiment. In this experiment,
roots were loaded to a quasi-equilibrium state with 65Zn,
and subsequently, the rate of 65Zn movement from roots
Table I. Zn accumulation and relative chlorophyll content in T. arvense and T.
caerulescens seedlings exposed for 10 days to different Zn levels.
Tubs containing 22-day-old seedlings grown on nutrient solution containing 1f/ M
Zn2+ were refilled with nutrient solution containing 1 , 25, 50, or 100 f/M Zn. After
20 days, Zn concentration in roots and shoots was determined by emission
spectroscopy. Relative chlorophyll content was determined with a chlorophyll
meter (SPAD-502). Results are presented as means ± SE.

Zn cone
T. arvense
3481 ±502
T. caerulescens
102± 8
104± 8
"Chlorophyll content

Table 2. Intracellular 65Zn compartmentation and half-
times for 65Zn efflux from different root compartments (t1/2)
for T. an/ense and T. caerulescens seedlings.
DPM and t1/2 values were calculated as described by
Lasatetal. (1998).

Cell wall
T. arvense
T. caerulescens
into an unlabeled (65Zn free) external solution was mea-
sured.The 65Zn efflux curve could be dissected into three
linear components which were interpreted to represent
efflux from three root compartments: cell wall, cytoplasm
and vacuole (Lasat et al., 1998). Two important results
were obtained in this study: a semi-quantitative estima-
tion of 65Zn accumulation in root compartments, and
estimates of rate constants forZn efflux from these com-
partments. Data shown in Table 2 indicate that approxi-
mately 2.5-fold more Zn was accumulated in the root
vacuole  of T arvense compared with T. caerulescens.
In addition, the mobility of vacuolarZn was significantly
lower (highert1/2 value) in T. arvense. These results indi-
cate that Zn is  sequestered in the root vacuole of T.
arvense and made unavailable for translocation to the
shoot. In summary, results obtained in radiotracer flux
studies conducted  with roots documented two major
differences  between the two Thlaspi species: 1) higher
capacity for Zn transport into  root cells  of  T.
caerulescens, and  2) inhibition  of Zn translocation  to
the shoots of T arvense due to Zn sequestration in the

A set of uptake experiments was conducted to investi-
gate Zn transport and accumulation in leaves of the two
Thlaspi species. In radio tracer flux studies, significantly
more Zn was accumulated  in the leaf sections of  T.
caerulescens compared with T. arvense.

Results obtained in uptake experiments with leaves and
roots point to a genetic  modification of Zn transport in
the hyperaccumulator Thlaspi species. To isolate and
characterize Zn transporters, a research strategy based
on functional complementation of a yeast  mutant de-
fective in Zn transport (zhy3) was employed.This strat-
egy relied on the construction of a T caerulescens cDNA
library in a  yeast expression vector. After transforma-
tion of zhy3 with this library, cDNAs of interest (encod-
ing Zn transporters) were identified  as  those that
permitted growth of the yeast colonies on a Zn-restric-
tive medium.To construct the library, a commonly used
yeast expression vector, pFL61, was employed. This
vector has been successfully used to isolate other plant
genes, including genes  involved in amino acid biosyn-
thesis, and genes encoding nutrient transporters. cDNA
from T caerulescens mRNA was synthesized and sub-
sequently size-selected for products that were greater
than 1 kb in length.This cDNAwas ligated into pFL61,
and a primary library consisting of 3 x 105 independent
clones with an average insert size of 1.3 kb was gener-

To identify genes involved in Zn transport, we isolated
zhy3 transformed clones capable  of growing  on a
screening medium containing restrictive Zn level (Lasat
etal., 2000). Screening of yeast transformants resulted
in the identification of 20 colonies capable of growing
on Zn limiting medium. DMA sequencing analysis re-
vealed that five of the seven clones represent the same
gene which was designated Z/VT7.The ability oiZNTI
to mediate Zn transport was independently confirmed
in a radiotracer experiment. Expression oiZNTI in yeast
mutant, zhy3, greatly enhanced cells' ability to accumu-
late Zn over a wide concentration range.

To compare the abundance of ZNT1 in T. caerulescens
(Zn  hyperaccumulator)  and T.  arvense  (Zn
nonaccumulator), a Northern analysis was conducted.
ZNT1 mRNA abundance is  greater  in both  roots and
shoots of T. caerulescens compared with T. arvense.
This pattern was obtained regardless whether North-
ern analysis was conducted with T. caerulescens ZNT1
cDNA, or a probe representing a ZNT1 homologue from
T. arvense (data nor shown). In addition, in the normal
(nonaccumulator) plant (T. arvense), ZNT1 gene  is ex-
pressed at very low levels in Zn sufficient plants. Impo-
sition of Zn deficiency induced  the expression of ZNT1
in  this species.  In the Zn  hyperaccumulator,  T.
caerulescens, ZNT1 was expressed  at high levels and
was less dependent on plant Zn status.

Maturation of phytoremediation into a commercial tech-
nology requires the  understanding of the basic plant
mechanisms that allow plants  to absorb and accumu-
late metals in roots and shoot.These mechanisms are
likely to  involve metal  transport regulation at several
sites, including influx across root-cell plasma membrane,
transport within root cells, unloading into the root vas-
cular tissues, translocation to the shoot, reabsorption
from the sap into leaf cells, and storage into leaves. In
this study, we characterize the  molecular physiology of
Zn  accumulation  and  translocation  in the  Zn
hyperaccumulator T. caerulescens compared with  T.
arvense, a related nonaccumulator.

Zn accumulation exhibited different patterns in the two
Thlaspi species. Thus, Zn was preferentially accumu-
lated in the shoot of T. caerulescens, whereas most Zn
remained in the root of T. arvense (Table 1). In addition,
T. caerulescens showed greater Zn tolerance. Thus, this
species showed no injury at Zn concentrations as high
as 100 n-M. In T. arvense, however, with the exception of
the solution supplemented with 1 jj,M Zn2+, all other Zn
additions were phytotoxic. Therefore it is possible that
high Zn levels measured in T. arvense roots were caused

by a loss of regulatory mechanisms or other physiologi-
cal properties due to Zn phytotoxicity as indicated in
Table 1. Results shown in Table 1 demonstrate the ex-
istence  of significant differences in  Zn transport and
accumulation between the two Thlaspi species. To fur-
ther investigate Zn transport in the two species, we con-
ducted a set of radiotracer flux studies. Forth is purpose,
we developed a protocol to measure unidirectional Zn
influx into  root cells (Lasat et al., 1996). Zn  influx into
root cells was significantly greater in T. caerulescens.
We have subsequently demonstrated that Zn transport
in the root cells of the two Thlaspi species is via similar
protein-mediated systems that exhibit saturated uptake
kinetics. However, capacity for Zn transport was signifi-
cantly higher in T. caerulescens, and we suggested that
this was caused by greater deployment of Zn  transport-
ers at the  root  cell plasma membrane of this species
(Lasat et al., 1998). In long-term uptake experiments,
we observed that significantly more Zn accumulated in
roots of T. arvense. This result was somewhat surpris-
ing because Zn  influx was shown to be higher in T.
caerulescens. However, Zn translocation from roots to
shoot was 8-fold greater in T. caerulescens  indicating
that in T. arvense Zn transport to the shoot was inhib-
ited possibly due to sequestration in the root.To investi-
gate this hypothesis, we conducted an efflux
(compartmentation) study. Advantages and limitations
associated with this technique were discussed earlier
(Lasat et al., 1998). Results shown in Table  2 indicate
that Zn was sequestered in the root vacuole  of T.
arvense. In T. caerulescens, this mechanism is disabled
allowing more Zn to be translocated to the shoot. In
addition, leaves of T. caerulescens were shown to have
a greater capacity for Zn uptake than T. arvense. These
results have been confirmed in radiotracer experiments
with leaf proptoplasts (Lasat etal., 1998).

Results obtained in radiotracer flux experiments with
both roots and leaves point to a genetic alteration ofZn
transport in T. caerulescens. To identify Zn  transport
genes, we employed  an experimental strategy based
on functional complementation of a yeast mutant defi-
cient of Zn transport with a T. caerulescens cDNA li-
brary. This study resulted in the cloning of a Zn transport
gene, ZNT1 from T. caerulescens. Sequence analysis
of  ZNT1 indicated it is a member of  a recently discov-
ered  micronutrient transport gene family (Eide et al.,
1996; Grotz et al., 1998). Following identification of the
gene responsible for Zn transport, we analyzed its ex-
pression in the two Thlaspi species. The abundance of
ZNT1 was significantly greater in T. caerulescens com-
pared with T arvense. In addition, in I caerulescens the
expression of ZNT1 was less dependent on plant Zn
status, whereas in T. arvense Zn deficiency induced the
expression of ZNT1. These results suggest a constitu-
tively higher expression of Zn transporters in Zn
hyperaccumulator T. caerulescens. Clearly, there is an
alteration of the signal transduction pathway  linking Zn
status to expression of Zn transporter genes  in T.
caerulescens. It is likely that this alteration is linked to
the tolerance mechanism(s) employed in this species.

Baker AJM, Reeves RD, McGrath SP 1991. In situ de-
contamination of heavy metal polluted soils using crops
of metal-accumulating plants-a feasibility study. In Situ
Bioreclamation, ecfs RE Hinchee, RF Olfenbuttel,  pp
539-544, Butterworth-Heinemann, Stoneham MA

Baumann A.1885. Das verhalten von zinksatzen gegen
pflanzen und imboden. Landwirtscha Verss 3:1-53

Brown SL, Chaney RL, Angle JS, Baker AM. 1995. Zinc
and cadmium uptake  by hyperaccumulator Thlaspi
caerulescens and metal tolerant Silene vulgaris grown
on sludge-amended soils. Environ Sci Technol 29:1581 -

Byers HG. 1935. Selenium occurrence in certain soils
in the United States, with a discussion of the related
topics. US DeptAgricTechnol Bull 482:1-47

Chaney RL, LiYM, Angle JS,  Baker AJM, Reeves RD,
Brown SL, Homer FA, Malik M, Chin M. 1999. Improv-
ing metal hyperaccumulators wild plants to develop com-
mercial  phytoextraction  systems:  Approaches and
progress. In Phytoremediation of Contaminated Soil and
Water,  ecfs N Terry, GS BaZuelos,  CRC Press,  Boca
Raton, FL

Chaney RL. 1983. Plant uptake of inorganic waste. In
Land Treatment of Hazardous Waste, ecfs JE Parr,  PB
Marsh, JM Kla, pp 50-76, Noyes Data Corp, Park Ridge
Ebbs DS, Lasat MM, Brady DJ, Cornish J, Gordon R,
Kochian LV. 1997. Phytoextraction of cadmium and zinc
from a contaminated site. J Environ Qual 26:1424-1430

Eide D, Broderius M, Fett J, Guerinot ML. 1996. A novel
iron-regulated metal transporter from plants identified
by functional expression in yeast. Proc Natl Acad Sci
USA 93: 5624-5628

Glass DJ. 1999. Economic potential of phyto re mediation.
In Phytoremediation of Toxic Metals: Using Plants to
Clean up the Environment, ecfs I Raskin, BDEnsley, pp
15-31, John Wiley & Sons  Inc, New York, NY

Grotz N, FoxTC, Connolly E, Park W, Guerinot ML, Eide
D. 1998. Identification  of a family of zinc transporter
genes from Arabidopsis that responds to zinc deficiency.
Proc Natl Acad Sci USA 95: 7220-7224

Hartman WJ, Jr. 1975. An evaluation of land treatment
of municipal wastewater and physical siting of facility
installations. Washington DC; US Department of Army

Lasat MM, pence NS, Garvin DF, Ebbs SD, Kochian LV.
2000. Molecular physiology of zinc transport in the Zn
hyperaccumulator Thlaspi caerulescens. J Exp Botany

Lasat MM, Baker AJM,  Kochian LV. 1998. Altered Zn
compartmentation in the root symplasm and stimulated
Zn absorption into the leaf as mechanisms involved in
Zn hyperaccumulation in Thlaspi caerulescens. Plant
Physiol 118:875-883

Lasat MM, Baker AJM, Kochian LV. 1996. Physiological
characterization of root Zn2+ absorption and transloca-
tion   to  shoots  in  Zn  hyperaccumulator  and
nonaccumulator species of Thlaspi. Plant Physiol 112:

Mengel K, Kirkby EA. 1987. Principles of Plant Nutri-
tion, Ed 4. International Potash Institute, Bern, Switzer-

Minguzzi C, Vergnano 0.1948. II contento di nichel nelli
ceneri di Alyssum  bertlonii Desv. Atti della Societa
Toscana di Science Natural!, Mem Ser A 55:49-77

Rascio W. 1977. Metal accumulation  by some plants
growing on Zn mine deposits. Oikos 29:250-253

UtsunamyiaT. 1980. Japanese Patent Application No.

                         T. arvense
                    O  T. caerulescens
                 0   20   40   60   80   100  120  140 160 180  200
                                     Time (min)
Figure 1. Short-term time-course of 65Zn accumulation in roots. Roots of intact T.
arvense and T. caerulescens seedlings were immersed in an uptake solution containing 10
HM 65Zn. At the end of the time intervals shown, roots were desorbed for 15 min to remove
cell wall bound Zn. Following desorption, roots were separated from shoots, blotted,
weighed and gamma activity (65Zn) measured.

                2.4- '
          3 £
 * i/i


0.4- '

0.2- :

                      A) Roots
                   .. B) Shoots
                                          T. arvense
                                      "O" T. caerulescen,
                    0 20  30  40  50  60  70  80  90  100
                                   Time (h)
                            i  i
Figure 2. Loi^-term time-course of s%a accumulation in: A) roots and B) shoots of T.
arvense and T. caerulescens. Roots of intact seedlings were immersed in a radioactive uptake
solution containing 10 /zM65Zn. Following inciabation periods shown, roots were desorbed for 15
mia Roots were then excised, blotted, and both toots and shoots weighed and gamma activity

a "?
0 ox
3 fl
« S3
               D   r. caerulescens
T.  arvense
Figure 3. Time course of ^Zn accumulation in leaf sections of the two Thlaspi species.
Leaves of T. arvense and T. caerulescens seedlings were cut into 10 to 20 mm2 sections and
immersed in an uptake solution containing 1,000 uM65Za Following exposure times shown, leaf
sections were desorbed for 15 minutes. Leaf sections were then harvested, blotted, weighed, and
gamma activity measured.

    Zn adequate medium
Zn restrictive medium
Figure 4. Functional complementation of yeast Zn transport deficient mutant, zhy3, with T.
caerulescens Zn transporter gene, ZNT1. In A, growth medium contained adequate Zn levels. In B, growth
medium was supplemented with EDTA to maintain low Zn activity. Wild type yeast, wt, grew in both media.
However, the growth of Zn transport deficient yeast mutant, zhy3, was precluded on Zn restrictive medium
due to mutant inability to acquire Zn from low external supply. Transformation of zhy3 with ZNT1 restored
the growth of yeast mutant on the medium containing low Zn level (B).

           u  d
           a  ,«
           fl  £
          N  §
          s   s
                  6 „




                            pZNTl, z/ry3 yeast+ZNH
                            z/i.y3, Zn transport defective
                              2      5    10     20    40
                                 65Zn concentration
                                                   60     80
Figure 5. Zn uptake in yeast Zn transport defective mutant, zhy3, and in yeast mutant transformed with
ZNTL Cells were exposed to65Zn concentrations shown. After 20 min, cells were separated from the uptake
solution by centrifugation through a layer of silicon oil and gamma activity measured.

              TC    TA    TC    TA    TC   TA   TC    TA
Figure 6. Northern analysis ofZNTl expression in shoots and roots of T. caerulescens (TC) and T. arvense
(TA) grown on Zn-sufficient (+) or Zn deficient (-) medium.


                            Chasing Subsurface Contaminants
                                      Joel G. Burken, Ph.D., BIT
                             Assistant Professor, Civil Engineering Department
                                       University of Missouri-Rolla
                                     Rolla, Missouri 65409-0030
Dr. Burken received his Ph.D. in Civil & Environmental
Engineering from the University of Iowa,  December
1996. He subsequently took a position as an Assistant
Professor of Civil Engineering at the University of Mis-
souri- Rolla.The primary focus of his research has been
in the area of phytoremediation of organic pollutants.
Dr. Burken has authored 11 articles and book chapters,
primarily in the area of phytoremediation. Dr. Burken's
work has resulted in a 1999 National Science Founda-
tion Career Award, a  1999 Faculty Excellence Award
from the University of Missouri-Rolla, and the  1998
Rudolph Hering Medal for the Most Valuable Contribu-
tion to the Environmental Branch of Engineering, Ameri-
can Society of Civil Engineers.

Dr. Burken is the advisor to the UMR Student Chapter
of Water Environment Federation, assistant advisor to
Chi Epsilon Civil Engineering Honor Society, and advi-
sorto Department of Conservation StreamTeam #1293.
He also serves as Chairman of the Student Organiza-
tions Committee -Assoc. of Environmental Engineering
& Science Professors and as Vice President/President
elect; Midwest Missouri Section, American Society of
Civil Engineers.

This talk investigates the mechanisms that can impact
the translocation and  fate of contaminants  in the sub-
surface, in a theoretical look at contaminant transport
in a phytoremediation  system. Laboratory data pertain-
ing to uptake, transport, degradation, and volatilization
will be used to gain  better understanding of these
mechanisms in action. Finally the talk includes an over-
view of how these mechanisms might be impacted when
moving to field-scale  systems and of why field results
and laboratory results are somewhat divergent.

Phytoremediation of organic contaminants has rapidly
grown from a  novel idea to a full-scale treatment pro-
cess in under a decade. When a literature search was
performed in 1991, the literature search engine used
produced only six papers in total. The majority of the
papers that were located  focused upon metals
remediation,  which  was the first use  of plants in
remediation of contaminated sites. Since that time, there
has been a "chase" in the field of organic contaminant
phytoremediation. This chase has led to numerous stud-
ies into the impacts that plants have on contaminated
sites. Figure 1 highlights the mass flows and biological
processes of plants.  Studies  have focused upon the
interaction of contaminants and plant systems, investi-
gating how these processes can be exploited for use in
remedial efforts. The summary presented here will over-
view studies performed at the University or Iowa  and
University of Missouri-Rolla, as well as related studies
from other sources.

Rhizodegradation  is the enhanced degradation of or-
ganic contaminants in the rhizosphere. The rhizosphere
is  considered to be the area of soil impacted by the
vascular root system of plants.  Definitions of the rhizo-
sphere range from the soil volume in intimate contact
with the root system, extending only a few millimeters
out from the roots, to much of the vadose zone, where
the impacts might  be physical disturbance of the over-
all soil structure, to altered watertable elevation. In the
close proximity of the roots, there are known to be
greater microbial populations than in the bulk soil.  Re-
ports have shown that microbial populations  are an av-
erage of 2- to 10-fold greater in the rhizosphere than in
bulk soil. With the greater microbial numbers, increased
microbial degradation was expected.  In many studies
there has been  an increase in the microbial degrada-
tion and even mineralization  (Anderson and  Walton,
1995; Aprill and Sims, 1990; Schwab and Banks, 1994).
However in some experiments, the mineralization  of
organic compounds was actually decreased (Nairefa/.,
1993). The decreased mineralization was contrary to
the anticipated results.  Further study into the fate  of
organics in plant/soil systems  brought about new hy-
potheses and new considerations. One consideration
is the population dynamics of the rhizosphere microbes.
While total microbial numbers are generally higher in
the rhizosphere, it has also been shown  that certain
strains can predominate in the rhizosphere.  If these
microbes are not capable of degrading the contaminants
of concern, microbial degradation could be suppressed.
Another hypothesis that could explain the decreased

                     CO2+ H2O
                                                               O2 + exud ates
                                                               e.g. CHsCOOH
                    Figure  1.  Mass flows in Populus spp. that may impact organic
                    contaminants in phytoremediation. (Burken, 1996)
mineralization in the rhizosphere is altered availability
of the contaminants to the microbes present. Plant up-
take of the organic contaminants is a potential fate path-
way that can make the contaminants unavailable for
microbial degradation. In total, the effect of the rhizo-
sphere is considered to  be beneficial concerning the
fate of organic contaminants, however this is far from
being a universal constant.

Uptake in Laboratory Studies
Phytodegradation is the plant-mediated metabolism of
contaminants.  The term "plant-mediated" is used be-
cause in many cases the true mechanism of degrada-
tion is not  fully known and could include microbial
contributions. However, direct metabolic activity by the
plants has been  proven.  The first step in the
phytodegradation process is the interaction (or contact)
of the plant and contaminant. This often occurs through
transport of the organic compounds with the water used
by the plants.  Studies with atrazine that showed de-
creased mineralization in soil systems also showed that
atrazine was taken  up with the transpiration stream
(Burken and Schnoor, 1997).  In 14C-labeled atrazine
studies conducted in the laboratory, plant tissues were
shown to contain large fractions of the 14C at the termi-
nation of the experiments with the uptake being vari-
able with soil and  plant conditions.  Such uptake has
been shown for a variety of compounds and a variety of
plants.  Early work by Shone and Woods (1972) dis-

played the ability of organic compounds to be trans-
ported from soil water or hydroponic solutions into the
plant tissues  and move along with the transpiration
stream. This "translocation" has been examined in many
studies. The earliest studies on the uptake of organic
compounds were looking at herbicidal compounds and
crop species.  Research by Briggs et al. (1982) pro-
posed  relationships for the uptake of herbicides (o-
methylcarbamoyloximes and substituted phenylureas)
by barley plants.  The uptake of the compounds was
related to the octanol-water partition  coefficient, K^.
Uptake was presented as the Transpiration Stream Co-
efficient Factor (TSCF). The TSCF is defined as the
concentration in the transpiration stream of the plant
divided by the concentration in  the aqueous solution
the plant is growing in at the time. Determining the tran-
spiration stream concentration has been approached
in many ways.  In some studies the final concentration
in the plant after the uptake has occurred is measured
(Briggs, et al. 1982; Burken and Schnoor, 1998) and in
other studies the concentration in the stream has been
directly measured (Hsu  et al., 1990).  The TSCF rela-
tionships that have been developed are not precise, but
show a general trend related to the Log Kow of the com-
pound in question. Uptake from aqueous°solutions ap-
pears to be highest for compounds  with a Log Kow
between 1.5 and 3.5. The plant in question also plays a
large role in the uptake,  i.e. uptake is species-specific.
Briggs et al. (1982) compiled data from many studies
and plotted the data vs. the relationship which they pro-
posed.  For the  same  contaminants, uptake varied
greatly between uptake studies on  lettuce and turnip
vs. carrot and parsnip or vs. barley and wheat.

The uptake of contaminants varies greatly with the avail-
ability of the contaminant. In the case atrazine, uptake
was greatly impacted by the soil or media in which the
poplar cutting was grown. In relatively organic carbon-
free silica sand, uptake of over90% of the applied label
occurred in less than ten days. Whereas in an organic
carbon-rich silt loam, uptake reached a relative maxi-
mum of 20% of the applied label after 80 days. A mod-
eling approach by Ryan  et al. (1988) approximated the
impact of soil organic matter, predicting the uptake-in-
hibiting effect that was shown in the atrazine studies
discussed  here.  In  this  model, the compounds with a
Log Kow between  1 and 2 are still mobile in the soil pro-
file an°d are taken up in the transpiration stream.  This
approach shows the importance of environmental con-
ditions.  Many of the uptake studies have been con-
ducted in hydroponic laboratory studies, without the
impacts of sorption to soil. The conditions of experi-
ments such as growth media, lighting, and reactor de-
sign should be considered when interpreting data that
is gathered.  Experimental  conditions can greatly im-
pact the outcomes.

Phytodegradation and Volatilization
Contaminants that enter plant tissues can still have a
number of fates.  Compounds can  be  retained in the
tissues as the parent compound. Retention of the par-
ent compound is an undesired fate, as it could increase
the availability of the compound to insects and herbi-
vores, and thus entry into the food chain. Retention
and storage has been observed for some  compounds
such as RDX (Thompson et al.,  1999), but this does
not appear to be the fate most commonly observed.
Even RDX concentrations appear to dissipate in plant
tissues over time (Burken et al., 2000). Compounds
can also be metabolized when retained in plant tissue.
A number of studies have shown plant metabolism to
occurfor a number of compounds (Hughes  et al., 1997;
Newman  et al., 1997; Bhadra et al., 1999).  One model
of plant metabolism that has been put forth and sup-
ported suggests that compounds translocated by plants
can subsequently be transformed, conjugated, and se-
questered permanently in the tissues. The term "green-
liver model" has been used to describe this  metabolism
(Sandermann, 1994;Trapp1995). Plants generally rely
on photosynthates as  their carbon source and thus
metabolism of xenobiotic compounds is considered to
be a defense mechanism, and thus the term  "green liver."
The three steps are a sequential process. After a com-
pound has entered the plant tissues, a transformation
step takes place in the green liver process. Hydrolysis
reactions are the predominant transformation, although
reduction and oxidation reactions have also been  ob-
served (KomoBa et al.,  1995).  Hydroxylation reactions
have been identified as a key first step and have been
shown to  be catalyzed by cytochrome P-450.

Conjugation reactions are the  second  step in  the
green liver model. Compounds synthesized  by  the
plant are responsible  for the conjugation.  Glucose
and malonate are  examples  of the plant generated
conjugating compounds that  are added to the trans-
formation product by glucosyltransferases  and
malonyltransferases, respectively (Coleman  et  al.,
1997).  Sequestration is the  final step in the green
liver model.  Conjugation is followed by  sequestra-
tion in the lignin fraction or in the cell vacuole. Once
sequestered, these compounds are commonly called
"bound residue."  Bound residues exhibit very  low
bioavailability. Numerous studies have investigated the
fate of compounds that have been sequestered and
generally have found that parent compounds are  not
available, however some studies have questioned the
bioavailability to ruminant animals. In most cases the
complete impact of the bound residues is  not fully un-

Volatile organic compounds (VOCs) have  yet another
potential fate following uptake into plant tissues. Labo-
ratory studies have shown that VOCs are transpired or
volatilized from plant tissues  (Newman et al., 1997;
Burken and Schnoor, 1997). These studies  have shown
that compounds such at trichloroethylene (TCE) can
be captured in the off-gas from the aerial portion of hy-
brid poplars. However  in many field locations, studies
searching forVOCs from leaves enclosed in teflon bags
(Newman et al., 1997; Compton et al., 1998) or using
FTIR analysis, have found little detectable volatilization.
Recent studies detected chlorinated VOCs  (TCE, tetra-
chloroethylene,  and dichloroethylene)  (Vroblesky

et a/., 1998, Schumacher and Burken 2000), while BTEX
compounds, MTBE and other hydrocarbons have also
been detected in tree cores  at a number  of sites
(Landesmeyer, 2000). These tree core studies have
shown clear evidence that VOCs are in the transpira-
tion stream within the tree trunks, however VOCs are
not being detected in the leaf tissues at similar concen-
trations or emanating from the leaves.

The differences mentioned above, regarding the volatil-
ization of VOCs from the  plant tissues, is  a prime ex-
ample of the disparity that can exist between laboratory
and field studies.  Laboratory studies are designed to
isolate certain reactions or interactions and remove as
much variability as possible. Only by eliminating  incon-
sistencies except for the experimental variables being
studied, can the impacts  and rates  of the  variables in
question be understood.  In doing so, laboratory stud-
ies become inherently non-representative of the  condi-
tions that exist in nature.  Many laboratory studies are
done with plant cell cultures, plant cultures, sterile con-
ditions, and artificial lights. While these studies do pro-
vide  much knowledge right down to the molecular level
of plant metabolism, they do not provide information that
is directly transferable to  field conditions.  Laboratory
studies should obviously  be conducted and the data
gathered be closely examined.  However the  findings
gathered should not be used alone for field design.

Engineering Advancements
The current state of the art for phytoremediation gener-
ally relies on the inherent capabilities of plant systems,
and applying the plant systems in ways to utilize the
inherent capabilities to remediate contaminated sites.
This approach generally leads to planting contaminated
sites and little more. Some applications have gone be-
yond this to incorporate current engineering techniques.
One such application is the use of impermeable sleeves
to encase hybrid poplar cuttings. This method was pio-
neered and  patented  by Applied Natural Systems of
Ohio. In this method, the poplars are  planted to great
depths and rooting is "forced" at the depth as the open
end of the sleeve is the only source  of water. Other
design aspects must be addressed to allow the trees to
survive this type of planting. At another site, the Ports-
mouth Gas Diffusion Plant in Ohio, contaminated ground
water at a considerable depth was treated in a different
manner.  The contaminated groundwater was located
beyond the reach of conventionally rooted hybrid pop-
lars in a confined aquifer, which was  at pressure.  In
order to use phytoremediation the contaminated water
must  be brought into contact with the  poplar trees. To
bring  the contaminated water to the trees, bore holes
were drilled in the impermeable clay layers that overlay
the confined aquifer, and the bore holes were backfilled
with sand. The natural potential of the water (pressure)
forced the water to up-well through the bore holes and
into trenches where the trees were planted. This method
served as a natural "pump and treat,"  where the pres-
sure in the confined aquifer delivers the water to the
rooted poplars and the transpiration by the poplars con-
tinues to pump the water from the trenches. A sche-
matic of this system is seen in Figure 2 (Rieske et al.
              Figure 2 A. Shows the site prior to treatment. B. Shows the current phytoremediation
                        application where: 1. Trenches were formed, 2. Bore-holes were placed through
                        the confining aquitard to the underlying, contaminated aquifer, 3. Hybrid poplar
                        and willows were planted, 4. Proposed movement of contaminated water up bore-
                        holes to phytoremediation system planted above.


Engineering the way that phytoremediation tools are
applied is one method that can have benefit. Engineer-
ing of the phytorel mediation tools at the molecular level
is  another  way that engineering can  improve
phytoremediation. Currently, efforts are underway at a
number of institutes to engineerthe metabolic capabili-
ties of the plants themselves. These efforts range from
engineering metal resistance into plants, engineering
metal transformation pathways, orengineering enzymes
to metabolize organic contaminants. These methods
of engineering the plants themselves lead to enhanced
results  in phytoremediation applications (Hooker and
Skeen, 1999). Other methods to reach the same end
result, degradation and even mineralization, include en-
gineering the plant-microbe symbiotic relationship. Re-
searchers have  taken the approach to  inoculate the
seeds or cuttings used in phytoremediation with organ-
isms known to degrade the targeted pollutants (Siciliano
and Germida, 1998). Other research has taken the ap-
proach to inoculate the seeds or cuttings with geneti-
cally engineered microorganisms (Yee et al 1998,
Crowley et al. 1996). Some results of such efforts can
be seen in the speakers notes associated with this talk,
and in Figure 3. In the experiment that generated these
       data, microbes were cultured from hybrid poplar cut-
       tings.  These cultures were selected from plating the
       natural hetertrophs growing  on the poplar roots and
       selecting colonies that appeared to be most prevalent.
       A genetic sequence for a toluene-o-monoxygenase
       (TOM) was then incorporated in the host genome and
       recombinant strains were generated. These recombi-
       nants and others generated from two rhizobium strains
       acquired from the American Test Culture Center (ATCC)
       were tested for growth rates and TCE degrading ca-
       pacity. Figure 3 shows the results where two recombi-
       nants (one from the poplar rhizosphere  and one
       rhizobium) were able to degrade the TCE in the sealed
       reactors.  This and  other related  work prove that the
       concept of combining genetically engineered microbes
       has tremendous potential and requires further study.

       Concluding Comments
       Phytoremediation of organic contaminants has under-
       gone a number of rapid advancements. Following these
       rapid advancements in the field and  in laboratory re-
       search, gaps have appeared between the understand-
       ing  of the science involved and the application in the
       field. As these gaps have appeared, the best efforts
         P   0.04
5                    10

    Time (days)
                        Figure 3 TCE concentrations in sealed 2 liter reactors.
                        Sampling was done in the headspace.  The two reactors
                        inoculated with recombinant strains pb 3-1 and rhizobium

have been made to ever increase our understanding of
what is happening and how the systems can  be  im-
proved, thus the "chase of contaminants" has contin-
ued. This chase has come to include molecular sciences
and genetic engineering, and the current indication is
that this chase will continue and that the successful ap-
plication and redefining of phytoremediation systems
will also continue.

Anderson, T.A. and B.T. Walton. "Comparative fate of
14C trichloroethylene  in the root zone of plants from a
former solvent disposal site" Environ. Toxicol. Chem. 14,

Aprill, W.S. and R.C. Sims. "Evaluation of the use of prai-
rie grass for stimulating PAH treatment in soil." Chemo-
sphere,  20,253-265,1990.

Briggs, G.G., R.H. Bromilow, and A.A. Evans. "Relation-
ships between lipophicity and root uptake and translo-
cation of non-ionized chemicals by barley." Pestic. Sci.

Bhadra, R., D. Wayment, J.B. Hughes, and J.V. Shanks.
"Characterization of oxidation products of TNT metabo-
lism in aquatic  phytoremediation  systems of
Myriophyllum aquaticum" Environ. Sci. Tech. 33:3354-

Burken, J.G. 1996. Ph.D. Thesis, University of Iowa.

Burken,   J.G.,  J.V.  Shanks,  PL.  Thompson.
"Phytoremediation and plant metabolism of explosives
and nitroaromatic compounds."  In: Biodegradation of
Nitroaromatic Compounds and Explosives, J.C. Spain,
J.B. Hughes, H.J. Knackmuss (eds.) Lewis Pubs. Boca
Raton, FL. 2000,239-276.

Burken, J.G. and J.L. Schnoor.  "Uptake and metabo-
lism of atrazine  by hybrid  poplar trees." Environ. Sci.
Technol. 31:1399-1406,1997.

Burken, J.G. and J.L. Schnoor. "Predictive relationships
for uptake of organic contaminants  by hybrid  poplar
trees." Environ. Sci. Technol. 32:3379-3385, 1998.

Coleman, J. O. D., M. M. A. Blake-Kalff, and T G. E.,
Davies. "Detoxification of xenobiotics by plants: chemi-
cal modification and vacuolarcompartmentation." Trends
Plant Sci. 2:144-151,1997.

Compton,  H.R., D.M.  Harosi,  S.R. Hirsch, and J.G.
Wrobel. "Pilot-scale use of trees to address voc con-
tamination." In Bioremediation and Phytoremediation,
Chlorinated and Recalcitrant Compounds. G.B.
Wickramanayake and  R.E. Hinchee, (eds.), Battelle
Press, Columbus, OH.  1998.

Crowley, D. E., M. V. Brennerova, C.  Irwin, V. Brenner,
and D. D. Focht.  "Rhizosphere effects on biodegrada-
tion of2,5-dichlorobenzoate by a bioluminescent strain
of root-colonizing Pseudomonas fluorescens" FEMS
Microbiol. Ecolo., 20, 79-89, 1996.

Hooker,   B.S,  and  R.S.  Skeen.  "Transgenic
phytoremediation blasts onto the scene." Nature/
Biotechnol. 17:428,1999.

Hsu, F.C., R.L. Marxmiller, and A.Y.Yang. "Study of root
uptake andxylemtranslocation of cinamethylin and re-
lated compounds in detopped soybean roots using a
pressure  chamber technique." Plant Physiology.

Hughes, J. B., J.V. Shanks, M.Vanderford, J. Lauritzen,
and R. Bhadra.."Transformation of TNT by aquatic plants
and plant tissue cultures." Environ. Sci. Technol. 31:266-

Komo(3a, D., C. Langerbartels and  H. Sandermann.
"Metabolic processes for organic chemicals in plants."
In Plant contamination - modeling and simulation of or-
ganic chemical processes. Trapp, S. and J. McFarland
(ed.). CRC Press. 1995.69-103.

Landesmeyer, J. this document. 2000.

Nair, D.R., J.G. Burken, L.A. Licht,  and J.L. Schnoor.
"Mineralization and uptake of triazine pesticide in soil-
plant systems." ASCE J. Environ. Eng., 119, (5) 842-

Ryan, J.A., R.M. Bell, J.M. Davidson, and G.A. O'Connor.
"Plant uptake of non-ionic organic chemicals from soils,"
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Newman, L. A., S. E. Strand, N. Choe, J. Duffy, G. Ekuan,
M. Ruszaj, B. Shurtleff, J. Wilmoth, PE. Heilman, M.P
Gordon. "Uptake and transformation of TCE by hybrid
poplars." Environ. Sci. Technol. 31, 1062-1067, 1997.

Rieske, D.E., G.W. Snyder, T.L. Grossman. "Trench and
'Sand pipe'design for phytoremediation of chlorinated
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 Chasing Subsurface Contaminants
    Joel G. Burken, Assistant Professor

    Department of Civil Engineering
    University of Missouri-Rolla
  What's in a title?
  Mechanisms at work
  Lab Stories
  Looking Back
  Looking Ahead

Rationale: Why chase

• Solar driven pumps, with metabolic
  abilities and many potential advantages.
• Plant/organic chemicals research was
  primarily agri-crop related <1990.
• Laboratory studies provide laboratory
  Remediation is not completed under lab
  conditions.. The Chase Continues

Held of Phytoremediation
    •f Phytoextraction - uptake & harvest, goal of 1%
    •f Rhizofiltration - binding to roots, generally aquatic
    •f Physical stabilization - less transport & leaching

    •f Uptake - transport to above ground, ?fate?
       * Phytodegradation - Direct metabolism
       * Volatilization - Direct from leaf/plant tissues
    •f Rhizodegradation - increased degradation & binding
    •f Physical stabilization - less transport & leaching

Story of Atrazine
  Most widely used herbicide, found in
  groundwater, surface water, even rainwater.
  Persistent, will degrade aerobically,  but slowly'
  No efficient treatment methods.
      plants increase degradation?
 NO.  Plants decreased mineralization in all tests.
      Root biomass stimulated some degredation.

