United States Region 5
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Radionuclide Biological
Remediation Resource
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O C DA Radionuclide Biological
Remediation Resource Guide
Prepared by:
Victor Madu Ibeanusi, Ph.D.
Denise Antonia Grab
August 2004
In collaboration with
Larry Jens en
Stephen Ostrodka
U.S. Environmental Protection Agency, Region 5
Superfund Division
Chicago, Illinois 60604
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Acknowledgements
This resource guide was prepared by U.S. Environmental Protection Agency (U.S. EPA),
Region 5, Superfund Division, Program Management Branch, Field Services Section, 77 W.
Jackson Blvd, Chicago, IL 60604 under fellowships for the National Network for
Environmental Management Studies (NNEMS) and the Oak Ridge Institute for Science and
Education (ORISE). Special gratitude to Levester Spearman, Director, Office of Civil
Rights and to Margrett Hardman, Regional Special Emphasis Program Coordinator, Office
of Civil Rights and to Ms. Sheri Jojokian, NNEMS Program Coordinator, Office of
Environmental Education, U.S. EPA Headquarters, whose efforts made it possible to
receive funding from ORISE. Our sincere gratitude to Dr. M. Cristina Negri of the Argonne
National Laboratory for providing literature sources and a review article on treatment of
radionuclides and to all the reviewers: Richard Graham, Larry Jensen, Warren Layne, Charles
Maurice, Stephen Ostrodka, John Peterson, Steven Rock, and Ellen Rubin.
Our gratitude to our cover photo contributors: Pam Gallichio (U.S. EPA Region 5), Willow
tree background and graphics; Dr. Victor Madu Ibeanusi (Spelman College), Willow and
Poplar trees at Argonne National Laboratory, and a bioremediation process showing an
assemblage of bacterial and cyanobacterial cells; David Jones (Aldershot, County Hampshire,
England), White Rot Fungus. And with much thanks to Karen Reshkin whose software
expertise smoothed the final editing. For more information about this project contact: Larry
Jensen, U.S. Environmental Protection Agency, Region 5, Superfund Division, Program
Management Branch, Field Services Section, 77 W. Jackson Blvd (SMF-4J), Chicago, IL
60604, e-mail:JENSEN.LARRY@epa.gov
11
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Disclaimer
Neither the U.S. EPA, nor any employees, contractors nor representatives, make any
warranty, expressed or implied, or assume any legal liability or responsibility for the accuracy,
completeness or usefulness of any information, apparatus, product, or process disclosed, or
represent that its use would not infringe on privately owned rights. Reference herein to any
specific commercial product, process, or service by trade name, trademark, manufacturer, or
otherwise does not necessarily constitute or imply its endorsement, recommendation, or
favoring by the EPA or any agency thereof.
in
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Foreword
Identifying and accessing pertinent information resources that will help site cleanup
managers evaluate innovative technologies is key to the broader use of these technologies.
This guide is intended to increase awareness about technical information and specialized
resources related to phytotechnology, bioremediation and other technologies as they relate
to radioactive materials.
Specifically, this document identifies a cross section of information intended to aid users in
remedial decision-making, including abstracts of field demonstrations, research documents,
and information to assist in the ordering of publications. In addition, the cross reference
and look-up format of this document allows the user to quickly scan available resources and
access more detailed abstracts.
Please let us know about additional information that could make this guide (and others in
the series) more useful to you. It will be recognized that this area of research could be
expanded in many ways. We encourage readers to apply these methods or to develop new
ones and then add to the body of research papers because expanded use of these methods
should improve cleanup strategies. This guide and others listed below are available to the
public through http://www.epa.gov/region5superfund. http: / /www.epa.gov/tio. and
http: / /clu-in.org. and cfpub.epa.gov/si.
bioremediation Resource Guide
Groundwater Treatment Resource Guide
Physical/ Chemical Treatment Technology Resource Guide
Phytoremediation Resource Guide
Soil Vapor Extraction (SVE) Enhancement Technology Resource Guide
Soil Vapor Extraction Treatment Technology Resource Guide
IV
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Table of Contents
Introduction 1
Current Radionuclide Treatment Methods and
Rationale for Alternatives 1
Background on Biological Remediation 1
Is Biological Remediation Right for Your Site? 2
Inside this Guide 3
Criteria for Selection of Resources 3
Future Research Opportunities 4
Literature Search 5
Glossary 7
How to Use this Guide 10
Cross-Reference Matrix 12
Abstracts 23
Phytotechnology 23
Bioremediation 39
Other 53
Future Research Opportunities 59
Abstracts 60
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Introduction
Current Radionuclide Treatment Methods and Rationale for Alternatives
Presently, excavation and shipping to a distant waste disposal site is the most commonly
used method for handling soil contaminated with radionuclides. Treatment of surface water
or groundwater usually creates sludges or residues that must be treated like soils. This
excavation and shipping of soils is very expensive and can be disruptive to the environment
in which the contamination is found.
Biological treatment methods, such as phytoremediation and bioremediation, could provide
an attractive alternative to the excavation of soil. In some cases, off-site shipment might not
be necessary at all, if radioactive decay can be utilized, and in other cases, the volume of
shipped material (and, thus, the cost of shipping) could be dramatically reduced. Moreover,
these biological methods would minimize the disruption to the environment caused by
excavation. Biological treatment methods may also be more efficient and cost-effective than
traditional methods in the case of contaminated groundwater or surface water. In many
cases, the classes of contaminants which have shown successes in chemical cleanups are the
same classes associated with radioactive contaminants (e.g., metals). The primary differences
being the latter are isotopic forms of these chemical elements. It is entirely possible that
methods successful for chemical elements may be successful for the same radioactive
elements.
Background on Biological Remediation
The widespread distribution of environmental pollutants and the need for cost-effective
treatment methods have stimulated the emergence of new technologies using biological
remediation processes. These new treatment options include phytotechnology the use of
plants for in situ remediation of contaminated soil, sludges, sediments, and groundwater
through contaminant removal, degradation, or containment; and bioremediation the use of
microbes to sequester contaminants or transform them into a less-toxic state in soil, water
and activated sludge systems. Other biological treatment methods include the use of
microbial mats, a combination of plant biomass and microbes to immobilize contaminants;
the bioaccumulation of pollutants through the use of shellfish; and the use of fungi species
for biodegradation processes.
Treatment options such as these utilizing natural processes have been found to be efficient
and cost-effective. For example, other well-known natural processes such as in: nutrient
cycling of nitrogen, phosphorus, sulfur, carbon dioxide, and water; flow of energy through
the various trophic levels of the ecosystems; and natural attenuation of pollutants have
served as the underlying template in the sustainability of the ecosystems around the world.
By understanding and enhancing these important natural processes, the need for cost-
efficiency and sustainability has now emerged as the underlying factors for measuring
remediation processes and assessment of environmental quality.
It is in this context, that the efficient natural uptake of nutrients by plants has been utilized
in specific remedial-phytotechnological terms such as in: phytostabilization, rhizofilteration,
phytoextraction, rhizodegradation, and phytovolatilization. For more information on
phytotechnology, please see the glossary on pages 7-9, the U.S. EPA Phytoremediation Resource
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Guide (http://www.epa.gov/tio/download/remed/phytoresgude.pdf ) or the EPA Citizen's
Guide to Phytoremediation (http://www.epa.gov/tio/download/citi2ens/citphyto.pdf).
Similarly, the inherent ability of microbes to incorporate chemicals and radionuclides on
specific binding sites of their membranes have been adopted in bioremediation applications
such as in: biostimulation, mineralization, bioaugmentation, chelation, and sequesterization
indicating the growing importance for a better understanding and use of these emerging
biotechnologies. See the glossary on pages 7-9 for a definition of these terms. Additional
information on bioremediation technologies can be found at the following web sites:
Bioremediation Resources
http://www.nal.usda.gov/bic/Biorem/biorem.htm
EPA Office of Research and Development (ORD) Bioremediation Documents
http://www.epa.gov/ord/WebPubs/biorem/index.html
http: / /www.epa.gov/tio /download/citizens /bioremediation.pdf (A Citizen's Guide to
http: / /www.epa.gov/tio /pubitech.htm
DOE Natural and Accelerated Bioremediation Research (NABIR)
http: / 7www.lbl.gov/NABIR
U.S. Geological Survey
http: / /www.usgs -gov
http://water.usgs.gov/wid/html/bioremed.html
The other biological treatment methods as described in this guide include studies on fungi,
natural attenuation processes, and microbial mats. Fungi represent an important part of the
ecosystem and play a major role in nutrient cycling in both aquatic and terrestrial ecosystems.
Similar to plant roots, their extensive networks of hyphae, aided by mycorrhizal-plant
interactions, have made fungal species a good candidate for remediation of radionuclides in
both soil and water.
The long-term restorations of ecosystems and contaminated sites have been attributed to
natural attenuation processes. The efficiency of this mode of remediation will vary based on
the biological and chemical nature of the contaminated site. For example, the impact of an
effluent from uranium mine tailing to groundwater could naturally be mitigated if the soil is
rich in carbonate or other reducing agents. Another example of a natural attenuation process
is seen in aquatic systems, which serve as a medium for the assemblage of algae, bacteria, and
phytoplankton. This kind of assemblage, described in this guide as microbial mats, has been
utilized in remediation of chemicals and radionuclides. Additional information on these
studies is contained in the DOE Natural and Accelerated Bioremediation Research website:
http: / 7www.lbl.gov/NABIR.
Is Biological Remediation Right for Your Site?
Biological remediation is not a viable option for every site. An initial site characterization is
highly recommended to determine whether biological remediation will be an effective
treatment of choice. Among others tests, a typical site characterization should include the
following:
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analysis of nutrient availability to ensure that the site has the necessary nutrient
sources (such as nitrates, phosphates, carbon source, and minerals) to support the
microbial or plant species
sequential extraction processes to determine the bioavailability of the pollutant for
effective treatment
analysis of soil acidity/alkalinity to determine if the addition of fertilizers and
aeration will be necessary to support the growth of microbes or plants.
determination of the chemical form of the radioactive species
identification of the half-life of the radionuclide involved, and
identification of which plant or microbial species are best suited to the radionuclide-
contaminated site
The radiological half-life must be considered, as well. If the half-life is relatively short, it may
lead to the effective disappearance of the contaminant in a practical amount of time.
Conversely, if the half-life is relatively long, it may necessitate regulated disposal.
Furthermore, it is important to ensure that the plants, bacteria, or other organisms that have
concentrated radionuclides in their tissue will not be inadvertently transported off-site by
wind or water.
In optimal conditions, however, biological remediation methods can be quite effective. In
general, phytotechnology works best on large areas of land with low levels of contamination.
Given the proper set of conditions, biological remediation can be a welcome alternative to
the expensive, traditional methods of remediation. However, because the methods utilize
biological modes of cleanup, rather than excavation, phytotechnology and bioremediation
can, in some instances, require a longer treatment time than traditional cleanup methods.
Inside this Guide
This Radionuclide biological Remediation Resource Guide outlines various potential
phytotechnology and bioremediation methods for treating radionuclide-contaminated sites.
Included in this guide are other biotechnologies that show promise at pilot scales and are in
need of validation in field demonstrations, such as the use of fungi, microbial mats, and
bioaccumulation by shellfish. This current resource guide is part of a series of technology-
focused documents prepared by the U.S. EPA, designed in part to address specific
contaminants. The U.S. EPA has produced a similar reference in compiling the
Phytoremediation Resource Guide. This radionuclide guide should serve as a useful reference for
EPA Superfund remedial project managers, EPA on-scene coordinators, and EPA health
physicists. It may also serve as reference for other federal and state agencies, academic
institutions, private contractors, public interest groups, and individual citizens for whom
cleanup of radionuclides is an issue and may spur renewed interests in radionuclide research.
Criteria for Selection of Resources
Our goal in this guide is to cite those technologies which, in our opinion, have real practical
relevance to the end user in the field. However, we also recognize that there are several
other biological remediation research efforts that are in varied degrees of readiness for field
deployment. In this context, this document is by no means an exhaustive reference guide.
Specifically, we chose to include a particular resource if it met one or more of the following
criteria:
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Has gone through a field demonstration
Has applicability for treating multiple radionuclides
Has applications for field-based modeling
Has a high-degree of tolerance of a variety of environmental conditions
Future Research Opportunities
As this guide was being prepared, studies that involved the use of shellfish were reviewed
and seemed to be potential options for future biotechnology. A few of the abstracts that
described these areas are included on pages 59-62. Although the abstracts did not meet the
criteria set for this current guide, perhaps, by including them, new opportunities for future
research and field tests in these areas may be explored.
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Literature Search
In developing this resource guide, a literature search was conducted on a variety of
government databases, commercial databases, and websites including:
Agency for Toxic Substances and Disease Registry
http: / 7www.atsdr.cdc.gov
BIOSIS Previews
http: / /www.biosis .com
Environmental Protection Agency
http: / 7www.epa.gov
Environmental Sciences and Pollution Management Database
http: 7 7www.csa.com
Haz-Map: Information on Hazardous Chemicals and Occupational Diseases
http: 7 /hazmap.nlm.nih.gov
The Hazardous Waste Cleanup Information Page
http://clu-in.org
National Center for Environmental Health
http: / /www.cdc.gov/nceh
National Institute of Environmental Health Sciences
http: / /www.niehs.nih.gov
National Library of Medicine
- MedlinePlus http://www.medlineplus.gov
Looked under Health Topics for Radiation Exposure
- PubMed http: / /www.pubmed.gov
TOXNET: Cluster of databases on Toxicology, Hazardous Chemicals and Related
Issues http: / /toxnet.nlm.nih.gov
- GENE-TOX: Genetic Toxicology (Mutagenicity)
- HSDR: Hazardous Substances Data Bank
- IRIS: Integrated Risk Information System
- ITER: International Toxicology Estimates for Risks
- Toxline: Toxicology Bibliographic Information
U.S. Nuclear Regulatory Commission
http: / Avww.nrc.gov
U.S. Department of Energy
http: / /www. doe.gov
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U.S. Department of Agriculture
http: / 7www.usda.gov
Web of Science
http: / /www.isinet.com/products /citation/wos
The search terms used included various combinations of the keywords: bioremediation,
phytoremediation, phytotechnology, bioremediation, plants, bacteria, fungi, shellfish,
remediation, radionuclide, radioisotope, cesium, strontium, radium, plutonium, cobalt,
technetium, and uranium.
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Glossary
Bioavailability
Bioremediation
Biostimulation
Bioaugmentation
Chelation
Energy flow
Half-life
Mineralisation
Nutrient cycling
Phytodegradation
The degree that a contaminant can be taken up by organisms
under specific environmental conditions. In the context of
biological remediation, high bioavailability is necessary, and
the bioavailability can be increased through various treatment
processes.
The use of naturally-occurring microorganisms or genetically
engineered microbes to sequester toxic and radioactive
compounds or transform them into less harmful forms.
The addition of fertilizers and/or aeration to supply nutrients,
thus enhancing the growth of indigenous microbes during
bioremediation.
The addition of microbes that are known to interact
aggressively with a particular contaminant or a pollution site
in order to speed-up a bioremediation process
The binding of a contaminant to a biological or a chemical
molecule, such as a metal binding to a protein. Chelation can
change the bioavailability or phytoextraction properties of a
metal or radionuclide.
The transfer of energy through an ecosystem. Energy flow
starts through the process of photosynthesis by primary
producers (such as plants and blue-green algae) and makes
energy available through out the various trophic levels of the
ecosystem.
The time interval whereby radioactive decay reduces the
number of atoms of a radioisotope by one-half.
The process by which substances are converted to inorganic
compounds.
The movement of nutrients (such as nitrogen, phosphorus,
sulfur, carbon, and carbon dioxide in the environment) within
an ecosystem, primarily by microorganisms.
The breakdown of contaminants by plants, either internally
through metabolic processes within a plant, or externally
through the release of compounds (such as enzymes)
produced by a plant. Pollutants can be degraded,
incorporated into the plant tissues, and used as nutrients.
Even though chemical forms can be degraded, there is no
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Phytoextraction
(or phytoaccumulation)
Phytostabili^ation
Phytotechnology
Phytovolatili^ation
way to alter a radionuclide except as it radioactively decays in
its own fixed way. Nor can the radioactive decay process be
accelerated or decelerated.
The uptake and translocation of contaminants, either
chemical or radioactive, by plant roots into the above ground
portions of the plants. Certain plants called
hyperaccumulators absorb unusually large amounts of
radionuclides in comparison to other plants. One or a
combination of these plants is selected and planted at a site
based on the type of radionuclides present and other site
conditions. After the plants have been grown to a
predetermined size, age, or growth stage, they are harvested
and tested for radioactive content. The radioactive content
of the plant, value of the material, half-life, and regulations
determine the appropriate disposal of radioactive plant
matter, either into recycling, solid waste, or hazardous waste
disposal. In some cases plants may be dried, composted, or
incinerated to reduce volume.
The use of certain plant species to immobilize contaminants
in the soil and groundwater through absorption and
accumulation in plant tissues, adsorption onto roots, or
precipitation within the root zone. This process reduces the
mobility of the contaminant by retarding migration to the
groundwater or air and by reducing bioavailability for entry
into the food chain. This technique can be used to reestablish
a vegetative cover at sites where natural vegetation is lacking
due to high radioactivity concentrations in surface soils or
physical disturbances to surficial materials. Radioactivity-
tolerant species can be used to restore vegetation to the sites,
thereby decreasing the potential migration of contamination
through wind erosion, transport of exposed surface soils, and
leaching of soil contamination to groundwater.