Poplar Uptake of 14C Labeled Atrazine from
Sit-Loam SD!! (2.4%om) (trans, inmL/d)
            Silt Loam
                                    Model, T=51
                                    Model, T=43
                                    Model, T=38
                        Time, Days
Atrazine degradation:
8 products were found,
suggested compounds
    Proposed Mechanism:
    Products not confirmed



Hydroponic Reactor, VOC studies
       Air Flow.
traps      VOC trap,\
         ORBO tube
                                      Air Flow.
       Airtight separation of
       aerial and subsurface
                         Root zone, N,
                        growth media
                              sampling &
                              feeding valve

Volatile Organic Compounds
  What is the impact of plants in VOC contaminated sites?
  Alfalfa did not enhance degradation of benzene in
  laboratory studies.
  Stomatal pathways dominated uptake & transformation.
  Benzene and toluene conversion in leaves occurs with
  the aromatic ring cleavage & incorporation.
  Benzene oxidation by intact chloroplasts and enzyme
  preparation from spinach leaves resulted in  phenol being
  detected as an intermediate product.

Organic Compound Fate

• For all compounds the movement in the
  plant tissues was followed.
• Transpiration Stream Concentration Factors
  (TSCFs) were determined.
    TSCF =
Concentration in the Trans. Stream
Concentration in the bulk Solution

Briggsplot, TSCF, literature studies
    C-K—/  J.
                                        herbicides by barley
                                        Isoprothiolane by rice

                                        atrazine and linuron by
                                        carrot and parsnip
                                        atrazine and linuron by
                                        lettuce and turnip
                                        atrazine by wheat

                                        TSCF =
                                          0.784 exp -[(log £  -1
                  Log Kow

Laboratory Set-up
                       Light 210 umol/m2-sec,
                       mercury halide
                       16 hour photo period
                       20-30° C
                       Air t = 2 L/minute
                       Air b = 0.1- 0.5 L/minute
                       H20 « 100 mL/day
                       Benzene =  25 mg/L

14CIrput and Data

• Input of 15uCi, over a three day period
• Injected directly into the flow path, one
  time per day.
• Effluent 14C02to quantify mineralization,
  trapping effluent C02 in IN NaOH.
• Biological Oxidation of plant tissues and
  soil  samples, followed by LSC.



Summary VOC Hydroponic/Soil

• Effluent concentrations and mass were
  much greater for unplanted controls.
• Elevated soil levels of 14C02 were in the
  presence of the poplar cuttings.
• Storage of benzene or metabolites was
  negligible (0.27%) in plant tissues.
• Volatilization was much lower than
  hydroponic studies.
Summary, Looking back

• Root zone of planted reactors was aerobic,
  whereas the unplanted controls were 02
  deprived, requiring the utilization of
  alternate terminal electron acceptors (not
  02 required for aerobic respiration).
• Earlier hydroponic experiments appear to
  be adequate in some aspects, however
  uptake from the vadose zone is not

TCE degradation
 Recombinant  Specific growth rate (hr")  Initial TCE degradation rate
 Pb5-l A
 35645A ]
             Recombinant  Host     (mnol/min»ms protein)
  (poplar isolate)  Rhizobiumsp.   P. fluorescens

Genetically Engineered Materials/Phytoremedia

• Recombinant strains retain competitiveness.
• Recombinants are stable w.r.t. TOM activity
  and expression.
• No inducer needed (phenol, toluene).
• Plants appear to control viability of the
  GEMs, and there is specificity to plant
Why Phyto?

• Natural approach: Simplistic elegance,
• Long term solution-short term cost,
• Potentially favorable fates/outcomes,
  Restoration & remediation,
• Public Acceptance.

  Juel Gibbons, Carla Ross, Lisa Harrison, Lars
  Zetterstrom, Adrian Marsh (UMR), Tom Wood,
  Hojae Shim (U. Connecticut), Craig Just, Jerry
  Schnoor (U. Iowa), Lou Licht (EcoloTree)
  EPA Regions 7 & 8 - Hazardous Substances
  Research Center, Kansas State University
  Center for Environmental Science and
  Technology, University of Missouri-Rolla
  Department of Agriculture, #99-35106-8244

   Effect of Woody Plants on Groundwater Hydrology and Contaminant

                                        James Landmeyer
                                      U.S. Geological Survey
                                        720 Gracern Road
                                       Columbia, SC 29210
James E. Landmeyer, Ph.D., received a B.S. in Geol-
ogy/Chemistry from Allegheny College in 1989, and a
M.S. and Ph.D. in Geology/Microbiology from the Uni-
versity of South Carolina in 1991 and 1995, respectively.
He has been employed by the U.S. Geological Survey,
Water Resources Division, since 1990,  and currently
lives in Columbia, SC. His research interests include
how microorganisms and plants effect both pristine and
contaminated groundwater systems. He has authored
or co-authored more than 20 papers.

The effect  of woody plants on groundwater hydrology
and contaminant fate at two sites in South Carolina has
been investigated since the late 1990s. At the first site,
in 1998 up to 600 poplar trees (Populus deltoides x
Populus nigra - clone  DN-34) were planted at an his-
torically contaminated site near Charleston,  SC, cur-
rently undergoing significant commercial redevelopment.
The trees are now about 14-ft tall, and evidence from
excavation activities has confirmed that the roots have
grown down to about 1 -ft above the water table, located
about 4-ft  below land  surface. In this shallow aquifer,
groundwater levels have been  monitored using pres-
sure transducers placed in wells near representative
trees. In some cases, the lowest daily groundwater level
is around noontime, coinciding with the period of peak
solar radiation measured by an on-site PAR sensor. This
preliminary data provides at least indirect evidence that
even the 1-yr old trees were using ground waterto meet
transpiration demands (less than 0.1 gallons/day/tree).
The groundwater level fluctuation evidence is indirect,
however, because an  adjacent tidally  influenced river
also can potentially affect groundwater  levels. Nonethe-
less, the Penmann-Montieth equation was used to de-
termine the potential evapotranspiration rate (PET) for
these trees, using meteorological data collected at our
weather station located on site. As such, a PET rate of
0.55 in/day was estimated. When applied over the total
planted  area (18,000 ft2), this PET rate translates to
about 2,000 gallons of ground water/soil moisture used
per day.  Finally, because it has yet to be unequivocally
demonstrated that the young poplar trees are indeed
removing substantial amounts of ground waterfrom the
shallow watertable beneath the planted area, observed
changes in concentrations of dissolved-phase ground-
water contaminants (PAH's  and BTEX) in the aquifer
cannot yet be attributed to uptake by the trees.

At the second site, we examined the potential for previ-
ously established, mature (>40 years old) oak trees
(Quercus virginiana) growing above a gasoline plume
near Beaufort, SC, to take up and remove MTBE and
other gasoline compounds from a shallow aquifer con-
taminated by a leaky underground storage tank. Using
material cored from the oaks, MTBE and the conven-
tional gasoline compounds  benzene,  toluene,
ethylbenzene, and the isomers of xylene and
trimethylbenzene were detected and  identified using
purge-and-trapgas chromatography/mass spectrometry
methods in the live oaks located above the plume. Con-
versely, these gasoline compounds were not detected
in core material of oaks located outside of the gasoline
plume. This detection of gasoline compounds in trees
at a contaminated field site is important, particularly for
the more soluble and  less biodegradable MTBE, be-
cause it  provides unequivocal field evidence that trees
can act  as sinks to remove such contaminants from
groundwater systems. Moreover, if the uptaken MTBE
is volatilized from leaf surfaces, the half-life of MTBE in
the atmosphere is orders of magnitude less than the
range of half-lives of MTBE under aerobic or anaerobic
conditions in contaminated aquifer systems.

  Effect of Woody Plants on
   Ground-Water Hydrology
    and Contaminant Fate
       James E. Landmeyer
       U.S. Geological Survey

EPA Phyto Meeting, Boston, MA May 2000
    Two Field Sites in South
         Charleston (1998-)
         Beaufort (1997-)

      Main Objectives:
Can we get the poplar trees to grow?
Do poplar roots reach the water table
(2-4 ft below ground)?
Do the poplars use ground water?
Do the poplars effect ground-water
geochemistry (DO, etc)?
Do the poplars take up dissolved-
phase contaminants (PAHs, BTEX,


      Main Objectives:
Can poplar trees grow in Charleston?
Do poplar roots reach the water table (2-4
ft below ground)?
Do the poplars use ground water?
Do the poplars effect ground-water
geochemistry (DO, etc)?
Do the poplars take up dissolved-phase
contaminants (PAHs, BTEX, etc.)?

  Theoretical Approach
    Penmann Equation
Wind Speed
Air Temperature
Solar Radiation (400-700 nm)
Relative Humidity


  Results for Theoretical
   Ground-Water Use :
PET = 0.5 mm/hr (0.5 in/day) For 1-yr
old poplars
18,000 ft2 area of poplars planted
Est. GW use = 2,000 gpd (for 12 hour
Est. GWflux through area = 1,500
Need to monitor GW levels!

Ground-Water Fluctuations
 • Early August 1999
 • Late August-September 1999

   Early April 2000

Q. <
K. <
(D O
< O



     1.0 ]


     0.8 H

                      Date (August 1999)
                                             ^y t



 Estimated Ground-Water
Average Head Change
(about 0.12 inches)
0.12 inches over 4 ft2
0.30 porosity
0.08 gallons per day
per tree
Q = 0.0002 gpm
Average specific yield of 8 MW's at site
Less than 0.5 gpm

25   26     27    28   29     30     31

  Date (August 24 - September 2, 1999)

:ipitation (ii
u.io -



24 25 26 27 28 29 30 31 1 2

Date (August 24-September 2, 1 999)
                                              <•.!• U ' nVtrinO",,! f!

6      78      9      10     11

          Date (August 1999)


0.15 -
0.10 -
in o
o c
o o

4/6 4/7 4/8

L 4/9
         Date (4/5-9/00)

 6   8    10   12   14  16   18  20   22   24
           Hours (April 6, 2000)

    24   26   28   30   32   34   36   38   40   42  44   46  48

                         Hours (April 7, 2000)
   j "'"III III'ill'."I I  I"111,,"'-  '" III III li I,,,'"' '    -It'" III I III'' "' "III

0.26 i
    48  50  52   54   56   58   60   62   64   66   68   70   72

                          Hours (April 8, 2000)

72  74   76  78   80  82   84   86   88   90   92   94   96

                   Hours (April 9, 2000)


              (Dilution By
        78        9       10

          Date (August 6-11,1999)
678       9       10      11

         Date (August 6-11,1999)

Conclusions at Charleston
  Ground-Water Hydrology-
 - Trees survived drought (anecdotal)
 - Some evidence of plant uptake of
   ground water using transducers
 - Trees were 1 year old; Q=0.0002 gpm
 - No evidence of hydraulic "capture"
 - Tidal influences
 - Sap Flow in 2000
Conclusions at Charleston
  Contaminant Fate:
  -  PAHs and BTEX in ground water
  -  Evidence of some PAHs and BTEX in
    Tree Leaves using GC/MS
  -  BUT, inconclusive at this time if
    mechanism was by ground-water
    uptake, b/c of equivocal evidence of
    ground-water use by 1-vr old trees

Two Field Sites in South
     Charleston (1998-)
     Beaufort (1997-)




Ethyl benz
(Landmeyer et al., submitted)
                                                      '.>• • i

What about cross-media
 contaminant transfer?
MTBE half-life in anaerobic aquifer
on order of years

MTBE half-life in atmosphere on
order of hours to days

 Conclusions at Beaufort
Trees take up BTEX and MTBE
dissolved in ground water used for
No hydraulic "capture", b/c flow rate
is too fast (100+ ft/yr) and ground
water too deep (16 ft)


       Modeling Plume Capture at Argonne National Laboratory  - East
                                           John J. Quinn
                                 Environmental Assessment Division
                                    Argonne National Laboratory
                                         Argonne, IL 60439
John J. Quinn has a B.S. in geosciences and a B.S.E. in
geo-engineering from Purdue University and an M.S. in
hydrogeology from the University of Minnesota. His ten
years of work experience have been focused on ground-
water and soils projects. For seven years, he has been
a staff member at Argonne National Laboratory and has
conducted work for numerous DOE and DOD sites. His
interest in phytoremediation stems from his involvement
in the ANL site's phytoremediation project.

Phytoremediation is becoming a viable technology for
remediating  volatile organic compounds (VOCs) and
other contaminants in groundwater and soil. Phreato-
phytes such  as poplars transpire VOCs through their
leaves during the growing season, metabolize VOCs in
the rhizosphere through the biotic activity of fungi and
bacteria growing symbiotically along the roots, and de-
press water levels in an aquifer by removal of ground-
water through transpiration. One technique is the use
of engineered systems of hybrid poplars with roots di-
rected to relatively deep aquifers.

In 1999, approximately 450 such poplars were planted
in a groundwater remediation project at Argonne Na-
tional Laboratory-East (ANL-E), near Chicago. Trees
were planted in large-diameter boreholes drilled through
approximately 30 ft of glacial tills and perched saturated
zones to a contaminated sand and gravel unit.The bore-
holes were lined with plastic and filled with mixtures of
topsoil, manure, and sand to constrain the developing
roots downward.

Groundwater modeling was performed to evaluate the
anticipated effects of the trees on the groundwater flow
system. Initially the modeling determined best estimates
of input parameters and boundary conditions to pro-
vide a suitable match to pre-remedial transient condi-
tions. Then the future effects of mature, deep-rooted
hybrid poplars on the flow system were  modeled,  in-
cluding transient seasonal effects. Estimates of the
transpirative  stresses of the poplars were developed to
model the month-by-month water use of the developing
trees. The modeling suggests that the  mature trees will
provide containment of groundwater from the upgradient
source areas despite the trees'dormant winter periods,
and groundwater will have a residence time of 5 to 17
months in the microbially active rhizosphere of the pop-
lars. During the summer, dewatering of portions of the
aquifer is likely due to the high water demand of the
trees combined with the decreased flux of water into
the aquifer.

Phytoremediation offers the potential for remediating
groundwater and soil with the following benefits:  rea-
sonably low installation cost, remediation within a suit-
able time frame, low operation and maintenance costs,
aesthetic value, low ecological impact, and public ap-

In the last decade, hybrid poplars have been studied to
determine their ability to remove or destroy contami-
nants such as volatile organic compounds (VOCs). Other
advantages of using poplars in certain phytoremediation
systems include their fast growth rates and their ability
to use vast amounts of water. Poplars can achieve
growth rates as  high as 10 to 16 ft/yr (3  to 5 m/yr)
(Chappell, 1998). While they can transpire tremendous
amounts of water (Nyer and Gatliff, 1996), the rate var-
ies, depending  on climatic factors and tree density
(Chappell  1998). Their ability to lower the water table
indicates that they have the potential to provide ground-
water containment (Nyer and Gatliff, 1996; Compton et
al., 1998; Newman et al., 1999).

Poplars are phreatophytes; they extend their roots into
the capillary fringe and can survive periods of being
within the saturated zone of an aquifer as water levels
fluctuate. Because phreatophytes send roots into both
the vadose and phreatic zones, they have the potential
to remediate soil, groundwater, and saturated soil me-
dia. In terms of total root length, a stand of poplars  may
have as much as 75,000 miles per acre (300,000 krn
per hectare) (Gordon etal., 1997).The subsurface  may
consist of units of widely varying lateral or vertical ex-
tent, with gradational or sharp transitions in permeabil-
ity. The fibrous nature of the roots allows the trees to
penetrate and remediate both the relatively fast-flowing
pore spaces and the less permeable zones. Fundamen-

tally, this distinguishes phytoremediation from extrac-
tion wells, which remove water mainly from the most
permeable aquifer media (Gatliff, 1994).

Groundwater modeling was performed in support of a
large-scale phytoremediation project. The modeling fo-
cused on evaluating the seasonal containment capabil-
ity of a  deep-rooted  hybrid poplar  phytoremediation
system installed at Argonne National Laboratory (ANL)
in June 1999. The study included a detailed analysis of
subsurface hydrogeological conditions, seasonal hydro-
logic changes,  and  the  seasonality  of  the
phytoremediation system. Animated visualizations were
generated to facilitate understanding the  results. The
large-scale program and the complexity of the subsur-
face make the site challenging in terms of understand-
ing  its  history, hydrogeology, seasonality,  and
implementation of the remedial technology.

Study  Area
Past waste disposal practices at the 317 and 319 Ar-
eas at ANL near Chicago, Illinois have resulted in the
presence of VOCs and tritium in groundwater. Histori-
cal groundwater VOC concentrations  near the 317
French Drain have been  in the thousands and ten of
thousands of parts per billion. Contaminants are trans-
ported off the ANL property at fairly low concentrations
and appear at several seeps in ravines of adjacent for-
est preserve property. In 1999, a groundwater and soil
treatment program was initiated that relies on
phytoremediation to (1) provide hydraulic containment
in the aquifer of concern,  (2) extract and transpire con-
taminants, (3) incorporate and/or degrade the contami-
nants in the  biomass, and (4) cometabolize VOCs in
the root  zone. More than 800 trees were planted in the
summer of 1999 to achieve these goals. Willows were
generally planted at the surface in areas of contami-
nated soil. Four hundred twenty poplars were specially
installed using TreeWellTm technology.These trees were
planted in 2-ft (0.6 m) diameter caisson boreholes lined
with  plastic sleeves in order to  direct the  roots to the
main contaminated aquifer, exclude shallow groundwa-
ter, and optimize deep groundwater removal efficiency.
This technology was  necessary for implementing the
phytoremediation system because  of the  site's
hydrogeological setting. The boreholes were filled with
a mixture of topsoil, sand, peat, and manure to pro-
mote root growth and tree development.

The study focused on modeling the predicted effect of
the engineered deployment of the 420 specially installed
poplars with  roots directed to a confined aquifer 25 to
30 ft (8 to 9 m) deep. An additional 389 surficially planted
willows and poplars were not included in the analysis
because their  purpose is to remediate contaminated
soil or shallow groundwater that is essentially separated
from the aquifer of interest.
Hydrogeological Setting And Conceptual
Flow Model
The subsurface is a complex arrangement of approxi-
mately 60 ft (18 m) of glacial  geologic deposits over
Silurian dolomite bed rock. The glacial sequence is com-
posed of Lemont Drift overlain by the Wadsworth For-
mation. Both units are dominated by fine-grained,
low-permeability till. Permeable zones of varying char-
acter and thickness are present in each.These materi-
als range from silty sands, to sandy, clayey gravels, to
gravelly sands. In some locations, pure silt is encoun-
tered. If deep enough, this silt is saturated and assumed
to play an important role in the flow of groundwater in
the study area. The permeable zones vary widely in
shape, including thin, lenticular, alluvial deposits; thick
plugs of possible slump or  channel-fill material;
interfingerings; and a thick, basal, proglacial sand and
gravel. In general, the permeable units are poorly sorted,
and many of them may represent slope-induced mass
movement, which results in transport and mixing of sedi-
ments (e.g., Lawson, 1982). Their thicknesses range
from less than 1 ft (0.3 m) to roughly 15 ft (4.5 m), and
they have limited lateral extent.

The modeling was focused on phytoremediation efforts
directed at the site's main contaminated aquifer. Over
75 continuously sampled boreholes give an indication
of the structure of this unit. The depth to the top of this
unit ranges from 22 to 28 ft (6.7 to 8.5 m) in the 317
French Drain area, to 22 to 34  ft (6.7 to 10.4 m) at the
southern edge of the ANL site.  Because its top and
bottom surfaces vary spatially, its thickness is variable.
The unit has been delineated on the basis of stratigra-
phy, a southeast trend in head  data, and, where avail-
able,  contaminant tracer data. This "aquifer" is best
described as consisting of numerous permeable bod-
ies of varying character and geometry that share some
similarity in depth and that have some degree of hy-
draulic connection. The aquifer is  not present  every-
where, and in some locations, the stratigraphicdata may
not support the presence of an  aquifer within a reason-
able depth interval.

On the basis of the southeast trend in water levels, while
considering stratigraphic and well construction informa-
tion, 23 monitoring wells with  up to 10 years of sea-
sonal  head data were assumed to represent the main
aquifer of interest and, therefore, were useful in cali-
brating the transient flow model.

The conceptual model of groundwater flow is  as fol-
lows. Groundwater in the aquifer is, in general, confined
and flows to the southeast. This finding is supported by
historical head measurements and is  in keeping with
the notion of regional flow mimicking  the topography
and flowing toward the Des Plaines River valley to the
southeast. The aquifer of interest is assumed to receive
input from upgradient sandy units to the northwest and
from infiltration from above. The recharge from infiltra-
tion may be localized and originates as seepage from
shallower perched aquifers or directly from precipita-

tion and conveyed by fractures within the overlying till.
Recharge to the dolomite aquifer beneath ANL has been
estimated by Walton (1965), who suggested a value of
3.3 in./yr (8.3 cm/yr). At the site scale, however, surficial
recharge to the aquifer of interest is likely to be less
than this value because of the predominance of
low-permeability till units at the surface.

Hydraulic conductivity estimates are available in the form
of a pump test and 12 slug tests. The pump test data
indicated a range of 4.4 to 10.5 ft/d (1.6 x 10-3to 3.7 x
10"' cm/s), or an average of 8.8 ft/d (3 x 10-3 cm/s).
Slug tests in the 12 appropriate monitoring wells indi-
cate values of 0.011 to 170 ft/d (4 x 10-6to 6 x 10'" cm/
s), with an average of 10.8 ft/d (3.8  x 10-3cm/s). The
slug tests indicate variable permeability across the site,
without any trend. The permeability likely varies greatly
over extremely short distances.

Most groundwater in the aquifer of interest travels south-
east to the forest preserve where it discharges as seep-
age, either in the deep portions of the ravines or along
the base of the main bluff of the Des Plaines valley. The
seepage along the bluff is expected to be transient, and
it may consist of a combination of localized, flowing
seeps and broad, diffuse seepage that is subject to tran-
spiration and evaporation. A  minimal amount of this
groundwater may recharge the dolomite aquifer.

Natural Transient Conditions
Modeling Approach
The U.S. Geological Survey finite-difference code
MODFLOW (McDonald and Harbaugh,  1988) was se-
lected because of its capability to address steady-state
and transient flow, varying upper and lower aquifer sur-
faces, and aquifer 'input and  output. MODFLOW has
efficient solvers, and the code  includes the capability of
rewetting  model cells that  have been dewatered
(McDonald etal., 1991). To analyze and display the rate
of groundwater movement, MODPATH (Pollock, 1994)
was used in combination with  MODFLOW flow output.

A  discussion of the modeling domain and boundary
conditions may be found in Quinn et al. (2000). Cells in
the computational grid were a uniform 10 ft x 10 ft (3 m
x 3 m); the thickness varied according to the spatially
irregular upper and lower surfaces of the  permeable
zone. This grid spacing was small relative to the  dis-
tances between monitoring wells to provide high reso-
lution of results in the modeling domain. The design
allowed the placement of each tree into a model cell at
any reasonable tree spacing.

Calibration was achieved by striving to match not only
the target heads from the monitoring well network, but
also discharge measurements at the  contaminated
seeps. A discussion of the steady state and transient
calibration methods and resulting parameter values may
be found in Quinn et al. (2000). Animations of the cali-
brated natural transient flowfield may be viewed at http:/
/web. ead. anl. gov/Phyto

Prediction Of Effect Of Mature
Phytoremediation System
Modeling Approach
The  calibrated transient flow model was then used to
model the effect of the phytoremediation on the ground-
water flow system. The modeling covered a period of
six years. The initial three years simulated the effect
over the plantation's development;  the following three
years modeled the first three years  of the mature plan-
tations, when the canopies have closed together and
water consumption is maximized.The trees, which are
planted on 16-ft (4.9-m) centers, were each placed in
an individual model cell.  Because of the difference in
the model cell spacing compared with the tree spacing,
the tree locations did not appear as orderly as their ac-
tual locations; however, for the purposes of the model,
they were accurately placed.To model the trees'pump-
ing effect, the variable recharge and upgradient bound-
ary condition were  used, as described  above. The
leaf-on period was assumed to be six months, from April
through September, with water use rates assigned as
tabulated.The rates are conservative estimates derived
on the basis of studies of phreatophytes, such as pop-
lar, willow, and tamarisk (Fletcher and Elmendorf, 1955;
Robinson, 1964), and on literature values for water use
by another phreatrophyte, alfalfa (Jensen, Burman, and
Allen, 1990). These estimates are  also supported by
experience with the luxury water consumption condi-
tions that are expected to occur at the site. The tabu-
lated water usage is similarto the range found in studies
of poplars in various growing conditions (Wullschleger,
Meinzer, and Vertessy, 1998; Hinckley et al., 1994).

The  tabulated  maximum transpiration was attainable
when the head in a model cell was  at or above the top
of the aquifer. Transpiration decreased linearly with de-
creasing head to a cutoff depth, which was assigned as
the midpoint of each model cell containing a tree.

Calculations indicated a significant, seasonal effect on
groundwater flow caused by the trees. The influence of
the trees was apparent as early as the summer of the
second year (2001). Attached figures illustrate repre-
sentative results for a low-head  period  resulting from
transpiration of mature trees and decreases in seasonal
flux (e.g., September of the fourth year, 2003) and for a
high-head period resulting from recharge of the aquifer
(e.g., April of the fifth year, 2004), respectively. Anima-
tions of  the  results  are  available  at  http://
web.ead.anl.gov/Phyto. The animations allow visualiza-
tion of the changes occurring in each month of the three
years of tree development and in the first three years of
maturity. The heads and the sizes of the dewatered ar-
eas in years 4 through 6 are essentially the same, which
indicates that the pumping effects of the plantations are
not  cumulative,  but  rather that  the  mature

phytoremedation system maintains the same cycle of
change each year.

Because the penetration depth of roots is limited in the
model, dewatering of a given model cell is not caused
by a tree that may be  in the cell, but by cumulative
transpirative stresses that lower the water table to the
elevation of the bottom of the aquifer. These dewatered
areas are depicted in the figures as areas bounded by
polygons. The onset of  dewatering coincides with the
highest elevations in the bottom surface of the aquifer.
Rewetting  of  many of the dewatered model cells oc-
curred during recharge periods (e.g., Novemberthrough

A particle tracking analysis was performed to evaluate
the hydraulic capture potential of the plantations and to
determine the residence time of contaminated ground-
water in the microbially  active rhizosphere created by
the poplars' roots and  associated microbes.  Particle
starting locations were  set to the center depth of the
aquifer of interest along the  upgradient edges of the
plantations. Starting times for particles were in January
2000, which coincides with the beginning of the six-year
simulation period. The  results indicate that the trees
provide a large degree of hydraulic containment. In the
317 Area, most of the particles are captured; however,
one particle trace skirts  the edge of the 317 Area trees
before essentially stagnating east of the plantation. In
the 319 Area, most groundwater is  captured. A small
portion escapes  because of the gap in the  plantation
along a deep, steeply banked surface drainage. The
trend of this drainage happens  to be aligned with the
overall groundwater flow direction. Monitoring of heads
over the next few years will indicate whether contain-
ment is being achieved, and whetherthe system should
be modified with additional deep-rooted poplars.

Inflections along the particle traces indicated the re-
sponse of the flow system to changes in the transpirative
stresses and to changes in the seasonal inputs to the
system.The monthly particle locations showed variable
spacing, which represents relatively slower movement
of groundwaterduring natural gradient periods (i. e., leaf-
off) and relatively faster flow during pumping  periods (i.
e., leaf-on).

The monthly particle locations may be used to estimate
the residence time of groundwater in the microbially
active rhizosphere. Particles started north of the main
317 planting area are in  the rhizosphere approximately
6 to 24 months before being withdrawn by the plants. In
the 319 Area, particles started north of the planting area
are either removed after 3 to 10 months, or  may pass
through the remediation system. Those particles that
escape have residence times of approximately 10
months in  the rhizosphere of the 319 plantation. The
range in these estimates is due to numerous  factors:
the spatially variable saturated thickness of the aquifer,
the seasonal changes in groundwater flux into the sys-
tem,  the seasonal leaf-on and leaf-off periods,  and the
composite pumping effect of nearby trees.
Summary And Conclusions
This study demonstrates the usefulness of numerical
groundwater modeling  in addressing several issues
pertaining  to the  design or  evaluation  of  a
phytoremediation system that relies on phreatophytes.
While uptake or destruction of contaminants is not ex-
plicitly addressed,  the  engineered system of deep-
rooted poplars was predicted to provide a large degree
of hydraulic control, despite seasonal variation in water
use rates by the plantation.The results indicated areas
that are typically dewatered because of high seasonal
water use and irregular aquifer geometry; this informa-
tion may be useful in the future for explaining possible
different rates of tree development across the planting
areas.  Modeling  clearly  has  application  at
phytoremediation sites  for evaluating or  designing a
containment system with respect to factors such as tree
planting density, plume width versus groundwater flow
rate, seasonal effects, residence time of groundwater
within the microbially active  rhizosphere, prediction of
regions where seasonal dewatering may occur, and fu-
ture modifications to the system design to improve the
likelihood of hydraulic capture.

Future analysis at the ANL site will include a compari-
son of model results with measured water use by trees
and measured water levels. An improved  understand-
ing  of root development (i.e., lateral  and downward
growth) will provide a better conceptualization and imple-
mentation of roots in numerical models.

Work supported by the U-S. Department of Energy, Of-
fice of Environmental Management,  under contract

Chappell, J. Phytoremediation of ice  in groundwater
using populus. Status report prepared forthe U.S. Envi-
ronmental Protection Agency Technology Innovation
Office, 1998. Available at httn://clu-in.org.

Compton, H.R., Haroski, D.M., Hirsh, S.R., and Wrobel,
J.G. "Pilot-scale use of trees to address VOC contami-
nation." In Bioremediation and Phytoremediation: Chlo-
rinated and Recalcitrant Compounds. Columbus, OH,
Battelle Press, 245-250, 1998.

Fetter, C.W Applied Hydrogeology, 2nded. Columbus,
OH:, Merrill Publishing Co., 592 pp., 1988.

Fletcher,  H.C. and Elmendorf, H-B.     P h r e a t o -
phytes - a serious problem  in the West. Washington,
DC, USDA Yearbook of Agriculture 1955, pp. 423-456,

Freeze, R.A. and Cherry, J.A., Groundwater: Englewood
Cliffs, NJ: Prentice-Hall  Inc.,  604 pp., 1979.

Gatliff, E.G. "Vegetative remediation process offers ad-
vantages overtraditional pump-and-treattechnologies."
Remediation (summer), 343-352,1994.

Gordon, M.T., Choe, N., Duffy, J., Ekuan, G., Heilman,
R, Muiznieks, I., Newman, L, Muszaj, M., Shurleff, B.B.,
Strand, S., and Wilmoth, J."Phytoremediation oftrichlo-
roethylene with hybrid poplars." In Phytoremediation of
Soil and Water Contaminants, Washington, DC: Ameri-
can Chemical Society., 177-185, 1997.

Hinckley, T.M., Brooks, J.R., Cermak,  J.,  Ceulemans,
R., Kucera, J.,  Meinzer, F.C., and Roberts, D.A. "Water
fluxin a hybrid poplar stand."Tree Physiology 14,1005-

Jensen, M.E.,  Burman, R.D., and Allen, R.G. Evapo-
transpiration and irrigation water requirements. Manu-
als and Reports on Engineering Practice, No.70, New
York, NY, American Society of Civil Engineers, 1990.

Lawson, D.E. "Mobilization, movement, and deposition
of active subaerial sediment flows, Matanuska Glacier,
Alaska." J. Geol. 90, 279-300, 1982.

McDonald,  M.G. and Harbaugh, A.W A modularthree-
dimensional finite-difference ground-water flow model.
Techniques of water resources investigations, book 6,
chapter A1: Reston, VA: U.S. Geological  Survey, 528
pp., 1988.

McDonald, M.G.,  Harbaugh, A.W,  Orr, B.R., and
Ackerman,  D.J. A method of converting no flow cells to
variable-head cells for the U.S. Geological Survey
modularfinite-difference ground-waterflow model. U.S.
Geological  Survey, Open File Report  91-536, 99 pp.,
Newman, L.A., Strand, S.E., Choe, N., Duffy, J., Ekuan,
G., Ruszaj, M., Shurtleff, B.B., Wilmoth, J., Heilman, P.,
and Gordon, M.P "Uptake and  biotransformation of
tricholorethylene by hybrid poplars." Environ. Sci.Tech.

Newman, L.A., Wang, X., Muiznieks, I.A., Ekuan, G.,
Ruszaj, M., Cortellucci, R., Domroes, D.,  Karscig, G.,
Newman, T,  Crampton,  R., Hashmonay, R.A., Yost,
M.G., Heilman, P., Duffy, J., Gordon, M.P, and Strand,
S.E. "Remediation of tricholorethylene  in an artificial
aquifer with trees: a controlled case study." Environ. Sci.
Tech. 33, 2257-2265, 1999.

Nyer, E.K., and Gatliff, E.G."Phytoremediation."Ground
Water Monitoring and Remediation (winter), 58-62,1996.
Pollock, D.W User's guide for MODPATH/MODPATH-
PLOT- version 3: a particle  tracking post-processing
package for MODFLOW, the  U.S. Geological Survey fi-
nite-difference ground-waterflow model. U.S.G.S. Open-
File Report 94-464, 1994.

Quinn, J.J., M.C. Negri, R.R. Hinchman, L.M. Moos, J.B.
Wozniak, and E.G. Gatliff. "Predicting the Effect of Deep-
Rooted Hybrid Poplars on the Groundwater Flow Sys-
tem at a Phytoremediation Site."  International Journal
of Phytoremediation, (in press).

Robinson, T.W.  Phreatophyte research  in the western
states, March 1959 to July 1964. U.S.G.S. Circular 495-

Walton, WC. Ground-water recharge and  runoff in  Illi-
nois. Report of  Investigations 48. Champaign, IL:  Illi-
nois State Water Survey, 1965.

Wullschleger, S.D., Meinzer, F.C., and Vertessy, R.A."A
review of whole-plant water use studies in trees." Tree
Physiol. 18, 499-512,1998.

  Modeling  Plume Capture at ANL-E
      An Analysis of the Effect of the Argonne
   Phytoremediation System on Groundwater Flow
                 John J. Quinn
           Argonne National Laboratory
                 Argonne, IL
         Work supported by the U.S. Department of Energy, Office of Environmental
          Restoration and Waste Management, under contract W-31-109-ENG-38.
Phreatophytes (poplar and willow) useful
             in some settings

•  Transpire contaminants (VOCs, tritium)
•  metabolize VOCs in rhizosphere
•  degradation within the plant
•  depress water table -> containment

             Study Area:
    Argonne National Laboratory
            317/319 Area
Prior waste disposal area (french drains, rad
waste vaults, landfill)
contaminants of concern are solvents and
                         .3 •'
                         " i,


  ....	 r    •',•••
  i fjr,vj",v-rft, • •     \     /
•  vKKKKff1 ::-Myv^:   i

-/.J^M/."™ \j-.v

     Problem: contaminants 30 feet deep

Solution: engineered phytoremediation system
      389 willows and poplars planted
      at or near the surface
      420 specially installed poplars
      (roots directed to target aquifer)

                capillary fringe

                  sllt-sand-siUy clay deep aquifer
 Evaluation of Effect of Phytoremediation
      System on Groundwater Flow

• focus on aquifer of interest
• ignore shallower perched system
• calibrate initial transient model to the pre-
  phytoremediation flow field

                                  _-3~*!«»( Huutl'L«|r
        Transpiration vs.
        Head in a Model
        Cell containing a
Low Heads
 of Mature

 (Sept. of
fourth year)

  High Heads
   of Mature

   (April of
   fifth year)
a » J I &
 Particle   „                       j

Tracking                       ,  j\

  start in
  January      /     ''<             , '   ",
  2000)     •''     •'             '   , '|

    Effect of Phytoremediation on the
        Groundwater Flow Field...

  Best-estimate predictive modeling suggests
  - containment of groundwater by mature
    plantation, even during dormant winter
  - interim extraction well system phase out
  - residence time of groundwater in
    microbially active rhizosphere of 5-17
           ... and vice versa...
The Effect of the Groundwater Flow Field
    on the Phytoremediation System

• Dewatering of aquifer of interest could stress
  the poplars
   * future thinning of tree density

             What Next?
Groundwater sampling
Water level measurements
Weather data
Tissue sampling
Transpirate sampling
Rhizosphere soil sampling
Viewing tubes
     For your viewing pleasure...

 - animated visualization of transient flow
  field under pre- and post-phytoremediation

      Phytoremediation Potential of a
Chlorinated Solvents Plume in Central Florida

           Stacy Lewis Hutchinson
              James Weaver

Stacy Lewis Hutchinson has a B.S. in civil engineering from Montana State University
and a M.S. and Ph.D. in civil engineering from Kansas State University. She is currently
a research environmental engineer at the Ecosystem Research Division of the Office of
Research  and  Development of  the  U.S.  Environmental  Protection  Agency.    Dr.
Hutchinson works as part of a  multidisciplinary team on phytoprocesses in support of
multimedia modeling efforts for assessing risks from chemicals to human health and the
environment.  Her research focuses on the phytoremediation of water,  sediments, and
soils contaminated with toxic and hazardous chemicals and quantifying this  remediation
through changes in soil biological, chemical, and physical health.

       Phytoremediation Potential of a Chlorinated Solvents
                         Plume in Central Florida

                            Stacy Lewis Hutchinson
                               James W. Weaver

                         Ecosystems Research Division
                    National Exposure Research Laboratory
                 United States Environmental Protection Agency
                                Athens, Georgia
The potential for phytoremediation of a shallow chlorinated solvent plume was assessed
by application of ground water flow and evapotranspiration (ET) models for a site in
Orlando, Florida. The focus of the work was on the hydrologic and hydraulic factors that
influence phytoremediation effectiveness.  The primary phenomena of concern were
observed plume diving, spatially varying recharge and evapotranspiration from existing
and candidate trees.  The  observed contaminant distribution at the site showed sharp
plume diving immediately down gradient from the suspect source with partial discharge
to a lake approximately 250 feet  down gradient.   A ground water flow model  was
developed for the site that  included the potential for vertical flow  by including detailed
bathymetry of the lake.    Model results showed  that  the  plume diving is  directly
attributable to focussing of recharge from paved areas near the source.  Since plume
diving  represents the dominant feature -of vertical  flow at the site, the design for a
phytoremediation system included diverting recharge water from the paved area and
planting of trees to further minimize plume diving.  Estimates of evapotranspiration rates
were obtained from regional estimates, a  simple model of ET and from a previous ET
study conducted on site.  These estimates provided design  parameters for the remediation
system and an assessment of the amount of plume control possible at the site.