The direct use of living plants for in situ remediation of
contaminated soil, sludges, sediments, surface water, or
groundwater through contaminant removal, degradation, or
containment.
The uptake and transpiration of a contaminant by a plant,
with release of the contaminant or a modified form of the
contaminant to the atmosphere from the plant.
Phytovolatilization occurs as growing trees and other plants
take up water along with the contaminants. Some of these
contaminants can pass through the plants to the leaves and
volatilize into the atmosphere at comparatively low
concentrations.
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Rhi^pdegradation
Rhi^pfilteration
Sequential extraction
Sequesteri^ation
Sustainability
The breakdown of contaminants in the soil through microbial
activity that is enhanced by the presence of a plant's root
structure. Rhizodegradation is a much slower process than
phytodegradation. Microorganisms (yeast, fungi, or bacteria)
consume and digest organic substances for nutrition and
energy. Certain microorganisms can digest organic substances
such as fuels or solvents that are hazardous to humans and
break them down into harmless products through
biodegradation. Natural substances released by the plant
roots sugars, alcohols, and acids contain organic
carbon that provides food for soil microorganisms, which
enhances their activity. Biodegradation is also aided by the
way plants loosen the soil and transport water to the area.
The adsorption or precipitation onto plant roots or
absorption into and sequesterization in the roots of
contaminants that are in solution surrounding the root zone.
The plants to be used for cleanup are raised in greenhouses
with their roots in water rather than in soil. To acclimate the
plants once a large root system has been developed,
contaminated water is collected from a waste site and brought
to the plants where it is substituted for their water source.
The plants are then planted in the contaminated area where
the roots take up the water and the contaminants along with
it. As the roots become saturated with radioactive
contaminants, they are harvested. This could be followed by
incineration or composting to reduce the volume and/or by
storage to allow radioactive decay to reduce the volume of
contaminated material. Generally, this would be followed by
disposal in a regulated landfill.
The use of successive applications of various solvents and
other chemicals to ensure that the chemical or radioactive
contaminant is released from bound surfaces (such as soil
particles) so that effective treatment can be achieved. The
technique can be used for either diagnostic or treatment
purposes.
The isolation of contaminants in a medium in ways that make
them unavailable and less harmful to the environment.
The ability of a system to maintain itself over a prolonged
period of time. The quality of a system, biodiversity, and
economic status of a system affect its sustainability.
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How to Use this Guide
General Information
Within the Abstracts section of this guide, one can find the citations and abstracts, as written
by the article's authors, for approximately 100 articles on biological remediation of
radionuclides. The abstracts in this guide are organized primarily by technology type
(phytotechnology, bioremediation, and other), then by year (most recent to least recent),
then alphabetically by the first author's last name. One can look to the top right of the
heading on each page to determine the technology type and document numbers assigned to
the articles on that page.
Searching the Guide
There are two main ways to identify those resources in this guide that will be most helpful to
you:
Using the Cross-Reference Matrix
Browsing through the Abstract Keys
Cross-Reference Matrix
The Cross-Reference Matrix, on pages 12-22, provides a way to determine which articles
pertain to the contaminants at your site. Each row in the matrix corresponds to one article
in the Abstracts section. First the matrix lists the Media Addressed (soil, groundwater, or
surface water) in each article, as represented by a dot in the appropriate column. Then, the
matrix shows the Radionuclides Addressed (cesium-137, strontium-90, radium-226,
plutonium, technetium-99, uranium, thorium, or other) in each article, also represented by a
dot in the corresponding column. Less commonly addressed isotopes of the same elements
(for example, cesium-134) are listed under "other." Plutonium encompasses plutonium-238,
plutonium-239, plutonium-241, or combinations thereof. Uranium refers to the isotopes
uranium-234, uranium-235, uranium-238, or combinations thereof or to the Uranium Decay
Series. Thorium refers to the isotopes thorium-227, thorium-230 or thorium-232 or
combinations thereof or to the Thorium Decay Series. The matrix also shows the
Technology Type employed in the article (phytotechnology, bioremediation, or other).
To use this Cross-Reference Matrix, simply look for those rows that address the
combination of radionuclides and media that apply at your cleanup site. Look to the right of
the row, and you will find the title of the relevant document, the number of the document in
the booklet, and the page number on which the document appears. Once you have selected
the appropriate documents, use the page number (found at the bottom of each page of
abstracts) and document number (preceding each citation at the top of each abstract) to find
the full citation and abstract for each document in the abstract listings on pages 23-58.
Abstract Keys
If you already have a preference for the technology type you want to use at your site, you can
go directly to the Abstracts section and use the Abstract Keys to find those documents that
most effectively address your interests.
Within the abstract listings on pages 23-58, each document has its own Abstract Key located
between the citation and the abstract. Here is a sample Abstract Key:
10
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Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Phyto.
"Tc
90Sr
*
other
Media: Soil
A star is placed next to the radionuclides addressed in the articles in this case, "Tc. If a
less common radionuclide is mentioned, it will be written out in the "other" section. Like
the Cross-Reference Matrix, the Abstract Key lists the technology type (in this case,
phytotechnology) and the media addressed (in this case, soil). The technology type will be
abbreviated as "phyto." for phytotechnology and "biorem." for bioremediation. The media
will be abbreviated as "SW" for surface water and "GW" for groundwater.
More information
Within each technology type section, there are some review articles that are very helpful
overviews of the work within the field. These are highlighted with an asterisk at the end of
the citation, standing for a review article.
In this document, the radionuclides are represented by their chemical symbol. Some of the
more common radionuclides mentioned are:
137Cs
90Sr
226Ra
Pu
"Tc
U
Th
60Co
3H
cesium-137
strontium-90
radium-226
plutonium
technetium-99
uranium
thorium
cobalt-60
tritium
In some cases, the abstract may not be available for an article. This will be noted under the
Abstract Key.
When available, information on how to obtain the full article will be listed below the
abstract. In most cases, this will include a website for the journal in which the article
appeared. One can use the citation for the article to find the full text on this website. In
most cases, the website will charge a fee for obtaining the full text if you do not have a
subscription.
In some cases, a National Technical Information Service (NTIS) order number may be
available at the end of the abstract. To obtain one of these documents, call NTIS at (800)
553-6847 or order from their website at http: / /www.ntis.gov. In other cases, a book
number (ISBN) or no other information will be listed. A librarian should be able to help
you find these documents or any other documents you have trouble locating.
11
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Cross Reference Matrix
Media Addressed
Soil
Ground-
water
Surface
Water
Radionuclides Addressed
137Cs
90Sr
226Ra
Pu
"Tc
U
Th
Other
General
134Cs, 85Sr
Technology Type
Phytotechnology
Other
Bioremediation
Phytotechnology
Phytotechnology
Phytotechnology
Other
Phytotechnology
Phytotechnology
Document Title
Accumulation of 137Cs and 90Sr from
contaminated soil by three grass
species inoculated with mycorrhizal
fungi
Application of a dynamic model for
evaluating radionuclide concentration
in fungi
Bioremediation of a soil
contaminated with radioactive
elements
A comparison of 90Sr and 137Cs
uptake in plants via three pathways at
two Chernobyl-contaminated sites
A comparison of models for
characterizing the distribution of
radionuclides with depth in soils
Dynamics of 137Cs bioavailability in
soil-plant system in areas of the
Chernobyl Nuclear Power Plant
accident zone with a different
physico-chemical composition of
radioactive fallout
Effect of ectomycorrhizae and
ammonium on 134Cs and 85Sr uptake
into Picea abies seedlings
Effect of NO3" on the fate of 99TcO4"
in the soil-plant system
Environmental processes affecting
plant root uptake of radioactive trace
elements and variability of transfer
factor data: a review
Doc.
Number
26
91
61
11
28
39
92
29
7
Page
32
54
45
27
33
37
55
33
25
12
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Cross Reference Matrix
Media Addressed
Soil
Ground-
water
Surface
Water
Radionuclides Addressed
137Cs
90Sr
226Ra
Pu
"Tc
U
Th
Other
General
65Zn, 54Mn
134Cs
General
Technology Type
Other
Other
Phytotechnology
Phytotechnology
Phytotechnology
Phytotechnology
Phytotechnology
Other
Phytotechnology
Document Title
Fungal interactions with metals and
radionuclides for environmental
bioremediation
Fungi as potential bioremediation
agents in soil contaminated with
heavy or radioactive metals
Generic values for soil-to-plant
transfer factors of radiocesium
Identification and validation of heavy
metal and radionuclide
hyperaccumulating terrestial plant
specie
Incorporating soil structure and root
distribution into plant uptake models
for radionuclides: toward a more
physically based transfer model
Influence of agricultural
countermeasures on the ratio of
different chemical forms of
radionuclides in soil and soil solution
Influence of organic amendments on
the accumulation of 137Cs and 90Sr
from contaminated soil by three grass
species
Influence of soil fungi
(basidiomycetes) on the migration of
134+137Cs and 90Sr in coniferous forest
soils
In-situ remediation of soil
contaminated with low
concentrations of radionuclides
Doc.
Number
93
90
8
36
6
45
17
100
44
Page
55
54
26
36
25
38
29
57
38
13
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Cross Reference Matrix
Media Addressed
Soil
Ground-
water
Surface
Water
Radionuclides Addressed
137Cs
90Sr
226Ra
Pu
"Tc
U
Th
Other
General
General
General
Technology Type
Phytotechnology
Phytotechnology
Phytotechnology
Phytotechnology
Phytotechnology
Phytotechnology
Phytotechnology
Phytotechnology
Phytotechnology
Phytotechnology
Phytotechnology
Document Title
Long-term study on the transfer of
137 Cs and 90Sr from Chernobyl-
contaminated soils to grain crops
Mechanisms of casesium uptake by
plants
Modeling radium and radon transport
through soil and vegetation
Modeling the potential role of a
forest ecosystem in
phytostabilization and
phytoextraction of 90Sr at a
contaminated watershed
An overview of the effect of organic
matter on soil-radiocaesium
interaction: implications in root
uptake
Phytoaccumulation of chromium,
uranium, and plutonium in plant
systems
Phytoremediation and reclamation of
soils contaminated with
radionuclides
Phytoremediation of Chernobyl
contaminated land
Phytoremediation of radiocesium-
contaminated soil in the vicinity of
Chernobyl, Ukraine
Phytoremediation of soil
contaminated with low
concentrations of radionuclides
Phytoremediation of soils
contaminated with toxic elements
and radionuclides
Doc.
Number
37
23
4
27
14
32
35
22
25
41
42
Page
36
31
24
33
28
34
36
31
32
37
37
14
-------
Cross Reference Matrix
Media Addressed
Soil
Ground-
water
Surface
Water
Radionuclides Addressed
137Cs
90Sr
226Ra
Pu
"Tc
U
Th
Other
General
134Cs
60Co
General
General
Technology Type
Phytotechnology
Phytotechnology
Phytotechnology
Phytotechnology
Phytotechnology
Phytotechnology
Other
Other
Phytotechnology
Phytotechnology
Phytotechnology
Phytotechnology
Document Title
Phytoremediation of toxic elemental
and organic pollutants
Phytoremediation of uranium-
contaminated soils: role of organic
acids in triggering uranium
hyperaccumulation in plants
Plant uptake of 134Cs in relation to
soil properties and time
Plant uptake of radionuclides in
lysimeter experiments
Proceedings of the Chernobyl
Phytoremediation and biomass
energy conversion
Rhizopheric mobilization of
radiocesium in soils
Role for lichen melanins in uranium
remediation
The role of fungi in the transfer and
cycling of radionuclides in forest
ecosystems
Selection of plants for
Phytoremediation of soils
contaminated with radionuclides
Sequestration of 137Cs and 90Sr from
soil by seedlings of Eucalyptus
tereticornis
Soil availability, plant uptake and
soil to plant transfer of "Tc - a
review
Soil contamination with
radionuclides and potential
remediation
Doc.
Number
20
34
12
30
33
19
88
84
40
43
1
24
Page
30
35
27
34
35
29
54
53
37
38
23
31
15
-------
Cross Reference Matrix
Media Addressed
Soil
Ground-
water
Surface
Water
Radionuclides Addressed
137Cs
90Sr
226Ra
Pu
"Tc
U
Th
Other
General
General
General
General
General
Technology Type
Phytotechnology
Other
Phytotechnology
Bioremediation
Phytotechnology
Phytotechnology
Other
Other
Bioremediation
Bioremediation
Bioremediation
Document Title
Soil organic horizons as a major
source for radiocesium biorecycling
in forest ecosystems
Soil-fungi radiocesium transfers in
forest ecosystems
Soil-to-plant transfer of 226Ra in a
marsh area: modelling application
Solubilization of plutonium hydrous
oxide by iron-reducing bacteria
The true distribution and
accumulation of radiocaesium in
stem of Scots Pine (Pinus sylvestris
L.)
Uptake of cesium- 137 and strontium-
90 from contaminated soil by three
plant species; application to
phytoremediation
Natural attenuation of metals and
radionuclides
Assessment of bioremediation
technologies: focus on technologies
suitable for field-level
demonstrations and applicable to
DOD contaminants
Bioremediation of uranium
contaminated soils and wastes
Developments in terrestrial bacterial
remediation of metals
Direct and Fe(II)-mediated reduction
of technetiumby Fe (III) -reducing
bacteria
Doc.
Number
10
99
31
83
16
9
89
95
75
73
64
Page
26
57
34
51
28
26
24
56
49
48
45
16
-------
Cross Reference Matrix
Media Addressed
Soil
Ground-
water
Surface
Water
Radionuclides Addressed
137Cs
90Sr
226Ra
Pu
"Tc
U
Th
Other
General
General
General
General
General
General
Technology Type
Other
Phytotechnology
Bioremediation
Bioremediation
Bioremediation
Bioremediation
Bioremediation
Bioremediation
Bioremediation
Bioremediation
Bioremediation
Document Title
Fungal processes for bioremediation
of toxic metal and radionuclide
pollution
Metal hyperaccumulation in plants
biodiversity prospecting for
phytoremediation technology
A procedure for quantitation of total
oxidized uranium for bioremediation
studies
Radionuclide contamination:
nanometre-size products of uranium
bioreduction
Radionuclide immobilization by the
formation of crystalline Fe
compounds resulting from the bio-
oxidation of Fe(II) by Dechlorosoma
suillum
Remediation of soils and wastes
contaminated with uranium and toxic
metals
Bacterial-metal/radionuclide
interaction
Influence of microorganisms on the
environmental fate of radionuclides
Metals and radionuclide
bioremediation: issues,
considerations and potentials
Microbial detoxification of metals
and radionuclides
Microbial interactions with
metals/radionuclides: the basis of
bioremediation
Doc.
Number
86
5
48
59
55
76
72
81
60
62
57
Page
53
24
39
44
43
49
48
51
44
45
44
17
-------
Cross Reference Matrix
Media Addressed
Soil
Ground-
water
Surface
Water
Radionuclides Addressed
137Cs
90Sr
226Ra
Pu
"Tc
U
Th
Other
General
General
General
Multiple
3H
60Co
Technology Type
Bioremediation
Phytotechnology
Bioremediation
Bioremediation
Bioremediation
Phytotechnology
Phytotechnology
Bioremediation
Bioremediation
Bioremediation
Bioremediation
Document Title
Microbial transformations of
uranium and environmental
restoration through bioremediation
Phytoremediation of metals,
metalloids, and radionuclides
Reduction of Fe(III), Cr(VI), U(VI),
and Tc(VII) by Deinococcus
radiodurans Rl
Report on 1st Euroconference on
bacterial-metal/radionuclide
interactions: basic research and
bioremediation
The role of microorganisms in
biosorption of toxic metals and
radionuclides
Trends in phytoremediation of
radionuclides
The use of plants for the treatment of
radionuclides
Biodegradation and speciation of
PuEDTA by bacterium BNCI
Effect of electron donor and solution
chemistry on products of
dissimilatory reduction of technetium
by Shewanella putrefaciens
Microbially mediated redox
processes in natural analogues for
radioactive waste
Microorganisms associated with
uranium bioremediation in a high-
salinity subsurface sediment
Doc.
Number
56
13
63
71
82
2
21
47
68
58
50
Page
43
27
45
48
51
23
30
39
47
44
40
18
-------
Cross Reference Matrix
Media Addressed
Soil
Ground-
water
Surface
Water
Radionuclides Addressed
137Cs
90Sr
226Ra
Pu
"Tc
U
Th
Other
Np
La
Technology Type
Bioremediation
Bioremediation
Bioremediation
Bioremediation
Bioremediation
Phytotechnology
Phytotechnology
Bioremediation
Other
Document Title
Potential for in situ bioremediation of
low-pH, high-nitrate uranium-
contaminated groundwater
Simulating bioremediation of
uranium-contaminated aquifiers;
uncertainty assessment of model
parameters
Remediation of metal contaminants
by microbially mediated calcite
precipitation
Stimulating the in situ activity of
Geobacter species to remove uranium
from the groundwater of a uranium-
contaminated aquifer
Biological reduction and removal of
Np(V) by two microorganisms
Removal of uranium from water
using terrestrial plants
Accumulation of 99Tc in duckweed
Lemna minor L. as function of
growth rate and 99Tc concentration
Bioaccumulation of lanthanum,
uranium and thorium, and use of a
model system to develop a method
for the biologically -mediated
removal of plutonium from solution
Bioaccumulation of metals by
lichens: Uptake of aqueous uranium
by Peltigera membranacea as a
function of time and pH
Doc.
Number
52
54
67
51
65
38
18
79
87
Page
41
42
41
40
46
36
29
50
53
19
-------
Cross Reference Matrix
Media Addressed
Soil
Ground-
water
Surface
Water
Radionuclides Addressed
137Cs
90Sr
226Ra
Pu
"Tc
U
Th
Other
General
Multiple
60Co
General
General
Technology Type
Other
Other
Bioremediation
Bioremediation
Bioremediation
Bioremediation
Other
Other
Bioremediation
Document Title
Bioremediation of aqueous pollutants
using biomass embedded in
hydrophilic foam
Biosorption of radionuclides by
fungal biomass
Continuous radionuclide recovery
from wastewater using magnetotactic
bacteria
Effect of microbes on the uptake of
60Co,85Sr,95Tc,131Iand134Csby
decomposing elm leaves in aquatic
microcosms
Enzymatically mediated
bioprecipitation of uranium by
Citrobacter sp.: a concerted role for
exocellular lipopolysaccharide and
associated phosphatase in biomineral
formation
In-situ bioreduction of technetium
and uranium in a nitrate-
contaminated aquifier
Interactions of microalgae and
cyanobacteria with toxic metals and
radionuclides
Metal accumulation by fungi:
applications in environmental
biotechnology
Metal immobilisation by biofilms:
mechanisms and analytical tools
Doc.
Number
94
101
74
80
66
46
96
97
53
Page
55
58
48
50
46
39
56
57
42
20
-------
Cross Reference Matrix
Media Addressed
Soil
Ground-
water
Surface
Water
Radionuclides Addressed
137Cs
90Sr
226Ra
Pu
"Tc
U
Th
Other
Np
General
241 Am, 95Zr,
144Ce,
152+154Eu
Technology Type
Bioremediation
Bioremediation
Bioremediation
Bioremediation
Other
Other
Phytotechnology
Document Title
Microbial reduction of technetiumby
Escherichia coli and Desulfovibrio
desulfuricans: enhancement via the
use of high-activity strains and effect
of process parameters
Microbially -enhanced chemisorption
of heavy metals: A method for the
bioremediation of solutions
containing long-lived isotopes of
neptunium and plutonium
Reduction of technetium by
Desulfovibrio desulfuricans:
biocatalyst characterization and use
in flowthrough bioreactor
Removal and recovery of metals
from a coal pile runoff
Removal of thorium from simulated
acid process streams by fungal
biomass: potential for thorium
desorption and reuse of biomass and
desorbent
Sorption of plutonium, americium
and fission products from
reprocessing effluents using
Rhizopus arrhizus
Suspended particle adhesion on
aquatic plant surfaces: implications
for 137Cs and 133Cs uptake rates and
water-to-plant concentration ratios
Doc.
Number
70
78
69
49
98
85
15
Page
48
50
47
40
57
53
28
21
-------
Cross Reference Matrix
Media Addressed
Soil
Ground-
water
Surface
Water
Radionuclides Addressed
137Cs
90Sr
226Ra
Pu
"Tc
U
Th
Other
Technology Type
Bioremediation
Phytotechnology
Document Title
Technetium reduction and
precipitation by sulfate-reducing
bacteria
Uptake, biotransformation, and
elimination of 99Tc in duckweed
Doc.
Number
77
3
Page
49
23
22
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Radionuclide Biological
Remediation Resource Guide
Phytotechnology
Articles 1-3
(1) Bennett, R and N Willey. 2003. Soil availability, plant
uptake and soil to plant transfer of "Tc- a review. Jour-
nal of Environmental Radioactivity 65: 215-231. *
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Phyto.
99Tc
90Sr
*
other
Media: Soil
Abstract: The fission yield of "Tc from 239Pu and 235U is simi-
lar to that of 137Cs or 90Sr and it is therefore an important
component of nuclear weapons fall-out, nuclear waste and
releases from nuclear facilities. There is particular current in-
terest in "Tc transfer from soil to plants for: (a) environmen-
tal impact assessments for terrestrial nuclear waste reposito-
ries, and (b) assessments of the potential for phytoextraction
of radionuclides from contaminated effluent and soil. Vascu-
lar plants have a high "Tc uptake capacity, a strong tendency
to transport it to shoot material and accumulate it in vegeta-
tive rather than reproductive structures. The mechanisms that
control "Tc entry to plants have not been identified and there
has been little discussion of the potential for phytoextraction
of "Tc contaminated effluents or soil. Here we review soil
availability, plant uptake mechanisms and soil to plant trans-
fer of "Tc in the light of recent advances in soil science, plant
molecular biology and phytoextraction technologies. We con-
clude that "Tc might not be highly available in the long term
from up to 50% of soils worldwide, and that no single mecha-
nism that might be easily targeted by recombinant DNA tech-
nologies controls "Tc uptake by plants. Overall, we suggest
that Tc might be less available in terrestrial ecosystems than is
often assumed but that nevertheless the potential of
phytoextraction as a decontamination strategy is probably
greater for "Tc than for any other nuclide of radioecological
interest.
Website: http://www.sciencedirect.com/science/journal/
0265931X
(2) Dushenkov, S. 2003. Trends in phytoremediation
of radionuclides. Plant and Soil 249:167-175. *
Radionuclides addressed:
226Ra "A"
U *
Technology:
Pu 1
137Cs *
t
Th W
Phyto.
"Tc
other
90Sr *
*
Multiple
Media: Soil, GW, SW
Abstract: Phytoremediation, a novel plant-based remediation
technology, is applied to a variety of radionuclide-contami-
nated sites all over the world. Phytoremediation is defined as
the use of green plants to remove pollutants from the envi-
ronment or to render them harmless. Current status of sev-
eral subsets of phytoremediation of radionuclides is discussed:
(a) phytoextraction, in which high biomass radionuclide-ac-
cumulating plants and appropriate soil amendments are used
to transport and concentrate radionuclides from the soil into
the above-ground shoots, which are harvested with conven-
tional agricultural methods, (b) rhizofiltration, in which plant
roots are used to precipitate and concentrate radionuclides
from polluted effluents, (c) phytovolatilization, in which plants
extract volatile radionuclides from soil and volatilize them
from the foliage and (d) phytostabilization, in which plants
stabilize radionuclides in soils, thus rendering them harmless.
It is shown that phytoremediation is a fast developing field
and the phytoremediation of radionuclides might soon be-
come an integral part of the environment management and
risk reduction process.
Website: http://www.kluweronline.com/issn/0032-079X/
contents
(3) Hattink, J, AV Harms and JJM de Goeij. 2003. Up-
take, biotransformation, and elimination of "Tc in duck-
weed. The Science of the Total Environment 312: 59-
65.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Phyto.
"Tc
90Sr
*
other
Media: SW
Abstract: Aquatic plants may play an important role in the
environmental fate of the long-lived radioactive waste prod-
uct "Tc. Aquatic plants show a strong accumulation and re-
tention of Tc, even after they have died. This study focuses
on possible bio-organic Tc compounds formed in the water
dwelling plant duckweed to possibly explain the accumula-
tion and retention. Moreover, a change in chemical specia-
tion often implies a different fate and behaviour in the bio-
sphere. A mild separation technique was used to distinguish
between reduced Tc species and TcO4~. Accumulation experi-
ments suggested that reduction of TcVIIO4~ and subsequent
complexation are responsible for the accumulation of Tc in
duckweed. A steady state concentration of TcO4~ in duck-
weed was reached within 24 h, but the total concentration of
Tc increased continuously. Only a small part (at most 5%) of
Tc was present as TcO4~. Elimination experiments showed that
TcO4~ is the only mobile species. Other Tc species are respon-
sible for the retention of Tc in duckweed. It is known that
these species are not bio-available and only slowly re-oxidise
to pertechnetate, resulting in a longer residence time in eco-
systems.
Website: http://www.sciencedirect.com/science/journal/
00489697
23
*-
Review Article
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Radionuclide Biological
Remediation Resource Guide
Phytotechnology
Articles 4-5
(4) Kozak, JA, HW Reeves and BA Lewis. 2003. Mod-
eling radium and radon transport through soil and veg-
etation. Contaminant Hydrology 66: 179-200.
Radionuclides addressed:
226Ra *
U
137Cs
Pu
Th
Technology: Phyto.
"Tc
90Sr
other
Media: Soil
Abstract: A one-dimensional flow and transport model was
developed to describe the movement of two fluid phases, gas
and water, within a porous medium and the transport of ^Ra
and ^Rn within and between these two phases. Included in
this model is the vegetative uptake of water and aqueous ^Ra
and 222Rn that can be extracted from the soil via the transpira-
tion stream. The mathematical model is formulated through
a set of phase balance equations and a set of species balance
equations. Mass exchange, sink terms and the dependence of
physical properties upon phase composition couple the two
sets of equations. Numerical solution of each set, with itera-
tion between the sets, is carried out leading to a set-iterative
compositional model. The PetrovGalerkin finite element
approach is used to allow for upstream weighting if required
for a given simulation. Mass lumping improves solution con-
vergence and stability behavior. The resulting numerical model
was applied to four problems and was found to produce ac-
curate, mass conservative solutions when compared to pub-
lished experimental and numerical results and theoretical col-
umn experiments. Preliminary results suggest that the model
can be used as an investigative tool to determine the feasibil-
ity of phytoremediating radium and radon-contaminated soil.
Website: http://www.sciencedirect.com/science/journal/
01697722
(5) Prasad, MNV and HM de Oliveira Freitas. 2003.
Metal hyperaccumulation in plantsbiodiversity pros-
pecting for phytoremediation technology. Electronic
Journal of Biotechnology 6. *
Radionuclides addressed:
226Ra
U *
137Cs *
Pu
Th
Technology: Phyto.
99Tc
90Sr *
other
Media: Soil, SW
Abstract: The importance of biodiversity (below and above
ground) is increasingly considered for the cleanup of the metal
contaminated and polluted ecosystems. This subject is emerg-
ing as a cutting edge area of research gaining commercial sig-
nificance in the contemporary field of environmental bio-
technology. Several microbes, including mycorrhizal and non-
mycorrhizal fungi, agricultural and vegetable crops, ornamen-
tals, and wild metal hyperaccumulating plants are being tested
both in lab and field conditions for decontaminating the met-
alliferous substrates in the environment. As on todate about
400 plants that hyperaccumulate metals are reported. The
families dominating these members are Asteraceae,
Brassicaceae, Caryophyllaceae, Cyperaceae, Cunouniaceae,
Fabaceae, Flacourtiaceae, Lamiaceae, Poaceae, Violaceae, and
Euphobiaceae. Brassicaceae had the largest number of taxa
viz. 11 genera and 87 species. Different genera of Brassicaceae
are known to accumulate metals. Ni hyperaccumulation is
reported in 7 genera and 72 species and Zn in 3 genera and
20 species. Thlaspi species are known to hyperaccumulate
more than one metal i.e. T caerulescence = Cd, Ni. Pb, and
Zn; T. goesingense = Ni and Zn and T. ochroleucum = Ni
and Zn and T. rotundifolium = Ni, Pb and Zn. Plants that
hyperaccumulate metals have tremendous potential for appli-
cation in remediation of metals in the environment. Signifi-
cant progress in phytoremediation has been made with met-
als and radionuclides. This process involves rising of plants
hydroponically and transplanting them into metal-polluted
waters where plants absorb and concentrate the metals in their
roots and shoots. As they become saturated with the metal
contaminants, roots or whole plants are harvested for dis-
posal. Most researchers believe that plants for
phytoremediation should accumulate metals only in the roots.
Several aquatic species have the ability to remove heavy met-
als from water, viz., water hyacinth (Eichhornia crassipes
(Mart.) Solms); pennywort (Hydrocotyle umbellata L.) and
duckweed (Lemna minor L.). The roots of Indian mustard
are effective in the removal of Cd, Cr, Cu, Ni, Pb, and Zn and
sunflower removes Pb, U, 137Cs, and 90Sr from hydroponic
solutions. Aquatic plants in freshwater, marine and estuarine
systems act as receptacle for several metals.
Hyperaccumulators accumulate appreciable quantities of
metal in their tissue regardless of the concentration of metal
in the soil, as long as the metal in question is present. The
phytoextraction process involves the use of plants to facili-
tate the removal of metal contaminants from a soil matrix. In
practice, metal-accumulating plants are seeded or transplanted
into metal-polluted soil and are cultivated using established
agricultural practices. If metal availability in the soil is not
adequate for sufficient plant uptake, chelates or acidifying
agents would be applied to liberate them into the soil solu-
tion. Use of soil amendments such as synthetics (ammonium
thiocyanate) and natural zeolites have yielded promising re-
sults. Synthetic cross-linked polyacrylates, hydrogels have pro-
tected plant roots from heavy metals toxicity and prevented
the entry of toxic metals into roots. After sufficient plant
growth and metal accumulation, the above-ground portions
of the plant are harvested and removed, resulting the perma-
nent removal of metals from the site. Soil metals should also
24
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Review Article
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Radionuclide Biological
Remediation Resource Guide
Phytotechnology
Articles 6-7
be bioavailable, or subject to absorption by plant roots. Chemi-
cals that are suggested for this purpose include various acidi-
fying agents, fertilizer salts and chelatingmaterials. The reten-
tion of metals to soil organic matter is also weaker at low pH,
resulting in more available metal in the soil solution for root
absorption. It is suggested that the phytoextraction process is
enhanced when metal availability to plant roots is facilitated
through the addition of acidifying agents to the soil. Chelates
are used to enhance the phytoextraction of a number of metal
contaminants including Cd, Cu, Ni, Pb, and Zn Researchers
initially applied hyperaccumulators to clean metal polluted soils.
Several researchers have screened fast-growing, high-biom-
ass-accumulating plants, including agronomic crops, for their
ability to tolerate and accumulate metals in their shoots. Genes
responsible for metal hyperaccumulation in plant tissues have
been identified and cloned. Glutathione and organic acids
metabolism plays a key role in metal tolerance in plants. Glu-
tathione is ubiquitous component cells from bacteria to plants
and animals. In phytoremediation of metals in the environ-
ment, organic acids play a major role in metal tolerance. Or-
ganic acids acids form complexes with metals, a process of
metal detoxification. Genetic strategies and transgenic plant
and microbe production and field trials will fetch
phytoremediaition field applications.The importance of
biodiversity and biotechnology to remediate potentially toxic
metals are discussed in this paper. Brassicaceae amenable to
biotechnological improvement and phytoremediation hype are
highlighted.
Website: http://www.ejbiotechnology.info
(6) Albrecht, A. 2002. Incorporating soil structure and
root distribution into plant uptake models for radionu-
clides: toward a more physically based transfer model.
Journal of Environmental Radioactivity 59: 329-350.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Phyto.
"Tc
other
90Sr
65Zn, 54Mn
Media: Soil
Abstract: Most biosphere and contamination assessment
models are based on uniform soil conditions, since single co-
efficients are used to describe the transfer of contaminants to
the plant. Indeed, physical and chemical characteristics and
root distribution are highly variable in the soil profile. These
parameters have to be considered in the formulation of a more
realistic soilplant transfer model for naturally structured soils.
The impact of monolith soil structure (repacked and struc-
tured) on Zn and Mn uptake by wheat was studied in a con-
trolled tracer application (dye and radioactive) experiment.
We used Brilliant Blue and Sulforhodamine B to dye flow lines
and 65Zn and 54Mn to trace soil distribution and plant uptake
of surface-applied particle-reactive contaminants. Spatial varia-
tion of the soil water content during irrigation and plant
growth informs indirectly about tracer and root location in
the soil profile. In the structured monolith, a till pan at a depth
of 30 cm limited vertical water flow and root penetration into
deeper soil layers and restricted tracers to the upper third of
the monolith. In the repacked monolith, roots were observed
at all depths and fingering flow allowed for the fast appear-
ance of all tracers in the outflow. These differences between
the two monoliths are reflected by significantly higher 54Mn
and S5Zn uptake in wheat grown on the structured monolith.
The higher uptake of Mn can be modelled on the basis of
radionuclide and root distribution as a function of depth and
using a combination of preferential flow and rooting. The
considerably higher uptake of Zn requires transfer factors
which account for variable biochemical uptake as a function
of location.
Website: http://www.sciencedirect.com/science/journal/
0265931X
(7) Ehlken, S and G Kirchner. 2002. Environmental
processes affecting plant root uptake of radioactive
trace elements and variability of transfer factor data: a
review. Journal of Environmental Radioactivity 58: 97-
112.*
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Phyto.
"Tc
90Sr *
other
Media: Soil
Abstract: Soil-to-plant transfer factors are commonly used
to estimate the food chain transfer of radionuclides. Their
definition assumes that the concentration of a radionuclide
in a plant relates linearly solely to its average concentration in
the rooting zone of the soil. However, the large range of trans-
fer factors reported in the literature shows that the concen-
tration of a radionuclide in a soil is not the only factor influ-
encing its uptake by a plant. With emphasis on radiocesium
and -strontium, this paper reviews the effects of competition
with major ions present in the soil-plant system, the effects
of rhizosphere processes and soil micro-organisms on
bio availability, the factors influencing transport to and uptake
by roots and the processes affecting long-term uptake rates.
Attention is given to summarizing the results of recent novel
electrophysiological and genetic techniques which provide a
25
Review Article
-------
Radionuclide Biological
Remediation Resource Guide
Phytotechnology
Articles 8-10
physiologically based understanding of the processes involved
in the uptake and translocation of radiocesium and -stron-
tium by plants.