 Phytoremediation Potential of a

  Chlorinated Solvents Plume  in

          Central Florida

    Stacy Lewis Hutchinson and Jim Weaver

          Ecosystems Research Division
        National Exposure Research Laboratory
      United States Environmental Protection Agency
               Athens, Georgia
Phytoremediation Effectiveness
 The water balance at a site determines
  - pattern of flow in the aquifer
  - amount of water withdrawn by vegetation
  - first order effectiveness of

     Water Balance Equation
•Scientific principle
governing ground water
•Equation solved in ground
water flow models
K = hydraulic Conductivity
b = aquifer thickness
h = hydraulic head
q = source/sink
P = precipitation
I = irrigation
Qs = surface runoff
ET = evapotranspiration
S = storage coefficient/ specific
  Ground Water Flow Equation
                                        •  ' rr ~ ?*> 1
   K = hydraulic Conductivity
   b = aquifer thickness
   q = source/sink
   S = storage coefficient/ specific
   P = precipitation
   I = irrigation
   Qs = surface runoff
   ET = evapotranspiration
aquifer test
site information
pump test      Calibration

climatic data
site information

Ground Water Flow Modeling
 Majority of ground water flow modeling
 is based upon steady state assumption
 - in solute transport-contaminant transport
   is slow compared to ground water
   response time
 - climate becomes averaged
       Design Approach
 Estimation of evapotranspiration rates
 Local pattern of aquifer recharge
 Effects on plume location and potential
 for phytoremediation

   Evapotranspiration ET
Reduces average net recharge of the
May prevent plume diving
May create upward flux of water
Penman-Monteith Equation

                           ¥•  \

 Pan Evaporation in Inches
Annual Precipitation in Inches

Evapotranspiration Estimates
 Central Florida—130 cm/year (Florida
 Agricultural Extension Service)
 Orange Groves—50 cm/year (USGS
 Report 96-4244)
 Site Specific—80 cm/year (Vose et al.)
 - contribution of understory not determined

 Precipitation Estimate—140 cm/yr
 BRAC site
 PCE/TCE source in a sump
 Flow toward and discharge into Lake
 Flow Path Land Use
 - Building>Paved>Ditch>Grass>Jungle>Shore

       Orlando Site
                   MA* Z. 19* THROUGH IVHf S, »«

"''   '

      Orlando NAS Site
Observed plume diving
- from vertical contaminant distribution
- dramatic/short distance/local
Contaminant Distribution at Source
0 20

^ Phyto
/ 	 TCE
/ 	 PCE

500 1000 1500
Concentration Qig/L)

 Analytical Recharge Model

One-dimensional analytical element
Flow in a water table aquifer
Predicts the upperbound of contaminant
distribution based on aquifer
parameters and recharge rate
Match observed plume diving to input
recharge rate
  Analytical Model  Results
     I 80
Calibrated Water Table
Predicted Plume Upper Bound 110 in/yr
Predicted Plume Upper Bound 55 in/yr
   400  600
   Distance (ft)

       Numerical Model
MODFLOW 3D, Steady State Ground
Water Flow
Based on USGS regional flow model
- source of calibrated parameters, boundary
Fine scale layering to simulate plume
diving and ET losses
      MODFLOW Model
Two layers of differing conductivity
 - upper 10 ft/d Ks, 3.8 ft/d vertical
 - lower 40 ft/d Ks, 17 ft/d vertical
Fine layering to define Lake Bathymetry
 -11 --2 foot thick layers
 - lower layers 5 or 10 feet thick
 -18 layers total

       MODFLOW Model
• Simulate
  - existing conditions with enhanced recharge
   from ditch
  - Plume diving with diversion of water from
  - ET with trees planted through parking lot
   (no recharge), but ET at 50, 80 and 130
  Orlando Current Conditions

      Re-route Runoff
Tree Plantation near Source

Comparison of Water Usage
                            Tree Plantation
                            using 80 cm/yr
                            Tree Plantation
                            using 130 cm/yr
 Penetration depth:
 - 80 cm/yr ET; upward gradient to 23 ft
 - 130 cm/yr ET; upward gradient to 30 ft
 Contamination depth is 34 ft

 Vertical characterization is required for
 delineating plumes (esp. Those
 considered for phytoremediation)
 Localized recharge distribution controls
 plume diving (accepting stratigraphy)
 ET estimates have uncertainty
 - generally bounded by pan evaporation
Numerical model with fine scale vertical
discretization needed for 3D flow features.
Potential to control plume by diversion of runoff.
Existing vegetation is ineffective in removing
Tree plantation at source potentially affects a
maximum of 77% to 88% of the contaminant
- ET = 80to 130cm/yr
- Recharge = 0


          Phytoremediation at Aberdeen  Proving  Ground, Maryland:
             Operation  and Maintenance,  Monitoring and Modeling
                                     Steven R. Hirsh U.S. EPA
                                            Region III
                                       Office of Superfund
                                     Federal Facilities Section
Steven Hirsh graduated from Temple University with a
degree in Environmental Engineering 1980. Steven is
currently taking Engineering Geology courses at Drexel
University. Steven has worked at the U.S. EPA for 20
years. Work at EPA includes Wastewater Permitting,
Emergency Response, Federal Facility Compliance and
Superfund Project Management.  Steven  previously
served as EPA's Project Manager for the Spring Valley
Chemical Munition Site.

Steven is also the Work Leader for all Federal Facility
Superfund Sites in the State of Maryland. Steven serves
as the Remedial Project Managerforthe Aberdeen Prov-
ing Ground Superfund Sites, and as On Scene Coordi-
nator for Munitions Removal activities at the Former
Nansemond Ordnance Depot Site in Tidewater Virginia.
Steven is the technical lead of a US team providing
remediation support and training forthe Government of
the Czech  Republic.

EPA  honors include bronze and gold medals for work
related to implementation of Superfund at Federal Fa-

This  talk summarizes the development of a remedial
clean-up option designed to remove contaminants (pri-
marily  1,1,2,2-tetrachloroethane and trichloroethene)
and provide hydraulic containment in a shallow water
table aquifer at the U.S. Army Aberdeen Proving Ground.
Phytoremediation at the Aberdeen Site consists of over
200 hybrid poplars planted in the flowpath of a high con-
centration  (hundreds  of PPM) plume. Monitoring natu-
ral attenuation parameters has shown that aerobic and
anaerobic indigenous microorganisms are significantly
reducing contaminants. The phytoremediation planta-
tion increases the degradation of the VOCs. Current field
efforts are being conducted to quantify this increased
contaminant destruction.

After three seasons  of developing and  refining
phytoremediation monitoring techniques, the EPA and
the Army are finalizing  a Feasibility Study for the site
which requires phytoremediation be  analyzed as a po-
tential remedial option,  and compared to other reme-
dial technologies. A component  of this analysis is an
evaluation of the costs associated with installation and
operation and maintenance of a phytoremediation plan-
tation.This analysis is being assisted by the use of sev-
eral groundwater-modeling techniques.The monitoring
program provides the data necessary for measuring the
effectiveness  of phytoremediation  in achieving
remediation goals, and  provides input parameters for
the modeling effort. Monitoring has also provided data
for evaluation of existing and potential environmental
contamination pathways. Groundwaterwithdrawal rates
have been estimated by measuring sap flow using the
Dynamax DynagageTM Flow 32  system. Sap flow and
on-site weather conditions were  examined seasonally
over a three-year period. Hydraulic containment was
evidenced through continuous groundwater level moni-
toring which showed a depression in the groundwater
table during summer and early fall.

Operation and maintenance of the  plantation has in-
cluded installation of replacement trees, additional tree
plantings in areas of contamination previously unknown,
fertilization to maintain and improve tree health, and tree
maintenance following severe storms.

 Phytoremediation Systems Designed to Control Contaminant Migration

                 A. Ferro1, R. Kjelgren2, D.Turner3, B. Chard1,!. Montague2, and ,J. Chard1

            'Phytokinetics, Inc. Logan, Utah; 2Utah State University, Logan, Utah; 3NDR Consulting, Cove, Utah.
Ari Ferro is President of Phytokinetics,  Inc., and an
Adjunct Associate Professor at Utah State University.
He and Jean Kennedy founded Phytokinetics in 1994 in
Logan, Utah  with the objective of commercializing
phytoremediation. The company's focus has been
phytoremediation of organic chemical contaminants in
soils and groundwater. Dr. Ferro earned a Ph.D. in bio-
chemistry from the University of Utah in 1973, and com-
pleted postdoctoral training at the University of Hamburg
and University of California at San Francisco. Before
founding Phytokinetics, he held a position as a Research
Faculty member at the University of Utah, Department
of Biology.

Two phytoremediation projects are discussed which il-
lustrate the use of trees to help control the migration of
contaminants. The first example is a phytoremediation
project at Chevron's former Light Petroleum Products
Terminal in Ogden, Utah. Groundwater at the site con-
tains petroleum hydrocarbons, and in 1996, a dense
triple row of hybrid poplar trees was installed  perpen-
dicular to the  direction of groundwater flow. The trees
were planted directly into the saturated zone in orderto
establish deep-rooted plants that use groundwater as
their primary source of moisture. Sap velocity measure-
ments have been conducted in orderto estimate total
transpirational water use. In addition, the structure of
the  root system of a single deep-rooted tree was in-
vestigated. Performance of the system has been evalu-
ated by  obtaining  ground-water elevation  and
contaminant concentration  data from piezometers lo-
cated up-gradient, down-gradient, and within the planted
zone. Preliminary data suggest that the concentrations
of BTEX compounds and TPH decreased as the ground-
water passed  through the rows of trees. Portions of this

study were conducted as part of the US EPA's SITE
Demonstration Program. The second example is a
project planned for the Bofors-Nobel Superfund site in
Muskegon, Michigan. Within a four-acre portion of the
site are several drained sludge lagoons devoid of veg-
etation.The sludge layer contains a complex mixture of
contaminants  that have the potential to leach into the
groundwater.The planned phytoremediation system in-
volves the installation of deep-rooted trees within the
lagoons. We expect that transpirational water use by
the trees will reduce contaminant leaching. Other ben-
eficial effects of the vegetation may include immobiliza-
tion of contaminants by binding to root tissue and
enhanced rhizosphere degradation. A small-scale out-
door study is underway to evaluate the tolerance of sev-
eral tree species to the sludge, as well as the efficacy
of various planting methods to encourage the forma-
tion of deep roots. After almost one year of growth, the
trees  in all treatments appear to be healthy. A green-
house study is planned to evaluate sludge phytotoxicity
and to assess the rate of removal of the contaminants
from planted soil.

Ogden, Utah
A phytoremediation system was installed at Chevron's
former Light Petroleum  Products Terminal  in Ogden,
Utah to control the migration of groundwater contami-
nants. Groundwater at the site contains petroleum hy-
drocarbons ranging in concentration from 5 to 10,000
parts per billion (ppb) and the water table at the site is 4
to  9 feet below ground surface (bgs).

In  April 1996, a dense triple row of hybrid poplar trees
('Imperial Carolina', PopulusdeltoidesxPnigra, DN34)
was installed perpendicular to the direction of ground-
water flow. Each of the three tree rows is 100 ft. long
with 7.5 ft. between trees and 6 ft. between rows. Indi-
vidual boreholes were drilled and the trees  (40 total)
were planted directly into the saturated zone in orderto
establish deep-rooted plants that use groundwater as
their primary source of moisture. The trees were planted
as long hardwood  cuttings and have grown rapidly, at a
rate of approximately 10 ft. per year without any supple-
mental irrigation.  Five piezometers were installed to
monitor groundwater quality and to measure changes
in water table elevation.

The water table elevation (WTE) at the Ogden site was
measured manually and groundwater samples were
taken  at each of the five piezometers at six sampling
times  from 8/98 to 8/99. Groundwater samples were
analyzed for BTEX and TPH using EPA Methods 8020
and 8015 modified, respectively. In addition, as part of
the USEPA SITE  Demonstration Program, WTE data

were measured continuously from 5/98 to 8/98 using
in-well pressure transducers.

Transpirational Water Use by the Tree
The total volumetric water use by a stand of trees (Vt)
during a given time period can be  estimated using the
following equation:

PET = potential evapotranspiration during the time pe-

Kc = "crop coefficient" = rate of water use per leaf as a
percentage of PET, LAI = leaf area index = the leaf area
per unit area of ground surface, and A = area of the
stand of trees.

Values for PET are site-specific. For a dense stand of
poplar trees, values for leaf area index (LAI) increase
gradually from years 2 through 5 and reach a plateau
at.the time of crown closure. Values for crop coefficient
(Kc) increase as the roots become better established,
and then decrease slightly in year 5 due to self-shading
in the dense crown.

In 1998, a temporary weather station was erected at
the Ogden site to record the parameters necessary for
calculation of PET (Allen etal., 1994). In addition, four
trees within the stand were equipped with thermal dis-
sipation probes to measure sap velocity, and transpira-
tional water use was calculated forthe individual trees.
Each tree was then completely defoliated and leaf area
was estimated by running a subsample of the harvested
leaves though a leaf area meter. LAI was then calcu-
lated forthe ground area, A, covered by the tree canopy.
The study was carried out in mid to late September 1998,
when the stand was at the end of its third growing sea-
son. The following values were obtained:

    Vt = 5.6 gallons per day per tree

    PET = 4.0 inches per month

    LAI = 2.9 ft2leaf area per ft2ground area

Rearranging Eq. I, a value for Kc was calculated using
the measured values for Vt, PET, and LAI.

    Kc = 0.5 (dimensionless)

These measured and calculated third year (1998) val-
ues validated ourVt, Kc and LAI estimates made previ-
ously forthe third growing  season.

Using our estimated values forVt, Kc, and LAI forthe
fourth growing season (1999), we calculated that the
stand of 40 trees transpired approximately 480 gallons
of groundwater per day. To determine whether transpi-
rational water use by the trees at the Ogden site was
significant relative to the total flow of groundwater, we
approximated the volume of water flowing beneath a
vertical cross-section of the stand. The rate of ground-
water flux through a 1-ft.-thick vertical cross-section
spanning the width of the stand's canopy (110 ft.) was
calculated using  Darcy's Law to be approximately 44
gallons per day. Although our water use estimates indi-
cate that the trees transpired a volume of water equiva-
lent to an 11-ft. thickness of the saturated zone, our
WTE data for 1999 did  not indicate a depression in the
watertable. We are currently investigating plausible ex-
planations forthe observation that an obvious zone of
depression in groundwater elevation was not observed
in the root zone of the trees (c.f. Ferro etal., 1997).

Root Distribution  Analysis
In the fall of 1998, the root system of a single poplar
tree at the southwest corner of the  stand was system-
atically characterized using classical methods for root
analysis (Bbhm, 1979). A backhoe was used to dig two
trenches nearthe base of a single tree. Roots along the
trench walls were exposed and systematically counted
using a grid system. A needle board was then placed in
along the vertical trench face closest to the tree and
stiff wire'needles'driven through the board and into the
root zone of the  tree. The portion  of the root system
penetrated by the needles was isolated by digging a
monolith (2 1/3 ft. wide, 1 1/2 ft. thick, 3 ft. high) and the
soil washed away while the needles held  the roots in
position.The analyses indicated that the tree roots grew
out of the borehole and  extended laterally > 5 ft. through-
out the vadose  zone. Within  the  vadose zone, the
largest.roots proliferated  in and around the  borehole.
Near  and within  the saturated zone, the roots  were
heavily concentrated in the borehole. The most deeply
penetrating roots extended from highly branched  roots
nearthe surface (< 2 ft. bgs) rather than from the  origi-
nal, deeply planted cutting.

Contaminant Removal/Evidencefor
Plume Control
Groundwater samples were collected at each of the five
piezometers at six different times from 8/98 to 8/99. The
multiresponse permutation procedure  (Mielke,1995)
was used to assess  statistical differences in contami-
nant concentration data at the various sampling times.
The preliminary data indicate that the dense triple row
of poplar trees was effective at removing BTEX and TPH
from the groundwater. At each sampling time, BTEX and
TPH contaminant concentrations decreased significantly
(p < 0.01) from the up-gradient piezometers to the down-
gradient piezometers. A decrease  in concentration of
both BTEX and TPH at  the up-gradient piezometer was

 Muskegon, Michigan
A phytoremediation project is planned forthe Bofors-
Nobel Superfund Site in Muskegon,  Michigan. Although
the project is still in the pre-design  stage, the concep-

tual design calls for the installation of approximately
13,000 trees of various species in four different zones
on the 20-acre site. Industrial chemicals such as deter-
gents, saccharin, dye intermediates, herbicides and
pesticides were produced at the site from 1960 to 1980,
during which time sludge and wastewaterwere disposed
of in various lagoons. Bofors-Nobel filed for bankruptcy
in 1985 and the site was placed on the National Priori-
ties List in 1989. The contaminants of concern,  local-
ized primarily in several drained sludge lagoons, include
halogenated semivolatile organics (trichlorobenzene,
dichlorobenzidene, chloroaniline),  non-halogenated
semi-volatile organics (benzidine, azobenzene, aniline)
and metals (chromium, lead, arsenic). The sludge ma-
terial is calcium sulfate (CaS04), and in some lagoons,
Zinc oxide (ZnO) is also present. Zone A is comprised
of several of the  most highly contaminated sludge la-
goons. In this area, contaminant concentrations  in the
vadose zone are high. In Zones B and C, the contami-
nants occur primarily in the groundwater at 30 ft. bgs
(Zone B) and 10 ft. bgs (Zone C). Zone D is an area
with  comparatively little contamination. A different
phytoremediation strategy will be applied in each of the
four zones, with the ultimate goal to prevent contami-
nant migration from the vadose zone to the groundwa-
ter and to  prevent the offsite migration of already
contaminated groundwater.

Pre-Design Study
A pre-design study was started in September 1999 and
we expect that the study will continue through the 2002
growing season.The objective of the study is to assess
the tolerance of seven tree species to the sludge and to
evaluate various planting methods.The three treatments
include 1) drilling boreholes in sludge lagoon 3 (in Zone
A), backfilling with sand and compost, and planting the
trees into the backfill; 2) planting trees directly into sludge
lagoon 3; and 3) planting trees in an uncontaminated
area adjacent to lagoon 3. There are five replicate plots
per treatment and seven trees (one of each species)
per replicate. The objective of Treatment 1 is to develop
deep roots that penetrate through the sludge layer.Trees
in Treatment 1 (planted in backfilled boreholes) are sub-
irrigated using drip lines. Trees in Treatments 2 and 3
are surface irrigated using spray emitters. We plan to
evaluate the root structures of trees in each treatment
using methods similar to those described above for the
Ogden site. As of June 2000, the trees subjected to the
various treatments have  not shown obvious  signs of

Allen R. G., Smith, M., Pereira, L. S., and Perrier, A.
1994. An update for the definition of reference evapo-
transpiration. ICID Bulletin 43, 35-92.

Bb'hm,  W. 1979. Methods of studying root systems. Vol-
ume 33 in the series,  Ecological studies: Analysis and
synthesis,  188 pp. (Billings, W. D. and  Lange, O.L., Eds.).
Berlin,  Springer-Verlag.

Ferro, A.M., J.P  Rieder, J. Kennedy and R.  Kjelgren.
1997. Phytoremediation of groundwater using poplar
trees. In: Phytoremediation. C.A. Thibeault and L.M.
Savage (eds.), pp. 201 -212. International Business Com-
munications, Inc., Southborough, MA.

Mielke, P. W. Jr. 1995. Multiresponse permutation pro-
cedures. In: Encyclopedia of Statistical Science, Volume
5, pp. 724-727. New York, NY, John Wiley & Sons.

                                       Deep Planting

                                          Edward Gatliff
Edward G. Gatliff earned a Ph.D. in Agronomy from the
University of Nebraska-Lincoln. He is founder and presi-
dent of Applied Natural Sciences, Inc. of Hamilton, Ohio,
an environmental consulting firm specializing in provid-
ing TreeMediation® and  other PhytoEngineered™
phytoremediation programs such as the TreeWellTM
methodology to treat specific horizons of soil or ground-

Since 1987, Dr. Gatliff has been active in the environ-
mental industry, primarily applying his understanding
of vegetation  and  agronomic principles to remediate
contaminated soil and ground water. In the fall of 1990
he conceived an engineered approach to utilizing trees
to remediate deep soil and ground water,  now known
as a TreeMediation program. With the implementation
of a TreeMediation program in the fall of 1991, he pio-
neered an engineered approach to phytoremediation
that has been used to remediate soil and groundwater
more than 30 feet deep. Through Applied Natural Sci-
ences, Dr. Gatliff has obtained 2 patents and continues
to develop innovative approaches to phytoremediation,
for projects nationwide.

Applied Natural Sciences, Inc.
       Deep" Tree Planting
          Edward G. Gatliff, Ph.D.

               presented at the
  EPA Phytoremediation: State of the Science Conference
             Boston, May 1-2, 2000

          "contact: (513) 895 6061; ans@fuse.net

          Deep Tree Planting?

       • What is it
       • Why & when do we use it
       • How do we do it
       + How effective is it
       • How deep can we go
       + How costly is it
     What is Deep Tree Planting?
• Planting a tree to
  achieve root
  development to an
  aquifer or a horizon of
  soil that is greater
  than 3 feet deep.
«• Typically
  accomplished by
  creating boreholes
  and/or trenching

     Why Do We Need Deep Planting?
 • To remediate or
   control deep
    - Depending on climate
     and soil conditions,
     vegetation very often
     does not develop
     rooting activity deeper
     than the top 3 feet of
    Why deep plant when vegetation
   can develop deep rooting naturally
• To Readily Establish
  & Insure Hydraulic
  Control and/or
  Remedial Effect
    In conditions where
    vegetation can develop
    rooting activity to the
    target horizon the
    predictability of timing
    and efficiency often
    precludes any meaningful
    assessment of the
    system's potential effect.
                          2 year old root system from borehole

     How is Deep Planting Best

 • Creating Boreholes or Trenches
 • Casing the borehole or Trench
   - Types of casing and no casing
 • Borehole Diameter
 • Planting the tree as deep as possible
  in the borehole or trench
         Creating Boreholes
• Diameter of hole and depth of boring
  often dictates the type of drill rig that
  should be used
• In general the following will apply
   - <5 feet a 3-point auger on a tractor
   - < 10 feet a skid-steer with an auger extension
   -10-20 feet a medium sized drill rig with an 8 foot
   - >20 feet a caisson rig


         Types of Casings
• Casing
   -ADS & metal culvert - cost, corrosion,
    handling & installation, erosion
   -sonotube - cost, degradation, handling &
    installation, erosion
   -plastic, handling & installation

• No Casing
   -clayey soil types

handling &
erosion or
channeling of
surface water
(depends on
soil & site

• Depends on site
   - Boreholes drilled into
    clayey soils will limit
    root development
    outside the borehole.
   -Without a casing,
    consideration must be
    given to the possibility
    that a preferential
    pathway for surface
    water to short-circuit
    to the GW has also
    been created.
  No Casing
(or, Is Casing Important?)


• Boreholes from 3
  inches to 3 feet
• With casing larger
  diameter boreholes are
• With no casing 3 inch
  boreholes have been
  used with cuttings
  Shallow Planting
 • Shallow planting
   the rootball of the
    - with cased trees,
     irrigation may be
    - longer time for roots
     to develop to depth

      Effects of Deep Planting
• Tree Growth Increased by Deep
• Remediation Effect realized by year 2
• Hydraulic effect realized in year 1

Above Ground Tree Height
Total Tree Height

      How Deep Can We Go?
• Acacia trees have been known to root as
 deep as 100 feet below ground surface
• Trees in semi-arid/arid areas known to
 root to GW as deep as 60 feet bgs
• At Staten Island, New York and Argonne,
 Illinois we are treating aquifers as deep
 as 35 feet below ground surface
• Root systems have been found
 developed to over 200 feet long

 How Deep Can We Go?
• Deep placement
  -A fifteen foot tall tree can be
    planted at least 10 feet bgs

• Elongated Roots
  - pregrown tree roots can be
    developed 10 or more feet in

 Example of Use

• Argonne National
  Laboratory Area 317/319
  Phytoremediation Project
» Root-engineered trees
  (trees with predeveloped
  elongated root systems)
  were planted into 30 foot
  deep boreholes.
• Rootballs were placed 5-10
  feet bgs with elongated
  roots suspended another 2
  to 8 feet thereby achieving
  rooting activity up to 18 fee
  bgs at planting.

  Applied Natural Sciences, Inc.
  Patented System
               Deep Planting Costs
  • Implementation costs will vary significantly between
    sites due to site conditions, methodology employed
    and whether client is commercial or government

  «• For systems with a target depth of 10 feet or less
     - Per tree costs will range between $100 and $300 per tree (or
      $20,000 to $60,000 per acre)

  «• For systems with a target depth of 10-20 feet
     - Per tree costs will range between $250 and $500 per tree (or
      $50,000 to $100,000 per acre)

  «• For systems with a target depth of > 20 feet
     - Per tree costs will range between $500 and $1,500 per tree (or
      $100,000 to $300,000 per acre)
        * assumes fewer trees per acre with deeper depths

• Deep Plantings reaching depths of 35 feet have been
  demonstrated while depths of 50 feet or more are
• Casing helps limit preferential shallow root
  development and surface water short-circuiting
• No casing has a place when used with clayey soils
  provided surface water short circuiting is accounted
• Borehole diameter can vary with  objectives but cased
  holes should be larger (>16")
• Effects can be readily realized and more predictable
• Costs can be controlled by utilizing the right
  methodologies and equipment for the given situation

                   Transpiration: Measurements and Forecasts
                                          James M.Vose
                                        USDA Forest Service
                                     Southern Research Station
                                   Coweeta Hydrologic Laboratory
                                          Otto, NC 28763
James M. Vose has a B.S. in Forestry from Southern
Illinois University, a M.S. in Forest Ecology from North-
ern Arizona University, and a Ph.D in Forest  Ecology
from North Carolina State University. He is currently
Project Leader of the USDA Forest Service Coweeta
Hydrologic Laboratory in western North Carolina. His
work  includes  measurement and modeling of forest
ecosystem  processes and their responses to distur-
bance. He specifically focuses on measurement and
modeling of carbon, nutrients, and water cycling and
has published more than 70 scientific papers on these

For soil and groundwater pollutants, a key factor in
phytoremediation is choosing plants species that tran-
spire a substantial quantity of water and subsequently
metabolize  or accumulate the contaminant. The suc-
cessful application of phytoremediation technology re-
quires a thorough and accurate assessment  of water
use patterns (i.e., transpiration rates, location of soil or
groundwater uptake, interactions with climate and soil
water availability) in plant species that are known
metabolizers of the specific pollutant. Accurate deter-
mination of tree or stand-level transpiration in the field
has, until recently, been difficult. Typically, three meth-
ods have been used: (1) precipitation minus runoff (P-
RO) relationships on gaged watersheds, (2) energy
balance (e.g.,  Penman-Montieth), and (3) hydrologic
models. The first two methods are integrated estimates
of the entire system and do not partition  water losses
based  on transpiration and evaporation. Hydrologic
models vary considerably in complexity, but usually only
detailed physiologically based models that link vegeta-
tion, soils, and atmosphere provide accurate estimates
of transpiration. Recent developments in sapflow tech-
niques have made direct estimates of transpiration at
the tree level under field conditions much more feasible.
Modeling or other scaling  techniques can be coupled
with these sapflow measurements to scale tree-level to
stand-level and extrapolate temporally. Overall ap-
proaches to measuring and modeling transpiration will
be discussed, with emphasis on a case study compar-
ing sapflow estimates of transpiration with those from a
physiologically based transpiration model.


Monitoring Alternative Covers
          Craig Benson

  Monitoring Alternative Covers:
        ACAP's Perspective
   William H. Albright, Craig H. Benson, Michael M.
   Bolen, Glendon W. Gee, Steven Rock, A. Roesler
     Purpose of Cover or Cap
- Limit percolation into underlying waste
- Control gases (methane, LFG, oxygen)
- Separate waste from surrounding environment

 Conventional  Covers: Compacted Clay
                egetated Surface Layer (150 mm)
                  Clay Liner (> 600 mm)
   - Prone to problems: desiccation cracking, frost damage, differential
    settlement, root intrusion

   - Fairly costly ($125,000 per acre)
      Frost Lenses in Compacted Clay

2% wet of

Large Desiccation Cracks in
Clay Barrier

~   100 f


                     1              2

               Number of Drying Cycles

                 - -•- -Original BL1
                 --^--Original BL2
                 —•— Rebuilt BL1
                 —*— Rebuilt BL2
400    600     800
 Elapsed Time (days)
1000   1200

Conventional Covers: Composites
               • 600 mm Soil Liner, < 10'7 cm/s
               •    •       • -    •

     ;;..: ' •;  •;;.;' '600 mm Vegetated Surface  ayer
      - Very effective (1- 3 mm/yr percolation).

      - Excellent performance record

      - Costly ($175,000 - 200,000 per acre)
  Alternative Earthen  Final Covers

                              Percolation if

  Why monitor alternative covers?

  - Principle is simple, but mechanism complex

  - Complex interaction between atmosphere, plants,
   cover surface, and flow in the cover
   Capability to make definitive predictions regarding
   performance currently is limited.

   Collect field data from a dispersed network of
   large-scale field test facilities to demonstrate
   principle and to check and refine design models.
                Monolithic Barriers
Thick layer of
  Design so storage capacity of finer layer is not exceeded

               Capillary Barriers

   Break ~~~-
                \    \
       • Rigorous treatment
         of unsaturated flow
       • Field performance
       • Understand of soil-
        What is Equivalency?
 RCRA Subtitle D: Percolation from
 alternative cover must be less than or
 equal to percolation from prescriptive

 ACAP Default Equivalency Values
Equivalency Value (mm/yr)
 Humid      Semi-Arid
Non-Composite   30
  Composite      3

Diversion 4
Berm N 	 _L





in meters


— s^S:






• • ' " • ; . . n

Large bathtub filled
o with cover soil and


 Typical Lysimeter Cross-Section
 Existing Slope (>2%)
Geocomposite Drain

                         1.5 mm
Aerial view of lysimeter lined with geomembrane.

Connection between sump boot and percolation pipe.

Extrusion welding sump boot.
Spark testing weld on sump boot.

Leak-testing the sump using sight tubes.



                          Installing geocomposite drainage
                          layer above geomembrane.
                                ,. ±?
Tying panels of geocomposite drainage layer


Placing root barrier.

       •' -' -?•
Staking root barrier.


Completing first layer of soil above root barrier
 Corner of sidewall showing weld.

Trimming block sample from cover soil.

 Mini-disk infiltration testing of cover soil.
Aerial view of completed test sections at Kiefer
Landfill, Sacramento County, California.

            Kiefer Site:
Eight months after construction
                  Tost Site
USE PA Suparhind
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 Dosing siphon after placement on platform. |
     HB^H^^^^^H^^^B^^^^^^H!     -A
Interior of dosing siphon for percolation showing tipping bucket

   Covered Dosing Siphon     -._>

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           : ': **  .   .t *^"   -M.
   Instrument Nest

                               Anti-Seep Collar Detail
                      Heat Dissipation Unit
                      Water Content Reflectorreter
                      Heat Dissipation Unit
                     Water Content Reflectometer
                                  station &

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                         Growing a 1,000-Year Landfill Cover
                                          W. JodyWaugh
                            MACTEC Environmental Restoration Services*
                                     U.S. Department of Energy
                                Grand Junction Office  2597 B 3/4 Road
                                   Grand Junction, Colorado 81503
William J. (Jody) Waugh, Ph.D received a  Ph.D. in
Rangeland Ecology from the University of Wyoming in
1986. He has 19 years of research and applied experi-
ence evaluating and manipulating the ecology of haz-
ardous and radioactive waste sites. He is recognized
for original research on the water balance and plant
ecology of evapotranspiration (ET) covers, the use of
lysimetry for field measurements of soil water balance
of covers, and  the use of natural analogs to evaluate
the ecology of  covers intended to last for hundreds to
thousands of years. His other research interests include
retrospective     environmental    monitoring,
phytoremediation   in  deserts,  paleoecology,
dendroclimatology, and pedogenesis of engineered soils.
He has served  on technology needs panels for the Na-
tional Academy of Sciences, the Department of Energy,
and the Environmental Protection Agency. Dr. Waugh is
currently Principal Scientist with Roy F. Weston, Inc., at
the DOE Environmental Sciences Laboratory in Grand
Junction, Colorado, and was formerly Research Scien-
tist at Pacific Northwest National Laboratory. He is also
Adjunct Professor at the  University of Arizona in Tuc-
son and at Mesa State College in Grand Junction.

The U.S. Department of Energy is preparing a guidance
document for end-users to design long-term covers for
internment of buried radioactive and hazardous waste.
In some cases the covers are intended to last hundreds
of years. The DOE framework for performance evalua-
tions combines three tools: numerical  modeling, field
tests, and natural analog  studies. Natural analog stud-
ies provide clues from present and past environments
as to possible long-term changes in the  performance of
engineered covers. Evidence from natural analogs is
needed to identify and evaluate emergent properties in
the evolution of covers that cannot be captured by short-
term field tests or numerical models. Natural analog data
is needed to help design  modeling and field tests that
reasonably bound possible future changes in waste site
environments. Natural analogs may also have a role in
communicating the results of the  performance assess-
*Wfork performed under DOE contract no. DE-AC13-96GJ87335 for the U.S.
Department of Energy Grand Junction Office.
ment to the public, to demonstrate that numerical pre-
dictions have real-world complements.

Natural analogs exist for climate change, ecological
change, and pedogenesis. Analog data can provide
evidence of how a changing climate or a secondary dis-
turbance may influence directions and rates of pedo-
genesis, vegetation structure and diversity, and animal
community composition at a waste site. Analogs of lo-
cal responses to future global climate change exist as
proxy ecological and archaeological records of similar
paleoclimates.  Many cover designs depend on water
extraction  by plants. Influences of vegetation change
can be inferred by evaluating plant communities repre-
senting successional chronosequences. Similarly, ani-
mal habitats like those created on waste sites can
provide evidence of the potential for biological intrusion.
Finally, future pedogenic effects on cover performance
can be inferred from measurements of key soil proper-
ties in  natural and archaeological soil profiles analo-
gous to engineered covers.

The typical cover design  approach evaluates perfor-
mance using a combination of short-term field tests and
numerical models.This approach implicitly assumes that
long-term  changes in the performance of covers can
be captured with model extrapolations based on a few
years of monitoring conditions in field tests. Field test
results and numerical models, alone, will not be suffi-
cient to predict long-term performance of alternative
covers.The ecology, soils, and thus the performance of
an engineered cover will change in ways that cannot be
predicted by short-term monitoring and numerical mod-
els. This is particularly true for alternative covers that
rely on vegetation to seasonally remove precipitation
stored in thick soil layers.  If the U.S. Department of En-
ergy (DOE) and others are serious about predicting long-
term performance covers (hundreds of years or longer),
the design process must include methods to bound rea-
sonable ranges of change in the cover environment.

Long-Term Cover Performance Issues
This paper addressed four issues concerning the de-
sign and long-term performance of landfill covers:

       Plant community dynamics and diversity

       Climate change

       Long-term ecological change


Plant Community Dynamics and
Many cover designs rely on vegetation for erosion pro-
tection and soil water extraction. Changes in plant com-
munities, particularly catastrophic losses of vegetation,
will influence the performance of these covers.  Changes
in the plant community are inevitable. Plant communi-
ties develop and change in  response to several inter-
acting factors: propagule accessibility, climatic variability,
change in soil characteristics, disturbances  (such as
fire), and species interactions (such as herbivory, com-
petition, or fluctuations in soil  microbe populations).
Plant community dynamics are  manifested by shifts in
vegetation abundance, species composition, and diver-
sity and may  be accompanied by changes in rates of
nutrient cycling, energy exchange, and transpiration.
Consequently, plant community dynamics are compli-
cated and effects are difficult to model and predict.

Seeding of monocultures or low-diversity mixtures on
engineered covers is common.  Instead, revegetation
activities should attempt to emulate the structure, func-
tion, diversity, and dynamics of native  plant communi-
ties in the area (Limbach et al. 1994). Diverse mixtures
of native and naturalized plants will maximize water re-
moval by evapotranspiration (Link et al. 1994a) and re-
main more resilient to catastrophes and fluctuations in
the environment. Diverse plant communities consist of
a mosaic of many species that structurally and func-
tionally change in response to disturbances and envi-
ronmental fluctuations (Tausch et al. 1993). Biological
diversity is necessary for plant community stability and
resilience given variable and unpredictable changes in
the environment resulting from pathogen and pest out-
breaks, disturbances (overgrazing, fire,  etc.), and cli-
matic fluctuations.  Local indigenous  genotypes that
have been selected over thousands of years are best
adapted to climatic  changes and biological perturba-
tions. In  contrast, the exotic grass plantings  common
on waste-site covers are genetically and structurally rigid
(Allen 1988) and, thus, more vulnerable to disturbance
or eradication by single factors.

Climate Change
Current cover design paradigms and practices rely on
meteorological records for  performance evaluations
(e.g., DOE 1989). Controlled experiments, field dem-
onstrations, and models of water infiltration, gas attenu-
ation, erosion, frost penetration, and biointrusion all
include meteorological parameters. Meteorological data
should be input only to evaluations of historical climate
change, but not to evaluations of possible future changes
in climate. Some performance evaluations assume that
meteorological records bound reasonable ranges of
future changes in climate (DOE 1989, Gilbert et al.
1988). However, climatologists generally agree that
during the next decades and centuries, global climatic
variation  will exceed the  historical record. This may
happen as has occurred naturally in the past (Houghton
etal.1990;Crowleyand North 1991) and/or as the lower
atmosphere warms in response to increasing concen-
trations  of anthropogenic carbon dioxide and other
greenhouse gases (Hansen et al. 1988; Ramanathan

Ecological Change
Plants and animals can have profound influences, both
positive and negative, on the performance of engineered
covers. Without human interference, overtime, ecologi-
cal development will take  place on all earthen covers.
Ecological succession is a directional change through
time in the plant and animal species that will occupy a
cover. Ecological succession  may alter the functional
performance of a cover in ways not initially anticipated.
As the plants and animals change,  so  also may key
performance parameters such as infiltration, evapotrans-
piration, water retention, soil loss, gas diffusion, root
penetration, burrow depths, and burrow volume. It will
be important to know, for example, how changes in the
plant community inhabiting a cover may influence soil
water movement, evapotranspiration, and the water
balance of a cover.