Website: http://www.sciencedirect.com/science/journal/
0265931X
(8) Frissel, MJ, DL Deb, M Fathony, YM Lin, AS Mollah,
NT Ngo, L Othman, WL Robison, V Skarlou-Alexiou,
S Topcuoglu, JR Twining, S Uchida and MA
Wasserman. 2002. Generic values for soil-to-plant
transfer factors of radiocesium. Journal of Environmen-
tal Radioactivity 5&: 113-128.
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Phyto.
99Tc
90Sr
other
Media: Soil
Abstract: This paper describes a generic system for 137Cs,
mainly based on a reference soil-to-plant transfer factor which
depends solely on soil properties such as nutrient status, ex-
changeable K-content, pH and moisture content. Crops are
divided into crop groups, cereals serving as reference group.
The transfer of other crop groups can be calculated by multi-
plying data for cereals by a conversion factor. Existing data
present in the IUR (International Union of Radioecologists)
databank and in large part the work of a FAO (Food and
Agriculture Organisation)/IAEA(International Atomic En-
ergy Agency)/IUR project on tropical systems provided the
basis for the derivation of the conversion factors and refer-
ence values.
Website: http://www.sciencedirect.com/science/journal/
0265931X
(9) Fuhrmann, M, MM Lasat, SD Ebbs, LV Kochian
and J Cornish. 2002. Uptake of cesium-137 and stron-
tium-90 from contaminated soil by three plant species;
application to phytoremediation. Journal of Environ-
mental Quality31: 904-909.
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Phyto.
"Tc
9°Sr *
other
Media: Soil
Abstract: A field test was conducted to determine the ability
of three plant species to extract 137Cs and 90Sr from contami-
nated soil. Redroot pigweed (Amoranthus retroflexus L.), Indian
mustard \Brassicajuncea (L.) Czern.], and teparybean (Phaseolus
acutifolius A. Gray) were planted in a series of spatially ran-
domized cells in soil that was contaminated in the 1950s and
1960s. We examined the potential for phytoextraction of 90Sr
and 137Cs by these three species. Concentration ratios (CR) for
137Cs for redroot pigweed, Indian mustard, and tepary bean
were 2.58, 0.46, and 0.17, respectively. For 90Sr they were sub-
stantially higher: 6.5, 8.2, and 15.2, respectively. The greatest
accumulation of both radionuclides was obtained with redroot
pigweed, even though its CR for 90Sr was the lowest, because
of its relatively large biomass. There was a linear relationship
between the 137Cs concentration in plants and its concentra-
tion in soil only for redroot pigweed. Uptake of 90Sr exhibits
no relationship to 90Sr concentrations in the soil. Estimates of
time required for removal of 50% of the two contaminants,
assuming two crops of redroot pigweed per year, are 7 yr for
90Srandl8yrfor137Cs.
Website: http://jeq.scijournals.org
(10) Kruyts, N and B Delvaux. 2002. Soil organic hori-
zons as a major source for radiocesium biorecycling
in forest ecosystems. Journal of Environmental Ra-
dioactivity 58: 175-190.
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Phyto.
»Tc
90Sr
other
Media: Soil
Abstract: Here we review some of the main processes and
key parameters affecting the mobility of radiocesium in soils
of semi-natural areas. We further illustrate them in a collec-
tion of soil surface horizons which largely differ in their or-
ganic matter contents. In soils, specific retention of
radiocesium occurs in a very small number of sorbing sites,
which are the frayed edge sites (FES) born out of weathered
micaceous minerals. The FES abundance directly governs the
mobility of trace Cs in the rhizosphere and thus its transfer
from soil to plant. Here, we show that the accumulation of
organic matter in topsoils can exert a dilution of FES-bearing
minerals in the thick humus of some forest soils. Consequently,
such accumulation significantly contributes to increasing 137Cs
soil-to-plant transfer. Potassium depletion and extensive ex-
ploration of the organic horizons by plant roots can further
enhance the contamination hazard. As humus thickness de-
pends on both ecological conditions and forest management,
our observations support the following ideas: (1) forest eco-
systems can be classified according to their sensitivity to
radiocesium bio-recycling, (2) specific forest management
26
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Radionuclide Biological
Remediation Resource Guide
could be searched to decrease such bio-recycling.
Website: http://www.sciencedirect.com/science/journal/
0265931X
(11) Malek, MA, TG Hinton and SB Webb. 2002. A com-
parison of90Srand 137Cs uptake in plants via three path-
ways at two Chernobyl-contaminated sites. Journal of
Environmental Radioactivity 58:129-141.
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Phyto.
99Tc
90Sr *
other
Media: Soil
Abstract: Foliar absorption of resuspended 90Sr, root uptake
and contamination adhering to leaf surfaces (i.e. soil loading)
were compared at two Chernobyl-contaminated sites,
Chistogalovka and Polesskoye. Although foliar absorption of
resuspended 90Sr was quantifiable, its contribution amounted
to less than 10% of the plants' total, above-ground contami-
nation. Root uptake was 200 times greater than foliar absorp-
tion at the near-field site of Chistogalovka and eight times
greater at Polesskoye, where the fallout consisted of the more
soluble condensation-type, rather than fuel particles.
Strontium's bioavailability exceeded that of 137Cs (analyzed in
the same plants) by orders of magnitude when compared us-
ing concentration ratios. Simplistic, cumulative effective dose
calculations for humans ingesting 90Sr- and 137Cs-contaminated
plants revealed that the dose at Chistogalovka was greater from
90Sr (185 mSv vs. 3 mSv from 137Cs), while at Polesskoye the
dose from 137Cs (66 mSv) was 30 times greater than from 90Sr
(2 mSv).
Website: http://www.sciencedirect.com/science/journal/
0265931X
(12) Massas, I, VSkarlou and C Haidouti. 2002. Plant
uptake of 134Cs in relation to soil properties and time.
Journal of Environmental Radioactivity 59: 245-255.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Phyto.
"Tc
other
90Sr
134Cs
Media: Soil
Abstract: 134Cs uptake by sunflower and soybean plants grown
on seven different soils and its relation to soil properties were
studied in a greenhouse pot experiment. Soil in each pot was
Phytotechnology
Articles 11-13
contaminated by dripping the 134Cs in layers, and sunflower
and soybean plants were grown for three and two successive
periods, respectively. 134Cs plant uptake was expressed as the
transfer factor (TF) (Bq kg4 plant/Bq kg4 soil) and as the
daily plant uptake (flux) (Bq pot4 day4) taking into account
biomass production and growth time. For the studied soils
and for both plants, no consistent trend of TFs with time was
observed. The use of fluxes, in general, provided less vari-
able results than TFs and stronger functional relationships. A
negative power functional relationship between exchangeable
potassium plus ammonium cations expressed as a percentage
of cation exchange capacity of each soil and 134Cs fluxes was
found for the sunflower plants. A similar but weaker relation-
ship was observed for soybean plants. The significant corre-
lation between sunflower and soybean TFs and fluxes, as well
as the almost identical highest/lowest 134Cs flux ratios, in the
studied soils, indicated a similar effect of soil characteristics
on 134Cs uptake by both plants. In all the studied soils, sun-
flower 134Cs TFs and fluxes were significantly higher than the
respective soybean values, while no significant difference was
observed in potassium content and daily potassium plant up-
take (flux) of the two plants.
Website: http://www.sciencedirect.com/science/journal/
0265931X
(13) McGrath, SP, J Zhao and E Lombi. 2002.
Phytoremediation of metals, metalloids, and radionu-
clides. Advances in Agronomy 75: 1-56. *
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Phyto.
"Tc
other
90Sr
General
Media: Soil, GW, SW
Abstract: Phytoremediation is a developing technology that
can potentially address the problems of contaminated agri-
cultural land or more intensely polluted areas affected by ur-
ban or industrial activities. Three main strategies currently
exist to phytoextract inorganic substances from soils using
plants:(1) use of natural hyperaccumulators; (2) enhancement
of element uptake of high biomass species by chemical addi-
tions to soil and plants; and (3) phytovolatilization of ele-
ments, which often involves alteration of their chemical form
within the plant prior to volatilization to the atmosphere.
Concentrating on the techniques that potentially remove in-
organic pollutants such as Ni, Zn, Cd, Cu, Co, Pb, Hg, As, Se,
and radionuclides, we review the progress in the understand-
ing of the processes involved and the development of the
technology. This includes the advances made in the study of
27
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Radionuclide Biological
Remediation Resource Guide
Phytotechnology
Articles 14-16
the physiology and biochemistry of metal uptake, transport
and sequestration by hyperaccumulator plants, as well as the
investigation of the processes occurring in soil and plant sys-
tems subject to the chemical enhancement approach. Enough
work has been carried out in the last decade to allow some
assessment of the situations and elements in which
phytoremediation is likely to be most successful. However,
we also identify where there is lack of knowledge. Finally, the
likely future directions for research and application are dis-
cussed.
Website: http://www.sciencedirect.com/science/
bookseries/00652113
(14) Rigol, A, M Vidal and G Rauret. 2002. An over-
view of the effect of organic matter on soil-
radiocaesium interaction: implications in root uptake.
Journal of Environmental Radioactivity 58: 191-216.
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Phyto.
99Tc
90Sr
other
Media: Soil
Abstract: This paper aims to give an overview of the effect
of organic matter on soil-radiocaesium interaction and its
implications on soil-to-plant transfer. Studies carried out af-
ter the Chernobyl accident have shown that high 137Cs soil-to-
plant transfer persists in organic soils over years. In most of
these soils, the specific sites in clays control radiocaesium ad-
sorption, organic compounds having an indirect effect. Only
in organic soils with more than 95% of organic matter con-
tent and negligible clay content does adsorption occur mostly
on non-specific sites. After a contamination event, two main
factors account for the high transfer: the low solid-liquid dis-
tribution coefficient, which is due to the low clay content and
high NH4+ concentration in the soil solution, and the low K+
availability, which enhances root uptake. The estimation of
the reversibly adsorbed fraction, by means of desorption pro-
tocols, agrees with the former conclusions, since it cannot be
correlated with the organic matter content and shows the lack
of specificity of the adsorption in the organic phase. More-
over, the time-dependent pattern of the exchangeable frac-
tion is related to soil-plant transfer dynamics.
Website: http://www.sciencedirect.com/science/journal/
0265931X
(15) Sansone, U, M Belli, Z Jeran, VV Kanivets, J Radojko,
M Riccardi and OV Voitsekhovitch. 2002. Suspended par-
ticle adhesion on aquatic plant surfaces: implications for
137Cs and 133Cs uptake rates and water-to-plant concentra-
tion ratios. Journal of Environmental Radioactivity 59'. 257-
271.
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Phyto.
99Tc
90Sr
other
Media: SW
Abstract: Suspended particle adhesion on aquatic biota can
significantly increase the apparent concentration of radionu-
clides above their endogenous value, leading to an overesti-
mation of the uptake rate and concentration ratios. This study
is an attempt to assess quantitatively the importance of sus-
pended particle adhesion on periphyton samples (biological
material coating submerged surfaces). The concentrations of
137Cs and stable Cs (133Cs) in periphyton, suspended particles
and filtered water were measured to determine the net water-
to-periphyton concentration ratios for 137Cs and stable Cs. The
net amount of 133Cs (or 137Cs) taken up by periphyton was
calculated by subtracting from the total amount of 133Cs (or
137Cs) on the collected material (periphyton+inorganic par-
ticles), the 133Cs (or 137Cs) due to the inorganic particles ad-
hering to periphyton. The mass of suspended particles adher-
ing to the periphyton surface was calculated using scandium
as an indicator of the mineral fraction of the suspended par-
ticles. The relationship between the concentration ratios for
137Cs and stable Cs and suspended particle adhesion on per-
iphyton external surfaces is discussed.
Website: http://www.sciencedirect.com/science/journal/
0265931X
(16) Thiry, Y, F Goor and T Riesen. 2002. The true dis-
tribution and accumulation of radiocaesium in stem of
Scots Pine (Pinus sylvestris L). Journal of Environ-
mental Radioactivity 58: 243-259.
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Phyto.
99Tc
90Sr
other
Media: Soil
Abstract: The radial and vertical distributions of
radiocaesium, potassium and calcium were determined in two
Scots pine stands (17 and 58 yr old) similarly affected by the
Chernobyl fallout. For both age classes, concentrations are
always the lowest in the stemwood, highest in the inner bark
and intermediary levels were observed for the outer bark. Due
to the cumulative character of its biomass, however, stemwood
is a long-term major reservoir of 137Cs. With tree develop-
ment, changes in the 137Cs radial distribution are well described
by variations in the sap ascent pattern and reveal an impor-
tant transfer between tree rings. It is shown that, both the
28
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Radionuclide Biological
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Phytotechnology
Articles 17-19
biomass evolution and knowledge of the evolution of the
137Cs radial gradient are important to predicting 137Cs accu-
mulation in wood with time. According to the common trans-
fer factor (TF) approach, one would expect a decrease in
radiocaesium accumulation with time (from 0.0047+0.0013
to 0.0035±0.0008 m2/kg for the 17 and 58 yr old trees, re-
spectively). With the wood immobilisation potential (WIP)
approach, it was, however, clearly shown that additional an-
nual uptake was highest for the older stand (3.12+0.23 Bq/
cm3 yr for the 58-year-old stand compared to 1.99+0.30 Bq/
cm3 yr for the younger stand). Following the WIP approach,
it was moreover possible to distinguish between the 137Cs in-
corporated via the root uptake process and a possible lasting
effect of interception. It is shown that, whereas for the younger
stand (5 yr old at the time of the accident) root uptake con-
tributed exclusively to the wood contamination, the former
process explained only 48% of the measured total 137Cs con-
tent in the wood of the older tree.
Website: http://www.sciencedirect.com/science/journal/
0265931X
(17) Entry, JA, LS Watrud and M Reeves. 2001. Influ-
ence of organic amendments on the accumulation of
137Cs and 90Sr from contaminated soil by three grass
species. Water, Air and Soil Pollution 126: 385-398.
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Phyto.
"Tc
90Sr *
other
Media: Soil
Abstract: Bahia grass (Paspalum notatum), Johnson grass (Sor-
ghum halpense) and switchgrass (Panicum virginatutii) were com-
pared for their ability to accumulate 137Cs and 90Sr from three
different contaminated soils in the presence and absence of
either sphagnum peat or poultry litter amendments. Above-
ground plant biomass did not differ between plants that were
not exposed to these radionuclides and those that were ex-
posed to soil containing 137Cs or 90Sr. After three harvests,
bahia, Johnson and switchgrass plants accumulated from 17.2
to 67.3% of the 137Cs and from 25.1 to 61.7% of the 90Sr
added to the soil. Poultry litter and peat moss amendments
increased aboveground plant biomass, activity of 137Cs or 90Sr
in plant tissue, % accumulation of 137Cs or 90Sr from soil and
the plant bioconcentration ratio at each harvest compared to
the control (no amendment) treatment. The greatest increases
in plant biomass, and radionuclide accumulation were ob-
served with poultry litter for each of the three grass species.
Johnson grass had greater aboveground plant biomass, activ-
ity of 137Cs and 90Sr in plant tissue, % accumulation of 137Cs
or 90Sr from soil and bioconcentration ratio in each soil amend-
ment, at each harvest compared to bahia and switchgrass. The
greatest accumulation of 137Cs and 90Sr was measured in
Johnson grass grown in soil that was amended with poultry
litter. These results suggest that plant species selection and
agronomic practices may need to be considered to maximize
phytoremediation of radionuclide contaminated soils.
Website: www.kluweronline.com/issn/0049-6979/contents
(18) Hattink, J and HT Wolterbeek. 2001. Accumula-
tion of "Tc in duckweed Lemna minorL. as function of
growth rate and "Tc concentration. Journal of Envi-
ronmental Radioactivity 57: 117-138.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Phyto.
99Tc
90Sr
if
other
Media: SW
Abstract: This study focuses on the question of whether
short-term studies can be used to forecast the accumulation
of the long-lived fission product "Tc in duckweed, Lemna
minorL., grown in the field; in other words, are the accumula-
tion parameters independent of changing growth rates typi-
cal of natural populations of duckweed. Two processes de-
termine the "Tc accumulation: (i) uptake and release of "TcO4~
, characterised by a concentration factor, Kd, and (ii) first-or-
der reduction and complexation of Tcvn, characterised by k^d.
At various "Tc concentrations, the growth, total Tc and TcO4~
accumulation were monitored over 10 days; parameters were
fitted and compared with earlier results. Both Kd and kicd turn
out to be independent of time, concentration and growth rate
up to a concentration of 10~6 mol I"1 "TcO4. Concentrations
above this level result in toxic effects. The Tc accumulation in
field populations of duckweed at Tc concentrations which
generally occur in the environment can be forecasted by us-
ing the results from short-term experiments.
Website: http://www.sciencedirect.com/science/journal/
0265931X
(19) Delvaux, B, N Kruyts and A Cremers. 2000.
Rhizopheric mobilization of radiocesium in soils. Envi-
ronmental Science & Technology 34: 1489-1493.
Radionuclides addressed:
226Ra
U
137Cs +
Pu
Th
Technology: Phyto.