The  ecology of a site will change in response to cli-
mate, to soil development, and  to disturbances such as
fire, grazing, or inadvertent cultivation (e.g., Allen 1988;
Betancourt et al. 1990; Boone and Keller 1993; Laundre
and  Reynolds  1993). Even in the absence of large-
scale disturbances,  seasonal  and yearly variability in
precipitation and temperature will cause  changes in
species abundance, diversity, biomass production, and
soil water extraction rates (Anderson et al. 1987; Link et
al. 1990).  In the long term, changes in the waste-site
ecology may occur in ways not captured by predictive
models or short-term field  tests. For example, succes-
sional changes in the vegetation can create small-scale
topographic patterns that  foster greater  heterogeneity
in the soil water balance.  At  arid sites, desert shrub
communities that are likely to develop on  covers tend to
trap wind-borne sediments causing a hummock-swale
relief with variable soil physical and  hydraulic proper-
ties  (Link et al. 1994b).   Similarly, at humid sites,
blowdown of mature trees  growing on engineered cov-
ers will create depressions for water accumulation (Suter
etal. 1993).

Pedogenic (soil development) processes will change the
physical and hydraulic properties of soils used as con-
struction materials in engineered covers. Pedogenesis
includes processes such as soil structural development
(aggregation of fines and development of macropores),
secondary mineralization  and illuviation of materials
causing the formation of distinct layers or horizons, and

pedoturbation or natural soil mixing. Although rates and
magnitudes of change vary, pedogenesis takes place
to some degree in all soils (Boul et al. 1980).  Rates of
change are greatest following the stabilization of engi-
neered soils as a result of the establishment of vegeta-

The evolution and architecture of macropores associ-
ated with root growth, animal holes, and soil structural
development are highly relevant to the long-term  per-
formance of engineered covers. Overall, soil structural
development creates preferential flow paths under satu-
rated conditions (Collis-George 1991), causing water
movement through fine-textured soil layers to behave
more like coarse, gravely soils.  Eluviation and illuvia-
tion (similar to emigration and immigration) of fine  par-
ticles, colloids, soluble salts and oxides in an engineered
cover may create secondary layers or horizons,  with
diverging physical and hydraulic characteristics (Boul
et al. 1980).  Accumulation of these materials in the
macropores of sand and gravel layers in engineered
covers could reduce the permeability of lateral drain-
age layers, increase the rate of downward redistribu-
tion of water through capillary barriers, and reduce the
water storage capacity of overlying soil layers.

Pedoturbation, or natural soil mixing, caused byfreeze-
thaw activity, burrowing animals, plant root growth, and
the shrink-swell action of expansive clays could homog-
enize engineered layer interfaces. Burrowing could  also
cast soil above gravel mulch and admixture layers in-
tended for erosion protection, potentially accelerating
soil loss. The formation of lag layers by winnowing, frost
heaving, movement of soil gases during and after rain,
and the shrink-swell action of expansive clays can cause
the  gradual movement of gravels  toward the surface.
Loess deposited on the surface can be  transported
below surface gravels in cracks that form in underlying
vesicular soil, gradually elevating the gravel above the
former land surface (McFadden et al. 1987).

Evaluation of Long-Term System
The primary difference between near-term and long-
term performance assessment is the need to define
reasonable ranges of future changes in climate, ecol-
ogy, and soils. Once reasonable ranges of long-term
changes in covers systems have been defined, the sen-
sitivity of the system to these ranges of conditions should
be evaluated.  Furthermore, long-term performance
assessment  methods and  risk assessment methods
must be closely coupled. Any proposed design modifi-
cation or cost  increase arising from an evaluation of
long-term system changes must be justified by a re-
duction in risk to human health and the environment.

Three conformable approaches for evaluating the ef-
fects of long-term system changes on cover perfor-
mance  are  recommended:  predictive models,
monitoring existing covers, and natural analogs.
Predictive Models
Numerical models of soil-water movement, erosion, and
gas diffusion engender an understanding of the com-
plexity of environmental processes acting on engineered
covers and, if verified, can be used to estimate re-
sponses of designs to myriad conditions.  However,
verification  studies only require models to reproduce
short-term  monitoring data.  The  most widely used
model, HELP (EPA 1994), has been applied repeatedly
as the primary cover design tool with little or no data to
back the reliability of predictions. Therefore, long-term
predictions  using  models are implicitly based on the
assumption that near-term conditions of material prop-
erties, ecology, and climate—processes that drive con-
taminant transport—will persist.  Future modeling
studies should focus on estimates of performance over
a range of possible future conditions of cover systems.

Monitoring Existing Covers
Field demonstrations and monitoring of existing cov-
ers, although expensive, provide the only direct mea-
sures of performance and are needed to  test the
credibility of models. DOE has made a considerable
investment in research facilities and in existing, opera-
tional covers that encompass a diversity of designs and
that exist in a broad range  of environmental  settings.
Many existing research facilities were conceived to ad-
dress near-term performance issues, as well as model
verification, but monitoring has been repeatedly discon-
tinued, and  complete monitoring data sets are rare.

Because the performance of many existing covers has
not been monitored, we have few means for evaluating
the efficacy of designs. The DOE Uranium Mill Tailings
Remedial Action  (UMTRA) Project is  an exception.
UMTRA embodies most of the United States operational
experience  with the design and construction of engi-
neered covers intended to last hundreds of years. DOE's
Long-term Surveillance and Maintenance (LTSM)  pro-
gram recently created the Long-Term Performance (LTP)
project to evaluate how changes in UMTRA disposal
cell environments, both ongoing changes and projected
changes over hundreds of years, may alter cover  per-
formance. This project was created  not only to improve
site inspections, but also to support development of
design guidance for the next generation of covers at
DOE weapons sites, and to support the preparation of
new cover design guidance by EPA (DOE 2000).

Natural Analogs
Natural analog studies provide clues from present and
past environments as to possible long-term changes in
engineered covers (Waugh et al. 1994). Analog studies
involve the use of logical analogy to investigate natural
materials, conditions, or processes that are similar to
those known or predicted to occur in some component
of an engineered cover system.  As such, analogs can
be thought of as uncontrolled, long-term experiments.
Evidence from natural analogs is needed (1) to identify
and evaluate emergent properties  in the evolution of
engineered covers that cannot be  captured by short-

term tests or numerical models and (2) as input to the
development of modeling and field tests that reason-
ably bound possible future changes in waste site envi-

Natural analogs exist for climate change, ecological
change, and pedogenesis (Waugh etal. 1994). Analog
data will provide evidence of how climate change or a
secondary disturbance (e.g., fire) can influence direc-
tions and  rates of pedogenesis, vegetation structure and
diversity, and animal community composition at a single
location through time. The interaction of these compo-
nents and the generation of feedback loops, by defini-
tion the  ecology of the  engineered cover,  can
dramatically affect its long-term performance. Analogs
of local responses to future global climate change exist
as proxy ecological and archaeological records of simi-
lar paleoclimates.  Many cover designs depend on wa-
ter extraction by plants. Influences of vegetation change
can be inferred by measuring water extraction param-
eters in plant communities  representing successional
chronosequences. Similarly, animal habitats like those
created on waste sites can provide evidence of the po-
tential for biological intrusion. Finally, future pedogenic
effects can be inferred from measurements of key soil
properties in natural and archaeological soil profiles
analogous to engineered covers.

Public acceptance of plans to leave residual waste in
place will  depend  largely on public confidence in the
long-term performance of  engineered  covers. Engi-
neered covers are central to perceptions of in-place dis-
posal, yet long-term performance  data are nonexistent,
and short-term performance data and model predictions
are largely experimental. The limited amount of moni-
toring data suggests that after a few years many exist-
ing covers for hazardous wastes are not meeting design
and performance objectives, largely because of unan-
ticipated ecological effects. The design and  construc-
tion of long-term covers throughout the DOE complex
will be very costly, but postconstruction maintenance
costs may be much greater than installation costs if
covers begin to degrade after a few years.

Performance assessment of engineered covers is com-
monly an exercise of trying to create confidence by us-
ing numerical  simulations to extrapolate long-term
performance from short-term field tests. In contrast, data
from natural systems, past and present, should be used
in the performance assessment to bound possible fu-
ture changes in waste site environments. Evidence from
these natural analogs is needed to physically simulate
changes in engineered covers that cannot be captured
by short-term field tests. Natural analogs will also have
a role in communicating the results of the performance
assess-ment to the public. Evidence from natural ana-
logs will help demonstrate that numerical simulations
have real-world complements.

Allen, E.B. (ed.). 1988. The Reconstruction of Disturbed
Arid Lands: An Ecological Approach. AAAS Selected
Symposium 109, American Association forthe Advance-
ment of Science, Washington, DC.

Anderson, J.E., M.L.Shumar, N.L.Toft, and R.S.Novak.
1987. Control  of the soil water balance by sagebrush
and three perennial grasses in a cold-desert environ-
ment. Arid Soil Res. Rehab. 1:229-244.

Betancourt, J.L., T.R. Van Devender, and PS. Martin
(eds.).  1990. Packrat Middens: The Last 40,000 Years
of Biotic Change. University of Arizona Press, Tucson,

Boone, J.D., and B.L. Keller.  1993. Temporal and spa-
tial patterns of small mammal density and species com-
position on a radioactive waste disposal area: The role
of edge habitat. Great Basin Naturalist 53:341-349.

Boul, S.W.,  F.D. Hole, and R.J. McCracken. 1980. Soil
Genesis and Classification, Second Edition. Iowa State
University Press, Ames, IA.

Collis-George,  N. 1991. Drainage and soil structure: A
review. Australian J. Soil Res. 29:923-933.

Crowley, T.J., and G.R. North. 1991. Paleoclimatology.
Oxford Monographs on Geology and Geophysics No.
16. Oxford University Press, New York.

DOE (U.S.  Department of Energy).  1989.  Technical
Approach Document,  Revision II.  UMTRA-DOE/AL
050425.0002,  Uranium Mill Tailings Remedial Action
Program, U.S. Department  of Energy, Albuquerque
Operations  Office, Albuquerque, NM.

DOE\ 2000. Long-Term Surveillance and Maintenance
Program 1999 Report. GJO-2000-139-TAR, Long-
Term Surveillance and Maintenance Program, U.S.
Department of Energy Grand Junction Office, Grand
Junction, CO.

EPA (U.S. Environmental Protection Agency). 1994. The
Hydrologic Evaluation of Landfill Performance (HELP)
Model, User's Guide for Version 3. EPA/600/R-94/168b.
Washington, DC.

Gilbert, T.L., S.F. Camasta, and N.K. Meshkov.  1988.
Assessing the performance of engineered barriers and
materials for confinement of low-level radioactive waste.
In: Proceedings of the Ninth Annual DOE Low-Level
Waste  Management Forum.  CONF-870859, National
Low-Level Radioactive Waste Management Program,
Idaho Falls, ID.

Hansen,  J., I. Fung., A. Lacis, D. Rind, S. Lebedeff, R.
Ruedy, and  G. Russell. 1988. Global climate changes
and forecast by Goddard Institute  of Space Studies
three-dimensional model. Journal of Geophysical Re-
search 93:9341-9364.

Houghton, J.T., G.J. Jenkins, and J.J. Ephraums (eds.).
1990. Climate Change: The IPCC Scientific Assess-
ment. Cambridge University Press, Cambridge, United

Laundre, J.W., and T.D.Reynolds.  1993. Effects of soil
structure on burrow characteristics of five small mam-
mal species. Great Basin Naturalist 53:358-366.

Limbach,  W.E., T.D. Ratzlaff, J.E. Anderson, T.D.
Reynolds,  and J.W. Laundre. 1994. Design and imple-
mentation  of the protective cap/biobarrier experiment
at the Idaho National Engineering Laboratory. In G.W.
Gee and N.R. Wing (eds.) In-Situ Remediation: Scien-
tific Basis for Current and Future Technologies. Battelle
Press, Richland,WA.

Link, S.O., G.W. Gee, M.E.Thiede, and PA. Beedlow.
1990. Response of a shrub-steppe ecosystem to fire:
Soil water  and vegetational change. Arid Soil Res. Re-

Link, S.O., WJ.Waugh, J.L. Downs.  1994. The role of
plants on isolation barrier systems.  In G.W. Gee and
N.R. Wing  (eds.), In-Situ Remediation Scientific Basis
for Current and Future Technologies,  Battelle Press,
Link, S.O., WJ.Waugh, J.L. Downs, M.E.Thiede, J.C.
Chatters, and G.W. Gee. 1994. Effects of coppice dune
topography and vegetation on soil water dynamics in a
cold-desert ecosystem. J. Arid Environ. 27:265-278.

McFadden, L.D., S.G. Wells, and M.J. Jercinovich. 1987.
Influences of eolian and pedogenic processes on the
origin and evolution of desert pavements.  Geology

Ramanathan, V. 1988. The greenhouse theory of cli-
mate change:  A test by an inadvertent  global experi-
ment. Science 240:293-299.

Suter, G.W,  II, R.J. Luxmoore, and E.D. Smith.  1993.
Compacted soil barriers at abandoned landfill sites are
likely to fail in the long term. J. Environ. Qua/. 217-226.

Tausch,  R.J., PE. Wigand, and J.W. Burkhardt.  1993.
Plant community thresholds, multiple steady states, and
multiple  succession pathways: Legacy of the Quater-
nary. J. Range. Manage., 46:4394-47.

Waugh, W.J., K.L. Petersen, S.O. Link, B.N. Bjornstad,
and G.W. Gee, 1994. Natural analogs of the long term
performance of engineered covers. In G.W. Gee and
N.R. Wing (eds.), In Situ Remediation: Scientific Basis
for Current and Future Technologies, Battelle Press,

Growing a 1000-Year
    Landfill Cover
       W. Jody Waugh
Environmental Sciences Laboratory*
   U.S. Department of Energy
feston, Inc., under


implementation protocol,
established for end users and
accepted by regulators, that
limits contaminant migration
consistent with long-te
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Methods of Verifying Barrier Performance

     Cover Analog Studies
  Evaluation of natural and
  archaeological settings tl
  are similar in some respect to
  processes known or predicted
  to occur during the
  of landfill cov
    "Secrets of the past pn

Needs for Cover Analog Data
  Discern emergent attributes in the
  evolution of landfill covers
  Form hypotheses and select
  treatments for short-term field
  (e.g., lysimeter) studies
  Define reasonable  ranges of
  values for model input parameters
  Demonstrate to stakeholders
  that numerical predictions have
  real-world complements

{soil development)

Ecological Change

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     Parting Thoughts
 Cover components will not
 function—and must not be
 1000-year cover performance
 cannot be extrapolated from
 initial conditions—changes in
 physical and ecological attributes
 are inevitable
Parting Thoughts (continued)
 Projections of long-term
 performance require a coupling
 of monitoring, modeling, and
 analog studies
 Designing covers to endure
 environmental change could
 save DOE billions in stewardship
 costs over the long term


           Tree Covers for Containment and  Leachate  Recirculation

                                           Eric Aitchison
                                          Ecolotree® Inc.
                                 505 E.Washington Street, Suite 300
                                         Iowa City, IA 52240
                              Phone: (319)-358-9753 Fax: (319)-358-9773
                                        Ecolotree @ aol.com
                               For more information: www.Ecolotree.com
Eric Aitchison is an environmental engineer and project
manager at Ecolotree, the oldest phytoremediation com-
pany in the U.S.  Eric  has worked  on over  25
phytoremediation projects, and is experienced in de-
sign, site preparation, site installation, maintenance, and
reporting. Eric also  coordinates greenhouse experi-
ments to evaluate phytoremediation potential at vari-
ous sites.

Eric obtained a BS degree in civil engineering from Iowa
State University and a MS degree in environmental en-
gineering from The University of Iowa. His MS research
evaluated the potential for phytoremediation of 1,4-di-
oxane by hybrid poplar trees.  Eric has experience in
consulting as an environmental engineer with Shive-
Hattery, Inc., and as a researcher with The University
of Iowa.

The  Ecolotree® Cap (E-Cap) is a patented crop sys-
tem that reduces water percolation into the ground.The
E-Cap grows tall poplar trees with deep root  systems
planted into specially prepared soils. E-Caps pump water
from the cover soils, thus dehydrating the soil during
the growing season and creating water storage capac-
ity for the dormant winter months. Plants take up this
water for growth or release it into the atmosphere by
transpiration.  E-Caps have been installed as alterna-
tive covers at 17 landfill sites in nine states.  Applica-
tions include municipal solid waste landfills, industrial
landfills (fly ash, casting sand), construction debris land-
fills,  and Superfund hazardous waste landfills. The E-
Cap  has been approved and installed as final closure
over old pre-subtitle D landfills in Pennsylvania, Ten-
nessee, and Washington.
E-Caps can reduce long-term liability and minimize post-
closure operation and maintenance  ,costs. Communi-
ties are planning to use E-Caps at landfills for managing
municipal sludges (biosolids, lime stabilization sludges,
leaf litter, wood waste, and snow removal debris), and
as recreational parks. The multiple benefits to wildlife
habitat, greenhouse gas cycling, greening of a former
eyesore,  and reduction  in costs help to make the E-
Cap a technology worth the investment.

Ecolotree recently participated in the US EPA Alterna-
tive Cover Assessment  Project (ACAP) at a landfill in
Georgia.This project will provide valuable data with re-
gards to the performance  of an E-Cap verses a tradi-
tional clay cover.

Wastewater and leachate  have been successfully irri-
gated onto E-Caps at four sites. The vegetation takes
up a significant portion of the water (up to 10,000 gal-
lons/acre/day in summer months for 3-year old  poplars),
thus providing a wastewater/leachate sink. Contami-
nants, such as  ammonium, nitrate,  BOD,  and BTEX
compounds, are removed by 1) direct uptake into plants,
2) sorption to roots and  soil organic matter, and 3) en-
hanced microbial degradation in the root zone. Irriga-
tion rates can be adjusted to ensure that the desired
performance standards are achieved. At the Great River
Regional Waste Authority Landfill in Fort Madison, Iowa,
6 million gallons of leachate are being irrigated annu-
ally onto a 6-acre E-Cap. The E-Cap had a  payback of
two years when considering the previous cost of haul-
ing the leachate to a wastewater treatment plant.

 Tree Covers for Containment and
        Leachate Recirculation

Phytoremediation: State of the Science Conference
                May 1-2, 2000

         Eric Aitchison, Ecolotree® Inc.
              www. Ecolotree.com
           Ecolotree Sites as of April 2000
 O Landfills
 © Wastewater/leachate treatment
 0 Superfund
 A Agrochemical/fertilizer spill
 —y— Biosolids/manure management
 •& Study
 L Other

   Poplars dehydrated soil at the Bluestem Landfill (Cedar Rapids,
           Iowa) more than the traditional IDNR cover.
 90% survival
 . 5-8' of vertical growth per year
 . Roots have penetrated cover soil and rooted into
 • Owner has received regulatory permission for full-site
   tree capping

     Leachate Irrigation onto Ecolotree® Buffer:
         Riverbend Landfill - McMinnville, Oregon

• Designed to treat 7 MGY of ammonium-rich leachate
. Installed in 1992-93 -17 acres with 35,000 hybrid poplars
• 4th year of operation - 860,000 gallons/acre irrigated; 450 Ibs
  N/acre removed
• Roots zone extended 7 feet below surface
• Worms dragged leaf matter to 7 feet below surface
• Soil moisture monitored by Time Domain Reflectometry
• CH2M HILL and Ecolotree received the 1994 Engineering
  Excellence Award from Oregon CEC and a national top 25
  project award from National Society of Professional Engineers
  Wastewater Treatment with an Ecolotree® Buffer:
   City of Woodbum (Oregon) Wastewater Treatment Plant

    • 1 Quaere demo (17,000 trees) planted in 1995;
      expanded to 90 acres in 1999
    • Goal = tertiary treatment of wastewater for removal of
      thermal energy and ammonium
    • Conservative design - water and nutrients irrigated to
      match plant uptake; treat 1.5 million gpd during
      summer months
    • CH2M  HILL and Ecolotree received the 1996
      Engineering Excellence Grand Award by Oregon

  Leachate Irrigation onto an Ecolotree® Buffer:
         GRRWA Landfill - Fort Madison, Iowa

  Designed to treat 7 MGY of MSW leachate; interim cap
  over Subtitle-D liner
  Regulatory agency very cooperative: approval 3 days
  after design submittal
  Installed in 1997-98 - 6 acres with 6,800 hybrid poplars
  Has provided the owner a payback of 2 years
  Organic waste will be applied between the tree rows
  Stanley Consultants and Ecolotree received the 1999-
  2000 Grand Conceptor Award for Engineering
  Excellence from the Iowa CEC

Ecolotree® Caps and Buffers use poplar trees and a
grass understory for containment and
leachate/wastewater treatment.

Vegetative systems offer numerous benefits to landfills:
 .  Effective and economical
 .  Acceptable by the neighboring community
 .  Noise and visual barriers
The data collected to date has supported the
effectiveness of hybrid poplars for containment and
treatment; more data is coming.

                   EPA Draft Guidance on Final Landfill Covers
                                   Andrea Mclaughlin, Ken Skahn
                                U.S. Environmental Protection Agency
                                         Ariel Rios Building
                        1200 Pennsylvania Avenue, NW Washington D.C. 20460
Andrea Mclaughlin has a B.A. in Environmental Policy
from Hood College in Frederick, Maryland. She has
worked in both the private sector and with EPA on poli-
cies related to the management of hazardous wastes
for 14 years.

Andrea is an Environmental Protection Specialist with
EPA's Office of Emergency and Remedial Response,
where she has worked on Superfund landfill policy is-
sues  for approximately ten  years.  Prior to joining
Superfund, Andrea developed proposed and final rules
restricting the land disposal  of hazardous waste  for
EPA's Office of Solid Waste. Andrea is currently respon-
sible for the development of a policy directive related to
the use of alternative covers  on  Superfund Landfills,
and is developing guidance on methods for assessing
landfill gas emissions and health risks at  Superfund

Ken Skahn has a B.S. in Civil Engineering from the
University of Illinois. Ken is registered both as a Profes-
sional Engineer and Structural Engineer in the State of
Illinois. He has 25 years experience with EPA, 5 years
with the Corps of Engineers, and 5 years in private prac-
tice as a consulting engineer.  He has been closely in-
volved with establishing EPA's landfill regulations and
policy for 13 years.

Ken is currently employed by EPA as an Environmental
Engineer. For the past 10 years he has been working
on design, construction, and  post-remediation issues
for the Superfund  program at EPA's  headquarters in
Washington, DC. He is the Superfund Program's liaison
to the Corps of Engineers as well as its landfill capping
expert. He is currently leading a team in a  revision of
EPA's landfill capping guidance that will include discus-
sion of alternative cover designs.
EPA is currently developing two guidance documents
related to final landfill covers that are regulated under
the Resource Conservation and Recovery Act (RCRA)
and  the Comprehensive  Environmental Response,
Compensation, and  Liability Act (CERCLA). The first
document, "Use of  Selected  Alternative Covers at
CERCLA Municipal Landfills," is specific to Superfund
landfills, and provides guidance on how alternative cov-
ers may be considered as remedial alternatives in the
CERCLA remedy selection process. Generally, the regu-
latory mechanism for approval of an alternative design
will involve a demonstration of technical  equivalence.
This policy directive  will explain what is  meant by an
"equivalent standard of performance" based on
CERCLA and the National Contingency Plan (NCP). In
addition, this guidance will identify factors (e.g., climatic
conditions, landfill gas generation,  and ground-water
protection) that should be evaluated when determining
whether or not consideration of an alternative landfill
design is appropriate on a site-specific basis.This guid-
ance is expected in January 2001.

The second guidance, "Technical Guidance for RCRA/
CERCLA Final Covers," provides an update to the pre-
vious U.S. EPA guidance on this subject, "Design and
Construction of RCRA/CERCLA Final Covers," EPA/625/
4-92/025 (1991). In comparison to the scope of the 1991
guidance, this document has been expanded to address
a number of new topics. In  particular, this guidance ad-
dresses how technical equivalence may be demon-
strated for alternative landfill designs, including capillary
barriers and evapotranspirative barriers. The guidance
also provides information on cover system design, de-
sign  criteria development,  new types of geosynthetics
(such as geosynthetic clay liners),  special design is-
sues, lessons learned from the closure of existing land-
fills,  performance  monitoring of closed landfills, and
maintenance of cover systems to achieve the required
design life. This guidance was expected in December

     State of the Science Conference
                                  3 m m ro
                                  *    £
                May 2, 2000




EPA Liquids Management Strategy


Draft Landfill Guidance




Draft Landfill Guidance (cont.)








       1 X 10 5 cm/sec, WHICHEVER IS LESS


     (1 X 10 5 cm/sec)







CERCLA (cont.)



CERCLA (cont.)



CERCLA (cont.)
    ARAR WAIVER (SECTION 300.430(f) OF NCP):

       "The alternative will attain a standard of performance
           that is equivalent to that required under the
      otherwise applicable standard ....through use of another
                   method or approach."

CERCLA (cont.)







     State of the Science Conference
               May 2, 2000












  + LONG TERM MAINTENANCE                I    1




     DRAINAGE SYSTEM                     ^^

    - LONG TERM MAINTENANCE              I   I


                                                   3     \
ET Barrier


                                    Topsoil/Surface Treatment

Capillary Barrier
                             Topsoil/Surface Treatment
                             Fine-Texture Soil















                       Hydrocarbon Treatment  Using Grasses
                                         M. Katherine Banks
                                         Purdue University
                                         West Lafayette, IN
M. Katherine Banks is currently an associate professor
of civil engineering at Purdue University. She received
a B.S. in environmental engineering from the University
of Florida, a M.S.E.E. in water resources engineering
from the University of North Carolina, and a Ph.D. in
civil and environmental engineering from Duke Univer-
sity. Dr. Banks was a member of the faculty at Kansas
State University from 1989 to  1997.  Her research
projects focus on the use of phytoremediation for haz-
ardous organic compunds using deep-rooted grasses.
Overthe past 8 years, Dr. Banks has been involved with
phytoremediation field projects in California, Kansas,
Virginia, Texas, and Indiana.

Petroleum contamination of soil  is a serious problem
throughout the United States. Bioremediation of petro-
leum in soil using indigenous microorganisms  has
proven effective; however, the biodegradation rate of
more recalcitrant and potentially toxic petroleum con-
taminants, such as polycyclic aromatic  hydrocarbons,
is rapid  at first but declines quickly. Biodegradation of
such compounds is limited by their strong  adsorption
potential and low solubility. Vegetation may play an  im-
portant role in the biodegradation of toxic  organic chemi-
cals in soil. For petroleum compounds, the presence of
rhizosphere microorganisms may accelerate biodegra-
dation of the contaminants. The establishment of veg-
etation on hazardous waste sites is an  economic,
potentially effective, low maintenance approach to waste
remediation and stabilization.

In  a number of field trials, it has been demonstrated
that phytoremediation is a viable treatment alternative
for aged petroleum contaminated soil. Degradation of
total petroleum hydrocarbons was found to be greater
in vegetated treatments compared to unvegetated con-
trols. The rate of remediation in the planted plots did not
diminish with time; a "plateau" effect was not observed.
However, there are limitations to this technology. Con-
siderable time is needed to achieve regulated levels,
depending upon the initial concentrations and the de-
sired end points. Phytoremediation using grasses and
legumes is a reasonable alternative forsurface contami-
nation but will have minimal impact below 100 cm. More
information is needed concerning the plant species that
are best adapted to phytoremediation. A more complete
understanding of the mechanisms involved will allow
foroptimal selection of plants forfuture phytoremediation

               Phy to re mediation of Explosives Phillip Thompson

                      Phillip L.Thompson, Seattle University, Seattle, Washington
      Steven McCutcheon and N. Lee Wolfe U.S. EPA National Exposure Laboratory Athens, Georgia
Phillip Thompson has a B.A. in Biology and an M.S.
and Ph.D. in  Environmental  Engineering from the
University of  Iowa. He is a registered professional
engineer in the State of Washington and has been
involved in projects ranging from drinking water
treatment to phytoremediation. Phillip has been an
assistant professor in the Department of Civil and
Environmental Engineering at Seattle University since
the Fall of 1997 where he teaches He teaches courses
in water supply, wastewater treatment, hazardous waste
management and engineering economics. His current
research interests are in the areas  hazardous waste
remediation and water re-use.

List of Related Publications

This research  evaluated the toxicity, uptake and fate of
the explosives 2,4,6-trinitrotoluene (TNT)  and
hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in hybrid
poplar trees (Populus deltoides x nigra, DN34). TNT
was toxic to the hybrid poplar at a concentration of 5
mg/L. It also reacted quickly at the root surface where
it was transformed into a number of known and unknown
products, Transformation likely caused the retention of
up to 75 percent of the TNT-related 14C in the root
tissues. Less than 10 percent of the applied TNT was
translocated to leaf tissues, all in the form of as yet
defined products. The  identification  of  these
transformation products may be important to field-scale
phytoremediation efforts.

RDX uptake and fate was quite different than  that of
TNT.  Over 60 percent  of the  applied  RDX
bioaccumulated in leaf tissues as parent compound.
The transformation  of RDX was very slow with only
small fractions of degradation  in leaf tissues overtime
periods of months. The accumulation of RDX in leaf
tissues may be a concern with regard to leaf litter
transport and consumption by herbivorous species.
Since the rate of contaminant removal from soil is a
function of concentration, the  timeframe  for
phytoremediation to achieve near-pristine conditions will
vary from several years to many decades. A discussion
of this  and other design-related questions will be

Department of Civil and Environmental Engineering
Seattle University, Seattle,

                        Phytoremediation of Explosives Contamination
                                      Phillip L. Thompson
                           Department of Civil and Environmental Engineering
                                Seattle University, Seattle, Washington
                              Steven McCutcheon and N. Lee Wolfe
                                U.S. EPA National Exposure Laboratory
                                         Athens, Georgia

       TNT (2,4,6-trinitrotoluene) and RDX (hexahydro-l,3,5-trinitro-l,3,5-triazine) are two of
the most commonly used explosives in the world. Liquid wastes containing TNT and RDX are
generated at ammunition production facilities as a result of cleaning operations. Historically,
these waste streams were discharged to lagoons that subsequently were released into local
streams (Higson, 1992).  Although this method of disposal is no longer practiced, thousands of
acres across the United States are still highly contaminated (Funk et al., 1993). For example,
TNT and RDX have contaminated several acres of land at the Iowa Army Ammunition Plant
(IAAP) at Middletown, Iowa.
       The chemical structures of TNT and RDX are shown in Figure 1.  The dimensionless
Henry's constants have been estimated to be  1.5 x  10 9 and 1.5 x 10"5 for RDX and TNT,
respectively. Physical and chemical properties of the two explosives are presented in Table 1.
                 02N,   JL  XNQ2              CW^  .NQz

                    Figure 1: The chemical structures of TNT and RDX
Table 1: Some physical and chemical properties of TNT and RDX
Molar Mass, g
Solubility at
25* C,mg/L
Log Vapor
Pressure at
25* C,Torr
a = Budavari, 1990; b = Spanggord, 1996; c = Chen, 1993; d = Lange's Handbook
of Chemistry;  e = Haderlein, 1996

       A number of approaches have been used to remediate TNT and RDX contamination
including carbon adsorption, incineration, and microbial bioremediation (Kaplan, 1990).
Incineration and carbon adsorption are widely accepted treatment methods, but they are both
generally very expensive (Funk et al., 1993). Microbial transformations of TNT and RDX also
have limitations in that mineralization is rarely achieved. Since existing treatment technologies
are inadequate or too expensive, alternatives such as phytoremediation should be considered.
       This research evaluated the potential for using poplar trees to remediate TNT and RDX
contamination at the IAAP. It was hypothesized that 1) the poplar tree hybrid (Populus deltoides
xnigra , DN34) has the intrinsic ability to translocate and transform TNT and RDX from water
and soil 2) these explosives are not toxic to the tree and 3) sorption to IAAP soil controls the
bioavailability of TNT, RDX and any transformation products.  The information gathered from
these laboratory studies was used to develop a finite difference model.
       The sorption of RDX, TNT, and the TNT metabolites 4-amino-2,6-dinitrotoluene (4-
ADNT) and 2-amino-4,6-dinitrotoluene (2-ADNT) to the organic-rich (foc=0.019) soil from the
IAAP was evaluated to understand the potential transport and bioavailability of these chemicals.
" Soil-chemical equilibria were achieved in less than 24 hours for all compounds except for TNT
which exhibited slow sorption for several days. The mobility and bioavailability were
determined to be RDX>TNT>2-ADNT>4-ADNT based on linear sorption distribution
coefficients (Kj). The values obtained for RDX and TNT agreed well with those found in the
literature. Coefficients determined for 2-ADNT and 4-ADNT were an order of magnitude larger
than predicted by empirical relationships and are new contributions to the literature with respect
to organic-rich soils.
       Hydroponic experiments with the hybrid poplar revealed that radiolabeled RDX and TNT
behave quite differently in terms of uptake, transport and fate. The removal of RDX from
solution was slow  as demonstrated by the increase of RDX concentrations in hydroponic solution
 over time and the low transpiration stream concentration factor (TSCF) of 0.16+0.06 (n=9).
 RDX was taken-up from soil more quickly  relative to TNT due to its greater availability (weaker
        RDX-related radiolabel was distributed throughout/plant in similar proportions for
 experiments lasting from 2 to 26 days. The largest amounts (60 percent of that taken-up) of label
 were found in leaf tissues with the remainder being equally distributed between root and stem

tissues. Mass balances for RDX showed a linear decrease in recovery over time that could not be
explained through the capture of  CC>2 or volatile organics.  An average of 85 percent of the
absorbed RDX-related radiolabel was extracted from plant tissues, and radiochromatograph
analysis demonstrated that no RDX transformation had occurred. In uptake experiments, there
was a fraction of radiolabel that could not be extracted! with the acetone procedure. It is thought
that this fraction was bound residue, a transformation product of RDX in the plant. Recent
preliminary results by researchers at the University of Iowa have suggested that previously
unrecovered radiolabel is in the form of formic acid (Just, 2000).
       Contrary to RDX, the removal of TNT from hydroponic solution by poplar was quite
rapid and was a result of both uptake to stems and leaves and root-mediated transformation. One
unidentified polar product was  detected in the hydroponic solutions while at least three
unknowns (all more polar than  TNT) were detected in root extracts.  These compounds did not
appear to be mobile within the plant as they were not detected in xylem tissues or leaves. Small
amounts of transformation products 4-ADNT, 2-ADNT and 2,4-DANT were detected in all plant
tissues except for the leaves where polar unknown(s) comprised the only detectable 14C products.
In all, these transformation products comprised about ten percent of the radioactivity taken-up by
the plant and about 20 percent of the extractable label.  On average, only 50 percent  of the TNT-
related label was extractable by organic solvents such as methanol or acetone.
       The majority (about 70 percent) of the TNT-related radiolabel taken-up remained
immobilized in root tissues for  periods ranging from two to 42 days. This immobilization may
reflect the transformation to 4-ADNT and 2-ADNT, compounds which are generally less mobile
in the environment.  The remaining absorbed radiolabel was equally distributed to the stem and
leaf tissues.  The fortuitous separation of secondary xylem and phloem tissues showed that there
was 10 times the label contained in the xylem and the transport of radiolabel to the phloem from
the leaves was possible. The removal of TNT from solution was quick and the TSCF for TNT
was estimated at 0.46+0.19 (n=18).
       Phytoremediation of organic wastes requires the evaluation of toxicity of contaminants to
plant species. The common method of measuring phytotoxicity is based on declines in biomass
production, a destructive endpoint. Results indicated that plant toxicity can also be estimated by
measuring the transpiration of exposed plants. Gravimetric measurement of transpiration is a
simple technique and can be a useful means of complementing data from other toxicity tests such

 as overall growth rate. Hydroponic, bench-scale experiments showed that TNT removal from
 solution by hybrid poplar cuttings can be rapid, and that TNT concentrations greater than or
 equal to 5 mg/L were toxic to the cuttings; whereas 1 mg/L doses had no observed adverse-
 effects in 21 day tests. Therefore, the poplar hybrid has a tolerance for TNT that is greater than
 duckweed (Schott,  1974) and similar to yellow nutsedge (Leggett and Palazzo, 1986).  A
 comparison between bench-scale and pilot-scale experiments suggested that the laboratory
 approach used for much  of the poplar research at the University of Iowa was valid for estimating
 phytotoxicity at larger scales. The pilot-scale experiment established that a 5 mg/L TNT was not
 toxic for acute (<14 days) exposures, but there were indications that prolonged exposure would
 be detrimental. There appears to be only a small scale-up difference between the large
 greenhouse-grown trees  and the small lab-grown cuttings. The poplar hybrid showed no signs of
 toxicity when exposed to concentrations of RDX up to 21 mg/L for up to 14 days.
       Results from this research were used to develop a finite difference model for the
 estimation of cleanup times.  The model assumed a uniform volume of contamination (50 mg/kg
 TNT and 20 mg/kg RDX) with an area of 0.4 hectares (one acre) and a depth of three meters.
 Model inputs included the use of experimentally determined TSCF values and partition
 coefficients. It was  also  assumed that 650 trees would be planted per acre and these trees would
 maximally transpire 15 gallons of water per day. Over a 180-day growing season, the total
 amount of transpiration would be on the order of 10,000 liters. Model results indicated that the
 half-life for RDX would  be approximately five years and for TNT it would be fifteen to twenty
       Since the time to  cleanup for the remaining TNT and RDX contamination at IAAP are
 relatively long, explosives uptake by poplar may be less important than the tree's hydraulic
 capacity to protect groundwater. Another concern may be the translocation of RDX to the leaves
 of the tree and the subsequent consumption by deer, hence monitoring of leaf tissue for RDX is
       Future research needs include determining if the formation of volatile products is a major
 fate pathway for TNT and especially RDX.  This may involve the development of a capture-
 system that is both efficient and capable of mimicking natural growing conditions.  The
 identification of the  unknown transformation products would also broaden our understanding
TNT fate.


Budavari, S. (1989), The Merck Index, Merck, Whitehouse Station, N.J.

Chen, D. (1993). Plant uptake and soil adsorption of RDX. University of Illinois, Master's

Funk, S. B. et al. (1993). Initial-Phase Optimization for Bioremediation of Munition Compound-
   Contaminated Soils, Applied and Environmental Microbiology, (July, 1993) 2171-2177.

Haderlein, S. B. et al. (1996). Specific Adsorption of Nitroaromatic Explosives and Pesticides to
   Clay Minerals, Environmental Science and Technology,  30, (2) 612-622.

Higson, F. H. (1992). Microbial Degradation of Nitroaromatic Compounds, Advances in
    Applied Microbiology, 27, 1-19.

Just, C. (2000). Personal Communication.

Kaplan, D. L. (1990). Biotransformation pathways of Hazardous Energetic Organo-Nitro
   Compounds in: Biotechnology and Biotransformation. eds:D. e. a. Kamely; Portfolio
   Publishing Co, Houston, TX.

Lange, N. A. (1979). Lange's Handbook of Chemistry.  McGraw-Hill, New York.

Leggett, D. C.  and Palazzo, A. J. (1986). Effect and Disposition of TNT in a Terrestrial Plant,
   Journal of Environmental Quality, 15, (1) 49-52.

Schott, C. D. et al. (1974). The Toxicity of TNT and Related Wastes to an Aquatic Flowering
   Plant, 'Lemna Perpusilla" Torr. Edgewood Arsenal, Aberdeen proving Ground, MD, EB-TR-

Spanggord, R.  J.  (1996).  Personal communication.

Phytoremediation of Explosives

          Phillip L. Thompson,
           Seattle University
         Steven C. McCutcheon
            and N. Lee Wolfe
             U.S. EPA NERL

                2 May 2000
                            N   N
( 1,3,5-trinitro- 1 ,3,5-triazine)
 Log Kow = 1.9              Log Kow = 0.9
 Solubility = 100 mg/L at 25°C    Solubility = 40 mg/L at 25°C

2-HA 4,6-
               Metabolic pathways for TNT
                        NQ> \
                       TNT  \
                    •.     ,-     NHOH
                     X >'
                  Azoxy compound's
            Metabolic Pathways continued.
 2A 4,6-DNT
                NH,      NOv^XMo,
                                  4-A 2,6-DNT
                2,4-DA 6-NT

Uptake by Terrestrial Plants

I Yellow Nutsedge
I Bush Bean, Maize, Wheat
I Poplar
I Grasses (tall fescue, switchgrass)
TNT Toxicity
  Yellow Nutsedge - 5 mg/L
  Poplar - 5 mg/L
  Tall fescue - 30 mg/L
  Switchgrass - 15 mg/L
  Common Bean - 500 mg/kg

Translocation of TNT and RDX

Metabolism of TNT
  Possible Novel Products
     CHO  t^
   6-hydroxybenzaldehyde   2,4-dinitro-6-hydroxytoluene

Fate of RDX
I No significant transformation in short-
  term (7-d) studies
I 8-30% degradation to unknown products
  in bush bean after 60-d
I Transformation under field conditions
  questionable due to detection of RDX in
  foliage of native plants
I Leaf litter issues...
          of Terrestrial Systems
I Needs:
  I Toxicity Assessment
  I Uptake = eTC
     I TSCF (e, uptake efficiency)
     I Anticipated Water Use (Forestry Literature)
     I Porewater Concentration
       • Soil Concentration, Kp

Model Assumptions
I 1 acre of contamination, 3 meters deep
I Bulk Density of 1500 kg/m3
I Porosity = 0.3
I Homogeneous Contamination
I Instantaneous Desorption of Contaminant
I Kd = 5.3 L/kg
I 1500 Trees per acre
I 600 Gallons of Annual Transpiration per
I Microbial influence negligible
    TNT & RDX Extraction from Soil Over Time
       0     20    40    60
                Time, years
80   100

 Model Results & Implications

 I Depends Greatly on Soil Concentration
 I Time to complete clean-up: years to
I How will natural conditions affect RDX
  concentrations in the leaves?
I How will microbial/mycorrhizal associations
  affect the overall system?
I Effect of Co-contaminants?
I True timeframe

Future Concerns
I Toxicity of plant tissues, bioavailability of
  residues and RDX.
I Design of systems for long-term efficacy.

Case Study: Union Pacific Railroad

             Felix Flechas

  Felix W. Flechas, P.E.
  USEPA, Region VIII
  Denver, Colorado
Remedy Evaluation Criteria For
Waste Sites
« Protection of human health and the
» Compliance with applicable rules and
» Attainment of clean-up standards
» Control sources of releases
* Long-term effectiveness and permanence
• Reduction of toxicity, mobility or volume
 through treatment

Remedy Evaluation Criteria
• Short-term effectiveness
* Implementability
» Cost
» Community acceptance

« Treatment?
» Immobilization?
» Containment?

Functionality (continued)
  Waste Cover:  Containment or Treatment
Timing Issues

« Demonstrable Progress
* Technical Impracticability
» Baseline Data Needs
« Achievement of Clean-up Goals

Ecological Considerations

« Baseline Ecological Assesment
• New Exposures
Community Acceptance
 Community Perception of Phytoremediation
 Parks and Recreation
 Ultimate Landuse







Phyto Project:
Performance Criteria
» Plant Survival and Growth
» Establishment and Increase in Vegetative
• Reduction in GW Extraction Rate
» Increase in Soil Oxygen Levels with Depth
• Beneficial Site Use
» Plant Rooting into Contaminated Zones
« Increasing Soil Organic Matter
» Decrease in PNAs and PCP
Phyto Project:
Performance Criteria (continued)
• Advancement Toward Site Restoration

Phytoremediation in Alaska and Korea
          Charles Reynolds
     Slide Hard Copy Unavailable

                              Charles M. (Mike) Reynolds
Present Position:
Research Physical Scientist, Engineering Research Development Center - Cold Regions
Research and Engineering Laboratory (ERDC-CRREL), 72 Lyme Rd., Hanover, NH 03755,
Phone: (603) 646-4394, Fax: (603) 646-4561, email:reynolds@crrel.usace.army.mil
   BS        Soils Science, University of Maryland
   MS        Soil Chemistry, University of Maryland
   Ph.D.      Soil Microbiology, University of Arkansas
   Postdoctoral Research.  Numerical Modeling of Soil Enzymatic Processes, NCSU
Research Focus:
   Cold region soil microbial processes, including:
       (1) Using microbial characterization to evaluate field-bioremediation processes
       (2) Low input/natural attenuation strategies such as rhizosphere enhancement and
          nutrient optimization
       (2) Influence of freezing and cold temperatures on microbial phenomena that govern
          chemical fate in soils.
Editorial Service:
   Invited Editor, Journal of Soil Contamination, Special Cold Regions Remediation  Issue, In
   Associate Editor, 1999 - present. Journal of Environmental Quality
   Editorial Board. 1998 - present. International Journal of Phytoremediation
Recent Projects:
    ESTCP  Project #1011 - Field Demo, of Rhizosphere-Enhanced Trt. of Organics Contam.
       Soils on Native American Lands with Application to Northern FUD Sites.
    SERDP Project #712 - Enhancing Bioremediation Processes in Cold Regions
    Army EQT Project - Bioremediation Processes in Cold-Adapted Soil Systems

Selected Recent Publications Related to Soil Microbiology / Bioremediation:
   Reynolds, C. M. and D. C. Wolf. 1999. Microbial based strategies for assessing rhizosphere-
       enhanced phytoremediation. Environmental Technology Advancement Directorate
       (ETAD) of Environment Canada - Phytoremediation Technical Seminar, May 31-June 1,
       1999. Calgary, Alberta, CA. Pp. 125-135.
   Miyares, P. H., C. M. Reynolds, J. C. Pennington, R. B. Coffin, T. F. Jenkins, and L.
       Ciruentes. 1999. Using stable isotopes of carbon and nitrogen as in-situ tracers for
      monitoring the natural attenuation of explosives. CRREL Special Report 99-18.
   Reynolds, C. M., C. S. Pidgeon, L. B. Perry and B. A. Koenen, D. Pelton, H.L. Nichols and
      D.C.  Wolf. 1999. Using Microbial Community Structure Changes to Evaluate
      Phytoremediation. Fifth International Symposium, In-Situ and Onsite Bioreclamation.
      April 19-22, San Diego CA. Battelle Press. 5(6):33-38.
   Reynolds, C. M., D. C. Wolf, T. J. Gentry, L. B. Perry, C. S. Pidgeon, B.  A. Koenen, H. B.
      Rogers, and C. A. Beyrouty. 1999. Root-based Treatment of Organic-Contaminated Soils
       in Cold Regions: Rationale and Initial Results. Polar Record. 35:33-40.

                      Phytoremediation in Alaska and Korea

Dr. Mike Reynolds
US Army Engineer Research and Development Center - Cold Regions Research and
Engineering Laboratory
72 Lyme Road
Hanover, NH 03755
revnolds@crrel.usace.army.mil  603 646 4394
DoD has numerous sites that have been contaminated by previous operations. Many sites
are relatively remote, many are in cold climates, and frequently, treatment alternatives are
limited. Cost effective and defensible treatment options are needed.
In earlier laboratory research, we have shown a positive rhizosphere effect on enhancing
remediation of petroleum compounds. For the compounds we monitored, the magnitude
of the rhizosphere effect was greater for the more recalcitrant compounds than for the
readily degraded compounds.  In field research conducted in Alaska, we observed greater
remediation using grasses and fertilizer than either grasses alone, fertilizer alone, or a
control treatment. We also observed that the vegetation and fertilizer treatment both
increased microbial numbers and influenced microbial diversity relative to the control
Our initial data from a series of field demonstrations that are still underway will be
presented. These data suggest that vegetation has a beneficial effect on lowering the
concentration of extractable petroleum compounds in the soil and that the effect is
differentially dependent on the nature of the contaminant. Additionally, our initial data
suggest that there are fertilization - vegetation interactions that can influence remediation
of heavier PAHs, and thus may offer low-cost implementation and management
Research and field demonstrations were supported by 1.) Army Environmental Quality
Technology (EQT) program, work units BT-25-EC-B06 and AF ,  2.) Environmental
Security Technology Certification Program (ESTCP) Project #  1011,  3.) HQ
PACAF/CE, and 4.) Strategic Environmental Research and  Development Program
(SERDP), project #712.

        Status of Phytoremediation Demonstrations at Remote Locations:
                                        Alaska and Korea

                           C. M. Reynolds, L. B. Perry, B. A. Koenen, K. L. Foley
                           US Army Engineer Research and Development Center
                             Cold Regions Research and Engineering Laboratory
                                           Hanover, NH, USA

                                               D. C. Wolf
                                         University of Arkansas
                                            Fayetteville, AR

                                             K. J. McCarthy
                                       Battelle Duxbury Operations
                                             Duxbury, MA
Contaminated  soils  at installations built by the  U.S.
Department  of  Defense  may present human  and
environmental  health risks.  Many'  installations  are
remote, are  relatively  inaccessible,  or  have limited
infrastructure.  The United States has many individual
areas of petroleum-contaminated soil  at formerly  used
defense (FUD)  sites located  in  cold  regions.  The
expenses to  mobilize and demobilize cleanup efforts
coupled with  short treatment  seasons result  in  high
costs and  restrict  treatment  options.  Rhizosphere-
enhanced  biotreatment—a  low-cost,  easily  imple-
mented treatment technology that relies on  stimulating
indigenous microorganisms—overcomes many of the
limitations  and  may stimulate degradation of more
complex compounds. Wider application is held back by
limited defensible data that show advantages relative to
natural attenuation.  Our field data  from several sites
suggest  that  vegetation  and  nutrients  enhanced
degradation of more recalcitrant polyaromatic hydro-
carbons relative to  natural  attenuation  or nutrient
additions without plants, but these differences can be
masked by the chemical monitoring techniques that are
routinely used. We have measured increases in bacterial
diversity that occur concomitantly  with decreases  in
contaminant  concentrations  and  suggest  that  soil
microbial community structure changes may provide a
biological   method  of monitoring  phytoremediation
progress, completion, or both.
In cold regions, low temperatures, the brevity of the treatment season, or both reduce treatment rates. Site
monitoring often is difficult because of the remote locations of many sites, the inherent heterogeneity of contaminant
distribution, and the accumulation of numerous small contaminant releases that have occurred in the general area.
Phytoremediation may be an attractive treatment option for these sites, yet our knowledge and experience with using
phytoremediation to treat contaminated soils, especially in cold regions, is imperfect. These specifics combine to
limit application of phytoremediation.

With almost any treatment technology, there is a compromise between treatment costs and treatment times.
Treatment costs, although site specific, tend to be inversely related to treatment times. The magnitude of savings is
site specific, but, in general, implementing phytoremediation can be a relatively low-cost option. Although
phytoremediation systems can be inexpensive to implement and maintain, there is an inherent trade-off of longer
treatment times than would be required for more costly technologies (Figure 1).

 High Input                          Low Input

Dig and haul
  Low temperature thermal
     Soil washing
        Btoslurry reactors
              Air sparging and bloventlng
                       Rhizosphere-enhanced bloremedlatlon
                                      Natural attenuation
                                                   Time            V           GO

                           Figure 1. Relative Costs and Treatment Times for Selected
                           Remediation Options.

 Many traditional treatment technologies are sufficiently aggressive so that treatment times are relatively predictable
 and monitoring during the process is not necessary. Sampling and analysis can be done before and after the
 treatment, and target contaminant concentrations can be confirmed after the estimated treatment time has passed.
 The other extreme, natural  attenuation, is increasingly viewed as an acceptable treatment for groundwater
 contaminated with benzene, toluene, ethyl benzene, and xylene (BTEX). Treatment rates and times in contaminated
 groundwater often can be realistically predicted because there is a database of groundwater chemistry from past
 monitoring of plumes and because groundwater systems are mixed and subsurface conditions, including
 temperature, are relatively constant, thereby reducing sample heterogeneity and facilitating monitoring. By contrast,
 rhizosphere-enhanced phytoremediation is suited to relatively shallow contamination of less mobile, and typically
 more recalcitrant, contaminants. Much of the treatment zone that  is defined by the rooting depth is subject to
 temperature and moisture fluctuations and is generally not well mixed. These conditions can result in longer
* treatment times.

 Understandably, acceptance and use of phytoremediation  may be delayed because of longer treatment times and the
 uncertainty of achievable rates and endpoints. To overcome these uncertainties, requirements to increase spatial
 sampling density, temporal sampling frequency, or both may be imposed. Additional monitoring requirements
 increase overall treatment costs and can counteract many of the benefits of using phytoremediation. Although we are
 gaining experience in using phytoremediation at a number of sites, we are somewhat limited in our ability to
 effectively predict success.

 For widest application, new technologies should be usable over permafrost without destroying permafrost integrity
 and should withstand or recover from freezing and freeze-thaw cycling.  In the past, conventional remediation
 techniques modified for operation in the cold have proven to be expensive due to mobilization-demobilization,
 precautions for working over permafrost, and operation in cold or freezing conditions. There is convincing evidence
 from both laboratory and field studies showing that phytoremediation can be effective for treating contaminated
 soils. Although the majority of these studies were conducted in temperate climates (Anderson et ai, 1993; Aprill
 and Sims, 1990; Cunningham and Ow, 1996; Cunningham et al.,  1996; Reilley et ai, 1996, Schwab et al., 1995; and
 Wiltse et al.,  1998), some were conducted in a subarctic climate (e.g., Reynolds et at., 1999). From these studies the
 operative mechanisms for phytoremediation appear to be largely contaminant dependent. For many organic
 contaminants, especially petroleum compounds, the generally accepted phytoremediation mechanism is enhanced
 microbial activity in the rhizosphere, which in turn accelerates the rate of degradation of contaminants. Plant-
 produced compounds may  serve as co-metabolites for more recalcitrant compounds, and this may result in lower
 contaminant concentration  endpoints than can be obtained without plants (Fletcher et a/.,  1995). We propose that a
 potential tool for evaluating phytoremediation, monitoring endpoints, or perhaps predicting long-term success of
 phytoremediation may be based on changes in the soil microbial ecology. We hypothesize that changes in the
 microbial ecology may be more apparent than subtle changes in contaminant concentrations and, therefore, provide
 a practical monitoring or confirmation tool (Figure 2). The objective of our research has been to conduct proof-of-
 concept evaluations for low-input, rhizosphere-enhanced bioremediation techniques for treating contaminated soils
 in cold regions. If successful, the potential benefits of these techniques would include reduced costs, applicability to
 cold and remote sites, operation over permafrost, and freedom from massive infrastructure requirements.








                                       	7 f
                                          Microbial Changes
                                                             Contaminant Cone.
                               Contaminant Cone.
                             Rhlzosphere Treatment
                                         Microbial Changes
                                        Rapid Changes
                                      Months? Seasons?
                             Long Term Changes
                               Figure 2. Theoretical Changes in Soil Microbial
                               Characteristics and Contaminant Concentrations
                               during Phytoremediation.
Limits to Bioremediation
Ideally, contaminant concentrations from bioremediation would approach zero, similar to the lower curve in Figure
3. In field situations this seldom happens, and decreases in contaminant concentrations often follow a path similar to
the upper curve shown in Figure 3. These idealized curves illustrate two common field occurrences: typical
bioremediation rates may be slower than ideal, and final contaminant concentrations tend to reach an asymptotic
limit, or residual concentration, that is non-zero.
"a 100

                              §  60

                              c  40
                                              Lag Period
                    Typical Biotreatment
                                                            Residual Concentration
                                              Ideal Biotreatment
                              ir:                      Time

                          Figure 3. Typical versus Ideal Results from Bioremediation.

A number of phenomena potentially limit treatment rates and final concentrations attainable by bioremediation. As
soil moisture and temperature change in a field soil, conditions for microbial activity—and the resulting
biotreatment—fluctuate between inhibitory and favorable. Following the onset of favorable conditions, there is
usually a lag period before significant microbial activity commences (Figure 3). Consequently, decreases in
contaminant concentrations are not-instantaneous but are somewhat delayed relative to favorable changes in soil
conditions. The length of the lag phase, although well documented and routinely observed in laboratory incubations,
is difficult to predict in field soils. Moreover, not all contaminants in the soil are bioavailable (Alexander, 1994). In
cold regions, these limitations are exacerbated by low temperatures and relatively brief bioremediation seasons.

The challenges in developing low-cost remediation technologies include  1) lowering the asymptotic value or,
practically speaking, the residual or endpoint contaminant concentration, 2) increasing the process rates sufficiently
so that the treatment is applicable in the relatively short summer seasons available in cold regions, and 3)
accomplishing these in a cost-effective manner. At  a field site, the annual biotreatment rate can be improved by

either increasing the degradation rate during the operational season, which would result in a steeper slope to the
"typical" curve on Figure 3, or lengthening the season, which can be done by soil heating or by reducing the lag
period. Exploiting the rhizosphere effect may accomplish both.

Rather than expending energy and resources to create near-optimum soil conditions in an ex-situ vessel, an
alternative approach is to exploit the natural cycles in soils. We are capitalizing on naturally occurring processes that
are enhanced in the rhizosphere—the zone of soil that is influenced by the plant root. For petroleum-contaminated
soils, the objective is not increased plant uptake but increased microbial numbers and activity and the exploitation of
that increased microbial activity to enhance biotreatment.

During both growth and senescence, plants release carbon compounds through their roots and into the soil. Microbes
use many of the compounds released from plant roots as energy and carbon sources.  This phenomenon, the
rhizosphere effect, has been well documented (Curl and Truelove, 1986). The rhizosphere effect results in increased
microbial numbers, activity, and, in all likelihood, microbial regeneration.

To optimize survival and growth, microbes maximize their efficiency of carbon metabolism by preferentially using
readily available compounds before using more resistant compounds. In general, there is a negative correlation
between the complexity of a compound and the percentage of soil microorganisms that have the capability to
metabolize the compound. Simple compounds are readily metabolized by many microorganisms. More complex
compounds, such as many environmental contaminants, are metabolized by a smaller percentage of the total
microbial population. However, given sufficient time and conditions, the soil microbial community may adapt to
better use the carbon sources that are available. Adaptive processes include natural selection for microorganisms
capable of using a carbon source, stimulation of the entire population, or production of specific enzymes (Alexander,
1994). Maintaining a large and active soil microbial population would, in theory, facilitate faster biotreatment rates,
lower residual contaminant concentrations, and increased efficacy of degradation for a wider range of organic

Rhizosphere effects may promote regeneration or turnover of the soil microbial population and may increase
biotreatment rates by decreasing the time for microbial acclimation or adaptation to new carbon sources
(contaminants) (Alexander, 1994). The increased microbial  activity has the potential to enhance biotreatment of
contaminated soils. Other benefits also may accrue. Because roots explore increasing volumes of soil as plants grow,
there may be a reduction in mass transfer limitations. In some cases, roots may release specific compounds that are
analogs of contaminants, thereby inducing production of enzyme systems capable of degrading similar contaminants
(Fletcher and Hedge, 1995).

Materials and Methods
Results presented herein are from a series of laboratory and field studies. In general,  we have investigated the effects
of vegetation and nutrient additions on remediating petroleum-contaminated soils. We have completed an initial
field study and also have ongoing field demonstrations at several other sites.

Initial field study. Our initial field study in interior Alaska  was conducted at the Permafrost Research Facility in
Fairbanks, Alaska.

Southern coastal Alaska site. This site is located on the southern panhandle of Alaska. The climate is wet and
relati-.ely mild by cold-regions standards. The area receives a high annual precipitation averaging 155 inches a year,
with an average temperature of 45.9°F.

Interior Alaska site. The site is about 250 miles west-northwest of Fairbanks and 350 miles northwest of
Anchorage. Interior Alaska is cold and somewhat dry. Precipitation and surface winds are generally light with a
mean annual precipitation of about 12 inches. Temperature variations between winter and summer can be extreme,
with a mean annual temperature of 27°F.

Northern Alaska site. The site is 6 miles southwest of the northernmost point in Alaska and is bordered by the
Chukchi Sea to the west, the Arctic Ocean to the north, and the Beaufort Sea to the east. The climate is very cold
and dry; temperatures range from -19°F in February to 40°F in July. The average annual precipitation is 14.6 inches.
High relative humidity (90-95%) in the summer leads to foggy conditions about 25% of the time. Ground-based
inversions are common in the winter and can concentrate airborne pollutants in low-lying areas when not dissipated
by wind. The site's location between the Aleutian low-pressure system and the polar high-pressure system creates
continual surface winds, predominately easterly and generally strongest in the fall and early winter.

Overseas sites: We have several studies ongoing in the Republic of Korea. These sites have longer and warmer
summers than the interior and northern Alaska sites.

General Approach
We typically have used a time-series sampling approach for both field and laboratory studies and have used these
samples to monitor changes in petroleum concentrations. In some studies, we have concomitantly characterized the
microbial  populations by different indices, including species richness (d) and the Shannon- Weaver diversity index
For most of our work, we have used grasses, including Arctared red fescue (Festuca rubra) and annual ryegrass
(Lolium multiflorum). These have been chosen for their cold hardiness and rapid growth, respectively. Both grasses
have extensive root distribution and tolerance to low-fertility soils. In field studies, seeds were planted each spring to
account for winter kill. We have fertilized only at the beginning of the experiment by hand-broadcasting
commercially available agricultural fertilizer. To limit the number of trips to a site, we have surface-applied
fertilizer at fairly high rates that approached the maximum fertilizer rate that we could use without inhibiting
microbial activity by inducing osmotic stress in the soils (Walworth etal., 1997). We reasoned that this approach
could readily be used at remote field sites at minimal cost. After the initial fertilizer application, no further fertilizer
was added.

For microbial characterization, soil samples were serially diluted and plated on 0.1-strength tryptic-soy agar to
determine viable numbers of bacteria (Zuberer, 1994). For each soil sample characterized, we evaluated between 50
and 100 randomly chosen  isolates from dilution plates having between 30 and 300 colonies. Bacterial isolates were
identified to the  species level by characterizing their fatty acid methyl ester (FAME) profiles following the
procedures outlined by Sasser (1990) and Sasser and Wichman (1991) in which fatty acid (FA) profiles  are
identified by comparison to a bacterial reference library (MIDI, 1995). Isolates that we could not identify using the
library were given an internal laboratory identifier and added to the library. Unknown isolates having fatty acid
profiles distinctively different from other unknowns were treated as individual species. Unknowns having similar
fatty acid profiles were characterized as individuals of the same, although unidentified, species.

We used two indices, species richness (d) and Shannon- Weaver index  ( H ).

Species richness (d) was defined  as (Odum, 1971; Pielou, 1975):

                         d = (S-l)/logN                                                                 (1)

where   S = number of species
         N = number of individuals.
The Shannon- Weaver index ( H) was defined as (Shannon and Weaver,  1963):

                         H = (ON) (N log N - Zn, log n$                                                (2)

where   C = 2.3
         N = number of individuals
         «i = number of individuals in the i* species.

The diversity index H incorporates terms for the total number of individuals and the number of members of each
species within the community.

Soil total petroleum hydrocarbon (TPH) was extracted by sonication with CH2C12. Anhydrous Na2SO4 was added to
the soil during extraction as a drying agent. Extracts were analyzed by gas chromatography using flame ionization
detection (GC-FID).

Chemical Monitoring Approaches
Various analytical methods can be used to characterize petroleum compounds in the soil. For example, total
petroleum hydrocarbon (TPH) data are expressed as a concentration of mass of petroleum per mass of soil. Although
this approach measures an integrated value of the total amount of petroleum products present, we cannot distinguish
among specific compounds or changes in composition due to degree of weathering or degradation from a single
numerical value. We have therefore used TPH in conjunction with more advanced methods to determine
contaminant degradation and the time-related depletion of specific fractions. The subsections below briefly describe
these approaches.

Total Petroleum Hydrocarbons
We used high-resolution gas chromatography using flame ionization detection (HRGC/FID). This method is based
on integrating relative amounts of petroleum compounds as they differentially elute from a chromatographic
column. Integrating the area under the curve and between two defined retention times provides a measure of TPH.
TPH data are generally provided as a single, numeric concentration value, such as mg/kg or ppm; thus, much of the
data contained in the chromatogram is lost because a numeric TPH value gives no qualitative information about the
distribution of fractions. Nonetheless, when monitored over time, TPH data can show, in general, if concentrations
of petroleum products are decreasing. To rely mainly on TPH as a monitoring tool, you must assume homogeneity
of initial concentrations.

Depletion Monitoring with a Selected Biomarker: 
Results and Discussion
At our completed research and demonstration site at Fairbanks in interior Alaska, we have been able to show a
change in microbial community structure that occurs concomitant with decreases in contaminant TPH. Soil TPH
concentrations in both the natural attenuation and rhizosphere treatments decreased relative to the initial TPH
concentrations. The rhizosphere treatment had significantly lower TPH concentrations after approximately 640 days
of treatment for both diesel- and crude-oil-contaminated soils. For each treatment in the crude-oil-contaminated soil,
TPH concentrations decreased, but they remained greater than TPH values in the corresponding treatments in the
diesel-contaminated soil.

In the diesel-contaminated soil, diversity, expressed as both species richness (d) and the Shannon-Weaver index
(~H), initially increased after approximately 300 days for both the control and rhizosphere treatments (Figures 4 and
5). For the control treatment, H was stable at 420 and 640 days (Figure 5).

Using d and ~H  as indicators, we showed that bacterial diversity  increased after  contaminant concentrations in the
soil had reached relatively low levels. This effect, as well as the decrease in contaminant concentration,  was greater
in the rhizosphere treatment compared to the control treatment. From approximately 300 to 640 days, TPH
concentrations remained above 2000 mg/kg in the control treatment but had dropped to approximately 700 mg/kg in
the rhizosphere treatment after 420 days. During this time, increases in diversity, expressed as d, were relatively
constant for the control treatment but accelerated for the rhizosphere treatment. Continued increases in H were
seen only for the rhizosphere treatment.



             -•— TPH Control Treatment
             •v • TPH Rhizosphere Treatment •
             -o— d Control Treatment
             •v • of Rhizosphere Treatment .'
                                                                            - 20
                                   0    100   200   300   400   500   600   700
                                                   Time (Days)
                          Figure 4. TPH and Bacterial Species Richness in the Diesel-
                          Contaminated Soil during Remediation.



            TPH Control Treatment
            TPH Rhizosphere Treatment
            H Control Treatment
            H Rhizosphere Treatment  . • '
                                   0    100   200   300  400   500   600   700
                                                   Time (Days)
                          Figure 5. TPH and Shannon-Weaver Index for Bacteria in
                          the Diesel-Contaminated Soil during Remediation.

Three relatively new sites in Alaska are still ongoing, and data are not yet conclusive. However, analysis of variance
on the TPH depletion data from the northern Alaska site indicates that the plant-plus-nutrient treatment is having a
greater effect (at the 20% level) than the controls, plants alone, or nutrients alone (Figure 6). These data, although
not yet conclusive, are encouraging in suggesting that phytoremediation may have application in extreme climates.
From our earlier work and allied laboratory studies, we believe the role of nutrients is critical (Wai worth et al.,
1997).  Additionally, there likely are plants better suited to such an extreme environment. An initial database of cold-
hardy plants for petroleum remediation has "recently been compiled and should soon be available (Environment
Canada, 2000).
                                    80 -
                                    60  -
                                    40 -
                                            Control Seeded Fertilized  Seeded*
                              Figure 6. TPH Depletions at Northern Alaska Site.

Using a similar variant, TPH depletion data for two demonstration sites in the Republic of Korea do not show an
effect for nutrients, plants, or their combination when compared against a control (Figure 7).
                                   80 -
                                   60 -
                                                  Seeded Fertilized  Seeded +
                                  Figure 7. TPH Depletions at Korea Site 1.

However, if we capitalize on the more specific information gained from using a biomarker-based approach, we can
obtain greater information from a single soil sample. Using data identified by HRGC/MS, we can plot the hopane-
normalized percentage depletion for a range of compounds identified in each soil sample. The resulting data appear
as a plot with percentage depletion on the ordinate and a range of compounds, generally in increasing recalcitrance,
on the abscissa. As expected, as recalcitrance increases, percentage depletion of each individual compound
decreases (Figure 8).

                                                                             % Depletion
                      Figure 8. Two-Dimensional Depletion Data by Increasing
                      Recalcitrance of Compounds.

For our field demonstrations, where we are following a modified Remediation Technologies Development Forum
(RTDF) developed protocol (http://www.rtdf.org), we have four replications and four treatments:

         1.   Fertilizer and seed
         2.   Seed only
         3.   Fertilizer only
         4.   Control (no seed, no fertilizer).

By plotting the data for each composite sample, from each treatment, and grouping the treatments, we observe a
pattern in the treatment efficacies (Figure 9).

                                                                       C2-f tuo r arith • nc 5* jr »m • s

the fertilizer-only treatments. If one uses only TPH as a measurement criterion, this difference is not observable.
Moreover, the data suggest that depletion of the more recalcitrant compounds may be inhibited, relative to the
control, by using fertilizer alone. These data are for one treatment season and represent the results of processes that
have occurred at that time. Given more time, the treatment effects may diverge or converge. We obtained similar
results at another site.

Discussion and Conclusions
Ecologists use the term diversity to indicate the heterogeneity of the microbial populations within a community
occupying a given habitat (Hauxhurst et al., 1981). Communities with low diversities tend to be relatively
specialized,  which can be an indication of severe environmental stress (Hauxhurst et al., 1981). When the microbial
community is altered by stress, community structure  and the diversity of the community change (Atlas, 1984).
Generally, introducing moderate to high levels of pollutants into the habitat results in decreased microbial diversity
due to toxicity of the pollutant that eliminates sensitive species. This, in turn, reduces competition and results in
enrichment of tolerant populations (Atlas, 1984; Mills and Wassel,  1980; Peele et al., 1981).

Crude oil and gasoline contamination have been shown to reduce species diversity (Atlas, 1984). The greatest
diversity reduction was noted in an Arctic tundra pond for the more toxic hydrocarbons found in gasoline^ where
only one species survived and proliferated. The crude-oil amendment resulted in a gradual reduction of H = 4 to
H = 2 over several weeks. The results indicated that petroleum hydrocarbons reduced microbial diversity and
reflected fewer species but increased numbers of metabolically specialized microorganisms.

In addition to diversity, microbial  communities can be characterized by productivity (Atlas and Bartha, 1993).
Greater diversity generally coincides with decreased  productivity, reflecting the increased interactions and
complexities of a mature community that has reduced productivity. Conversely, high productivity systems are more
likely to be dominated by a few species, and these selected species  are likely to have  more individuals that are
highly productive. For contaminated soils undergoing phytoremediation, or for bioremediation in general, we may
be able to use changes and stability of the microbial community structure to  make inferences about the
bioavailability of the remaining contaminants.

The microbial structure data we have collected to date are encouraging in suggesting  a means to evaluate
"completeness" of bioremediation, but we caution that they represent only two soils, and we have characterized only
the bacterial component of these systems. The fungal component of most soils is generally believed to have
significant contaminant degradation potential, but characterization is less mature than for bacteria.

Measurement of microbial diversity, community structure, contaminant degrader activity, and frequency of
degradative  genes could be combined to enhance our understanding of remediation processes (Langworthy et al.,
1998; Mills  and Wassel,  1980; and Song and Bartha, 1990). An improved understanding of the time-dependent
relationships between contaminant concentration changes and microbial community changes, coupled with
improved techniques to readily characterize microbial communities, may provide a useful tool for monitoring the
functioning of phytoremediation, evaluating desirable endpoints when bioavailable contaminants are diminished, or

Our chemical field data at two sites show that the benefits of rhizosphere enhancement—rather than being uniform
for all petroleum compounds—are greater for more recalcitrant compounds. These findings are supported by our
earlier laboratory studies. The practical significance of this includes:

        1.  Because the benefits of rhizosphere-enhanced treatment compared to non-plant-associated treatments
            are greater for recalcitrant compounds than for readily degraded compounds, there may be a greater
            cost benefit to applying rhizosphere-enhanced treatment to heavy or residual compounds than there is
            for readily degraded compounds.

        2.  Using compound-specific depletion data is a more sensitive monitoring approach for rhizosphere-
            enhanced remediation and may identify desirable processes that are otherwise masked by less specific
            analytical methods.

This research was supported by the Army Environmental Quality Technology (EQT) program, Project BT25-EC-
B06 "Biodegradation Processes of Explosives/Organics Using Cold Adapted Soil Systems;" the Environmental
Security Technology Certification Program (ESTCP) Project # 1011, "Field demonstration of rhizosphere-enhanced
treatment of organics-contaminated soils on Native American lands with application to Northern FUD sites;" the
Strategic Environmental Research and Development Program (SERDP), Project CU-712-Army "Enhancing
Bioremediation Processes in Cold Regions;" and support from PACAF. We gratefully acknowledge the efforts and
expertise of S.E. Hardy, C. Pidgeon, and M. Husain. We also gratefully acknowledge the RTDF Phytoremediation
of Organics - Total Petroleum Hydrocarbons in Soil Subgroup for their collective input and perspectives from
numerous discussions and conference calls.

Alexander, M. Biodegradation and Bioremediation. California: Academic Press, Inc., 1994.

Anderson, T.A., E.A. Guthrie, and B.T.  Walton. "Bioremediation." Environmental Science and Technology
27:2630-2636, 1993.

Aprill, W., and R.C. Sims. "Evaluation of the use of prairie grasses for stimulating polycyclic aromatic hydrocarbon
treatment in soil." Chemosphere 20:253-265, 1990.

Atlas, R.M. "Use of microbial diversity  measurements to assess environmental stress." In Current Perspectives in
Microbial  Ecology, Proceedings of the Third International Symposium on Microbial Ecology. Washington, D.C.:
American Society for Microbiology, 1984, 540-545.   .

Atlas, R.M., and R. Bartha. Microbial Ecology - Fundamentals and Applications. Redwood City, CA: The
Benjamin/Cummings Publishing Company, 1993.

Cunningham, S.D., T.A. Anderson, A.P. Schwab, and F.C. Hsu. "Phytoremediation of soils contaminated with
organic pollutants." Advances in Agronomy 56:55-114, 1996.

Cunningham, S.D., and D.W. Ow. "Promises and prospects of phytoremediation." Plant Physiology 110:715-719,

Curl, E. A., and B. Truelove. The Rhiiosphere. New York: Springer-Verlag, 1986.

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plants that play a role n the phytoremediation of petroleum hydrocarbons. Environment Canada, Petroleum
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Fletcher, J.S., and R.S. Hedge. "Release of phenols by perennial plant roots and their potential importance in
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Fletcher, J.S., P.K.  Donnelly, and R.S. Hegde. "Biostimulation of PCB-degrading bacteria by compounds released
from plant roots." In Bioremediation of Recalcitrant Organics. R.E. Hinchee, D.B. Anderson, and R.E. Hoeppel
(eds.), Columbus, OH: Battelle Press, 1995,131-136.

Hauxhurst, J.D., T. Kaneko, and R.M. Atlas. "Characteristics of bacterial communities in the Gulf of Alaska."
Microbial Ecology 1:167-182, 1981.

Langworthy, D.E., R.D. Stapleton, G.S. Sayler, and R.H. Findlay. "Genotypic and phenotypic responses of a
riverine microbial community to polycyclic aromatic hydrocarbon contamination." Applied and Environmental
Microbiology 64:3422-3428, 1998.

MIDI, Inc. Sherlock Microbial Identification System. Newark, DE: MIDI, Inc., 1995.

 Mills, A.L. and R.A. Wassel. "Aspects of diversity measurement for microbial communities." Applied and
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 Odum, E. P. Fundamentals of Ecology. W. B. Philadelphia, PA: Saunders Company, 1971.