"Tc
90Sr
other
Media: Soil
Abstract: Though soil-plant transfer is the first step by which
radiocesium enters the food chain, it has been scarcely stud-
ied in the rhizosphere. Forty-seven soil horizons from 17
pedons with widely varying properties were contaminated with
carrier-free 137Cs+ and placed into close contact with an active
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Radionuclide Biological
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Phytotechnology
Articles 20-21
macroscopic rhizosphere of ryegrass for 4 days. The 137Cs
rhizospheric mobilization was strongly correlated with the so-
dium tetraphenylboron-extractable 137Cs (r= 0.94), support-
ing that K depletion in the rhizosphere is a capital driving
force in 137Cs uptake. The 137Cs soil-plant transfer factor var-
ied from 0.02 to 3.69 g g"1 between soil materials and was
strongly negatively correlated to the radiocesium interception
potential (RIP) (r- -0.88), a common Cs binding characteris-
tic in soil. RIP largely differed between soil materials (13-
4861 mol g4) and was directly related with the soil vermicu-
lite content (r- 0.70). Our results, validated in a wide variety
of soils, show that both vermiculitic minerals and plant roots
act as competitive sinks for 137Cs+ in the rhizosphere. They
further support that many 137Cs-polluted soils in semi-natural
environments can act as a potential source for long-term con-
tamination of the above standing vegetation because they have
low K availability.
Website: http://pubs.acs.org/journals/esthag
(20) Meagher, RB. 2000. Phytoremediation of toxic el-
emental and organic pollutants. Current Opinion in
P/anfB;o/ogy3:153-162.*
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Phyto.
99Tc
90Sr
other General
Media: Soil
Abstract: Phytoremediation is the use of plants to extract,
sequester, and/or detoxify pollutants. Phytoremediation is
widely viewed as the ecologically responsible alternative to
the environmentally destructive physical remediation meth-
ods currently practiced. Plants have many endogenous ge-
netic, biochemical, and physiological properties that make
them ideal agents for soil and water remediation. Significant
progress has been made in recent years in developing native
or genetically modified plants for the remediation of envi-
ronmental contaminants. Because elements are immutable,
phytoremediation strategies for radionuclide and heavy metal
pollutants focus on hyperaccumulation above-ground. In con-
trast, organic pollutants can potentially be completely miner-
alized by plants.
Website: http://www.sciencedirect.com/science/journal/
13695266
(21) Negri, MC and RR Hinchman. 2000. The use of
plants for the treatment of radionuclides. Pp. 107-132
In Phytoremediation of Toxic Metals: Using Plants to
Clean Up the Environment. I Raskin, ed. Wiley-
Interscience, John Wiley and Sons, Inc. New York,
NY*
Radionuclides addressed:
226Ra
U *
Pu 1
137Cs *
t
Th
Technology: Phyto.
99Tc
90Sr *
other 3H
Media: Soil, GW, SW
Abstract: Radioactive contamination has been a problem since
the development of nuclear technology in the second half of
this century. Causes for radioactive contamination are spills
and emissions from all of the operations typical of the nuclear
fuel cycle, fallout from nuclear testing, and accidents, like the
Chernobyl disaster. The challenges associated with the
remediation of soil, groundwater, and wastewater from ra-
dionuclides are similar to those associated with the remediation
of other inorganic contaminants, with the added radioactive
health risk. Also the radioactive decay component may influ-
ence, especially for shorter-lived radionuclides, the selection
of the most appropriate technology.
A significant amount of literature has been generated since
the mid 1960's to describe the chemical behavior in soil and
plant uptake of radionuclides of environmental interest. On
this basis, phytoremediation has been studied at the bench
scale and finally tested in the field at a few sites: for the
remediation of uranium-contaminated wastewater and soil at
a uranium processing site in Ashtabula, Ohio, and of ura-
nium-contaminated soil from the Fernald site in Ohio. Other
field experiments include feasibility studies of the removal of
Cesium-137 from soil at Brookhaven National Laboratory,
NY, and field trials to remove cesium-137 from soil at Argonne
National Laboratory West site, within the Idaho National
Engineering and Environmental Laboratory (INEEL).
Phytoremediation of both cesium-137 and strontium-90 has
been also studied for application at a pond near Chernobyl in
Ukraine. Tritiated water is being hydraulically contained by
phytoremediation at a field site at Argonne National Labora-
tory in Illinois.
As in the case of treating heavy metals, phytoremediation
has been proven to be most effective and at a more advanced
stage of development for treating readily available
contaminants and therefore to treat wastewater, surface water
and groundwater contamination, including the hydraulic
control of tritiated groundwater. Soil-adsorbed radionuclides
have been more difficult to treat, and success in soil treatment
at this stage depends on the development of specific
amendments and treatments that can increase the rate of
transfer of the radionuclide into plant-available forms, without
further dispersing radionuclides into the environment.
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Articles 22-24
(22) Victorova, N, O Voitesekhovitch, B Sorochinsky,
H Vandenhove, A Konoplev and I Konopleva. 2000.
Phytoremediation of Chernobyl contaminated land.
Radiation Protection DosimetryQ2: 59-64.
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Phyto.
99Tc
90Sr *
other
Media: Soil
Abstract: Most of the land within a 10 km radius of the
Chernobyl Nuclear Plant is still heavily contaminated by the
1986 accident. In 1998, a 3 year investigation of the potential
of willow vegetation systems to stabilise the contaminated land
and thereby reduce the dispersion of radionuclides was initi-
ated under the PHYTORproject. During the first year, a num-
ber of screening tests were carried out on the contaminated
flood plain of the river Pripyat. Survival of new willow plan-
tations was tested at severallocations. Except for the predomi-
nantly moist peaty soil in the vicinity of Yanov (where sur-
vival was nearly 100%), survival was low (0-30%). Notwith-
standing, willows are found everywhere on the Pripyat flood
plains: 7-8 year old plantations exist on the upper terraces and
1-2 year old saplings cover the newly deposited alluvial sands.
For these willows radiocaesium transfer factors ranged from
10~4 and 10J m2kg4 and strontium transfer factors from 10J
and 10~2 m2kg4. Biomass production was low: 70-100 kg ha4
y4. Therefore, the radionuclide immobilisation in the biomass
was insignificant. Even when based on the exchangeable cae-
sium fraction, less then 0.1% for radiocaesium and less than
1% for radio strontium became incorporated into the wood.
Nevertheless, establishment of willow would reduce
resuspension and erosion of soil and sediment.
Website: http://rpd.oupjournals.org/cgi/content/
abstract/92/1-3/59
(23) White, PJ and MR Broadley. 2000. Mechanisms
of casesium uptake by plants. NewPhytologisfl^^W-
256.
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Phyto.
99Tc
90Sr
other
Media: Soil
Abstract: Caesium (Cs) is a Group I alkali metal with chemi-
cal properties similar to potassium (K). It is present in solu-
tion as the monovalent cation Cs+. Concentrations of the
stable caesium isotope 133 Cs in soils occur up to 25 g g-1 dry
soil. This corresponds to low micromolar Cs+ concentrations
in soil solutions. There is no known role for Cs in plant nutri-
tion, but excessive Cs can be toxic to plants. Studies of the
mechanism of Cs+ uptake are important for understanding
the implications arising from releases of radioisotopes of Cs,
which are produced in nuclear reactors and thermonuclear
explosions. Two radioisotopes of Cs (134 Cs and 13? Cs) are of
environmental concern owing to their relatively long half-lives,
emissions of beta and gamma radiation during decay and rapid
incorporation into biological systems. The soil concentrations
of these radioisotopes are six orders of magnitude lower than
those of 133 Cs. Early physiological studies demonstrated that
K+ and Cs+ competed for influx to excised roots, suggesting
that the influx of these cations to root cells is mediated by
the same molecular mechanism(s). The molecular identity
and/or electrophysiological signature of many K+ transport-
ers expressed in the plasma membrane of root cells have been
described. The inward-rectifying K+ (KIR), outward-rectify-
ing K+ (KOR) and voltage-insensitive cation (VIC) channels
are all permeable to Cs+ and, by analogy with their bacterial
counterparts, it is likely that 'high-affinity' K+/H+ symporters
(tentatively ascribed here to KUP genes) also transport Cs+.
By modelling cation fluxes through these transporters into a
stereotypical root cell, it can be predicted that VIC channels
mediate most (30-90 influx under physiological conditions
and that the KUP transporters mediate the bulk of the re-
mainder. Cation influx through KIR channels is likely to be
blocked by extracellular Cs+ under typical ionic conditions in
the soil. Further simulations suggest that the combined Cs+
influxes through VIC channels and KUP transporters can
produce the characteristic 'dual isotherm' relationship between
Cs+ influx to excised roots and external Cs+ concentrations
below 200 M. Thus, molecular targets for modulating Cs+
influx to root cells have been identified. This information
can be used to direct future genetic modification of plants,
allowing them to accumulate more, or less, Cs and thereby to
remediate contaminated sites.
Website: http://www.jstor.org/journals/0028646X.html
(24) Zhu, YG and G Shaw. 2000. Soil contamination
with radionuclides and potential remediation. Chemo-
sp/?ere41: 121-128. *
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Phyto.
99Tc
90Sr *
other
Media: Soil
Abstract: Soils contaminated with radionuclides, particularly
137Cs and 90Sr, pose a long-term radiation hazard to human
*= Review Article
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Radionuclide Biological
Remediation Resource Guide
Phytotechnology
Articles 25-26
health through exposure via the foodchain and other path-
ways. Remediation of radionuclide-contaminated soils has
become increasingly important. Removal of the contaminated
surface soil (often up to 40 cm) or immobilization of radio-
nuclides in soils by applying mineral and chemical amend-
ments are physically difficult and not likely cost-effective in
practicality. Reducing plant uptake of radionuclides, especially
137Cs and 90Sr by competitive cations contained in chemical
fertilizers has the general advantage in large scale, low-level
contamination incidents on arable land, and has been widely
practiced in central and Western Europe after the Chernobyl
accident. Phytoextraction of radionuclides by specific plant
species from contaminated sites has rapidly stimulated inter-
est among industrialists as well as academics, and is consid-
ered to be a promising bio-remediation method. This paper
examines the existing remediation approaches and discusses
phytoextraction of radionuclides from contaminated soils in
detail.
Website: http://www.sciencedirect.com/science/journal/
00456535
(25) Dushenkov, S, A Mikheev, A Prokhnevsky, M
Ruchko and B Sorochinsky. 1999. Phytoremediation
of radiocesium-contaminated soil in the vicinity of
Chernobyl, Ukraine. Environmental Science & Tech-
nology 33: 469-475.
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Phyto.
99Tc
90Sr
other
Media: Soil
Abstract: Remediation of soil contaminated with 137Cs re-
mains one of the most challenging tasks after the Chernobyl
1986 accident. The objectives of this research were to (1)
identify extractants that may be used to solubilize 137Cs in soil
solution, (2) study the effect of soil amendments on 137Cs
accumulation by plants, and (3) evaluate the applicability of
phytoextraction for environmental restoration of soil con-
taminated with 137Cs. The availability of 137Cs to the plants in
Chernobyl soil was limited, because this radionuclide was
tightly bound to exchange sites of soil particles or incorpo-
rated into the crystalline structure of primary and secondary
minerals. Out of 20 soil amendments tested to increase 137Cs
desorption/solubility in the soil, ammonium salts were found
to be the most practical soil amendment that can potentially
increase 137Cs bioavailability. Among the screened plants,
Amaranth cultivars had the highest 137Cs accumulation. Three
sequential crops of Indian mustard grown in one vegetation
season at the experimental plot resulted in a small decrease
of 137Cs specific activity within the top 15 cm of soil. Further
improvements are necessary to make phytoremediation tech-
nology a feasible option for restoration of 137Cs-contaminated
territories.
Website: http://pubs.acs.org/journals/esthag
(26) Entry, JA, LS Watrud and M Reeves. 1999. Accu-
mulation of 137Cs and 90Sr from contaminated soil by
three grass species inoculated with mycorrhizal fungi.
Environmental Pollution 104: 449-457.
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Phyto.
99Tc
90Sr *
other
Media: Soil
Abstract: The use of plants to accumulate low level radioac-
tive waste from soil, followed by incineration of plant mate-
rial to concentrate radionuclides may prove to be a viable and
economical method of remediating contaminated areas. We
tested the influence of arbuscular mycorrhizae on 137Cs and
90Sr uptake by bahia grass (Paspalum notatum), Johnson grass
(Sorghum halpense) and switchgrass (Panicum virginatutii) for the
effectiveness on three different contaminated soil types. Ex-
posure to 137Cs or 90Sr over the course of the experiment did
not affect above ground biomass of the three grasses. The
above ground biomass of bahia, Johnson and switchgrass
plants accumulated from 26.3 to 71.7% of the total amount
of the 137Cs and from 23.8 to 88.7% of the total amount of
the 90Sr added to the soil after three harvests. In each of the
three grass species tested, plants inoculated with Glamus mosseae
or Glamus intraradices had greater aboveground plant biomass,
higher concentrations of 137Cs or 90Sr in plant tissue, % accu-
mulation of 137Cs or 90Sr from soil and plant bioconcentration
ratios at each harvest than those that did not receive mycor-
rhizal inoculation. Johnson grass had greater aboveground
plant biomass, greater accumulation of 137Cs or 90Sr from soil
and plant higher bioconcentration ratios with arbuscular my-
corrhizal fungi than bahia grass and switchgrass. The greatest
accumulation of 137Cs and 90Sr was observed in Johnson grass
inoculated with G. mosseae. Grasses can grow in wide geo-
graphical ranges that include a broad variety of edaphic con-
ditions. The highly efficient removal of these radionuclides
by these grass species after inoculation with arbuscular myc-
orrhizae supports the concept that remediation of radionu-
clide contaminated soils using mycorrhizal plants may present
a viable strategy to remediate and reclaim sites contaminated
with radionuclides.
Website: http://www.sciencedirect.com/science/journal/
02697491
32
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Radionuclide Biological
Remediation Resource Guide
Phytotechnology
Articles 27-29
(27) Garten, CT, Jr. 1999. Modeling the potential role
of a forest ecosystem in phytostabilization and
phytoextraction of 90Sr at a contaminated watershed.
Journal of Environmental Radioactivity 43: 305-323.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Phyto.
"Tc
90Sr *
other
Media: Soil
Abstract: The behavior of 90Sr at forest sites in the White
Oak Creek watershed, near Oak Ridge, Tennessee, was simu-
lated with a simple, site-specific, multicompartment model
that linked biomass and element cycling dynamics. The model
was used to predict the role of forest cover in mitigating hy-
drologic losses of 90Sr from contaminated soils (i.e.
phytostabilization) under conditions where contaminant trans-
port is governed mainly by shallow subsurface flow. The model
was also used to predict the removal of 90Sr from soil (i.e.
phytoextraction) through the growth and harvest of short
rotation woody crops over a period of 30 years. Simulations
with the model indicated that (1) forest preservation on the
watershed is a form of phytostabilization because forest cover
helps to minimize hydrologic losses of 90Sr and (2) an attempt
to significantly reduce amounts of 90Sr in soil through
phytoextraction would be unsuccessful. Over a period of 30
years, and under various management strategies, the model
predicted that <15% of the 90Sr initially present in soil at a
contaminated site was lost through hydrologic transport and
<53% was lost by radioactive decay. Phytostabilization may
be important in the management of radioactive land when
issues like waste minimization and pollution prevention af-
fect the selection of technologies to be used in environmen-
tal restoration.
Website: http://www.sciencedirect.com/science/journal/
0265931X
(28) Smith, JT and DG Elder. 1999. A comparison of
models for characterizing the distribution of radionu-
clides with depth in soils. European Journal of Soil
Science 50: 295-307.
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Phyto.
99Tc
90Sr
other
Media: Soil
Abstract: It is common practice to fit mathematical models
to radionuclide activity-depth profiles in soils in order to quan-
tify rates of vertical migration through the soil profile. We
have fitted six such models to 21 different activity-depth pro-
files of radiocaesium (137Cs) derived from Chernobyl and de-
termined relations between the models and the values of their
parameters. The advection and dispersion parameters obtained
using four solutions to the advection-dispersion equation (each
based on different initial and boundary conditions or differ-
ent simplifications) are in good agreement. We further de-
velop a relation between parameter values obtained using the
advection-dispersion models and those determined by a sim-
pler exponential function of the form A~Bt where z'is the time
and A and B are parameters to be estimated. One of the ad-
vection-dispersion models proved to be significantly better
than the others in terms of goodness-of-fit, versatility and
ease of use. A simple model, using calculations based on
measured characteristics of the activity-depth profile, was
shown to accord well with parameters derived from more
complex models based on statistical curve fitting. We have
also evaluated the 'residence time' or 'compartmentaT model
approach to characterizing radionuclide activity-depth pro-
files. We relate such models to a numerical solution of a simple
advection equation, and we show that apparent dispersion in
compartmental models is an artefact of numerical dispersion,
which can be quantified by the Courant condition. For activ-
ity profiles that have a significant advection component, us-
ing solutions to the advection-dispersion equation, we have
observed a strong positive correlation between advection and
dispersion in the profile.
Website: http://www.blackwellpublishing.com/
journal.asp?ref= 1351-0754
(29) Echevarria, G, Vong, PC and JL Morel. 1998. Ef-
fect of NGy on the fate of "TcGy in the soil-plant sys-
tem. Journal of Environmental Radioactivity 38: 163-
171.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Phyto.
"Tc
90Sr
*
other
Media: Soil
Abstract: This work was undertaken to study the effect of
NO3~ fertilization on the uptake of "TcO4~ by plants. Rye-
grass (Lolium perenne) was grown in a growth chamber on a
silty loam soil to which were added increasing quantities of
ammonium nitrate (21, 50 and 100 mg N kg4). Soil samples
were then amended with "TcO4~ at a constant level of 29.6
kBq kg'1 dry weight. Total initial NO3~ content was 43.3, 57.8
and 82.8 mg N kg1, and total NH4+ content was 24.7, 39.2
and 64.2 mg N kg1. Three cuts were made at 4-week inter-
33
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Radionuclide Biological
Remediation Resource Guide
Phytotechnology
Articles 30-32
vals, and aerial biomass was analysed for total "Tc and N.