 Peele, E.R., F.L. Singleton, J.W. Deming, B. Cavari, and R.R. Colwell, "Effects of pharmaceutical wastes on
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 Environmental Microbiology 41:873-879, 1981.
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 Reynolds, C.M., D.C. Wolf, T.J. Gentry, L.B. Perry, C.S. Pidgeon, B.A. Koenen, H.B. Rogers, and C.A. Beyrouty.
 "Plant enhancement of indigenous soil micro-organisms: A low-cost treatment of contaminated soils." Polar Record
 35:33-40,  1999.

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 (ed.), Madison WI: Soil Science Society of America, 1994, 119-144.


  Using  Excavated Material for the Remediation of Sewage Farm Land in
                                 Berlin and Brandenburg
                        Holger Bb'ken1, Reinhart Metz1, and Christian Hoffmann2
Holger Boken is Diplom Ingenieur in Agricultural Sci-
ence and Engineering from the University of Applied
Science of Osnabruck, Germany. He is currently em-
ployed as an engineer in the Soil Protection Division of
the Federal Environmental Agency (Umweltbundesamt,
DBA) Germany. He has 3 years of experience as a team
researcher for setting precautionary trigger and action
values for heavy metals in soil under the ordinance of
the Federal Soil Protection Act. He is responsible for
the TRANSFER database; a utility for the derivation of
a standard in soil values, with regard to different thresh-
old values, e.g., food plant quality, fodder plant quality
and phytotoxicity, for hazard  assessment of adverse
effects of soil contamination on plants. He is part of the
project management for the design and  development
of a CIS-based Federal Soil Information System, to cre-
ate thematic maps about soil contamination, background
values in Germany.

Currently, Holger Boken is a  member of the Federal
Association Soil work group "Risk Prevention of Soil
Erosion;"-making guidelines for enforcement underthe
Federal Soil Protection Ordinance forthe Bundeslander.
He is simultaneously working  as a Ph.D. candidate at
the Humboldt University of Berlin, forthe Faculty of Ag-
riculture and Horticulture on a joint research project for
the Remediation of Sewage Farm Land  in Berlin and

Metz, R.; Boken, H.; Hoffmann, C. & Renger, M. (2000):
Einsatz von unbelastetem Bodenaushub zur Sicherung
von flachgrundig kontaminierten Altlasten in Berlin and
Brandenburg. Okologische Hefte der Landwirtschaftlich-
Gartnerischen Fakultat der Humboldt-Universitat, in

Metz, R.; Hoffmann, C. & Boken, H. (1999): Verwendung
von unbelastetem Bodenaushub zur Sicherung
gro(3flachig schadstoffkontaminierter Flachen.
1Humboldt University, Berlin - Faculty of Agriculture and Horticulture; Dorfstr.
9, D-13051 Berlin; Germany
'Technical University, Berlin; Institute of Ecology, Dept. of Soil Science; Salzufer
12, D-10587 Berlin; Germany

Dipl. Ing. (FH) Holger Boken: Holger.Boeken@uba.de
Dipl. Ing.Christian Hoffmann: Christian.Hoffmann@tu-berlin.de
Tagungsband der 19. Arbeitstagung: "Mengen- and
Spurenelemente" an der Uni Jena vom 3.-4.12.1999.

Knoche, H.; P Brand; LViereck-gotte & H. Boken (1997):
Erarbeitung fachlicherGrundlagen zu untergesetzlichen
Regelungen im Bodenschutz: Schwermetalltransfer
Boden-Pflanze, Ergebnisse der  Auswertungen
hinsichtlich der  Kb'nigswasser-und Ammonium-
nitrat-Extraktion  anhand  der Datenbank Transfer.
Umweltbundesamt (Hrsg.)  Reihe: UBA-Texte 11/99,

In the vicinity of Berlin, a total area of 20.000 ha has
been treated with municipal wastewater for almost 100
years, resulting in changes of various soil properties
and high accumulation of organic and inorganic pollut-
ants [Blume  et al., 1980; Schlenther et al.; 1996]. For
many decades, constant waste water supply and ar-
able farming prevented the leakage of contaminants into
the groundwater. Since the continued irrigation of crops
presented a  potential risk of pollutant accumulation in
the food chain, farming activities were stopped and the
proposed land-use was changed to forestation. After
stopping wastewatersupply the groundwater level sank,
which lead to rapid soil acidification and mineralization
and an increase of dissolved heavy metals in the soil; -
the forestation failed.

Today, due to intense mineralization of organic matter
and strong soil acidification, toxic elements are being
mobilized and transported  into the  groundwater
[Hoffmann et al.; 1998; Hoffmann & Renger; 1998].The
German Federal Soil Protection Act [1998] and the cor-
responding Federal Soil Protection Ordinance [ 1999]
demand that land owners take appropriate measures
to prevent on-site  and off-site environmental endanger-
ment. As yet there is no  economically or ecologically
viable technique to remediate such wide spread and
heterogeneous contamination.

The scope of our current research  is to introduce a
remediation technique forthe  fixation of contaminants
in the top soil, to  improve soils capacity to hold heavy
metals and plant nutrients, to improve the soil water
economy and to dilute the contaminants by mixing con-
taminated soil with dead loamy material (from a depth

of 5-15m underground) as a precondition to a more
successful afforestation attempt on formersewage farm

In spring 1998, a 12ha area of the sewage farm land
was spread with a layer of boulder clay and marly soil
(70-80% sand, 15-20% silt, 7-14% clay; pH 7.5 (CaCI2);
CEC 14 mmol/kg; carbonate 11%) from construction
activities in Berlin, to a thickness of 20-40 cm. After 4 to
6 month of soil coverage  the soil was mixed with the
contaminated top soil by deep rotary tilling down to a
total depth of 60-80 cm, giving a mixing ratio of con-
taminated soil to cover material of 1:1). Aftertilling, the
biological soil parameters recovered  quickly from the
intake of new material and vast improvement  of chemi-
cal and physical soil properties were achieved.The plant
available water (nFK) in 10 cm depth rose from 1301/
m2to 2001/m2, the humus contents decreased from 3%
to roughly 2%, the pH grew from 4.5 to 7.0 (CaCI2), the
heavy metal values were reduced by 60 to 70% (dilu-
tion) and the values  of dissolved heavy metals were
reduced by element specific sorption for Zn:  35.4% to
05%; Cd: 21.6% to 2.6%; Cu: 0.5% to 0.2%.

In the first year, there is already a vast change in the
flora found on the remediated land. A widespread car-
pet of couchgrass turned into a rich plant association,
which predominantly reflects the former land-use as
arable farm land.
Anonymous (1999):  Bundes-Bodenschutz  and
Altlastenverordnung.  Bundesgesetzblatt  vom
16.07.1999, Teil 36, 1554-1582

Anonymous:  (DIN   19731)   Verwertung   von
Bodenmaterial, Normenausschu(3 Wasserwesen (NAW)
im DIN Deutsches Institut fur Normung e. V.

Slume, H.-P; R. Horn; F. Alaily; A. N. Jajakody and H.
Meshref (1980): Sand Cambisol functioning as a filter
through long-term irrigation with wastwater. Soil Sci. 130
(4), 186-192

Hoffmann,   C.   and   M.    Renger   (1998):
Schwermetallmobilitat   in    Rieselfeldboden.
Bodenokologie and Bodengenese 26, 30-39

Hoffmann, C.; B. Marschnerand M. Renger (1998): In-
fluence of DOM-Quality, DOM-Quantity and Water Re-
gime on the Transport of Selected Heavy Metals. Phys.
Chem. Earth 23 (2), 205-209

Schlenther, L; B. Marschner; C. Hoffmann and M.
Renger (1996): Ursachen mangelnderAnwachserfolge
bei der Aufforstung der Rieselfelder in Berlin-Buch-
bodenkundliche Aspekte. Verh. Ges. Okol. 25, 349-359.

U.S. and International Activities in Phytoremediation:
           Industry and Market Overview

                    David Glass

               U.S. and International Activities in Phytoremediation:
                         Industry and Market Overview

                              David J. Glass, Ph.D.
                             D. Glass Associates, Inc.
                                 124 Bird Street
                              Needham, MA 02492
Introduction. This presentation discusses the commercial aspects of phytoremediation.
Included are an overview of the companies that are developing and commercializing
phytoremediation in the U.S. and around the world, as well as major non-profit
research groups, a brief summary of the 200-plus field uses of phytoremediation to date,
and estimates of phytoremediation's market potential. Although the bulk of today's
commercial market is in the United States, there are significant industrial, academic and
government activities taking place in Canada, Europe, and elsewhere in the world.

U.S. Phytoremediation Industry. The U.S. phytoremediation industry consists of
several dozen companies falling within discrete categories. Most visible are the
dedicated phytoremediation companies, whose sole or primary remediation technology
is phytoremediation. This category includes a number of companies that have been
using deep-rooted trees for hydraulic control for ten years or more (that is, before the
term "phytoremediation" was even coined), as well as several companies formed more
recently with the specific purpose of commercializing innovative phytoremediation
technologies for the remediation of either organic or heavy metal contaminants.

A related category includes other specialty companies that are diversifying into
hazardous waste or wastewater phytoremediation. The most prevalent examples are
companies having experience with managed or constructed wetlands, which are
seeking to leverage their expertise using aquatic plants, generally for wastewater
treatment, to enter phytoremediation markets. Another group of companies have used
trees and other plants for other environmental purposes, such as erosion control,
riparian zone buffers and other uses.

Perhaps the most active segment includes a number of the large to midsize
consul ting/engineering firms that have developed an expertise in phytoremediation.
The number of these firms with credible phytoremediation expertise has grown
significantly in the past two years, and these companies are beginning to play a
dominant role in the U.S. market. These firms utilize phytoremediation as one of many
remedial technologies that may be applicable to different contaminated sites.

A number of large industrial companies, principally in the oil or chemicals industry, are
also active in conducting or supporting phytoremediation research. Most of these

 companies have been involved in phytoremediation more as site owners than as
 technology developers, and for the most part these companies are interested in
 phytoremediation for its possible use on their own contaminated sites. A number of
 these corporations are participating in EPA's RTDF Phytoremediation of Organics
 Action Team and the Petroleum Environmental Research Forum group.

 Although at an early stage of its growth, the U.S. phytoremediation industry appears to
 be developing similarly to other industry sectors devoted to innovative remediation
 technologies. The dedicated companies drive much of the innovation, and dominate the
 market in its early days, but run the risk of seeing the market dominated over time by
 larger, diversified companies, once the technology is better proven and the necessary
 expertise more widely disseminated. In phytoremediation's case, competition is also
 faced from specialty companies such as nurseries, plant breeders, agricultural
 biotechnology companies and other firms having expertise in plant agriculture, some of
 which have already begun to show an interest in phytoremediation. In the past two
 years, competition from the specialty sector has not emerged to any significant degree,
 while a more formidable challenge has come from  the growing number of
 consulting/engineering firms now servicing the phytoremediation market.

 Phytoremediation Industry Outside the U.S. Commercial phytoremediation activities
 have been slower to develop outside the United States. However, industrial interest is
•developing in several countries, notably Canada and several European countries, as
 well as Australia and Japan.

 In Europe, there are today more than a dozen small firms possessing phytoremediation
 expertise of some kind or to some degree. Most of them fall into the category mentioned
 above of "diversifying specialty companies", and derive their expertise from constructed
 wetlands or various agricultural specialties. However, other than treatment of
 wastewater or  landfill leachate with willow trees or constructed wetlands, there has not
 been a great deal of actual commercial use of phytoremediation in Europe, and the
 market remains at a very preliminary stage. This is likely due to the fact that the overall
 remediation market is less well developed in Europe than in the U.S., although this is

 In Canada, although there has been significant government interest in. and promotion
 of, phytoremediation, this has to date translated into very little industrial activity. This
 replicates a trend in Canada that we have previously noted in the field of microbial
 bioremediation, and may simply be indicative of the smaller remediation market found
 in Canada today. There are also a small number of companies with phytoremediation
 interests in Australia, Japan and elsewhere in the world, where remediation markets are
just starting to  take shape.

 Academic Research Activities. There are a large number of academic and public sector
 research laboratories conducting research in phytoremediation. Almost all the

pioneering work in phytoremediation took place in academic laboratories, and today
university research groups carry out valuable basic and applied research in this field.
Government agencies are also responsible for large amounts of basic and applied
phytoremediation research, either conducted in-house at government laboratories,
military bases and research stations, or through funding of extramural research at the
nation's universities. A portion of academic phytoremediation research is directed at
field studies and other applied research, while another group of researchers is
investigating ways of improving phytoremediation's efficacy, including creation and
use of transgenic plants.

There is also a great deal of excellent research being conducted in Canada, Europe, and
elsewhere in the world. Through the funding efforts of the European Union (EU) and
the unifying effects of the Internet, international research collaborations and consortia
have been formed,  which are helping coordinate activities and reduce possible
duplication of efforts. Some of these efforts have been funded by national governments
around the world, and in the EU.  Among these are several international research
consortia funded by the EU, and the COST program, whose Action 837 brings together
over 100 European scientists studying various aspects of phytoremediation.

Phytoremediation  Field Activities.  Phytoremediation has been carried out
commercially or demonstrated at  pilot scale at perhaps 200 sites in the U.S. These sites
have involved contaminated soils, groundwater, wastewater and other polluted
aqueous wastestreams, and have included all of the many contaminant categories to
which phytoremediation is applicable.  In addition to projects completed by for-profit
firms, there are a number of demonstration projects underway, many of which are
funded, supported, or conducted by U.S. federal government agencies. The goals of
many of these projects include the generation of economic and technical data to support
the efficacy of phytoremediation in specific remediation scenarios.

There have also been a number of field tests, demonstrations, and commercial
remediations in Canada and Europe. Projects in Canada have generally involved either
remediation of petroleum hydrocarbons or heavy metals. Research projects in Europe
have focused to a large extent on heavy metal and radionuclide pollution, although
there has also been limited field work on hydrocarbon contamination. Both these
regions have only recently begun  the transition from academic research to commercial
remediation projects.

Markets for Phytoremediation. Phytoremediation's market success will be governed by
many factors, not least of which are  its own strengths and weaknesses. Among its
greatest advantages are its low cost  (although solid economic data are generally still
lacking), the fact that it is a permanent, in situ technology, its applicability to a wide
variety of contaminants, and its attractiveness to the general public. Among limitations
are that some phytoremediation activities are slower than competing remedial

technologies, the limitation of some applications to shallow soils or groundwater, the
inherent limitations of biological systems, and regulatory unfamiliarity.

Phytoremediation faces other barriers to market acceptance as well, ones that are
common to all innovative technologies. These include the need to prove efficacy and
cost-effectiveness to site owners, consultants and regulators, various barriers and biases
embodied in environmental laws and regulations that favor traditional technologies
over newer ones, and the challenges of the changing climate for remediation in the U.S.,
where economic factors are replacing regulatory factors as driving forces. However,
these obstacles may be mitigated by prospects for regulatory relaxation, and the
possibility that the new economic climate may favor low-cost technologies that can
address the riskiest portions of contaminated sites. Phytoremediation's growth may
also be assisted by a number of U.S. government programs for the promotion of
innovative technologies.

Phytoremediation is applicable to a number of hazardous waste and other remedial,
scenarios, which offer sizable potential markets. Markets for remediation of organics,
metals and radionuclides from soils and water, combined with municipal and industrial
wastewater treatment markets, the treatment of polluted runoff, primarily including
landfill leachate, and the market for removing inorganic contaminants such as nitrate
from drinking water supplies, offer a total potential market size of U.S. $33.8-49.7
billion per year.

The largest 1999 U.S. markets for phytoremediation are for treatment of organic
contaminants in groundwater, with revenues estimated at $7-12 million, control of
landfill leachate, approximately $5-8 million, remediation of organics in soil, estimated
at $5-7 million, and remediation of metals from soil, perhaps about $4.5-6 million. Other
significant markets are for removal of nonmetallic inorganics from groundwater and
wastewater, and the remediation of metals from groundwater. In general, the markets
involving organic and nonmetallic inorganic contaminants should see strong, steady
growth in the coming years, while the markets involving metals or radionuclides are
capable of dramatic growth as the technology's efficacy becomes better established.

The estimated 1999 U.S. market represents a significant increase from our estimates of
1998 revenues, and is close to a doubling of the market in one year's time. We attribute
the market increase primarily to the increased number of companies now offering
services in this market, particularly companies in the consulting/engineering sector,
and to growing acceptance of the technology. However, our current estimates of 1999
and 2000 revenues are slightly lower than what we had previously projected for these
years, which is largely attributable to the fact that phytoremediation applications for
metals and radionuclides appear to have been slower to reach commercial markets than
we had previously anticipated. We estimate the total U.S. phytoremediation market in
1999 to have been $30-49 million, and that the market will total $50-86 million in 2000.
Growth to $100-170 million by 2002 and $235-400 million by 2005 is predicted.

Although the United States represents the largest environmental market in the world,
markets for environmental goods and services, including remediation of contaminated
soil and water, exist elsewhere in the world, particularly in industrialized nations.
Smaller, but emerging, markets exist in developing nations, particularly in portions of
Asia. The total world remediation market in 1998 was approximately U.S. $15-18
billion/year. The next largest environmental market after the U.S. is found in Europe,
particularly  in the European Union. With an estimated remediation market of U.S. $2-4
billion/year, it is a sizable market, with excellent opportunities for growth in the
coming years as more  countries upgrade their environmental laws and regulations to be
in accordance with EU standards, and as more countries inventory and prioritize  their
contaminated sites.

Based on recent compilations of national inventories, it is now believed that there may
be as many as 1.5 million potentially contaminated sites in Europe, with perhaps 28,000-
61,000 of these actually proving to be contaminated. At least 5,000 sites in the latter
category are located at military installations, mostly sites in Eastern Europe abandoned
by the Soviet Army. The costs to remediate all these sites are estimated at U.S. $80-140
billion, using exchange rates current at the time of these estimates (the late 1990s).

Phytoremediation is already practiced commercially in Canada, Europe, and several
other countries; however, the current markets outside the U.S. are believed to be small.
We estimate 1999 Canadian phytoremediation revenues at U.S. $1-2 million, and
European revenues at $2-5 million. Both regions show significant potential for growth
in the early years of the new century.

Although there is little commercial phytoremediation activity outside these major
world regions, we are optimistic about phytoremediation's ultimate international
market potential. Many countries, including the former Soviet bloc countries and  many
developing nations in Asia and Latin America, have significant problems of improper
landfilling and wastewater treatment. Although site remediation is generally not  a
priority in these countries, phytoremediation is capable of addressing certain of the
high priority issues including wastewater treatment and control of leachate from
uncontrolled dumping sites so these markets may present opportunities for
phytoremediation which would not present themselves for other remedial technologies.
These markets might offer opportunities for market growth later in the first decade of
the 21st Century.

U.S. and International Activities in
    Industry and Market Overview
             David J. Glass, Ph.D.
           D. Glass Associates, Inc.
       United States Dedicated
   Phytoremediation Companies

Applied Natural Sciences
Edenspace Systems Corp.

Thomas Consultants
TreeTec Environmental

Verdant Technologies
Viridian Environmental

Poplar trees for treatment of organics.
Poplar trees for treatment of organics.
Plants for treatment of metals.
Poplar trees, plants and grasses
treatment of organics.
Poplar trees for treatment of organics.
Specialty trees for control of effluents,
treatment of organics.
Poplar trees for treatment of organics.
Plants for treatment and recovery of

      United States Diversifying
          Specialty Companies
                                  Lemna Technologies
Constructed Wetlands
Azurea               Ecoscience
BioConcepts, Inc.       GreenGold
Constructed ecosystems for wastewater treatment
Sustainable Strategies          Living Technologies
Wolverton Environmental       West Wind Technologies
Revegetation, erosion control
Bitterroot Restoration          The Bioengineering Group
Bacterial bioremediation, wastewater treatment
los Corporation
Electrokinetic soil treatment
Lynntech, Inc.
     U.S. Consulting/Engineering
   Firms Using Phytoremediation
Alliant Tech
August Mack
CRA Services
ICF Kaiser
Kingston Environ.
               ARCADIS G&M
               CH2M Hill
               IT Corporation
               LIB Group, Inc.
               McLaren Hart
               Parsons Engineering
               Sand Creek
ARM Group
Braun Intertec
CoreGroup Services
Fuss & O'Neill
Global Remediation
Key Engineering
Malcolm Pimie
Mitretek Systems
Roy F. Weston
URS/Dames & Moore

 U.S. Industrial Companies Conducting
       Phytoremediation Research
Aramco Services
BP Amoco
Coastal Corporation
Eastman Chemical
Kaiser Aluminum
Rohm and Haas
Koch Industries
Arco Chemical
Elf Aquitaine
Occidental Chem.
Union Carbide
Marathon Oil
           European Companies
  Commercializing Phytoremediation
Agritec (Czech Republic)
Hedeselskabet (Denmark)
Rhone-Poulenc (France)
BioPlanta (Germany)
Piccoplant (Germany)
Consulagri (Italy)
Ecobios (Italy)
Metapontum Agrobios (Italy)
Plantechno (Italy)
          Reset SRL (Italy)
          Euramtecna (Portugal)
          Battelle Europe (Switzerland)
          Biotec SA (Switzerland)
          Hydropol (Slovakia)
          VBB VIAK (Sweden)
          Slater (U.K.) Ltd.
          OEEL (U.K.)
          Quest Environmental (U.K.)

       Companies Commercializing
    Phytoremediation: Rest of World
Aquaphyte Remediation
CH2M Gore & Storrie
Conor Pacific
Erin Consulting
Federated Co-Operatives
Global Forestry Consulting
Harrington & Hoyle
Jacques Whitford
Nature Works Remediation
Canada (continued)
Roy Consultants

Rest of World
Above Capricorn (Australia)
Envirogreen (South Africa)
HortResearch (New Zealand)
John Bray & Assoc. (Australia)
Taisei Company (Japan)
 Phytoremediation Research Proposals
 Funded by the European Union DG12
Bioremediation and Economic Renewal of Industrially Degraded Land
by Biomass Fuel Crops (BIORENEW).
Coordinator: Dr. D. Riddell-Black, U.K. Rehabilitation of heavy metal
contaminated land (Zn, Cd) using biomass fuel crops (Salix, Miscanthus,
Pharalis and Eucalyptus).
An Integrated Approach to the Phytoremediation of Organic
Pollutants in the Rhizosphere.
Coordinator. Dr. C. Leyval, France. Remediation of PAHs in the
rhizosphere by enhancing microbial activity in mixed grass-legume
systems and the symbiotic arbuscular mycorrhizal fungi and rhizobia.
In situ Remediation of Contaminated Soil by Plants (PHYTOREM).
Coordinator. Dr. S. C. McGrath, U.K. Transport and accumulation of
metals (Zn, Cd, Cu) in plants and methods to enhance metal accumulation.

Phytoremediation Research in Europe
  Phytonet Internet Discussion Group.

  Several research programs funded by EU, national
  governments (BIORENEW, PHYTOREM, etc.).

  COST: European Cooperation in the Field of
  Scientific and Technical Research --
  Phytoremediation Action.

  NICOLE: Network for Industrially Contaminated
  Land in Europe (project withdrawn).
    Phytoremediation COST Action
  Program includes > 95 scientists from at least 18
  countries, will run from November 1998 -
  November 2003.

  Objectives include coordination of information-
  sharing to promote phytoremediation,
  development of standardized testing protocols,
  improvement of scientific education and training.

  Four working groups: Organics, Metals, Metabolic
  Engineering, Cultivation and Utilization.

     European Phytoremediation
         Selected Field Projects

Katowice, Poland
•Removal of lead from contaminated soil at a refinery.
(Florida State University, Phytotech).
Chernobyl Nuclear Reactor Site, Ukraine
•Sunflowers for rhizofiltration of uranium-contaminated water;
•Industrial hemp for radionuclide-contaminated soil.
(Phytotech and collaborators).
Liepzig, Germany
•Phytoremediation to clean sewage sludge. (BioPlanta).
      European Phytoremediation
          Selected Field Projects

•Use of poplars on a contaminated plume. (Hydropol).
Trecate, Italy
•Remediation of crude oil contaminated soils (Battelle Europe).
•Phytostabilization of heavy metal contaminated soil.
(Vangronsveld, et al., University of Limburg).
Several other academic field experiments
•Germany, Denmark, Poland, Czech Republic.

     European Phytoremediation

         Selected Field Projects

Municipalities in Sweden
•Use of willow trees to treat wastewater, landfill leachate.
•Field tests of willows on Cd contaminated soils.
•Field tests of willows at a Zinc landfill.
•Field tests of phytoextraction at a Zinc/Copper site.
United Kingdom
•Field tests of willows on Ni, Cd, Zn contaminated soils.
 Estimated U.S. Phytoremediation Markets
Market Sector
Organics in groundwater
Organics in soil
Inorganics in groundwater
Metals in groundwater
Metals in soil
Landfill leachate
Organics in wastewater
Inorganics in wastewater
Metals in wastewater
Millions of U.S. Dollars

Estimated Worldwide Phytoremediation
          Markets, 1999-2002

United States
Millions of U.S. Dollars



  Phytoremediation Market Trends
  U.S. market nearly doubled from
  1998 to 1999.
  Much of this growth results from the companies
  newly entering the market (mostly c/e firms).

  Rapid growth (50 + % per year) is likely through
  Continued strong growth (30% per year) is
  expected 2001 to 2005.

       Market Sector Trends
Remediation of organics from groundwater
continues to be the strongest sector.

Considerable ongoing work with nonmetallic
inorganics in groundwater, wastewater.

Remediation of metals from soils, radionuclides,
have been slow to develop.

Prospects for remediation of metals from
groundwater, wastewater are more positive if trees
can be used.
Phytoremediation Industry Trends
The number ot c/eMrms with credible
phytoremediation expertise is growing rapidly.

Most dedicated phytoremediation firms are doing
well and are finding plenty of jobs.

Some dedicated phytoremediation firms have
gone out of business or have been acquired.

Involvement, interest from the industrial sector
(i.e., private site owners) appears to be increasing.

  International Phytoremediation

Significant research interest in Canada and
Europe, commercial activities are slowly starting
to develop.
Most European research is directed at heavy
metals, but overall site remediation market is
mostly limited to petroleum hydrocarbons.

History of existing uses of willows in Europe,
constructed wetlands in Europe, Canada.

Interest elsewhere in the world includes Japan,
Australia, Asia.
    Phytoremediation: Strengths

Low capital and operating costs.
Efficiency and performance are well-suited for
risk-based remediation and other scenarios.
Permanent treatment solution, capable of
mineralizing organics.
In situ application avoids excavation.
Applicable to large contaminated surface areas.
Public acceptance expected to be good.

         Phytoremediation: Limitations
      Slower than some alternatives; dependent on
      climate, seasons.
      Generally limited to surface soils, relatively
      shallow aquifers (with some exceptions).
      High contaminant concentrations toxic to plants.
      Efficiencies may be too low to meet rigorous
      Regulatory unfamiliarity.
      Lack of recognized performance data.
D. Glass Associates, Inc.

D. Glass Associates, Inc. is a consulting firm specializing in market analyses,
technology assessments, and technology transfer in the fields of site remediation and
environmental biotechnology. The firm has advised clients in several countries about
the structure of international remediation markets, and has assisted a number of
companies in the U.S., Canada, Europe, Australia, Japan and South America locate
partners for innovative remediation technologies.

This presentation is adapted from D. Glass Associates' market report "U.S. and
International Markets for Phytoremediation, 1999-2000", a comprehensive overview
of international activities in phytoremediation. The company has also published "TTie
2000 Phytoremediation Industry", an industry directory that features over 70 company
profiles of U.S. and international phytoremediation companies.

David Glass, Ph.D., president of D. Glass Associates, has nearly 20 years experience in
various fields of biotechnology, has published several market reports on bio- and
phytoremediation, and has been a featured speaker at a number of international
                       D. Glass Associates, Inc.
                           124 Bird Street
                        Needham, MA 02492


         U.S.  Government
 Phytoremediation Activities
U.S. Environmental Protection Agency
• Internal research laboratories
• Extramural research funding
• SITE Program, RTDF Program
• Technology Innovation Office, Clu-in.com website
U.S. Department of Agriculture
• Internal research laboratories
• Extramural research funding
U.S. Department of Defense
• SERDP, ESTCP Programs
• U.S. Army Corps of Engineers Waterways
 Experiment Station
• U.S. Navy Naval Facilities Engineering Service
• U.S. Air Force Center for Environmental Excellence
• U.S. Air Force Aeronautical Systems Center
• U.S. Department of Energy
• ITRD Program
• Research at national laboratories
Tennessee Valley Authority
• Environmental Research Center

        Selected U.S. Soil
 Phytoremediation Projects
          Metals and Radionuclides
Pig's Eye Landfill; St. Paul, MN
Cd, Zn, Pb         USDA (Chancy)
                 Zinc Corp. of America;
Palmerton, PA
Zn, Cd            USDA (Chancy)
Magic Marker site; Trenton, NJ
Pb               Phytotech (Edenspace)
                 Former metal-plating site;
Findlay, OH
Cd, Ni, Zn, Cr      Phytotech (Edenspace)
                 Brookhaven National Lab;
Long Island, NY
Cs-137           Phytotech, MSB, USDA
            Organic Contaminants
Superfund site; Portland, OR
PAHs             Phytokinetics
Land treatment site; Craney Island, VA
hydrocarbons, PAHs Kansas State Univ.
Naval Station; Port Hueneme, CA petroleum
hydrocarbons       Purdue University
Army test site; Fairbanks, AK

      Selected U.S. Water
 Phytoremediation Projects
Fuel transfer terminal; Ogden, UT
Fuel oil            Phytokinetics, Chevron
Naval Air Sta. Joint Reserve; Fort Worth, TX
TCE              ESTCP, USAF, EPA
Contaminated groundwater; Tacoma, WA
TCE              Univ. Washington
Aberdeen Proving Grounds; Edgewood, MD
Edward Sears Properties; New Gretna, NJ
TCE, metals         Weston, EPA, Thomas Consult.
Army Ammunition plants; Milan, TN, Burlington, IA
TNT, RDX, explosives Army Corps of Engineers
Municipal Treatment Facility; Woodburn, OR
Landfill leachate     Ecolotree, CH2M HILL
Landfills; Cedar Rapids, IA
Landfill leachate     Ecolotree, CH2M HILL
DOE site; Ashtabula, OH
                  Phytotech (Edenspace)
Upper Bear Creek; Oak Ridge, TN (Y-12 site)
                  Phytotech, SAIC, ORNL

    Phytoremediation Cost
$l-10/cu. meter
$10/cu. yard
$29-48/cu. meter
$80/cu. yard
$96/cu. yard
$100-150/cu. meter
(S. Cunningham, DuPont)
(Geraghty & Miller)
(E. Drake, Exxon)
(R. Levine, DOE)
(Jerger et al., IT Corporation)
(R. Chaney, USDA)
Water (per 1,000 gallons treated)
$0.64            (V. Medina, EPA)
$2.00 - 6.00       (Phytotech)

Vegetative Cover (e.g. Landfill Cap, Wastewater)
$10-20,000/acre    (Christensen-Kirsh 1996,
                 citing CH2M Hill data)
$ 14-30,000/acre    (EPA RTDF Action Team)

     Phytostabilization Practices for Riverbank and Wetland Problems
                                       Wendi Goldsmith and
                                           Bill Morgante
Wendi Goldsmith is senior bioengineerwith the Bioengi-
neering Group, Inc. She has extensive experience in all
phases of project design and implementation for lakes,
rivers, and tidal areas. As project manager, consulting
bioengineer, or horticultural advisor, she has often led
interdisciplinary joint-venture design teams. She has
played a key role in promoting local familiarity and ac-
ceptance of bioengineering methods, and has aided in
the logistical planning for innovative projects. Evaluat-
ing change in land  use  and its effect on geomorphic
stability, non-point source pollution, and habitat degra-
dation has been an integral part  of Ms. Goldsmith's
waterways assessments and restoration projects. Ms.
Goldsmith is skilled in the areas of soil science, fluvial
geomorphology, landscape design, and wetland man-
agement. She also has a thorough understanding of
federal, state, and local environmental regulatory policy.
Current research carried out by Ms. Goldsmith includes
phytoremediation study and testing as well as
Brownfields redevelopment.

William Morgante is a Plant and Soil Scientist with the
Bioengineering  Group,  Inc. His knowledge  of native
plants and soil genesis allows him to correctly interpret
field conditions and plan complex natural resource res-
toration projects. He participates in site evaluation, de-
sign  development,  construction documentation and
supervision, as well as the monitoring of bioengineer-
ing treatments for streambanks, shorelines  and wet-
lands. Mr. Morgante is skilled at landscape design as
well as delineating wetland borders through both veg-
etation and hydrology. He has recently carried out re-
search relating to phytoremediation of lead-contaminated
soils targeted toward the redevelopment of Brownfields.

Two Case Studies: Landfill Bank
Stabilization/Leachate Collection and
Salt Marsh Restoration

Poster Session Abstract
1.   Cincinnati, OH, bank stabilization was required to
    halt erosion along a creek that threatened to un-
    cover landfill materials. The stream bank contained
    an existing leachate collection system, located atop
    a clay soil layer overlain by highly permeable soils
    mixed  with landfill materials. Bioengineering was
    utilized because of its ability to aid in stabilization,
    assist  in leachate extraction and enhance wildlife
    habitat, water quality, and aesthetics.

2.   Salt marsh restoration in Salem, MA, was required
    to remedy an  area filled with lead-contaminated
    refuse. Fill was removed to restore former correct
    salt marsh hydrology, and salt marsh plant species
    were installed throughout site. Salt marsh vegeta-
    tion was reestablished on the former fill area re-
    storing wetland hydrology, enhancing wildlife habitat
    containing  residual contaminants, and  improving

                   Field Studies Examining Rhizosphere-enhanced

                        PCB Degradation in the Czech Republic

            Mary Beth Leigh3, John Fletcher3, David Nagle3, Martina Mackovab, and Thomas Macekc

            allniversity of Oklahoma, Department of Botany and Microbiology, 770 Van Vleet Oval,
            Norman OK 73019, USA.
            blnstitute of Chemical Technology, Department of Biochemistry and Microbiology,
            Faculty of Food and Biochemical Technology, Technicka 3, 166 28 Prague 6, Czech Republic.
            °Academy of Sciences of the Czech Republic, Institute of Organic Chemistry and Biochemistry, Flemingovo n. 2, 166 10
            Prague 6, Czech Republic.
Mary Beth Leigh has a B.F.A. in dance, an M.S. in botany
and is now  pursuing a Ph.D. in microbiology from the
University of Oklahoma. She is currently conducting field
research in  rhizosphere bioremediation of PCBs in the
Czech Republic with an NSEP Graduate International
Fellowship. She is examining the vegetation, root-asso-
ciated microflora and PCB congener profiles in contami-
nated sites to determine the influence of plant species
on microbial PCB degradation.

She has conducted root physiology and ozone research
with the EPA Western Ecology Division in Corvallis, OR,
as a NNEMS Fellow fortwo summers and forsix months
as plant physiologist/biochemist. She was also selected
for NASA's  Space Life Sciences Training Program at
Kennedy Space Center,  FL, and was employed in
NASA's Environmental Analytical Chemistry Laboratory.

John Fletcher holds a B.S. from Ohio State University,
an MS from Arizona  State University, and a Ph.D. in
plant physiology from Purdue University. He is a pro-
fessor of botany in the Dept. of Botany and Microbiol-
ogy at the  University of Oklahoma in  Norman, OK.
During hisSOyeartenureatthe University of Oklahoma
he and his graduate students have studied the metabo-
lism of nonphotosynthetic plant tissues, root uptake of
xenobiotics, ecological risk assessment (including
PHYTOTOX and UTAB database development), and
rhizosphere remediation of PCBs and PAHs. In  1997
Dr. Fletcher received  a Level 1 research award from
EPA's Office of Research Administration for phytotoxic-
ity research he conducted in collaboration with persons
at the EPA Laboratory in Corvallis, OR. His current re-
search is focused on rhizosphere remediation of PAHs
at a former industrial sludge basin in Texas and several
PCB-contaminated field sites in  the Czech Republic.
Both projects are being conducted with the cooperation
of industrial partners. Dr. Fletcher's professional service
activities related to environmental issues include: plant
editor for the Journal of Environmental Toxicology and
Chemistry, member of the Chemical Manufacture
Association's Technical Implementation  Panel for Eco-
logical Risk Assessment  Research,  and member of
EPA's Scientific Advisory Panel for the Federal Insecti-
cide, Fungicide and Rodenticide Act.

Research has  been initiated in the Czech Republic to
determine the long-term influence of vegetation on the
microbial degradation of PCBs in contaminated soil.Two
sites have been secured for this study in which a vari-
ety of plant species have naturally grown for at least 10
years in PCB-contaminated soil ranging in concentra-
tion from 50-500 ppm. The oldest  and  largest plants
present are maple (Acersp.) and birch (Betula sp.) trees,
in addition to several grasses and shrubs.The microor-
ganisms associated with the roots of different plant spe-
cies are being examined  and  compared to bulk soil
organisms to identify plants that  selectively foster the
growth of PCB  degraders.  Initial screening studies em-
ploying a 4-chlorobiphenyl agar plate assay have iden-
tified aggressive PCB-degrading bacteria  associated
with rhizosphere soil. In parallel, PCB-contaminated soil
from the rhizosphere of mature plants (at least 10 years
old) is being examined for evidence of congener degra-

      Natural Attenuation/Phytoremediation  at a Former Sludge Basin

                                           Paul E.Olson1
                                          John S. Fletcher
                               Department of Botany and Microbiology
                                           Paul R.Philip
                               Department of Geology and Geophysics
                                       University of Oklahoma
                                        Norman, OK 73019
                                      United States of America

            1 Present address: Colorado State University, Biology Department, Fort Collins CO 80523
Paul E. Olson received a B.S. in biology from Central
State University, an M.S. in biology from the University
of Central Oklahoma, and a Ph.D. in botany from the
University of Oklahoma under the direction of Dr. John
S. Fletcher. His dissertation  research focused on the
role of vegetation and root-associated microorganisms
in the phytoremediation and ecological  recovery of
former sludge lagoons contaminated with organic pol-
lutants. Results from these studies indicated that select
plant species and rhizosphere microflora have the ca-
pacity to alter site conditions, while providing the means
for the sustained  cleanup and restoration of soils con-
taminated with recalcitrant organic pollutants.

Currently,  Paul E. Olson is part of a collaborative re-
search group at Colorado State University as a post-
doctoral fellow. The research group at Colorado State
University, consisting of members from the Departments
of Biology, Microbiology, and Chemical and Bioresource
Engineering, is investigating the underlying mechanisms
between plants and soil microorganisms in the en-
hanced dissipation of organic pollutants, including poly-
cyclic aromatic hydrocarbons (PAHs).The overall goal
of this research group includes devising plant-microbe
remediation approaches that will lead to an improved
bioremediation strategy for sites contaminated with or-
ganic pollutants.

Colorado State University
Department of Biology; A/Z Building
Fort Collins, Colorado 80523
970-491-3320 (office)
970-491-0649 (fax)
E-mail: peolson@lamar.colostate.edu

John Fletcher holds a B.S. from  Ohio State University,
an M.S. from Arizona State University, and a Ph.D. in
plant physiology  from Purdue University. He is  a pro-
fessor of botany in the Dept. of Botany and Microbiol-
ogy  at the University of Oklahoma in  Norman, OK.
During his 30 yeartenure at the University of Oklahoma
he and his graduate students have studied the metabo-
lism of nonphotosynthetic plant tissues, root uptake of
xenobiotics, ecological risk assessment (including
PHYTOTOX and UTAB database development), and
rhizosphere remediation of PCBs and PAHs. In 1997
Dr. Fletcher received a Level 1 Research Award from
EPA's Office of Research Administration for phytotoxic-
ity research he conducted in collaboration with persons
at the EPA Laboratory in Corvallis, OR. His current re-
search is focused on rhizosphere remediation of PAHs
at a former industrial sludge basin in Texas and several
PCB-contaminated field sites in  the Czech Republic.
Both projects are being conducted with the cooperation
of industrial partners. Dr. Fletcher's professional service
activities related to environmental issues include: Plant
Editor for the Journal of Environmental Toxicology and
Chemistry, member of the  Chemical Manufacture
Association's Technical Implementation Panel for Eco-
logical Risk Assessment Research,  and member of
EPA's Scientific Advisory Panel for the Federal Insecti-
cide, Fungicide and Rodenticide Act.

The natural attenuation of polyaromatic hydrocarbons
(PAHs) in the vadose zone of a naturally revegetated
former industrial sludge basin was examined. This was
accomplished by comparing the concentration of 16 PAH
contaminants  present in sludge collected below the root
zone of plants with contaminants present at 3 shallower
depths within  the root zone. Chemical analysis of 240
samples from 60 cores showed that the average con-
centration of total and individual PAHs in the 0-30 cm,
30-60 cm, and bottom of the root zone strata were ap-
proximately 10,  20, and 50%, respectively, of the 16,
800 ppm average total PAH concentration in deep non-
rooted sludge. Statistically significant differences in av-
erage PAH  concentrations were  observed among  all
strata studied  and the non-rooted  sludge, except for the
concentrations of acenaphthene and chrysene present

at the bottom of the root zone, in comparison to sludge
values. The rooting depth of the vegetation growing in
the basin was dependent on vegetation type and plant
age. Average rooting depths fortrees, forbs (herbaceous
non-grasses), and grasses were 90, 60 and 50 cm, re-
spectively. The deepest root systems observed  (100-
120 cm) were associated with the oldest (12-14 year-old)
mulberry trees. Examination of root systems and PAH
concentrations at numerous locations and depths within
the basin indicated that plant roots and their microbially
active rhizospheres fostered PAH disappearance, includ-
ing water insoluble, low volatility compounds  i.e.
benzo(a)pyrene and benzo(ghi)perylene.The reduced
concentration of PAHs in the upper strata of this reveg-
etated former sludge basin indicates that natural attenu-
ation has occurred. This observation supports  the
concept that through appropriate planting and manage-
ment practices (phytoremediation) it will be possible to
accelerate, maximize, and sustain natural processes,
whereby even the most  recalcitrant PAH contaminants
(i.e. benzo(a)pyrene) can be remediated overtime.

       Phytoremediation of Heavy  Metals, Metalloids, and  Organics: A
                               Multidisciplinary  Approach

                         Elizabeth Pilon-Smits, Marinus Pilon, and Paul Olson
                           Colorado State University Department of Biology
                              A/Z Building Fort Collins, Colorado 80523
                              970-491-4991 (office) 970-491-0649 (fax)
                                E-mail: epsmits@lamar.colostate.edu
Elizabeth Pilon-Smits has a Ph.D. in biology from the
University of Utrecht, The Netherlands. She worked as
a postdoctoral fellow at the University of Utrecht from
1992-1994, and at UC Berkeley from 1994-1998 (in the
lab of Norman Terry). Since 1998, Elizabeth Pilon-Smits
is working as a tenure-track assistant professor in the
biology department at Colorado State University (Fort
Collins,  CO).  Her  main  topic of  research  is
phytoremediation of selenium and heavy metals (6 years
of research experience) and, more recently, of polycy-
clic aromatic hydrocarbons (PAHs). Other areas of ex-
pertise include plant drought tolerance  mechanisms,
and plant biotechnology.

Elizabeth Pilon-Smits has over twenty publications in
peer-reviewed scientific journals, and two patents pend-
ing for transgenic plants with superior capacity to accu-
mulate trace elements. Her current research is funded
by NSF (CAREER) and the EPA (two projects).

Our research centers on understanding the mechanisms
by which plants and their associated microbes metabo-
lize and accumulate environmental pollutants, with the
goal to improve phytoremediation efficiency. We study
phytoremediation processes at the molecular level, the
whole plant level, and in the field. One of ourapproaches
is  to  identify steps  that are rate-limiting for the
phytoremediation of different  pollutants  and then use
genetic engineering to improve phytoremediation effi-
ciency. We use Indian mustard (Brassicajuncea) as a
model system for studying trace element metabolism.
So far, we have created transgenic mustard plants with
increased accumulation of, and tolerance to, selenium
and cadmium. This was achieved by overexpression of
enzymes involved in the sulfate assimilation pathway
and in phytochelatin biosynthesis, respectively. We are
presently studying the capacity of these transgenics for
remediation of a range of trace elements (As, Cr, Cu,
Cd, Hg, Mn, Mo, Ni, Pb, Te, W, Zn), from synthetic sub-
strates and from contaminated environmental sub-

Other related research focuses on the creation and
analysis of new transgenic  plants  for trace element
remediation, and the  isolation of new plant genes in-
volved in trace element homeostasis and tolerance. Fi-
nally, we have recently formed a collaborative research
group with members from the CSU Departments of
Microbiology, and Chemical and Bioresource Engineer-
ing, to devise plant-microbe remediation approaches
toward recalcitrant organic pollutants. Research efforts
are presently focusing on the relative contributions and
interactions of plants and soil microorganisms in the
enhanced dissipation of polycyclic aromatic hydrocar-
bons (PAHs). Future research goals include implement-
ing ourfindings in field trials, forthe enhanced cleanup
and restoration of metal- and/or organic-contaminated

  Growth  and Contaminant Uptake by Hybrid Poplars and Willows in Re-
              sponse to Application of Municipal Landfill Leachate

                            Christopher Rog, Sand Creek Consultants, Inc.
                           Rhinelander, Wl 54501 (chrisr@sand-creek.com)
                                J.G. Isebrands, USDA-Forest Service
               Forestry Sciences Laboratory, Rhinelander, Wl 54501 (jisebrands@fs.fed.us)
Christopher J. Rog, has a B.S. in geology from Colo-
rado State University and an M.S. in geology from the
University of Minnesota-Duluth. He is a registered pro-
fessional geologist in  Wisconsin and Minnesota, and
has worked in  natural resource-related issues for 15
years on projects in the midwestern, northwestern, and
southwestern United States.

Mr. Rog is currently employed by Sand Creek Consult-
ants, Inc., as a senior hydrogeologist. Current project
work has increasingly involved the use of plant-based
remedies for low-level VOC, metal, and nutrient con-
tamination in groundwater affected by landfill leachate,
especially along riparian boundaries. Sand Creek Con-
sultants, Inc., is currently engaged  in a joint research
agreement with the U.S.D.A. Forestry Sciences Lab
exploring various aspects of the use of hybrid poplars
and willows for phytoremediation at closed municipal

Jud Isebrands has a B.S. and  Ph.D. in forestry and for-
est science with a minor in statistics from Iowa State
University, Ames, IA. He has worked at the USDA - For-
est Service, Forestry Sciences Laboratory, Rhinelander,
Wl, for 32 years, first as a tree physiologist and then as
project leader of a research team on ecophysiological

His primary research focus is on the effects of climate
change on forests and the environmental effects of trees
and forests including biomass for energy, riparian buff-
ers, and phytoremediation. He is presently the U.S. rep-
resentative to the International Poplar Commission and
serves on their executive committee. He is the author of
over 150 scientific papers and book chapters and an
active reviewer on national scientific panels on forestry

Phytoremediation is an emerging technology that is a
cost-effective and environmentally sound approach for
many municipal landfill cleanups. Two of the most com-
mon tree species used in phytoremediation are poplars
(Populusspp.) and willows (Sa/;xspp.); both exhibit rapid
growth rates and ease of vegetative propagation. More
information is needed on the proper choice of tree clones
for phytoremediation because soils, climate, and con-
taminants vary with sites. In this study we examined the
phytoremediation potential of 10 northern poplar and
willow clones in response to applications of Rhinelander,
Wl, municipal landfill leachate in a replicated factorial

Our objectives were to compare seasonal: 1) plant
growth, 2) hydrological  uptake, 3) volatile organic com-
pound (VOC) removal, and 4) inorganic macro- and
micro-ion removal for the 10 clones growing across four
experimental treatments (i.e., with and without contami-
nated water, and with and without trees).

Trees were grown from cuttings in  landfill soil in 600
plastic tanks, and watered weekly with applications of
either municipal water (control), or leachate ground
water (contaminated) during the 1999 growing season;
other tanks were treated similarly without trees. VOCs
of the influent and effluent were monitored periodically,
leaves were collected in October, and plant components
(i.e. stems and roots) harvested in December for micro-
and macro-ion analysis. Our results showed that height
and volume growth of the poplar and willow clones grow-
ing  in contaminated water were  not significantly differ-
ent from  the controls. There were growth differences
among the clones - 2 poplar and 2 willow clones per-
formed the "best." Tanks with trees took up 3 times the
quantity of water when compared to tanks without trees
indicating significant hydrologic uptake. Contaminant
VOCs from the Rhinelander landfill were removed at a
rate similar to the evaportranspiration rate including 2-
butanone (MEK), cis-1,2 dichloroethene, tetrahydrofu-
ran, benzene, and vinyl chloride. Significant quantities
of some trace metal ions were removed by the trees;
e.g., boron and zinc were found in leaves of some clones
at concentrations much higher than  most northern
plants. Moreover, there were significant differences
among clones in leaf concentrations of macro-ions such
as magnesium and calcium that are suggested as con-
tributing to ion toxicity in receiving waters near landfills.
Our overall results suggest that certain poplar and wil-
low clones have  much  potential for successful
phytoremediation at the Rhinelander landfill.

         Aqueous Phase Phytotreatment of Munitions Victor Medina

                                         Victor F. Medina
                        Assistant Professor of Civil & Environmental Engineering
                                Washington State University, Tri-Cities.
Victor Medina has a B.S. in Geology from the UCLA
and an M.S. and Ph.D. in Civil Engineering  from the
University of Southern California. He has worked for
three years as an environmental consultant, and served
a two-year post-doctoral research fellowship through the
National Research Council at U.S. Environmental Pro-
tection Agency National Exposure Research Labora-
tory in Athens, GA.

Victor is currently an assistant professor of  Civil and
Environmental Engineering at Washington State Uni-
versity Tri-Cities. His phytoremediation research has
focussed on the treatment of munitions both in water
and soil. More recently, he has begun work  on treat-
ment of metals in conjunction with the Army Corp  of
Engineers. He has four papers in print or press in refer-
eed journals on the topic of phytoremediation. Other
research Dr. Medina is currently involved with includes
water quality issues in irrigation  systems  and issues
involving tank wastes at the Hanford Nuclear Reserva-

This poster will summarize research to treat munitions
in the aqueous phase using phytoprocesses. Results
of batch experiments will cover the effect of plant type,
plant density, temperature,  and TNT concentration.
Batch treatment of RDX and HMX will also be presented.
Continuous flow reactors treating TNT will also be pre-
sented and will include data covering variations in influ-
ent concentration and flow rates. Problems in treating
aminodinitrotoluenes (ADNTs) will be discussed. Pre-
liminary results investigating toxic levels of TNT on
parrotfeather, a plant commonly used fortreatment, will
be shown. The development of new approaches using
exudates, minced plants and slurried plants will also be

                 Measuring Evapotranspiration in Hybrid Poplars

                                          Paul R.Thomas
                                     Thomas Consultants, Inc.
                                          P.O. Box 54924
                                      Cincinnati, Ohio 45254

Paul R.Thomas founded Thomas Consultants, Inc., in
1989. He has a B.S. in geology from Marshall Univer-
sity and twenty one years of professional consulting ex-
perience. He has served  as principal consultant for
remedial actions at major industrial facilities throughout
the United States and has been active in plant-based
remediation of hazardous waste sites since 1987.

Mr.Thomas has designed and installed phytoremediation
systems to address a range of groundwater and soil
contaminants including pesticides, volatile organics, and
metals. Projects have been completed or are underway
at CERCLA, RCRA, Brownfields, and voluntary cleanup
sites. Mr. Thomas'focus is on the optimization and prac-
tical use of woody phreatophytes in remediation prac-
tice. Current research areas include the effects of hybrid
poplars on soil microbial biomass and organochlorine
pesticide degradation.

Thomas, PR., and Buck, J. B. 1999. "Agronomic Man-
agement for Phytoremediation" in Phytoremediation and
Innovative Strategies for Specialized Remedial Appli-
cations, ed.  Andrea Leeson and Bruce  C. Alleman.
Battelle Press, vol.6, pp 115-120.

Thomas, PR., and Krueger, J.J. 1999. "Salt Tolerance
of Woody Phreatophytes for Phytoremediation Applica-
tions" in Phytoremediation and Innovative Strategies
for Specialized Remedial Applications, ed.  Andrea
Leeson and Bruce C. Alleman. Battelle Press, vol.6, pp
One important aspect of phytoremediation practice is
the proper application of evapotranspiration monitoring
techniques. The use of hybrid poplars (and other woody
phreatophytes) as water-moving remediation tools is
becoming more common with each growing season.
Methods for measuring and predicting evapotranspira-
tion at the stand level are well established, but recent
advances in sensors and software make it possible to
directly measure sap flow and its response to leaf area
and  climatic  variables  at specific sites where
phytoremediation is in use. Xylem sap flow strongly cor-
relates to variations in photosynthetically active solar
radiation (PAR). Calibration of sap flow (per unit of leaf
area) with PAR allows accurate scaling up of measured
water consumption rates to the stand level. Accurate
and precise measurement of PAR from all portions of
the stand are possible. PAR sensors also allow season-
long monitoring without the challenges associated with
extended duration sap flow measurement.

A method is proposed to  systematically characterize
the volume of consumptive water use in stands of woody
phreatophytes.The method involves monitoring weather
variables (including PAR) throughout the local growing
season as well as periodic measurements of sap flow
and leaf area. It is intended to allow prediction of changes
in consumptive rate as stands mature. Critical to the
method is the inclusion of agronomic management
methods that allow the effects of nutrient response,
drought, and predation to be accounted for and, hope-
fully, controlled. These variables have the potential to
significantly impact viable leaf area. Data from several
sites are presented.

      Sap Flow Methods to Measure Phy to re mediation Water Removal
                                          Mike van Bavel
                                          Dynamax Inc.
                                       10808 Fallstone, #350
                                       Houston, TX 770899
Michael van Bavel graduated from Texas A&M Univer-
sity with a B.S. in electrical engineering in 1972. He
served with Texas Instruments as design engineer, pro-
gram manager, and engineering manager in the devel-
opment  and  application of  microprocessors,
microcomputers, and digital signal processing. He was
awarded two patents for the self-testing and control of
microprocessor-based electronic systems in 1976. Af-
ter 13 years with Texas Instruments, he founded
Dynamax, Inc., in 1985 and began the development of
portable electronic systems, portable sensors, and ex-
panded the scope to include agricultural product devel-

Michael van Bavel is currently the president and CEO
of Dynamax, Inc. He is responsible for the engineering
service contacts, R&D direction and the long-term strat-
egy to support new emerging markets. He is  respon-
sible for the co-development of two new sap flow sensors
and was awarded two U.S. patents in 1990 and  in 1994.
He has worked with the remote  sensing and electronic
technology transfer from agricultural and forest science
to industry with the USDA, the National Forest Service,
INRA  - France, and Battelle National Laboratories. He
manages further development and product introduction
from patents licensed by  Battelle and INRA that mea-
sure the growth and water use of trees. He has  recently
provided  contract-engineering services  for Lockheed
Martin REAC on the  EPA phytoremediation studies at
Aberdeen Proving  Grounds. The primary objective was
to analyze three years of sap flow and tree growth data
to provide long-term forecasts, and to assist in solving
the hydrology models. Currently he is a member of the
American Society of Agronomy, National Irrigation As-
sociation, American Society of Horticultural Science,
Technical Association of the Pulp and Paper Industry,
and the American Society of Enology and Viticulture.
He was awarded three times for innovative sap flow
measurement products by the Agricultural Engineering
Society of America.

To support the proof of efficacy of phytoremediation,
two in situ measurement methods are employed that
record sap flow, the transpiration rate, of plants and trees.
The sap flow records support the hydrology models for
long-term predictions, the real time removal rate of
plants, and track the progress of plants' water uptake
as they mature. The sap flow sensor data can assist the
development of new and more cost efficient methods. A
number of plants are measured over the  active sea-
sons and tracked from year to year. These data are es-
sential to show the removal rates of trees planted in a
contaminated zone, to support the observations by sam-
pling of contaminates either being degraded, accumu-
lated, volatilized, extracted, or stabilized. Furthermore,
the  sap flow data support the establishment of high
water-using plants to prevent contaminants in the va-
dose zone or landfills from leaching into deeper layers,
as well as providing a  barrier to contaminated plume

As environmental engineering companies and regula-
tory agencies take on the phytoremediation projects, a
number of anecdotal and historically unproven water
consumption rates are quoted in proposals for a variety
of reasons. To provide  a realistic estimate  of the time
involved and  efficacy, the companies and agencies will
need to gather factual data derived from plants on loca-
tion. The sap flow data take  into account not only the
plant characteristics, but also the soil conditions, plant-
ing  density, weather patterns, rooting depth,  leaf area
progression,  and long-term growth rates.

Two sap flow measurement systems and related sup-
port tools are described in this presentation. The first,
Dynagage™, is based on patented mass flow sensors
that are wrapped around the stems ortrunks, and mea-
sure the flow rates by the heat carried by sap flow con-
vection  and  the temperature increase of the water
moved.These energy balance sensors require no cali-
bration, are portable, and have been used successfully
in the crop  and forest  sciences  since  1989. The
Dynagage sensors range from 1/8 in diameter up to
five-in. diameter. New  Flow32 systems software and
improved analysis methods are presented here.

The second  measurement method for larger trees is
based on the patented TOP - Sap Velocity Thermal Dis-
sipation Probes (TOP). The TOP sensors  are heated
and needles inserted into the xylem of trees three inches
in diameter or larger. The calibrations of the sensors

are widely accepted and convert the temperature dif-   plants, recommendations are made to help the selec-
ferential of the heated needle to a sap velocity (cm/hr   tion. Recent system designs are also presented here
or mm/s).The sap wood thickness and xylem area are   that combined both sensors into the same logging in-
then determined to convert to a volume flow.           strument. A summary follows which describes the rec-
                                                  ommended practices that will yield accurate remediation
Both methods of monitoring sap flow have their advan-   rate data.
tages, and depending on the progress of the remediation

     Transport of Methyl Tert-Butyl  Ether (MTBE) through Alfalfa Plants

                          Qizhi Zhang1, Lawrence C. Davis2, Larry E. Erickson1

            1Dept. of Chemical Engineering, Kansas State University, Manhattan, KS 66506
            Phone: (785)532-5584, Fax: (785)532-7372
            2Dept. of Biochemistry, Kansas State University, Manhattan, KS 66506
            Phone: (785)532-6124, Fax: (785)532-7278
Qizhi Zhang has a B.S. in environmental engineering
from East China University of Chemical Technology, an
M.S. in chemical engineering from Zhejiang University
and a Ph.D. in chemical engineering from Kansas State
University. She has 15 years of research and teaching
combined experience in chemical engineering. Currently
employed  by the Biological & Agricultural Engineering
Department at Kansas State University as a postdoctoral
research associate, Dr. Zhang  is working on the trans-
port and control of pathogens from feedlot surface run-
off and assessment of the effectiveness of vegetative
filter strips on the removal of contaminants.

Lawrence  C.  Davis has his Ph.D. degree from Albert
Einstein College of Medicine. He has broad research
interests including nitrogen fixation mutants, structure-
function relationships, associating  macromolecules;
environmental metabolic processes,  plant-based
bioremediation; and science education.  He is a profes-
sor of Biochemistry and Chair of the Graduate Biochem-
istry Group at Kansas State University. Dr. Davis has
more than 100 publications.

Larry E. Erickson has a B.S.Ch.E. and a Ph.D. in chemi-
cal engineering from Kansas State University. He has
been a member of the chemical engineering faculty at
Kansas State University since 1964. Dr. Erickson is pres-
ently professor of chemical engineering  and director of
the Great Plains/Rocky Mountain Hazardous Substance
Research Center. He has been  conducting research on
the beneficial effects of vegetation in contaminated soil
since 1991. He has been an author or co-author of more
than 300 papers published as journal articles or reports.
He is editor of the Journal of Hazardous Substance
Research, an online journal published by Kansas State
University at http://www.engg.ksu.edu/HSRC/.

Concentrations measured in alfalfa plant stem segments
indicated that plants grown in methyl tert-butyl ether
(MTBE)-contaminated soil took up the chemical through
their roots. Assuming a cylindrical shape for the plant
stem, a mathematical model was developed to describe
the transport of MTBE through the stems. Simulation
results from uniform and non-uniform initial concentra-
tion distributions across the stem radius were compared
with the experimental data. With known values of plant
stem radius, water usage, water content and the dis-
tance overwhich the concentration decreased bv50%,
the diffusion coefficient of contaminant across the plant
stem was calculated by using the modeling results. For
the experimental conditions of this work, the  diffusion
coefficient for radial transport of MTBE through alfalfa
stems was estimated to be in the range of 8.43 ~16.2 x
10-8cm2/sec, and for water it was 6.28 x 10-gcm2/sec.
The model is applicable to other species including sun-
flowers and poplars, upon  substitution of appropriate

Keywords: transport, MTBE, alfalfa, diffusion coecient



United States
Protection Agency
     State of the  Science  Conference
     Omni Parker House Hotel
     Boston, MA
     May 1-2, 2000
     MONDAY, MAY 1 ,  2000

     Note: All sessions, except the opening plenary, consist of 25 minute presentations and a 10 minute panel' O&A session.

       8:OOAM    Registration - Rooftop Ballroom Foyer

       8:30AM    Session I: Introduction and Plenary - Rooftop Ballroom

                Welcome and Introductions
                Norm Kuhijian, U.S. Environmental Protection Agency (EPA)

                EPA Policy Overview
                Stephen Luftig, Office of Solid Waste & Emergency Response (OSWER), EPA

                The Science and Practice of Phytoremediation
                Steven McCutcheon, EPA

                Interstate Technology Regulatory Cooperation (ITRC): Making It Easier for Regulators
                Robert Mueller, New Jersey Department of Environmental Protection/1TKC

                International Perspective on the Clean Up of Metals and Other Contaminants
                Terry Mdntyre, Environment Canada

                Looking Forward on Phytotechnologies
                Steven Rock, EPA

       10:45AM   BREAK
         Printed on flscycfed Paper



 11:OOAM     Session II: Fundamental Processes of Plants and Soil - Rooftop Ballroom
              Co-Chairs: Steven McCutcheon, EPA and Lee Newman, University of Washington

              Transport of Contaminants in Plant and Soil Systems
              Larry Erickson, Lawrence Davis, Qt^hi Zhang, and Muralidharan Narayanan,
              Kansas State University

              Enzymatic Processes Used by Plants to Degrade Organic Compounds
              Nelson Lee Wolfe, EPA

              Sustained Rhizosphere Remediation of Recalcitrant Contaminants in Soil:
              Forensic Investigations with Laboratory Confirmation
              John Fletcher, University of Oklahoma

              Speaker Panel and Audience Discussion

  12:30PM    LUNCH (on own)

   2:OOPM    Concurrent Sessions

              Session IIIA: Brownfields Applications and Beneficial Use of Land - Rooftop Ballroom
              Chair: Niall Kirkwood, Graduate School of Design, Harvard University

              Integrating Remediation  Into Landscape Design
              Niall Ydrkwood, Graduate School of Design, Harvard University

              Goals for Brownfields Pilots -  O'Sullivan Island
              John Podgurski, EPA, Region 1

              Hartford Brownfield Demonstration
              Panel discussion

              Speaker Panel and Audience Discussion

              Session IIIB: Radionuclides - Press Room
              Chair Scott McMullin, Department of Energy  (DOE)

              Department of Energy Projects, Report on Recent Department of Energy Workshop
              Scott McMullin, DOE

              Capturing a "Mixed" Contaminant Plume:
              Tritium Phytoevaporation at Argonne National Laboratory
              M. Cristina Negri, Ray Hincbman, and James  Wo^niak, Argonne NationalLaboratory

              Application of Phytoremediation to Remove Cs-137 at Argonne National Laboratory - West
              Scott Lee, Argonne National Laboratory

              Speaker Panel and Audience Discussion

   3:25PM    BREAK



   3:40PM    Concurrent Sessions

              Session IVA: The Fate of Chlorinated Solvents that Disappear from Planted Systems -
              Rooftop Ballroom
              Chain Gregory Hawey, U.S. Air Force

              Phytoremediation of Solvents
              Milton Gordon, University of Washington

              The Case for Volatilization
              William Doncette, Utah State University

              Phyto-Transformation Pathways and Mass Balance for Chlorinated Alkanes and Alkenes
               Valentine N^engung, University of Georgia

              Speaker Panel and Audience Discussion

              Session IVB: Innovative Solutions for Metals Removal - Press Room
              Chair: Mitch Lasat, EPA

              Phytoextraction of Metals from Contaminated and Mineralized Soils Using
              Hyperaccumulator Plants
              Rj/fi/s Chanty, U.S. Department of Agriculture

              Phytoextraction: Commercial Considerations
              Michael Blaylock, Edenspace

              Zinc Hyperaccumulation in Plants: The Case of Zinc Hyperaccumulation in Thlaspi caemlescens
              Mitch Lasat, EPA

               Speaker Panel and Audience Discussion

   5:OOPM     BREAK

   6:OOPM     Evening Poster Session and Reception (cash bar) - Wheatiey Terrace Room

   9-.OOPM      ADJOURN

 TUESDAY,   MAY  2, 2000

   8:OOAM     Session V: Plume Control: Simulations and Forecasts - Rooftop Ballroom
               Co-Chairs: Judy Canova, South Carolina Department of Environmental Protection and
               Steven Hirsh, EPA, Region 3

               Chasing Subsurface Contaminants
               Joel Burken, University of Missouri

               Effect of Woody Plants on Ground-Water Hydrology and Contaminant Fate
               James ~Landmeyer, U.S. Geological Survey



              Session V: Plume Control: Simulations and Forecasts - Continued

              Modeling Plume Capture at Argonne National Laboratory - East
              jobnQidnn, Argonne National Laboratory

              Phytoremediation Potential of a Chlorinated Solvents Plume in Central Florida
              Stacy Lewis Htitchinson and James Weaver,  EPA

              Speaker Panel and Audience Discussion

   9:50AM    BREAK

  10:05AM    Session VI: Plume Control: On the Ground Experience - Rooftop Ballroom
              Chair Harry Compton, EPA

              Phytoremediation at Aberdeen Proving Ground, Maryland:
              Operation and Maintenance, Monitoring and Modeling
              Steven Hirsh, EPA, Region 3 and Harry Compton, EPA

              Phytoremediation Systems Designed to Control Contaminant Migration
              Ari Fern, Phytokinetics

              Deep Planting
              Edward Gat/iff, Applied Natural Sciences

              Transpiration: Measurements and Forecasts
              James Vase, U.S. Forest Service

              Speaker Panel and Audience Discussion

  11:55AM    LUNCH  (on own)

   1:OOPM    Session VII: Vegetative Covers - Rooftop Ballroom
              Co-Chairs: Steven Rock, EPA and Donna McCartney, EPA, Region 3

              Monitoring Alternative Covers
              Craig Benson, University of Wisconsin

              Growing a 1000 Year Landfill Cover
               William ]ody Waugh, Roy F. Weston

              Tree Covers for Containment and Leachate Recirculation
              Eric Aitchison, Eco/otree, Inc.

               EPA Draft Guidance on Landfill Covers
              Andrea McLaughlin and Ken Skahn, EPA

               Speaker Panel and Audience Discussion

 2:50PM       BREAK


   3:05PM    Session VIII: Degradation of Organic Compounds in Soils - Rooftop Ballroom
              Chair Phil Sayre, EPA

              Hydrocarbon Treatment Using Grasses
              M. Katherine Banks, Purdue University

              Phytoremediation of Explosives
              Phillip Thompson, Seattle University

              Case Study: Union Pacific Railroad
              Fe/i\- Flechas, EPA, Region 8

              Phytoremediation in Alaska and Korea
              Charles (hlike) Reynolds, U.S. Army Corps of Engineers
Speaker Panel and Audience Discussion



Speaker List

United States Environmental Protection Agency
            State of the Science  Conference
Omni Parker House Hotel Boston, MA
May  1-2, 2000
Eric Aitchison
Environmental Engineer
Ecolotree, Inc.
505 East Washington Street
Suite 300
Iowa City, IA 52240
E-mail: ecolotreeE@aol,com

M. Katherine Banks
Associate Professor
School of Civil Engineering
Purdue University
1284 Civil Engineering Building
West Lafayette, IN 47906
Fax: 765-496-3424
E-mail: kbanks@ecn.purdue.edu

Craig Benson
Associate Professor
Geoengineering Program
Civil and Environmental
University of Wisconsin, Madison
1415 Engineering Drive
Engineering Hall 2214
Madison, Wl 53706
Fax: 608-262-7242
E-mail: benson@engr.wisc.edu
Michael Blaylock
Research Director
Edenspace Systems Corporation
11720 Sunrise Valley Drive
E-mail: soilrx@aol.com

Joel Burken
Assistant Professor
Civil Engineering
University of Missouri, Rolla
1870 Miner Circle - 204 Civil
Rolla, MO 65409-1060
E-mail: burken@umr.edu

Judy Canova
Project Manager
Bureau of Land  and Waste
South Carolina Department of
Health and Environmental Control
2600 Bull Street
Columbia, SC 29201
Fax: 803-896-4046
E-mail: jlcanova@aol.com
Rufus Chaney
Research Agronomist
ARS Environmental Chemistry
U.S. Department of Agriculture
Building 007 - BARC West
Beltsville, MD 20705
E-mail: rchaney@

Harry Compton
Raritan Depot
U.S. Environmental Protection
2890 Woodbridge Avenue
Edison, NJ 08837-3679
E-mail: compton.harry@epa.gov

William Doucette
Associate Professor
College of Engineering
Utah Water Research Laboratory
Utah State University
8200 Old Main Hill
Logan, UT 84322-8200
E-mail: doucette@cc.usu.edu

Larry Erickson                   Milton Gordon
Professor of Chemical Engineering and Professor
Director, Hazardous Substance
Research Center
Kansas State University
105 Durland Hall
Manhattan, KS 66506-5102
E-mail: lerick@ksu.edu
                                    James Landmeyer
Department of Biochemistry           U.S. Geological Survey
University of Washington              Stephenson Center - Suite 129
J391A Magnuson Health Sciences Center 720 Gracern Road
Box 357350
Seattle, \VA 98195
E-mail: miltong@u.wnshington.edu
Ari Ferro
1770 N Research Parkway - Suite 110
N Logan, UT 84341
Fax: 435-750-0985
E-mail: ariferro@phytokinedcs.com

Felix Flechas
Region 8
Gregory Harvey
Industrial Hygenist
1801 Tenth Street - Suite 2
Wright Patterson AFB, OH 45433
Fax: 937-255-7716
Steven Hitsh
Region 3
U.S. Environmental Protection Agency
                                    Columbia, SC 29210-7651
                                    Fax: 803-750-6100
                                    E-mail: jlandmey@usgs.gov

                                    Mitch Las at
                                    Office of Solid Waste and
                                    Emergency Response
                                    U.S. Environmental Protection Ae;ency
                                    401 M Street, SW (5102G)
                                    Washington, DC 20460
                                    Fax: 703-603-1234
                                    E-mail: lasat.mitch@epa.gov
U.S. Environmental Protection Agency 1650 Arch Street (3HS13)
999 18th Street - Suite 500 (8P-HW) '  Philadelphia, PA 19103-2029
Denver, CO 80202-2466
E-mail: flechas.felix@epa.gov

John Fletcher
Professor of Plant Physiology
Department of Botany and
University of Oklahoma
770 Van Vleet Oval
Norman, OK 73019-0245
Fax: 405-325-3174
E-mail: jfletcher@ou.edu

Ed Gatliff
Applied Natural Science, Inc.
4129 Tonya Trail
Hamilton, OH 45011
Fax: 513-895-6061
E-mail: hksh.steven@epa.gov
                                    Scott Lee
                                    Nuclear Technology Division
                                    Argonne National Laboratory - West
                                    P.O. Box 2528
                                    Idaho Falls, ID  83403
                                    Fax: 208-533-7829
                                    E-mail: scott.lee@anlw.anl.gov
Jennifer Kettanis
Connecticut Department of Health
410 Capital Avenue
Hartford, CT  06134
E-mail:jennifer.kertanis@po.state.ctusU-S- Environmental Protection Agency
                                    960 College Station Road
                                    Athens, GA 30605-2720
                                    Fax: 706-355-8267
                                    Stacy Lewis Hutchinson
                                    Research Environmental Engineer
                                    National Exposure Research Laboratory
                                    Ecosystems Research Division
Niall Kirkwood
Director, Center for Environment and
Technology and Associate Professor
Graduate School of Design
Harvard University
Gund 409A
Cambridge, MA 02138
Fax: 617-495-2367
E-mail: kirkwood@gsd.harvard.edu

Norm Kulujian
U.S. Environmental Protection Agency
1650 Arch Street
Philadelphia, PA  19103-2029
Fax: 215-814-3130
E-mail: kulujian.norm@epa.gov
                                    E-mail: lewis.stacy@epa.gov

                                    Stephen Luftig */'
                                    Director, Office of Emergency and
                                    Remedial Response
                                    U.S. Enivironmental Protection Agency
                                    Ariel Rios Building (5 201G)
                                    1200 Pennsylvania Avenue, NW
                                    Washington, DC 20460
                                    Fax: 703-603-8960
                                    E-mail: luftig.stephen@epa.gov

Donna McCartney
Project Manager
U.S. Environmental Protection Agency
1650 Arch Street 3WC23
Philadelphia, PA  19103-2029
E-mail: mccartney.donna@epa.gov

Steven McCutcheon
Research Environmental Engineer
National Exposure Research Laboratory
Ecosystems Research Division
U.S. Environmental Protection Agency
960 College Station Road
Athens, GA 30605
Fax: 706-355-8235
E-mail: mccutcheon.steven@epa.gov

Terry Mclntyre
Technology Industry Branch
Bioproducts Applications Division
Environment Canada
351 St. Joseph Boulevard - 18th Floor
Hull, Quebec K1A OH3
E-mail:  terry.mcintyre@ec.gc.ca

Andrea McLaughlin
Office of Emergency and
Remedial Response
U.S.  Environmental Protection Agency
1200 Pennsylvania Avenue, NW (5202G)
Washington, DC 20460
Fax: 703-603-8793
E-mail:  mclaughlin.andrea@epa.gov

Scott McMullin
Technology and Management Division
Savannah River Plant
Department of Energy
Building 703-A, Room E118N
Route Symbol: SR
Aiken, SC
Fax: 803-725-9596
E-mail: scott.mcmullin@srs.gov
Robert Mueller
Research Scientist
Newjersey Department of
Environmental Protection/ITRC
401 East State Street - P.O. Box 409
Trenton, NJ  08625
Fax: 609-984-3910
E-mail: bmueller@dep.state.nj.us

M. Cristina Negri
Soil Scientist/Environmental Engineer
Energy Systems Division
Argonne National Laboratory
9700 S. Cass  Avenue
Argonne, IL  60439
Fax: 630-252-9662
E-mail: negri@anl.gov

Lee Newman
Research Assistant Professor
College of Forest Resources
University of Washington
Box 352100
Seattle, WA  98195
Fax: 206-616-2388
E-mail: newmanla@u.washington.edu

Valentine Nzengung
Department  of Geology
University of Georgia
Athens, GA  30602
Fax: 706-542-2699
E-mail: vnzengun@arches.uga.edu

John Podgurski
U:S. Environmental Protection Agency
Region 1 Suite 1100 - HIO
1 Congress Street
Boston, MA 02114-2023
E-mail: podgurski.john@epa.gov

John Quinn
Environmental Assessment Division
Argonne National Laboratory
9700 South Cass Avenue - EAD 900
Argonne, IL 60439-4832
Fax: 630-252-5357
E-mail: quinnj@anl.gov

               - over -
Charles (Mike) Reynolds
Research Physical Scientist
Cold Regions Research &
Engineering Laboratory
U.S. Army Corps of Engineers
72 Lyme Road
Hanover, NH 03755
Fax: 603-646-4394
E-mail: reynolds@crrel.usace.army.mil