Results showed that total uptake of "Tc was decreased by
increasing mineral N additions at the first cut, as mineral ni-
trogen was not a limiting factor for plant growth at this stage.
Technetium-99 content in plants varied from 64% of the to-
tal applied "Tc with the lowest NO3~ content to 31% with the
highest. However, at the third cut, cumulative "Tc uptake
reached the same level for the three treatments (80-83%) with
no further effect of initial N applications, as NO3~ was de-
pleted in the soil. Therefore, "TcO4~ was diluted in the pool
of soil NO3~ and was absorbed proportionally to nitrate by
rye-grass.
Website: http://www.sciencedirect.com/science/journal/
0265931X
(30) Gerzabek, MH, F Strebl and BTemmel. 1998. Plant
uptake of radionuclides in lysimeter experiments. En-
vironmental Pollution 99: 93-103.
Radionuclides addressed:
226Ra *
U
137Cs *
Pu
Th
Technology: Phyto.
"Tc
90Sr
other 60Co
Media: Soil
Abstract: The results of seven years lysimeter experiments
to determine the uptake of 60Co, 137Cs and ^Ra into agricul-
tural crops (endive, maize, wheat, mustard, sugarbeet, potato,
Faba bean, rye grass) are described. The lysimeter consists of
twelve monolithic soil profiles (four soil types and three rep-
licates) and is located in Seibersdorf/Austria, a region with a
pannonian climate (pronounced differences between hot and
semi-arid summers and humid winter conditions, annual mean
of precipitation: 517 mm, mean annual temperature: 9.8°Q.
Besides soil-to-plant transfer factors (TF), fluxes were calcu-
lated taking into account biomas s production and growth time.
Total median values of TF's (dry matter basis) for the three
radionuclides decreased from ^Ra (0.068 kg kg4) to 137Cs
(0.043 kg kg1) and 60Co (0.018 kg kg1); flux values exhibited
the same ranking. The varying physical and chemical proper-
ties of the four experimental soils resulted in statistically sig-
nificant differences in transfer factors or fluxes between the
investigated soils for 137Cs and ^Ra, but not for 60Co. Differ-
ences in transfer between plant species and plant parts are
distinct, with graminaceous species showing, on average, TF
values 5.8 and 15 times lower than dicotyledonous species
for 137Cs and 60Co, respectively. This pattern was not found
for 226Ra. It can be concluded that 137Cs transfer is heavily
influenced by soil characteristics, whilst the plant-specific fac-
tors are the main source of TF variability for 60Co. The vari-
ability of 226Ra transfer originates both from soil properties
and plant species behaviour.
Website: http://www.sciencedirect.com/science/journal/
02697491
(31) Martinez-Aguirre, A and R Perianez. 1998. Soil-
to-plant transfer of 226Ra in a marsh area: modelling
application. Journal of Environmental Radioactivity 39:
199-213.
Radionuclides addressed:
226Ra *
U
137Cs
Pu
Th
Technology: Phyto.
"Tc
90Sr
other
Media: Soil
Abstract: The Odiel River forms an estuarine system which
surrounds a large marsh area. A phosphate fertilizer process-
ing complex releases its wastes into the estuary. The presence
of ^6Ra in soils and plants (Spartina Densiflora) from the
marsh has been investigated. Concentrations up to 700 and
15 mBq g4 have been detected in soil and plant samples, re-
spectively. Soil-to-plant concentration ratios have been calcu-
lated and some activity ratios have also been investigated. A
model which is able to simulate the dispersion of radionu-
clides in the marsh has been applied. The model includes the
exchange of radionuclides between water and the solid phase
(suspended matter and bottom sediments) and the transfer
of radionuclides to the plants. Model results are, in general, in
good agreement with measurements.
Website: http://www.sciencedirect.com/science/journal/
0265931X
(32) Hossner, LR, RH Loppert, RJ Newton, and PJ
Szaniszlo. 1998. Literature Review: Phytoaccumulation
of Chromium, Uranium, and Plutonium in Plant Sys-
tems. Amarillo National Resource Center for Plutonium,
Amarillo, Texas. 53 pp. *
Radionuclides addressed:
226Ra
U *
Pu 1
137Cs
t
Th
Technology: Phyto.
"Tc
90Sr
other
Media: Soil
Abstract: Phytoremediation is an integrated multidisciplinary
approach to the cleanup of contaminated soils, which com-
bines the disciplines of plant physiology, soil chemistry, and
soil microbiology. Metal hyperaccumulator plants are attract-
34
Review Article
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Radionuclide Biological
Remediation Resource Guide
Phytotechnology
Articles 33-34
ingincreasing attention because of their potential application
in decontamination of metal-polluted soils. Traditional engi-
neering technologies may be too expensive for the remediation
of most sites. Removal of metals from these soils using accu-
mulator plants is the goal of phytoremediation. The empha-
sis of this review has been placed on chromium (Cr), pluto-
nium (Pu), and uranium (U). With the exception of Cr, these
metals and their decay products exhibit two problems, spe-
cifically, radiation dose hazards and their chemical toxicity.
The radiation hazard introduces the need for special precau-
tions in reclamation beyond that associated with non-radio-
active metals. The uptake of beneficial metals by plants oc-
curs predominantly by way of channels, pores, and transport-
ers in the root plasma membrane. Plants characteristically
exhibit a remarkable capacity to absorb what they need and
exclude what they don't need. But most vascular plants ab-
sorb toxic and heavy metals through their roots to some ex-
tent, though to varying degrees, from negligible to substan-
tial. Sometimes absorption occurs because of the chemical
similarity between beneficial and toxic metals. Some plants
utilize exclusion mechanisms, where there is a reduced up-
take by the roots or a restricted transport of the metal from
root to shoot. At the other extreme, hyperaccumulator plants
absorb and concentrate metals in both roots and shoots. Some
plant species endemic to metalliferous soils accumulate met-
als in percent concentrations in the leaf dry matter.
Order Number: NTIS/DE98005257, Report Number:
ANRCP-1998-3
(33) Hartley, J and VTokarevsky. 1998. Proceedings
of the Chornobyl Phytoremediation and Biomass En-
ergy Conversion Workshop. U.S. DOE Assistant Sec-
retary for Nuclear Energy, Washington, DC. 555 pp.
Radionuclides addressed:
226Ra
U
137Cs ^
Pu
Th
Technology: Phyto.
99Tc
90Sr *k
other
Media: Soil
Abstract: Many concepts, systems, technical approaches, tech-
nologies, ideas, agreements, and disagreements were vigor-
ously discussed during the course of the 2-day workshop. The
workshop was successful in generating intensive discussions
on the merits of the proposed concept that includes removal
of radionuclides by plants and trees (phytoremediation) to
clean up soil in the Chornobyl Exclusion Zone (CEZ), use of
the resultant biomass (plants and trees) to generate electrical
power, and incorporation of ash in concrete casks to be used
as storage containers in a licensed repository for low-level
waste. Twelve years after the Chornobyl Nuclear Power Plant
(ChNPP) Unit 4 accident, which occurred on April 26,1986,
the primary radioactive contamination of concern is from
radioactive cesium (137Cs) and strontium ('"Sr). The 137Cs and
90Sr were widely distributed throughout the CEZ. The attend-
ees from Ukraine, Russia, Belarus, Denmark and the US pro-
vided information, discussed and debated the following is-
sues considerably: distribution and characteristics of radio-
nuclides in CEZ; efficacy of using trees and plants to extract
radioactive cesium (Cs) and strontium (Sr) from contaminated
soil; selection of energy conversion systems and technolo-
gies; necessary infrastructure for biomass harvesting, handling,
transportation, and energy conversion; radioactive ash and
emission management; occupational health and safety con-
cerns for the personnel involved in this work; and economics.
The attendees concluded that the overall concept has techni-
cal and possibly economic merits. However, many issues (tech-
nical, economic, risk) remain to be resolved before a viable
commercial-scale implementation could take place.
Order number: NTIS/DE98057942, Report Number:
PNNL-SA-29991
(34) Huang, JW, MJ Blaylock, Y Kapulnik and BD
Ensley. Phytoremediation of uranium-contaminated
soils: role of organic acids in triggering uranium
hyperaccumulation in plants. Environmental Science
& Technology 32: 2004-2008.
Radionuclides addressed:
226Ra
U *
137Cs
Pu
Th
Technology: Phyto.
"Tc
90Sr
other
Media: Soil
Abstract: Uranium phytoextraction, the use of plants to ex-
tract U from contaminated soils, is an emerging technology.
We report on the development of this technology for the
cleanup of U-contaminated soils. In this research, we investi-
gated the effects of various soil amendments on U desorp-
tion from soil to soil solution, studied the physiological char-
acteristics of U uptake and accumulation in plants, and de-
veloped techniques to trigger U hyperaccumulation in plants.
A key to the success of U phytoextraction is to increase soil
U availability to plants. We have found that some organic ac-
ids can be added to soils to increase U desorption from soil
to soil solution and to trigger a rapid U accumulation in plants.
Of the organic acids (acetic acid, citric acid, and malic acid)
tested, citric acid was the most effective in enhancing U accu-
mulation in plants. Shoot U concentrations of Brassicajuncea
and Brassifa chimnsis grown in a U-contaminated soil (total
soil U, 750 mg kg4) increased from less than 5 mg kg4 to
35
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Radionuclide Biological
Remediation Resource Guide
Phytotechnology
Articles 35-38
more than 5000 mg kg4 in citric acid-treated soils. To our
knowledge, this is the highest shoot U concentration reported
for plants grown on U-contaminated soils. Using this U
hyperaccumulation technique, we are now able to increase U
accumulation in shoots of selected plant species grown in
two U-contaminated soils (total soil U, 280 and 750 mg kg4)
by more than 1000-fold within a few days. Our results sug-
gest that U phytoextraction may provide an environmentally
friendly alternative for the cleanup of U-contaminated soils.
Website: http://pubs.acs.org/journals/esthag
(35) Entry, JA, LS Watrud, RS Manasse and NC Vance.
1997. Phytoremediation and reclamation of soils con-
taminated with radionuclides. Pp. 299-306 In
Phytoremediation of Soil and Water Contaminants
Kruger, EL, TA Anderson and JR Coats, eds. Ameri-
can Chemical Society, Washington, DC.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Phyto.
"Tc
90Sr
other General
Media: Soil
Abstract: No abstract available.
Book Number (ISBN): 0-8412-3503-1:664 (0)
(36) Kochian, L. 1997. Identification and Validation of
Heavy Metal and Radionuclide Hyperaccumulating
Terrestrial Plant Species. U.S. Department of Energy,
Washington, DC. 23 pp.
Radionuclides addressed:
226Ra
U *
137Cs *
Pu
Th
Technology: Phyto.
99Tc
90Sr
other
Media: Soil
Abstract: This laboratory has been involved in a collabora-
tive project focusing on a range of issues related to the
phytoremediation of heavy metal-and radionuclide- contami-
nated soils. While much of the research has been fundamen-
tal in nature, involving physiological and molecular character-
izations of the mechanisms of hyperaccumulation in plants,
the laboratory is also investigating more practical issues re-
lated to phytoremediation. A central issue in this latter re-
search has been the identification of amendments capable of
increasing the bio availability and subsequent phytoextraction
of radionuclides. The results described here detail these ef-
forts for uranium and Cs-137. A study was also conducted on
a Cs-137 contaminated site at Brookhaven National Labora-
tory (BNL), which allowed application of the laboratory and
greenhouse results to a field setting.
Order Number: NTIS/DE98050572, Report Number:
DOE/PC/95701-T9
(37) Krouglov, SV, AS Filipas, RM Alexakhin and NP
Arkhipov. 1997. Long-term study on the transfer of 137Cs
and 90Sr from Chernobyl-contaminated soils to grain
crops. Journal of Environmental Radioactivity34: 267-
286.
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Phyto.
"Tc
90Sr *
other
Media: Soil
Abstract: The level of 137Cs and 90Sr transfer to four grain
crops and the change in transfer with time have been studied
on two soils contaminated with fragments of nuclear fuel re-
leased during the Chernobyl accident. Field experiments were
carried out in 1987-1994 inside the heavily contaminated zone
around Chernobyl Nuclear Power Plant. Shortly after the depo-
sition, the rate of 90Sr accumulation by crops was comparable
with, or even slower, than that of 137Cs, which is in disagree-
ment with the usual findings. In the following years, 137Cs up-
take by plants was reduced by a factor in excess of than 50,
whereas the soil-to-plant concentration ratio of 90Sr increased
within one order of magnitude, and has remained on approxi-
mately the same level since 1991. Changes of the 90Sr and
137Cs concentration ratios for grain crops with time have been
used to evaluate the rate of radionuclide leaching from fuel
particles and the ageing processes.
Website: http://www.sciencedirect.com/science/journal/
0265931X
(38) Dushenkov, S, D Vasudev, Y Kapulnik, D Gleba,
D Fleisher, KG Ting and B Ensley. 1997. Removal of
uranium from water using terrestrial plants. Environ-
mental Science & Technology 37: 3468-3474.
Radionuclides addressed:
226Ra
U *
Pu
137Cs
Th
Technology: Phyto.
Media:
90Sr
"Tc
other
GW, SW
36
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Radionuclide Biological
Remediation Resource Guide
Abstract: Uranium (U) contamination of groundwater poses
a serious environmental problem in uranium mining areas and
in the vicinity of nuclear processing facilities. Preliminary labo-
ratory experiments and treatability studies indicated that the
roots of terrestrial plants could be efficiently used to remove
U from aqueous streams (rhizofiltration). Certain sunflower
plants were found to have a high affinity for U and were se-
lected for treatment of contaminated water. Almost all of the
U removed from the water in the laboratory was concentrated
in the roots. Bioaccumulation coefficients based on the ratios
of U concentrations in the roots vs U concentrations in the
aqueous phase reached 30 000. Rhizo filtration technology has
been tested in the field with U-contaminated water at con-
centrations of 21-874 micrograms/L at a former U process-
ing facility in Ashtabula, OH. The pilot-scale rhizofiltration
system provided final treatment to the site source water and
reduced U concentration to <20 micrograms/L (EPA Water
Quality Standard) before discharge to the environment. Sys-
tem performance was subsequently evaluated under different
flow rates permitting the development of effectiveness esti-
mates for the approach.
Website: http://pubs.acs.org/journals/esthag
(39) Fesenko, SV, SI Spiridonov, Nl Sanzharova and
RM Alexakhin. 1997. Dynamics of 137Cs bioavailability
in soil-plant system in areas of the Chernobyl Nuclear
Power Plant accident zone with a different physico-
chemical composition of radioactive fallout. Journal of
Environmental Radioactivity 34: 287-313.
Radionuclides addressed:
226Ra
U
137Cs ^
Pu
Th
Technology: Phyto.
99Tc
90Sr
other
Media: Soil
Abstract: A quantitative analysis of the dynamics of 137Cs
bioavailability in soils contaminated following the Chernobyl
NPP accident, based on a 6-year (19871992) observation
period, and a dynamic model describing the behaviour of
radiocaesium in meadow ecosystems are presented. It has been
shown that the type of deposition and soil characteristics are
main factors that significantly affect (up to five times) the
changes in bioavailability of this radionuclide in the soil-plant
system. The presence of particles, distinguished by their re-
sistance in the environment, can result in an irregular decrease
of 137Cs uptake by plants. During the first period after fallout,
137Cs uptake by plants is considerably (up to eight times) in-
fluenced by radionuclide distribution between the soil and
the mat. The rates of decrease of 137Cs uptake by plants can
differ by factor of 35, being dependent on soil properties.
Phytotechnology
Articles 39-42
The effect of these factors depends on the time lapsed after
the deposition.
Website: http://www.sciencedirect.com/science/journal/
0265931X
(40) Entry, J.A., N.C. Vance, and L.S. Watrud. 1996.
Selection of plants for phytoremediation of soils con-
taminated with radionuclides. Abstracts of Papers of
the American Chemical Society 212: AGRO 108.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Phyto.
"Tc
90Sr
other General
Media: Soil
Abstract: No abstract available.
(41) Entry, JA, NC Vance, MA Hamilton, DZZabowski,
LS Watrud and DC Adriano. 1996. Phytoremediation
of soil contaminated with low concentrations of radio-
nuclides. Water, Air, & Soil Pollution 88: 167-177.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Phyto.
"Tc
90Sr
other General
Media: Soil
Abstract: No abstract available.
(42) Cornish, JE, WC Goldberg, RS Levine, and JR
Benemann. 1995. Phytoremediation of soils contami-
nated with toxic elements and radionuclides. Pp. 55-
63 In Bioremediation of Inorganics. Hinchee, RE, JL
Means and DR Burris, eds. Battelle Press, Columbus,
OH.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Phyto.
»Tc
90Sr
other General
Media: Soil
Abstract: No abstract available.
37
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Radionuclide Biological
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Articles 43-45
(43) Entry, JA and WH Emmingham. 1995. Seques-
tration of 137Cs and 90Sr from soil by seedlings of Euca-
lyptus tereticornis. Canadian Journal of Forest Re-
search 25: 1044-1047.
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Phyto.