Steven Rock
Environmental Engineer
U.S. Environmental Protection Agency
26 West Martin Luther King Drive
Cincinnati, OH  45268
Fax: 513-569-7149
E-mail: rock.steven@epa.gov

Phil Sayre
U.S. Environmental Protection Agency
Ariel Rios Building 7403
1200 Pennsylvania Avenue, NW
Washington, DC 20460
E-mail: sayre.phil@epa.gov

Ken Skahn
Environmental Engineer
Superfund Program
U.S. Environmental Protection Agency
Ariel Rios Building (5202G)
1200 Pennsylvania Avenue, NW
Washington, DC 20460
Fax: 703-603-8801
E-mail: skahn.ken@epa.gov

Phillip Thompson
Assistant Professor
Department of Civil and
Environmental Engineering
Seatde University
900 Broadway - Room 524 (ENGR)
Seatde, WA  98122
Fax: 206-296-5521
E-mail: thompson@seatdeu.edu

James Vose
Coweeta Hydrologic Laboratory
Southern Research Station
3160 Coweeta Laboratory Road
Otto.NC  28763
Fax: 828-524-2128

William Jody Waugh
Principal Scientist
Roy F. Weston, Inc.
2597 B 3/4 Road
Building 938, Room 242
Grand Junction, CO  81503
Fax: 970-248-6431
E-mail: jody.waugh@doegjpo.com

Jeanne Webb
City of Hartford
Property Acquis don and Disposition
10 Prospect Street, 3rd Floor
Hartford,  CT  06103

Nelson Lee Wolfe
Senior Research Chemist
National Exposure Research Laboratory
Ecosystems Research Division
U.S. Environmental Protection Agency
960 College Station Road
Athens, GA  30605-2700
Fax: 706-355-8207
E-mail: \volfe.lee@epa.gov

L'                                APPENDIX C

                             Poster Presenter List

             United States
             Protection Agency
State of the  Science  Conference
Omni Parker House Hotel
Boston, MA
May 1-2, 2000

Poster Presenters
Holget B6ken
Dipl. IngAgr. (FH)
Agronomy/Soil Protection/Soil Use
Humboldt-University Berlin
Dorfstrasse 9
Berlin, D-13051
E-mail: holger.boeken@t-online.de

Larry Erickson
Professor of Chemical Engineering
and Director, Hazardous Substance
Research Center
Kansas State University
105 Durland Hall
Manhattan, KS  66506-5102
Fax: 785-532-4313
E-mail: lerick@ksu.edu

David Glass
D. Glass Associates, Inc.
124 Bkd Street
Needham,MA  02492
Fax: 617-726-5474
E-mail: dglassassc@aol.com
Wendi Goldsmith
Soil Scientist
The Bioengineering Group, Inc.
18 Commercial Street
Salem, MA 01970
Fax: 978-740-0096
E-mail: wgoldsmith@

Jud Isebrands
Project Leader
U.S. Department of Agriculture
Forest Sciences Lab
5985 Highway K
Rhinelander, WI 54501
Fax: 715-362-1116
E-mail: isebrands_jud/nc_rh@fs.fed.us

James Landmeyer
U.S. Geological Survey
Stephenson Center - Suite 129
720 Gracern Road
Columbia, SC  29210-7651
Fax: 803-750-6100
E-mail: jlandmey@usgs.gov
Maty Beth Leigh
Graduate Student
Department of Botany and Microbiology
University of Oklahoma
770 Van Vleet Oval - Room 135
Norman, OK 73019
Fax: 405-325-6502
E-mail: mleigh@ou.edu

Stacy Lewis Hutchinson
Research Environmental Engineer
National Exposure Research Laboratory
Ecosystems Research Division
U.S. Environmental Protection Agency
960 College Station Road
Athens, GA 30605-2720
Fax: 706-355-8267
E-mail: lewis.stacy@epa.gov

Steve McCutcheon
Research Environmental Engineer
National Exposure Research Laboratory
Ecosystems Research Division
U.S. Environmental Protection Agency
960 College Station Road
Athens, GA 30605
Fax: 706-355-8235
E-mail: mccutcheon.steven@epa.gov
   I Printed on Recycled Paper
                                        - over -

Victor Medina
Assistant Professor
Department of Civil & Environmental
Washington State University
Tri Cities Branch Campus
100 Sprout Road
Richland, WA 99352-1643
Fax: 509-372-7471
E-mail: vmedina@tricity.wsu.edu

Bill Motgante
Plant and Soil Scientist
The fiioengineering Group, Inc.
18 Commercial Street
Salem, MA 01970
Fax: 978-740-0096
E-mail: wmorgante@

Paul Olson
Post-Doctoral Fellow
Biology Department
Bioresources and Chemical Engineering
Colorado State University
A/Z Building (E414)
Fort Collins, CO  80523
Fax: 970-491-3320
E-mail: peolson@lamar.colostate.edu

Elizabeth Pilon-Smits
Assistant Professor
Biology Department
Colorado State University
Anatomy/Zoology Building
Fort Collins, CO  80523
Fax: 970-491-4991
E-mail: epsmits@lamar.colostate.edu

Christopher Rog
Senior Geologist
Sand Creek Consultants, Inc.
P.O. Box 1512
Rhinelander, WI 54501
Fax: 715-365-1818
E-mail: chrisr@sand-creek.com
Sridhar Susarla
National Exposure
Research Laboratory
Ecosystems Research Division
U.S. Environmental Protection
960 College Station Road
Athens, GA  30605-2720
Fax: 706-355-8216
E-mail: susarla.sridhar@epa.gov

Paul Thomas
Principal Consultant
Thomas Consultants
P.O. Box 54924
Cincinnati, OH 45254
Fax: 513-271-9923
E-mail: pthomas@cinci.rr.com

Mike van Bavel
Dynamax, Inc.
10808 Fallstone - #350
Houston, TX 77099
Fax: 281-564-5100
E-mail: mvb(2
           _ lynamax.com

Qizhi Zhang
Chemical Engineering
Kansas State University
105 Durland Hall
Manhattan, KS 66506
Fax: 785-532-2925
E-mail: cecy@ksu.edu


Attendee List

United States
Protection Agency
      State  of the  Science  Conference
      Omni Parker House Hotel
      Boston, MA
      May 1-2, 2000

      Final Attendee  List
      Lisa Alexander
      Environmental Engineer
      Bureau of Waste Site Cleanup
      Massachusetts Department of
      Environmental Protection
      One Winter Street
      Boston, MA  02108
      E-mail: lisa.alexander@state.ma.us

      Dorothy Allen
      Environmental Engineer
      Federal Superfund Section
      Bureau of Waste Site Cleanup
      Massachusetts Department of
      Environmental Protection
      One Winter Street
      Boston, MA  02108
      E-mail:  dorothy.allen@state.ma.us

      Christopher Alonge
      Environmental Engineer
      Bureau of Eastern Remedial Action
      Division of Environmental
      New York State Department of
      Environmental Conservation
      50 Wolf Road - Room 242
      Albany, NY 12233-7010
      Fax: 518-457-4198
      E-mail: cgalonge@gw.dec.state.ny.us
         t Printed on Recycled Paper
               Elizabeth Anderson
               Project Manager
               Tyree Organization
               9 Ottis Street
               Westborough, MA 01581
               Fax: 508-871-8301
               E-mail: eanderson@tyreeorg.com

               Jay Arnone
               Division of Earth & EcoSystem
               Desert Research Institute
               2215 Raggio  Parkway
               Reno, NV 89512
               Fax: 775-673-7485
               E-mail: jarnone@dri.edu

               Caroline Baier-Anderson
               TAG Consultant
               University of Maryland
               100 North Greene Street - Room 418
               Baltimore, MD 21201
               Fax: 410-706-6203
               E-mail: cbaie001@umaryland.edu

               Talaat Balba
               Technical Manager
               CRA Services
               2055 Niagara Falls Boulevard - Suite 3
               Niagara Falls, NY 14304
               Fax: 716-297-2266
               E-mail: tbalba@craservices.com
Mark Baldi
Environmental Analyst
Audits/Site Management
Bureau of Waste Site Cleanup
Massachusetts Department of
Environmental Protection
Central Regional Office
627 Main Street
Worcester, MA 01608
Fax: 508-792-7621
E-mail: mark.baldi@state.ma.us

Stephen Ball
Environmental Analyst
Massachusetts Department of
Environmental Protection
436 Dwight Street
Springfield, MA 01103
Fax: 413-784-1149
E-mail: Stephen.b

Michael Barry
Remedial Project Manager
Federal Facilities Super Section
Office of Site
Remediation & Restoration
U.S. Environmental Protection
One Congress Street - Suite 1100
Boston, MA 02114
Fax: 617-918-1291

Gail Batchelder
Principal Hydrogeologist
HGC Environmental
222 Glendale Road
Hampden, MA  01036
Fax: 413-566-8524
E-mail: glb@hgc-env.com

Kellyn Betts
Associate Editor
Environmental Science &
Technology Branch
American Chemical Society
1155 16th Street, NW
Washington, DC  20036
Fax: 202-872-4403
E-mail: k_betts@acs.org

Arthur Bogen
Down to Earth
73D East Broadway
Milford, CT 06460
Fax: 203-877-3830
E-mail: abogen®

Jon Bornholm
Remedial Project Manager
North Superfund Management
Waste Division
U.S. Environmental
Protection Agency
61 Forsyth Street, SW
Atlanta, GA 30303
Fax: 404-562-8788
E-mail: bornholm.jon@epa.gov

David Buckley
Project Manager
Bureau of Waste Site Cleanup
Massachusetts Department of
Environmental Protection
One Winter Street - 7th Floor
Boston, MA  02108
Fax: 617-292-5530
E-mail: david.buckley@state.ma.us
James Byrne
Environmental Protection Specialist
Office of Site
Remediation & Restoration
U.S. Environmental Protection
One Congress Street - Suite 1100 HIO
Boston, MA 02114-2023
Fax: 617-918-1291
E-mail: byrne.james@epa.gov

Julie Campbell
Contaminants Specialist
U.S. Fish and Wildlife Service
11103 East Montgomery Drive
Spokane, WA 99206
Fax: 509-891-6748
E-mail: julie_campbell@fws.gov

Kevin Carpenter
Project Manager
Bureau of Eastern Remedial Action
Division of Environmental
New York State Department of
Environmental Conservation
50 Wolf Road
Albany, NY 12233-7010
Fax: 518-475-4198
E-mail: kjcarpen@gw.dec.state.ny.us

Cliff Casey
Environmental Engineer
South Naval Facility
Engineering Command
Environmental Division
U.S. Navy
P.O. Box 190010 (1888)
North Charleston, SC 24919-9010
Fax: 843-820-7465
E-mail: caseycc®
Lynne Cayting
Environmental Specialist
Maine Department of
Environmental Protection
17 State House Station
Augusta, ME  04333
Fax: 207-287-7826
E-mail: lynne.a.caytii
Keng-Yong Chan
Graduate Student
Civil 8c Engineering Department
Massachusetts Institute of Technology
77 Massachusetts Avenue-
Room 1-143
Cambridge, MA 02139
E-mail: kychan@mit.edu

Margaret Chen
Environmental Analyst
Site Management Branch
Massachusetts Department of
Environmental Protection
One Winter Street - 7th Floor
Boston, MA 02108
Fax: 617-292-5530
E-mail: margaret.chen-
Jean Choi
Geo-Environmental Engineer
Technical Support Branch
Office of Site Remediation &
U.S. Environmental Protection
One Congress Street
Suite 1100 (HBS)
Boston, MA  02114
Fax: 617-918-1291
E-mail: choi.jean@epa.gov

Jeffrey Chormann
Assessment and Reporting
Business Compliance Division
Massachusetts Department of
Environmental Protection
One Winter Street - 9th Floor
Boston, MA 02108

James Chow
Project Manager
Brownfields Program
Office of Site
Remediation & Restoration
U.S. Environmental Protection
One Congress Street (HIO)
Boston, MA 02114
Fax: 617-918-1291
E-mail: chow.james@epa.gov

Linda Chrisey
Program Officer
Office of Naval Research
U.S. Navy
800 North Quincy Street - BCT #1
(Code 342)
Arlington, VA 22217-5660
Fax: 703-696-1212
E-mail:  chrisel@onr.navy.mil

Karen  Collette
Senior Data Analyst
Environmental Science &
Engineering, Inc.  (ESE)
410 Amherst Street - Suite 100
Nashua, NH 03063
Fax: 603-882-2223
E-mail: kmcollette@esemail.com
Janine Commerford
Bureau of Waste Site Cleanup
Division of Contract
Procurement & Management
Massachusetts Department of
Environmental Protection
One Winter Street - 7th Floor
Boston, MA 02108
Fax: 617-292-5530
E-mail: janine.commerford@

Paul Craffey
Project Manager
Bureau of Waste Site Cleanup
Response & Remediation Division
Massachusetts Department of
Environmental Protection
One Winter Street
Boston, MA 02108
Fax: 617-292-5530
E-mail: paul.craffey@state.ma.us

Gerald Cresap
Senior Associate
New England Branch
Braintree Division
LFR Levine-Fricke
8 Woodlawn Avenue (NA)
Wellesley, MA 02481
E-mail: jcresap@aol.com

Thomas Grossman
Manager, Bio/Phytoremediation
ARCADIS Geraghty & Miller, Inc.
14497 North Dale Mabry Highway
Suite 115
Tampa, FL 33618
E-mail: tcrossma@gmgw.com
Henry Cui
Environmental Engineer
Federal Facilities Branch
Bureau of Waste Site Cleanup
Massachusetts Department of
Environmental Protection
20 Riverside Drive
Lakeville, MA 02347
Fax: 508-947-6557
E-mail: henry.cui@state.ma.us

Ross  del Rosario
Remedial Project Manager
Remedial Response Branch
Superfund Division
U.S. Environmental Protection
77 West Jackson Boulevard (SR-6J)
Chicago, IL 60604
Fax: 312-886-4071
E-mail: delrosario.rosauro@epa.gov

Philipp  Dirk
The BioEngineering Group
Salem, MA 01970
Fax: 978-740-0097
E-mail: dphilipp@bioengineermg.com

Sarah Divakarla
Hazardous Waste Management
Environmental Protection Division
Georgia Department of
Natural Resources
205 Butler Street, SE - Suite 1462
Atlanta,  GA  30334
Fax: 404-657-0807
E-mail: sarah_divakarla@

Lynne Doty
Environmental Analyst
Bureau of Waste Site Cleanup
Massachusetts Department of
Environmental Protection
20 Riverside Drive
Lakeville, MA  02347
Fax: 508-947-6557

John Durnin
Environmental Engineer
Bureau of Central Remediation
Division of Environmental
New York State Department of
Environmental Conservation
50 Wolf Road - Room 228
Albany, NY  12233-7010
Fax: 518-457-7925
E-mail: jedurnin@gw.dec.state.ny.us

Slavik  Dushenkov
V.R. Professor
Biotech Center
Cook College
Rutgers University
59 Dudley Road
New Brunswick, NJ  08901
Fax: 732-932-6535
E-mail: dushenkov@aol.com

Kathryn Eastman
New York State Department of
Environmental Conservation
50 Wolf Road
Albany, NY  12233-7010
E-mail: kceastma@

Walter Eifert
Principal Hydrologist
Roux Associates, Inc.
5014 Hunterwood Lane
Martinsburg,  WV 25401
Fax: 304-274-0326
E-mail:  weifert@rouxinc.com

Sarah Caselli
Office of Waste Management
Rhode Island Department of
Environmental Management
235 Promenade Street
Providence, RI 02908
Fax: 401-222-3812
E-mail:  scaselli@dem.state.ri.us
Peg Engwall
Project Manager
Hazardous Waste Remediation
Waste Management Division
New Hampshire Department of
Environmental Services
6 Hazen Drive - P.O. Box 95
Concord, NH 03301
E-mail: m_engwall@des.state.nh.us

Kenneth Finkelstein
Environmental Scientist
National Oceanic &
Atmospheric Administration
c/o U.S. Environmental
Protection Agency
1 Congress Street (HIO)
Boston, MA  02114-2023
Fax: 617-918-1291
E-mail: ken.finkelstein@noaa.gov

Arthur Fisher
Environmental Engineer
Public Works Department
Environmental Division
Naval Air Station
4755 Pasture Road (187 AF)
Fallon.NV 89496
Fax: 702-426-2663

Scott Fredericks
Office of Solid Waste &
Emergency Response
U.S. Environmental Protection
Ariel Rios Building (5202G)
1200 Pennsylvania Avenue, NW
Washington, DC 20460
E-mail: fredricks.scott@epa.gov

Kris Geller
Research Scientist
New Jersey Department of
Environmental Protection
401 East State Street - P.O. Box 413
Trenton, NJ 08625
Fax: 609-292-0848
Matthew Gentry
Solid Waste Section
Hydrogeology Division
South Carolina Department of
Health & Environmental Control
2600 Bull Street
Columbia, SC 29201
Fax: 803-896-4292
E-mail: gentrymd@

Jalal Ghaemghami
Principal lexicologist
Office of Environmental Health
Boston Public Health Commision
1010 Massachusetts Avenue
2nd Floor
Boston, MA 02118
Fax: 617-534-2372
E-mail: jalal_ghaemghami@bphc.org

Aaron Gilbert
Environmental Engineer
RCRA Corrective Action
Office of Site  Remediation
& Restoration
U.S. Environmental Protection
One Congress Street
Suite 1100 (HBT)
Boston, MA 021,14-2023
Fax: 617-918-1291
E-mail: gilbert.aaron@epa.gov

Michael Gill
Superfund Technical Liaison
U.S. Environmental Protection
75 Hawthorne Street SFD-8B
San Francisco, CA 94105
Fax: 415-744-1917
E-mail: gill.michael@epa.gov

Deborah Goldblum
Geologist/Project Manager
General Operations Branch
Waste & Chemical
Management Division
U.S. Environmental Protection
1650 Arch Street 3WC23
Philadelphia, PA 19103
E-mail: goldblum.deborah@epa.gov

Christopher Gussman
Senior Biologist
Lockheed Martin/REAC
705 Bound Brook Avenue
E-mail: christpher.d.gussman®

Neil Handler
Remedial Project Manager
Office of Site
Remediation  & Restoration
U.S. Environmental Protection
One Congress Street - Suite 1100
Boston, MA  02114
E-mail: handler.neil@epa.gov

Mark Haney
Vice President, Remediation
 Environmental Science &
 Engineering, Inc. (ESE)
 410 Amherst Street - Suite 100
 Nashua, NH 03063
 Fax: 603-882-2223
 E-mail: mahaney@esemail.com

 Nancy Hayden
 Associate Professor
 Department of Civil &
 Environmental Engineering
 University of Vermont
 Burlington, VT 05405
 Fax: 802-656-8446
Sherry Hohn
ERIN Consulting
1055 Park Street - Suite 215
Regina, Saskatchewan S4N 5H4
Fax: 306-789-9490

David Hopper
Chief Engineer
Environmental Science &
Engineering, Inc.
410 Amherst Street - Suite 100
Nashua, NH  03063
Fax: 603-882-2223
E-mail: drhopper@esemail.com

Daniel Huber
Environmental Analyst
Office Research & Standards
Massachusetts Department of
Environmental Protection
One Winter Street - 8th Floor
Boston, MA  02108
Fax: 617-556-1006
E-mail: daniel.huber@state.ma.us

Damien Hughes
U.S. Environmental
Protection Agency
290 Broadway - 20th Floor
New York, NY 10007
 Fax: 212-637-4284
 E-mail: hughes.damien@epa.gov

James Ireland
 ERIN Consulting
 1055 Park Street - Suite 215
 Regina, Saskatchewan S4N 5H4
 Fax: 306-789-9490
J.G. Isebrands
Project Leader
Forest Service
U.S. Department of Agriculture
5985 Highway K
Rhinelander, WI 54501
E-mail: jisebrands@fs.fed.us

Gary Jablonski
Office of Waste Management
Rhode Island Department of
Environmental Management
235 Promenade Street
Providence, RI  02908
E-mail: gjablons@dem.state.ri.us

Eric Johnson
Ogden Environmental
and Energy Services
239 Littleton Road - Suite IB
Westford,MA  01886
Fax: 978-692-6633
E-mail: EVJohnson@oees.com

Penelope Johnston
 Environmental Engineer
Uncontrolled Sites Branch
 Hazardous Waste Division
 Mississippi Department of
 Environmental Quality
 P.O. Box 10385
 Jackson, MS 39289-0385
 Fax: 601-961-5300
 E-mail: penelope_johnston@

 Andrew Jones
 Massachusetts Department of
 Environmental Protection
 20 Riverside Drive
 Lakeville, MA 02347

Lisa Keller
Project Manager
Contaminated Sites Division
Environment Canada
351 St. Joseph Boulevard - 19th
Hull, Quebec K1A OH3
Fax: 819-953-0509
E-mail: lisa.keller@ec.gc.ca

Michael Kinkley
Director, Environmental
GATX Terminals Corporation
500 West Monroe Street
Chicago, IL 60661
Fax: 312-621-8110
E-mail: mlkinkley@gatx.com

Paul Kittner
The Louis Berger Group, Inc.
30 Vreeland Road - Building A
Florham Park, NJ 07932-1904
Fax: 973-676-3564
E-mail: pkittner@louisberger.com

Frank Klanchar
Remedial Project Manager
U.S. Environmental Protection
 1650 Arch Street
Philadelphia, PA  19103-2029
Fax: 215-814-3002
E-mail: klanchar.frank@epa.gov

Jeff Konsella
Environmental Engineer
 Division of Environmental
 New York State Department of
 Environmental Conservation
 50 Wolf Road
 Albany, NY 12233-7010
 E-mail: jakonsel@gw.dec.state.ny.us
Michael Koppang
Civil Engineer
Harding Lawson Associates
511 Congress Street
P.O. Box 7050
Portland, ME 04112-7050
Fax: 207-772-4762
E-mail: mkoppang@harding.com

Paul Kulpa
Senior Scientist
Office of Waste Management
Rhode Island Department of
Environmental Management
235 Promenade Street
Providence, RI 02908
Fax: 401-222-3812
E-mail: pkulpa@dem.state.ri.us

Larry Lampman
Environmental Engineer
Bureau of Hazardous
Site Investigation
Division of
Environmental Remediation
New York State Department of
Environmental Conservation
50 Wolf Road - Room 252
Albany, NY  12233-7010
Fax: 518-457-8989
E-mail: lxlampma@gw.dec.state.ny.us

David  Lang
Ground Water Consultants, Inc.
 100 Cummings Center - Suite 330J
Beverly, MA 01915
Fax: 978-922-3245
E-mail: gwcon@concentric.net

 Keith Latorre
 1093 Commerce Park Drive
 Suite 100
 Oak Ridge, TN  37830
 Fax: 865-483-9061
 E-mail: keith_latorre@urscorp.com
Yin Li                             ;
Chief Geneticist
ARS Environmental Chemistry Lab
U.S. Department of Agriculture
BARC-W, Building 007, Room 211
Beltsville, MD  20705
Fax: 301-504-5048
E-mail: yli@asrr.arsusda.gov

John Liptak
Project Manager
Hazardous Waste Branch
Waste Management Divison
New Hampshire Department of       !
Environmental Services
6 Hazen Drive
Concord, NH 03301                 ;
Fax: 603-271-2181
E-mail: jliptak@des.state.nh.us

Darryl Luce
Office of Site Remediation
& Restoration
U.S. Environmental Protection
JFK Federal Building (HBO)
Boston, MA 02201
E-mail: ev45190@aol.com

Michael MacCabe
Environmental Engineer
Eastern Remedial Action
Environmental Remediation
New York State Department of
Environmental Conservation
50 Wolf Road - Room 242
Albany, NY  12233-7010
Fax: 518-457-4198
E-mail: mdmaccab@gw.dec.state.ny.us

Michael Mackiewicz
Senior Hydrogeologist-Associate
Environmental Division
Anchor Engineering
21 Hollow Road
Wales, MA 01081
Fax: 413-734-0100
E-mail: dtmackiewicz@msn.com

Byron Mah
U.S. Environmental Protection
1 Congress Street (HBO)
Boston, MA 02114
Fax: 617-918-1291
E-mail: mah.byron@epa.gov

Dale Manty
Office of Research and
U.S. Environmental Protection
E-mail:  manty.dale@epa.gov

Anna Mayor
Environmental Analyst
Bureau of Waste Site Cleanup
 Response & Remediation Division
 Massachusetts Department of
 Environmental Protection
 One Winter Street - 7th Floor
 Boston, MA  02108
 Fax: 617-292-5530
 E-mail: anna.mayor@state.ma.us

 Christopher McClure
 Environmental Engineer
 Handex of New England
 398 Cedar Hill Street
 Marlborough, MA  01752
 Fax: 508-481-5159
 E-mail: cmcclure@handexmail.com
William McKenty
U.S. Environmental Protection
1650 Arch Street (3HS41)
Philadelphia, PA  19103
E-mail: mckenty.william@epa.gov

David McMillan
Natresco & Associates
101 Nye Road
Hershey, PA  17033
E-mail: dmmcmill@syr.edu

Leslie McVickar
Project Manager
Office of Site Remediation
& Restoration
U.S. Environmental
Protection Agency
One Congress Street
Suite 1100 (HBT)
Boston, MA  02114
Fax: 617-918-1291
E-mail: mcvickar.leslie@epa.gov

Jeff Meegoda
Associate Professor of Civil &
Environmental Engineering
Department of Civil &
Environmental Engineering
 New Jersey Institute of Technology
 Newark, NJ  07102
 Fax: 973-597-5790
 E-mail: meegoc
 Michael Miller
 Camp, Dresser & McKee, Inc.
 One Cambridge Place
 50 Hampshire Street
 Cambridge, MA 02139
 E-mail: millerme@cdm.com
De'Lyntoneus Moore
On-Scene Coordinator
U.S. Environmental
Protection Agency
6 IForsyth Street, SW
Atlanta, GA 30303
Fax: 404-562-8699
E-mail: moore.tony@epa.gov

Dawn Moses
Brownfields Coordinator
Mayor's Office of
Environmental Policy
Brownfields Redevelopment Program
City of Houston
901 Bagby Street - 4th Floor
Houston, TX 77002
Fax: 713-247-2100
E-mail: dmoses@myr.ci.houston.tx.us

Diane Mosher
Technical Specialist
ARCADIS Geraghty & Miller, Inc.
175 Cabot Street - Suite 503
Lowell, MA 01854
Fax: 978-937-7555
E-mail: dmosher@gmgw.com

Ellen Moyer
Program Manager
 35 Nagog Park
 Acton, MA 01720
 Fax: 978-635-9180
 E-mail: emoyer@ensr.com

 Nuria Muniz
 Brownefields Project Manager
 U.S. Environmental Protection
 290 Broadway
 New York, NY 10007
 Fax: 212-637-4360
 E-mail: muniz.nuria@epa.gov

Lori Murtaugh
Ground Water Quality Section
Bureau of Water
South Carolina Department of
Health and Environmental Control
2600 Bull Street
Columbia, SC 29201
Fax: 803-898-4190
E-mail: murtaudc@

Richard Nalbandiah
Westview Environmental
7 North Columbus Boulevard
Suite 115
Philadelphia, PA 19106-1423
Fax: 215-925-6590
E-mail: twhc2@netreach.net

Jay Naparstek
Section Chief
Bureau of Waste Sites Cleanup
Massachusetts Department of
Environmental Protection
One Winter Street - 7th Floor
Boston, MA 02108
Fax: 617-292-5530
E-mail: jay.naparstek@state.ma.us

Peter Nimmer
Geologist/Project Manager
EA Engineering, Science,
and Technology
The Maple Building
3 Washington Center
Newburgh.NY 12550
Fax: 914-565-8203
E-mail: pln@eaest.com

Michael O'Hara
MWO Environmental
Enginnering $c Consulting, P.C.
P.O. Box 569 - 17 Maple Lane
Monroe, NY 10950
Fax: 914-774-2690
Paul Ollila
Environmental Analyst
Site Management
Bureau of Waste Site Cleanup
Massachusetts Department of
Environmental Protection
627 Main Street
Worcester, MA 01608
Fax: 508-792-7621
E-mail: paul.ollila@state.ma.us

Cyril Onewokae
Environmental Engineer
U.S. Army Operations
Support Command
Building 350 - 3rd Floor D21
Rock Island, IL 61299-6000
Fax: 309-782-1379
E-mail: onewokaec@osc.army.mil

Harish Panchal
Environmental Engineer
Response & Remediation Branch
Bureau of Waste Sites Cleanup
Massachusetts Department of
Environmental Protection
One Winter Street
Boston, MA  02108
Fax: 617-292-5530
E-mail: harish.panchal@state.ma.us

Dirk Philipp
The Bioengineering Group, Inc.
18 Commercial Street
Salem, MA  01970
Fax: 978-740-0097
E-mail: dphilipp@bioengineering.com

Vincent Pitruzzello
Chief, Program Support Branch
Emergency & Remedial
Response Division
U.S. Environmental
Protection Agency
290 Broadway - 18th Floor
New York, NY 10007
Fax: 212-637-4360
Andrea Porter
Graduate Student
Department of Civil &
Environmental Engineering
University of Vermont
213 Votey
Burlington, VT 05401
E-mail: aporter@emba.uvm.edu

Tracy Punshon
Post-Doctoral Research Associate
Advanced Analytical Center for
Environmental Services
Savannah River Ecology Laboratory
Drawer E
Aiken, SC 29803
Fax: 803-725-3309
E-mail: punshon(Z

Michael Rafferty
Vice President
S.S. Papadopulos and Associates, Inc.
221 World Trade Center
The Ferry Building
San Francisco, CA 94111-4204
Fax: 415-837-3801
E-mail: mrafferty@sspa.com

Peter Ramanauskas
Environmental Engineer
Waste, Pesticides & Toxics Division
U.S. Environmental Protection
77 West Jackson Boulevard (DW-8J)
Chicago, IL 60604
Fax: 312-353-4788
E-mail: ramanauskas.peter@epa.gov

Thomas Reamon
Environmental Engineer
New York State Department of
Environmental Conservation
50 Wolf Road - Room 252
Albany, NY 12233-7010
Fax: 518-457-8989
E-mail: tareamon@gw.dec.state.ny.us

Peter Richards
Environmental Analyst
Massachusetts Department of
Environmental Protection
205 Lowell Street
Wilmington, MA  01887
Fax: 978-661-7615
E-mail: peter.richards@state.ma.us

Norm Richardson
Senior Environmental Scientist
Harding Lawson Associates
107 Audubon Road- Suite 301
Wakefield.MA 01880
E-mail: nrichardson@harding.com

Isabel Rodrigues
U.S. Environmental Protection
290 Broadway - 20th Floor
New York, NY 10007
Fax: 212-637-4284
E-mail: rodrigues.isabel@epa.gov

Cornell Rosiu
Environmental Scientist
Office of Site Remediation
& Restoration
U.S. Environmental Protection
 1 Congress Street - Suite 1100 (HBS)
Boston, MA  02114
Fax: 617-918-1291
E-mail:  rosiu.cornell@epa.gov

Clayton Rugh
Assistant Professor
Phytoremediation  Branch
Department of Crop & Soil Sciences
Michigan State University
 516 Plant & Soil Sciences Building
 East Lansing, MI  48824
 Fax: 517-355-0270
 E-mail: rugh@msu.edu
Don Russell
Principal Facility
Environmental Engineer
Ford Motor Company
One Parklane Boulevard - Suite 1400
Parklane Towers, E
Dearborn, MI 48124
Fax: 313-248-5030
E-mail: drussell@ford.com

Tony Russell
Chief, Uncontrolled Sites Section
Superfund Branch
Hazardous Waste Division
Mississippi Department of
Environmental Quality
101 West Capital Street
Jackson, MS 39201
Fax: 601-961-5300
E-mail: tony_russell@deq.state.ms.us

Claudia Sait
Remedial Project Manager
Bureau of Remediation &
Waste Management
Maine Department of
Environmental Protection
17 State House Station
Augusta, ME 04333
Fax: 207-287-7826
E-mail: claudia.b.sait@state.me.us

David Salvadore
Environmental Analyst
Massachusetts Department of
Environmental Protection
627 Main Street
Worcester, MA 01608
Fax: 508-792-7621
E-mail:  david.salvadore@state.ma.us

Kevin Sarnowicz
Environmental Engineer
Remediation Division
New York State Department of
Environmental Conservation
50 Wolf Road
Albany, NY 12233-7010
Fax: 518-457-7925
Robert Schmidt
Office of Waste Management
Rhode Island Department of
Environmental Management
235 Promenade Street
Providence, RI 02908-5767
Fax: 401-222-3813
E-mail: bschmidt@dem.state.fl.us

Roger Schweitzer
Solid Waste Section
Hydrogeology Division
South Carolina Department of Health
& Environmental Control
2600 Bull Street
Columbia, SC 29201
Fax: 803-896-4292
E-mail: schweire@

Philip Sheridan
Environmental Engineer
United Technologies
1 Financial Plaza
Hartsfield, CT 06103
Fax: 860-728-6563
E-mail: sheridan@corphq.utc.com

John Smaldone
Innovative Technology Contact
U.S. Environmental Protection
One Congress Street (HIO)
Boston, MA  02114
E-mail: smaldone.john@epa.gov

Stephen Smith
Civil Engineer
Rocky Mountain Arsenal
National Wildlife Refuge
U.S. Fish & Wildlife Service
Commerce City, CO  80022
Fax: 303-289-0579

Tracy Smith
Environmental Engineer
Division of Environmental
New York State Department of
Environmental Conservation
50 Wolf Road - Room 242
Albany, NY 12233-7010
Fax: 518-457-7925
E-mail: txsmith@gw.dec.state.ny.us

Benjamin Su
Lead Process Engineer
Winchester Branch
Environmental Division
GEI Consultants
1021 Main Street
Winchester, MA 01890
Fax: 781-721-4073
E-mail: bsu@geiconsultants.com

Thomas Tetreault
Environmental Analyst
Bureau of Waste Site Cleanup
Massachusetts Department of
Environmental Protection
20 Riverside Drive
Lakeville, MA  02347
Fax: 508-947-6557
E-mail: tom.tetreault@state .ma.us

Rhonda Tinsley
Senior Geologist
Southern Company Services
P.O. Box 2625
Birmingham, AL 35202
Fax: 205-992-0356
E-mail: rjtinsle@southernco.com

Gena Townsend
Remedial Project Manager
U.S. Environmental Protection
Sam Nunn Atlanta Federal Center
61 Forsyth Street, SW
Atlanta, GA 30303
Fax: 404-562-8518
Patti Tyler
Ecological Risk Assessor
Office of Ecosystem Assessment
Office of Environmental
Measures & Evalutation
U.S. Environmental Protection
60 Westview Street (EGA)
Lexington, MA 02421
Fax: 781-860-4397
E-mail: tyler.patti@epa.gov

Matt Vick
U.S. Fish & Wildlife Service
8588 Route 148
Marion, IL 62959
Fax: 618-997-8961
E-mail: matthew vie
Janet Waldron
Environmental Analyst
Response and Remediation Branch
Massachusetts Department of
Environmental Protection
One Winter Street - 7th Floor
Boston, MA 02108
Fax: 617-556-1049
E-maiL janet.waldron@state.ma.us

Victor Walkenhorst
Senior Engineer
Missouri/Kansas Branch
Superfund Division
U.S. Environmental
Protection Agency
901 North Fifth Street (SUPR-MOKS)
Kansas City, KS  66101
Fax: 913-551-7063
E-mail walkenhorst.victor@epa.gov

Philip Walling
Senior Environmental Engineer
Virginia Environmental Affairs
P.O. Box 27001
Richmond, VA 23261
Fax: 804-383-3785
Ernest Waterman
U.S. Environmental
Protection Agency
One Congress Street
Suite 1100 (HBT)
Boston, MA 02114-2023
Fax: 617-918-1291
E-mail: waterman.erraest@epa.gov

Peddrick Weis
Department of Anatomy
Aquatic Toxicology Laboratory
UMDNJ - New Jersey Medical School
Newark, NJ 07103
E-mail: weis@umdnjjedu

Judith Weiss
Department of Biology Sciences
Rutgers University
Newark, NJ 07102
Fax: 973-353-5518
E-mail: jweis@androraieda.rutgers.edu

Dale Weiss
Senior Program Manager
TRC, Inc.
Boot Mills South
Foot of John Street
Lowell, MA 01852
Fax: 978-453-7995
E-mail: daleweis@ix.rmetcom.com

Alan Weston
Director Remedial Technology
CRA Services
2055 Niagara Falls Boulevard - Suite 3
Niagara Falls, NY  14304
Fax: 716-297-2265
E-mail: aweston@crasservices.com

Nancy White
Environmental Analyst
Bureau of Waste Site Clean-up
Audits Division
Massachusetts Department of
Environmental Protection
205A Lowell Street
Wilmington, MA  01887
Fax: 978-661-7615
E-mail: nancy.white-
eqe@state .ma.us

Martha  Wilhelm Kessler
The Bureau of National Affairs, Inc.
275 Island Road
Millis, MA 02054
Fax: 508-376-4709
E-mail: mkessler@bna.com

Beth Willson
CH2M Hill
E-mail: bwillson@ch2m.com

Lisamarie Windham
Post-doctoral Fellow
Department of Biological Sciences
Rutgers University
101 Warren Street
Newark, NJ 07102
E-mail: windham®

Michael Young
Assistant Research Professor
Desert Research Institute
755 East  Flamingo Road
Las Vegas, NV 89119
Fax: 702-895-0427
E-mail: michael@dri.edu
James Zeppieri
Hazardous Waste Remediation
Waste Management Division
New Hampshire Department of
Environmental Services
P.O. Box 95 - 6 Hazen Drive
Concord, NH 03302-0095
E-mail: jzeppieri@des.state.nh.us

John Zupkus
Environmental Analyst
Northeast Region
Massachusetts Department of
Environmental Protection
205A Lowell Street
Wilmington, MA  01887
Fax: 978-661-7615
E-mail: john.zupkus<2