"Tc
90Sr *
other
Media: Soil
Abstract: The ability of seedlings of Eucalyptus tereticornis
Smith to accumulate 137Cs and 90Sr, characteristic radioiso-
topes of nuclear fallout, from contaminated growth medium
was tested. All seedlings were grown for 3 months in 165 cm"
3 of sphagnum peat moss - perlite (1:1 v/v) in a growth cham-
ber before treatment with an isotope. After 1 month of expo-
sure, seedlings had accumulated 31.0% of the 137Cs and 11.3%
of the 90Sr originally present in the growth medium, with
bioconcentration ratios of 54:1 for 137Cs and 13:1 for 90Sr.
Accumulation of 137Cs and 90Sr in plant tissue was correlated
curvilinearly with increasing time of exposure and with in-
creasing concentration of radioisotope in the growth medium.
Because seedlings of E. tereticornis accumulate these radio-
isotopes rapidly, they may be valuable in remediation of con-
taminated soils.
Website: http://www.nrc.ca/cgi-bin/cisti/journals/rp/
rp2_desc_e?cjfr
(44) Entry, JA, NC Vance, MA Hamilton and D
Zabowski. 1994. In-situ remediation of soil contami-
nated with low concentrations of radionuclides.
Pp.1055-1067 In In-Situ Remediation: Scientific Basis
for Current and Future Technologies. Gee, GW and
NR Wing, eds. Batelle Press, Columbus, Ohio.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Phyto.
"Tc
other
90Sr
General
Media: Soil
Abstract: No abstract available.
Book Number (ISBN): 0-935470-85-9
(45) Konoplev, AV, NV Viktorova, EP Virchenko, VE
Popov, AA Bulgakov and GM Desmet. 1993. Influence
of agricultural countermeasures on the ratio of differ-
ent chemical forms of radionuclides in soil and soil
solution. The Science of the Total Environment 137:
147-163.
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Phyto.
"Tc
90Sr *
other
Media: Soil
Abstract: The bioavailability of radionuclides derived from
the Chernobyl accident is discussed in terms of their specia-
tion in soils. A scheme representing transformation processes
of different chemical forms of these radionuclides in soil and
soil solution is proposed. The rate constants of the main trans-
formation processes were obtained experimentally. Various
agrochemical countermeasures are evaluated in terms of their
influence on the ratio of different radionuclide forms in soil
and soil solution. The influence of soil characteristics on the
potential effectiveness of countermeasures is discussed. Prac-
tically all agrochemical countermeasures currently in use have
positive and negative effects. The most effective countermea-
sures for radiocaesium and radiostrontium were liming of the
soil and the application of potassium containing fertilisers at
elevated rates.
Website: http://www.sciencedirect.com/science/journal/
00489697
Willow and poplar trees removing tritium from the groundwater at Argonne
National Laboratory.
Photo: Dr. Victor Ibeanusi
38
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Radionuclide Biological
Remediation Resource Guide
Bio re media tion
Articles 46-48
(46) Istok, JD, JM Senko, LR Krumholz, D Watson, LA
Bogle, A Peacock, Y-J Chang and DC White. 2004. In
situ bioreduction of technetium and uranium in a ni-
trate-contaminated aquifier. Environmental Science &
Technology 38: 468-475.
Radionuclides addressed:
226Ra
U *
137Cs
Pu
Th
Technology: Biorem.
99Tc
90Sr
if
other
Media: SW
Abstract: The potential to stimulate an indigenous microbial
community to reduce a mixture of U(VI) and Tc(VII) in the
presence of high (120 mM) initial NO ~ co-contamination was
evaluated in a shallow unconfined aquifer using a series of
single-well, push-pull tests. In the absence of added electron
donor, NO3~, Tc(VII), and U(VI) reduction was not detect-
able. However, in the presence of added ethanol, glucose, or
acetate to serve as electron donor, rapid NO3~ utilization was
observed. The accumulation of NO2~, the absence of detect-
able NH4+ accumulation, and the production of N2O during
in situ acetylene-block experiments suggest that NO3~ was be-
ing consumed via denitrification. Tc(VII) reduction occurred
concurrently with NO3~ reduction, but U(VI) reduction was
not observed until two or more donor additions resulted in
iron-reducing conditions, as detected by the production of
Fe(II). Reoxidation/remobilization of U(IV) was also observed
in tests conducted with high (apprx!20 mM) but not low
(apprxl mM) initial NO3~ concentrations and not during acety-
lene-block experiments conducted with high initial NO ".
These results suggest that NO3dependent microbial U(IV)
oxidation may inhibit or reverse U(VI) reduction and decrease
the stability of U(IV) in this environment. Changes in viable
biomass, community composition, metabolic status, and res-
piratory state of organisms harvested from down-well micro-
bial samplers deployed during these tests were consistent with
the conclusions that electron donor additions resulted in mi-
crobial growth, the creation of anaerobic conditions, and an
increase in activity of metal-reducing organisms (e.g.,
Geobacter). The results demonstrate that it is possible to stimu-
late the simultaneous bioreduction of U(VI) and Tc(VII) mix-
tures commonly found with NO3~ co-contamination at radio-
active waste sites.
Website: http://pubs.acs.org/journals/esthag
(47) Bolton, H, D Rai, H Kostandarithes, D Moore and
LXun. 2003. Biodegradation and speciation of PuEDTA
by bacterium BNCI. Abstracts of the General Meeting
of the American Society for Microbiology 103: Q-311.
Radionuclides addressed:
226Ra
U
Pu 1
137Cs
t
Th
Technology: Biorem.
99Tc
other
90Sr
60Co
Media: GW
Abstract: The contamination of DOE sites by plutonium
(Pu) is a long-term problem because of its long half-life and
low drinking water limit. The synthetic chelating agent EDTA
was co-disposed with radionuclides (e.g., Pu, 60Co) in the sub-
surface at DOE sites and has enhanced the transport of ra-
dionuclides in groundwater as the radionuclide-EDTA com-
plex. Biodegradation of EDTA should decrease Pu mobility.
One objective was to determine the biodegradation of EDTA
in the presence of PuEDTA complexes. The aqueous system
investigated at pH 7 (10"4 M EDTA and lO"6 M Pu) contained
predominantly Pu(OH)2EDTA2-. The EDTA was degraded
at a faster rate in the presence of Pu. As the total concentra-
tion of both EDTA and PuEDTA decreased (i.e., 10~5 M
EDTA and 10~7 M PuEDTA), the presence of Pu decreased
the biodegradation rate of the EDTA. It is currently unclear
why the concentration of Pu directly affects the increase/
decrease in rate of EDTA biodegradation. The soluble Pu
concentration decreased, in agreement with thermodynamic
predictions, as the EDTA was biodegraded, indicating that
biodegradation of EDTA will decrease Pu mobility when the
Pu is initially present as Pu(IV)EDTA. A second objective
was to investigate how the presence of a second metal will
influence the speciation and biodegradation of Pu(IV)EDTA.
Preliminary results indicate that the presence of Fe(III)
outcompetes the Pu(IV) for the EDTA complex. This indi-
cates that Pu(IV) will not form stable complexes with EDTA
for enhanced transport of Pu in Fe(III) dominated subsur-
face systems. Results from these studies provide mechanistic
understanding and approaches to assist in the bioremediate
PuEDTA and other radionuclide-EDTA complexes at DOE
sites.
(48) Elias, DA, JM Senko and LR Krumholz. 2003. A
procedure forquantitation of total oxidized uranium for
bioremediation studies. Journal of Microbiological
Methods 53: 343-353
Radionuclides addressed:
226Ra
U *
137Cs
Pu
Th
Technology: Biorem.
"Tc
90Sr
other
Media: Soil,
SW
Abstract: A procedure was developed for the quantitation of
complexed U(VI) during studies on U(VI) bioremediation.
These studies typically involve conversion of soluble or
complexed U(VT) (oxidized) to U(IV) (the reduced form which
39
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Radionuclide Biological
Remediation Resource Guide
Bio re media tion
Articles 49-51
is much less soluble). Since U(VI) freely exchanges between
material adsorbed to the solid phase and the dissolved phase,
uranium bioremediation experiments require a mass balance
of U in both its soluble and adsorbed forms as well as in the
reduced sediment bound phase. We set out to optimize a pro-
cedure for extraction and quantitation of sediment bound
U(VI). Various extractant volumes to sediment ratios were
tested and it was found that between 1:1 to 8:1 ratios (v/w)
there was a steady increase in U(VI) recovered, but no change
with further increases in v/w ratio. Various strengths of
NaHCOS, Na-EDTA, and Na-citrate were used to evaluate
complexed U(VI) recovery, while the efficiency of a single
versus repeated extraction steps was compared with synthe-
sized uranyl-phosphate and uranyl-hydroxide. Total recovery
with 1 M NaHCO3was 95.7% and 97.9% from uranyl-phos-
phate and uranyl-hydroxide, respectively, compared to 80.7%
and 89.9% using 450 mM NaHCO3. Performing the proce-
dure once yielded an efficiency of 81.1% and 92.3% for ura-
nyl-phosphate and uranyl-hydroxide, respectively, as compared
to three times. All other extractants yielded 7.9-82.0% in both
experiments. Biologically reduced U(IV) was treated either
alone or mixed with uncontaminated sediment slurries to en-
sure that the procedure was not interfering with subsequent
U(IV) quantitation. While U(VI) was recovered, it represented
0.07% of the total uranium alone or 7.8% when mixed with
sediments. Total uranium recovered did not change. The pro-
cedure was then used to monitor changes in complexed U(VI)
levels during uranium-reduction in pure culture and sediments.
There was no appreciable complexed U(VI) concentration in
pure culture. In sediments however, once soluble U(VI) lev-
els and reduction rates decreased, complexed U(VI) levels be-
gan to decrease while U(IV) levels continued to increase. This
indicated that once soluble U(VI) was nearly exhausted, sorbed
U(VI) became bioavailable and was reduced microbiologically.
Typically, uranium is quantified in two steps, soluble U(VI)
and U(IV). However, the present study shows that after suc-
cessive washings with water to remove soluble U(VI), a sig-
nificant pool of oxidized uranium remains which may be mis-
takenly quantified as U(IV). This procedure can be used to
quantify this pool, does not interfere with U(IV) quantitation,
and has an overall efficiency of 95.8%
Website: http://www.sciencedirect.com/science/journal/
01677012
(49) Ibeanusi, VM, D Phinney and M Thompson. 2003.
Removal and recovery of metals from a coal pile run-
off. Environmental Monitoring and Assessment 84: 35-
44.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Biorem.
99Tc
other
90Sr
General
Media: SW
Abstract: The removal and recovery of heavy metals from a
coal pile runoff water using a mixture of multiple metal-tol-
erant bacterial strains of ATCC 55673, and ATCC 55674 and
a Pseudomonas sp. was investigated. The analysis of elemen-
tal composition of metal precipitates recovered from the bac-
terial biomass by transmission electron microscopy and en-
ergy dispersive X-ray analysis revealed the presence of metals
originally present in the wastewater. In addition, analysis of
metals in culture supernatant and bacterial biomass by induc-
tively coupled plasma emission spectroscopy (ICP-ES) indi-
cated a removal range of 82-100% and a recovery of 15-58%
of metals from the wastewater and bacterial biomass, respec-
tively.
Website: http://www.kluweronline.com/issn/0167-6369/
contents
(50) Nevin, KP, KT Finneran and DR Lovley. 2003. Mi-
croorganisms associated with uranium bioremediation
in a high-salinity subsurface sediment. Applied and
Environmental Microbiology 6$: 3672-3675.
Radionuclides addressed:
226Ra
U *
137Cs
Pu
Th
Technology: Biorem.
99Tc
90Sr
other
Media: GW
Abstract: Although stimulation of dissimilatory metal reduc-
tion to promote the reductive precipitation of uranium has
been shown to successfully remove uranium from some aqui-
fer sediments, the organisms in the family Geobacteraceae
that have been found to be associated with metal reduction in
previous studies are not known to grow at the high salinities
found in some uranium-contaminated groundwaters. Studies
with a highly saline uranium-contaminated aquifer sediment
demonstrated that the addition of acetate could stimulate the
removal of U(VI) from the groundwater. This removal was
associated with an enrichment in microorganisms most closely
related to Pseudomonas and Desulfosporosinus species.
Website: http://aem.asm.Org/cgi/content/abstract/69/6/
3672
(51) Anderson, RT, HA Vrionis, I Ortiz-Bernad, CT
Resch, PE Long, R Dayvault, K Karp, S Marutzky, DR
Metzler, A Peacock, DC White, M Lowe and DR Lovley.
2003.
40
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Radionuclide Biological
Remediation Resource Guide
Bioremediation
Articles 52-53
Stimulating the in situ activity of Geobacter species to
remove uranium from the groundwater of a uranium-
contaminated aquifer. Applied and Environmental Mi-
crobiology 69: 5884-5891.
Radionuclides addressed:
226Ra
U *
137Cs
Pu
Th
Technology: Biorem.
"Tc
90Sr
other
Media: GW
Abstract: The potential for removing uranium from contami-
nated groundwater by stimulating the in situ activity of dis-
similatory metal-reducing microorganisms was evaluated in a
uranium-contaminated aquifer located in Rifle, Colo. Acetate
(1 to 3 mM) was injected into the subsurface over a 3-month
period via an injection gallery composed of 20 injection wells,
which was installed upgradient from a series of 15 monitor-
ing wells. U(VI) concentrations decreased in as little as 9 days
after acetate injection was initiated, and within 50 days ura-
nium had declined below the prescribed treatment level of
0.18 M in some of the monitoring wells. Analysis of 16S ri-
bosomal DNA (rDNA) sequences and phospholipid fatty acid
profiles demonstrated that the initial loss of uranium from
the groundwater was associated with an enrichment of
Geobacter species in the treatment zone Fe(II) in the ground-
water also increased during this period, suggesting that U(VI)
reduction was coincident with Fe(III) reduction. As the ac-
etate injection continued over 50 days there was a loss of
sulfate from the groundwater and an accumulation of sulfide
and the composition of the microbial community changed.
Organisms with 16S rDNA sequences most closely related
to those of sulfate reducers became predominant, and
Geobacter species became a minor component of the commu-
nity. This apparent switch from Fe(III) reduction to sulfate
reduction as the terminal electron accepting process for the
oxidation of the injected acetate was associated with an in-
crease in uranium concentration in the groundwater. These
results demonstrate that in situ bioremediation of uranium-
contaminated groundwater is feasible but suggest that the
strategy should be optimized to better maintain long-term
activity of Geobacter species.
Website: http://aem.asm.org/cgi/content/abstract/69/
10/5884
(52) Shelobolina, ES, K O'Neill, KT Finneran, LA Hayes
and DR Lovley. 2003. Potential for in situ
bioremediation of low-pH, high-nitrate uranium-con-
taminated groundwater. So;7 and Sediment Contami-
nation 12: 865-884.
Radionuclides addressed:
226Ra
U *
137Cs
Pu
Th
Technology: Biorem.
"Tc
90Sr
other
Media: GW
Abstract: The potential for stimulating microbial U(VI) re-
duction as an in situ bioremediation strategy for uranium-con-
taminated groundwater was evaluated in uranium-contami-
nated sediment from the FRC, Oak Ridge, TN. Sediment was
at low pH (pH 4) and contained high (55 mM) concentrations
of nitrate. The addition of organic electron donors resulted
in a slow removal of ca. 20% of the nitrate over 120 days with
a concurrent increase in pH. Uranium precipitated during ni-
trate reduction. This precipitation of U(VI) was not due to its
reduction to U(IV) because over 90% of the uranium in the
sediments remained as U(VI). Studies in which the pH of the
sediments was artificially raised suggested that an increase in
pH alone could not account for the precipitation of the U(VI)
during nitrate reduction. Metal-reducing bacteria were recov-
ered from the sediments in enrichment cultures, but molecu-
lar analysis of the sediment demonstrated that the addition
of electron donors did not stimulate the growth of these metal
reducers. Thus, although U(VI) was precipitated from the
groundwater with the simple addition of electron donors, most
of the uranium in the sediments was in the form of U(VI),
and thus was not effectively immobilized.
Website: http://www.aehs.com/journals/soilcontamination
(53) van Hullebusch ED, MH Zandvoort and PN Lens.
2003. Metal immobilisation by biofilms: mechanisms
and analytical tools. Reviews in Environmental Science
and Biotechnology 2: 9-33.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Biorem.
"Tc
90Sr
other General
Media: SW
Abstract: In bio film environments, heavy metal and radionu-
clide pollutants are removed by a variety of mechanisms, in-
cluding biosorption, precipitation as sulfides or phosphates
and microbial reductive precipitation. Even if the elemental
composition and localization of the precipitate trapped in the
biofilm is well described thanks to spectroscopic and micro-
scopic techniques, this review highlights that little is known
about metal immobilisation mechanisms in microbial biofilms,
i.e., mass transfer of metals, mechanisms involved in
(bio)sorption and precipitation and the influence of physico-
chemical micro-environments within the biofilm matrix. The
review shows the advantage of using a combination of differ-
ent techniques to evaluate the fate of metals within micro-
41
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Radionuclide Biological
Remediation Resource Guide
Bioremediation
Articles 54-55
bial biofilms. By combining a variety of techniques (e.g., se-
lective extraction, microscopy, spectroscopy and miniaturised
sensors), it is possible to gain high-resolution structural and
chemical information of biofilms on a level of the individual
cell. This approach will facilitate the characterization of the
metal immobilisation sites and the metal sorption and
(bio)crystallisation mechanisms in biofilms. The results pro-
vided by the combination of these techniques will allow to
predict the amount of metal accumulation in biofilms as well
as their chemical speciation. This review demonstrates that
an interdisciplinary approach is required to study metal fate
within the biofilm matrix.
Website: http://www.kluweronline.com/issn/1569-1705/
contents
(54) Wang, S, PR Jaffe, G Li, SWWang and HA Rabitz.
2003. Simulating bioremediation of uranium-contami-
nated aquifiers; uncertainty assessment of model pa-
rameters. Journal of Contaminant Hydrology Q4: 283-
307.
Radionuclides addressed:
226Ra
U *
137Cs
Pu
Th
Technology: Biorem.
99Tc
90Sr
other
Media: GW
Abstract: Bioremediation of trace metals and radionuclides
in groundwater may require the manipulation of redox con-
ditions via the injection of a carbon source. For example, af-
ter nitrate has been reduced, soluble U(VI) can be reduced
simultaneously with other electron acceptors such as Fe(III)
or sulfate to U(IV), which may precipitate as a solid (uraninite).
To simulate the numerous biogeochemical processes that will
occur during the bioremediation of trace- metal-contaminated
aquifers, a time-dependent one-dimensional reactive transport
model has been developed. The model consists of a set of
coupled mass balance equations, accounting for advection,
hydrodynamic dispersion, and a kinetic formulation of the
biological or chemical transformations affecting an organic
substrate, electron acceptors, corresponding reduced species,
and trace metal contaminants of interest, uranium in this study.
This set of equations is solved numerically, using a finite dif-
ference approximation. The redox conditions of the domain
are characterized by estimating the pE, based on the concen-
tration of the dominant terminal electron acceptor and its
corresponding reduced species. This pE and the concentra-
tions of relevant species are then used by a modified version
of MINTEQA2, which calculates the speciation/sorption and
precipitation/dissolution of the species of interest under equi-
librium conditions. Kinetics of precipitation/dissolution pro-
cesses are described as being proportional to the difference
between the actual and calculated equilibrium concentration.
A global uncertainty assessment, determined by Random Sam
pling High Dimensional Model Representation (RS-HDMR),
was performed to attain a phenomenological understanding
of the origins of output variability and to suggest input pa-
rameter refinements as well as to provide guidance for field
experiments to improve the quality of the model predictions.
By decomposing the model output variance into its different
input contributions, RS-HDMR can identify the model inputs
with the most influence on various model outputs, as well as
their behavior pattern on the model output. Simulations are
performed to illustrate the effect of biostimulation on the
fate of uranium in a saturated aquifer, and to identify the key
processes that need to be characterized with the highest accu-
racy prior to designing a uranium bioremediation scheme.
Website: http://www.sciencedirect.com/science/journal/
01697722
(55) Weber KA, SM O'Connor and JD Coates. 2003.
Radionuclide immobilization by the formation of crys-
talline Fe compounds resulting from the bio-oxidation
of Fe(ll) by Dechlorosoma suillum. Abstracts of the
General Meeting of the American Society for Microbi-
ology 103: Q-395.
Radionuclides addressed:
226Ra
U *
137Cs
Pu
Th
Technology: Biorem.
"Tc
90Sr
other
Media: Soil,
SW
Abstract: Previous studies examining microbial attenuation
of heavy metals and radionuclide (HMR) contamination have
demonstrated the potential of nitrate-dependent Fe(II) oxi-
dation for immobilization of HMR in sedimentary environ-
ments. Further investigation of the biogenic iron mineral
phases produced by Dechlorosoma suillum strain PS in the
presence of lOOmuM U(VI) were analyzed by density gradi-
ent centrifugation which resulted in the recovery of five dis-
tinct fractions. Differential solubility analysis of 0.5M HC1-
extractable Fe and 3M HCl-extractable Fe of each of these
fractions indicated a positive correlation between fraction
density and crystallinity. Percent of 0.5M HCl-extractable Fe
decreased from 100% to 3% with an increase in sucrose con-
centration (20 to 60%) indicating separation of crystalline Fe
ecreased from 100% to 3% with an increase in sucrose con-
centration (20 to 60%) indicating separation of crystalline Fe
compounds. Analysis of total iron content in each fraction
revealed that most of the iron (>86%) was present in the more
dense crystalline phases. The ratio of 3M HC1- extractable
Fe(II) to total Fe (0.68) was also highest in this fraction of
which only 1% of the Fe(II) was extractable in 0.5M HC1 sug-
gesting crystalline mixed Fe(II)/Fe(III) phases. Analysis of
the U(VI) content revealed that the majority (apprx80%) of
the U(VI) was also associated with the most dense crystalline
phase (3% 0.5M HCl-extractable Fe). These results dem-
onstrate that biogenic crystalline Fe compounds can seques
42
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Radionuclide Biological
Remediation Resource Guide
Biore media tion
Articles 56-59
ter significant proportions of HMR (U(VI)). The formation
of a mixed phase crystalline Fe compound sequestering a sig-
nificant proportion of U(VI) is an ideal remediation strategy
as this compound associated with the U(VI) would not be
easily re-mobilized by microbial reductive dissolution of Fe.
(56) Francis, AJ. 2002. Microbial transformations of
uranium and environmental restoration through
bioremediation. Pp. 137-138 In Proceedings of the In-
ternational Workshop 'Uranium Deposits: From Their
Genesis to Their EnvironmentalAspects.'Kribek, Band
J Zeman, eds. Czech Geological Survey, Prague.
Radionuclides addressed: I 137Cs I 90Sr
226Ra
U
Pu
Th
"Tc
other
Technology: Biorem. | Media: Soil, GW, SW
Abstract: Microorganisms present in the natural environment
play a significant role in the mobilization and immobilization
of uranium. Fundamental understanding of the mechanisms
of microbiological transformations of various chemical forms
of uranium present in wastes and contaminated soils and water
has led to the development of novel bioremediation processes.
One process uses anaerobic bacteria to stabilize the radionu-
clides and toxic metals from the waste, with a concurrent re-
duction in volume due to the dissolution and removal of non-
toxic elements from the waste matrix. In another process, ura-
nium and other toxic metals are removed from contaminated
soils and wastes by extracting with the chelating agent citric
acid. Uranium is recovered from the citric acid extract after
biodegradation/photodegradation in a concentrated form as
UO3'2H2O for recycling or appropriate disposal.
(57) Gadd, GM. 2002. Microbial interactions with met-
als/radionuclides:the basis of bioremediation. Pp.179-
203 In Radioactivity in the Environment. Keith-Roach,
MJ and FR Livens, eds. Elsevier Science Ltd., Oxford,
UK.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Biorem.
"Tc
other
90Sr
General
Media: Soil, GW, SW
Abstract: This paper discusses certain microbiological pro-
cesses which are of significance in determining radionuclide/
metal mobility and which have actual or potential applica-
tions in bioremediation of metal/radionuclide and metalloid
pollution. These include autotrophic and heterotrophic leach-
ing, biosorption (by cell walls and associated components and
by free and immobilized biomass), metal reduction and pre-
cipitation, metal-binding proteins, polys accharides and other
biomolecules, and metalloid transformation.
(58) Haveman, SA and K Pedersen. 2002. Microbially
mediated redox processes in natural analogues for
radioactive waste. Journal of Contaminant Hydrology
55:161-174.
Radionuclides addressed:
226Ra
U *
137Cs
Pu
Th
Technology: Biorem.
"Tc
90Sr
other
Media: GW
Abstract: Natural analogues allow scientists to investigate
biogeochemical processes relevant to radioactive waste dis-
posal that occur on time scales longer than those that may be
studied by time-limited laboratory experiments. The Palmottu
U-Th deposit in Finland and the Bangombe natural nuclear
reactor in Gabon involve the study of natural uranium, and
are both considered natural analogues for subsurface radio-
active waste disposal. The microbial population naturally
present in groundwater may affect the redox conditions, and
hence, the radionuclide solubility and migration. Therefore,
groundwater samples from the two sites were investigated
for microbial populations. The total numbers of cells ranged
from 104 to 106 cells ml4. Iron-reducing bacteria (IRB) were
the largest culturable microbial population in the Palmottu
groundwater and were present at up to 1.3 x 105 cells ml4.
Sulfate-reducing bacteria (SRB) and acetogens could also be
cultured from the Palmottu groundwater. The numbers of
IRB and SRB were largest in groundwater with the lowest
uranium concentrations. Removal of dissolved U(VI) from
solution was concomitant with the growth of IRB enrich-
ment cultures and the reduction of iron. The redox buffer in
the Palmottu groundwater consists of iron and uranium spec-
cies, both of which are affected by IRB. IRB and aerobic
heterotrophs were cultured from the Bangombe groundwa-
ter, where redox potentials are buffered by iron and organic
carbon species. Microbial populations similar to those
found at Palmottu and Bangombe are found throughout the
Fennoscandian Shield, a potential host rock for subsurface
radioactive waste disposal. These results confirm that micro-
organisms can be expected to play a role in stabilizing radio-
active waste disposed of in the subsurface by lowering redox
potential and immobilizing radionuclides.
Website: http://www.sciencedirect.com/science/journal/
01697722
(59) Yohey, S, SD Kelley, KM Kemner and JF Banfield.
2002. Radionuclide contamination: nanometre-size
products of uranium bioreduction. Nature 419: 134.
Radionuclides addressed:
137Cs
90Sr
226Ra
U
Pu
Th
"Tc
other
Technology: Biorem.
Media: Soil, SW
43
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Radionuclide Biological
Remediation Resource Guide
Biore media tion
Articles 60-63
Abstract: One strategy that is being pursued to tackle the
international problem of actinide contamination of soils, sedi-
ments and water is to use microbial activity to 'fix' these ra-
dionuclides into an insoluble form that cannot be readily dis-
persed. Here we show that uraninite (UO2) particles formed
from uranium in sediments by bacterial reduction are typi-
cally less than 2 nanometres across and that the small size has
important implications for uraninite reactivity and fate. Be-
cause these tiny particles may still be transported in an aque-
ous environment, precipitation of uranium as insoluble ura-
ninite cannot be presumed to immobilize it.
Website: http://www.nature.com/nature
(60) Barkay, T and J Schaefer. 2001. Metals and ra-
dionuclide bioremediation: issues, considerations and
potentials. Current Opinion in Microbiology 4: 318-
323.*
Radionuclides addressed:
226Ra
U *
137Cs
Pu
Th
Technology: Biorem.
"Tc
other
Media: Soil
90Sr
*
General
GW, SW
Abstract: Recent demonstrations of the removal and immo-
bilization of inorganic contaminants by microbial transfor-
mations, sorption and mineralization show the potential of
both natural and engineered microbes as bioremedial tools.
Demonstrations of microbe-mediated mineral formation in
biofilms implicate this mode of microbial life in geological
evolution and remediation of inorganic contaminants.
Website: http://www.sciencedirect.com/science/journal/
13695274
(61) Groudev, SN, PS Georgiev, II Spasova and K
Komnitsas. 2001. Bioremediation of a soil contami-
nated with radioactive elements. Hydrometallurgy 59:
311-318.
Radionuclides addressed:
226Ra *
U *
137Cs
Pu
Th "A"
Technology: Biorem.
"Tc
90Sr
other
Media: Soil
Abstract: Some agricultural lands located in the Vromos Bay
area, near the Black Sea coast, Southeastern Bulgaria, have
been contaminated with radioactive elements (uranium, ra-
dium and thorium) and toxic heavy metals (copper, cadmium
and lead) as a result of mining and mineral processing of
polymetallic ores. Laboratory experiments carried out with
soil samples from these lands revealed that an efficient
remediation of the soils was achieved by an in situ treatment
method based on the activity of the indigenous soil microf-
lora. The treatment was connected with the dissolution of
the contaminants in the upper soil horizons and their trans
fer into the deeply located soil horizons (mainly to the hori-
zon B ) where they were immobilized as different insoluble
compounds. The dissolution of contaminants was connected
with the activity of both heterotrophic and chemolithotrophic
aerobic microorganisms and the immobilization was due
mainly to the anaerobic sulphate-reducing bacteria. The ac-
tivity of these microorganisms was enhanced by suitable
changes in the levels of some essential environmental factors
such as water, oxygen and nutrient contents in the soil. On
the basis of the above-mentioned laboratory results, the
method was then applied under real field conditions in a
heavily contaminated experimental plot of land located in
the Vromos Bay area. Within 8 months of treatment, the con-
tents of radioactive elements and toxic heavy metals in the
soil were decreased below the relevant permissible levels.
Website: http://www.sciencedirect.com/science/journal/
0304386X
(62) Lloyd, JR and DR Lovley. 2001. Microbial detoxifi-
cation of metals and radionuclides. Current Opinion in
Biotechnology 12: 248-253. *
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Biorem.
"Tc
other
Media: Soil
90Sr
General
GW, SW
Abstract: Microorganisms have important roles in the bio-
geochemical cycling of toxic metals and radionuclides. Re-
cent advances have been made in understanding metalmi-
crobe interactions and new applications of these processes to
the detoxification of metal and radionuclide contamination
have been developed.
Website: http://www.sciencedirect.com/science/journal/
09581669
(63) Fredrickson, JK, HM Kostandarithes, SWLi, AE
Plymale and MJ Daly. 2000. Reduction of Fe(lll), Cr(VI),
U(VI), and Tc(VII) by Deinococcus radiodurans R1.
Applied and Environmental Microbiology 66: 2006-
2011.
Radionuclides addressed:
226Ra
U *
137Cs
Pu
Th
Technology: Biorem.
"Tc
90Sr
*
other
Media: Soil
GW, SW
44
Abstract: Deinococcus radiodurans is an exceptionally radia-
tion-resistant microorganism capable of surviving acute ex-
posures to ionizing radiation doses of 15,000 Gy and previ-
ously described as having a strictly aerobic respiratory me-
tabolism. Under strict anaerobic conditions, D radiodurans
Rl reduced FefHIVnitrilotriacetic acid coupled to the oxida-
*= Review Article
-------
Radionuclide Biological
Remediation Resource Guide
Bio re media tion
Articles 65-66
tion ot lactate to LUZ and acetate but was unable to link this
process to growth. D. radiodurans reduced the humic acid
analog anthraquinone-2,6-disulfonate (AQDS) to its
dihydroquinone form, AH2DS, which subsequently trans-
ferred electrons to the Fe(III) oxides hydrous ferric oxide
and goethite via a previously described electron shuttle mecha-
nism. D. radiodurans reduced the solid-phase Fe(III) oxides
in the presence of either 0.1 mM AQDS or leonardite humic
acids (2 mg ml4) but not in their absence. D. radiodurans also
reduced U(VI) and Tc(VII) in the presence of AQDS. In con-
trast, Cr(VI) was directly reduced in anaerobic cultures with
lactate although the rate of reduction was higher in the pres-
ence of AQDS. The results are the first evidence that D.
radiodurans can reduce Fe(III) coupled to the oxidation of
lactate or other organic compounds. Also, D. radiodurans, in
combination with humic acids or synthetic electron shuttle
agents, can reduce U and Tc and thus has potential applica-
tions for remediation of metal- and radionuclide-contami-
nated sites where ionizing radiation or other DNA-damaging
agents may restrict the activity of more sensitive organisms.
Website: http://aem.asm.Org/cgi/content/abstract/66/5/
2006
(64) Lloyd, JR, VA Sole, CVG Van Praagh and DR
Lovley. 2000. Direct and Fe(ll)-mediated reduction of
technetium by Fe(lll)-reducing bacteria. Applied and
Environmental Microbiology 66: 3743-3749.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Biorem.
"Tc
90Sr
*
other
Media: Soil, SW
Abstract: The dissimilatory Fe (111)-reducing bacterium
Geobacter sulfurreducens reduced and precipitated Tc(VII) by two
mechanisms. Washed cell suspensions coupled the oxidation
of hydrogen to enzymatic reduction of Tc(VII) to Tc(IV),
leading to the precipitation of TcO2 at the periphery of the
cell. An indirect, Fe(II)-mediatedmechanism was also identi-
fied. Acetate, although not utilized efficiently as an electron
donor for direct cell-mediated reduction of technetium, sup-
ported the reduction of Fe(III), and the Fe(II) formed was
able to transfer electrons abiotically to Tc(VII). Tc(VII) re-
duction was comparatively inefficient via this indirectmecha-
nism when soluble Fe(III) citrate was supplied to the cultures
but was enhanced in the presence of solid Fe(III) oxide. The
rate of Tc(VII) reduction was optimal, however, when Fe(III)
oxide reduction was stimulated by the addition of the humic
analog and electron shuttle anthaquinone-2,6-disulfonate, lead-
ing to the rapid formation of the Fe(II)-bearing mineral mag-
netite. Under these conditions, Tc(VII) was reduced and pre-
cipitated abiotically on the nanocrystals of biogenic magne-
tite as TcO2 and was removed from solution to concentra
tions below the limit of detection by scintillation counting.
Cultures of Fe(III)-reducing bacteria enriched from radio-
nuclide-contaminated sediment using Fe(III) oxide as an elec-
tron acceptor in the presence of 25 |j,M Tc(VII) contained a
single Geobaftersp. detected by 16S ribosomal DNA analysis
and were also able to reduce and precipitate the radionuclide
via biogenic magnetite. Fe(III) reduction was stimulated in
aquifer material, resulting in the formation of Fe(II)-con tain-
ing minerals that were able to reduce and precipitate Tc(VII).
These results suggest that Fe(III)-reducing bacteria may play
an important role in immobilizing technetium in sediments
via direct and indirect mechanisms.
Website: http://aem.asm.Org/cgi/content/abstract/66/9/
3743
(65) Lloyd, JR, P Yong and LE Macaskie. 2000. Bio-
logical reduction and removal of Np(V) by two micro-
organisms. Environmental Science & Technology 34:
1297-1301.
Radionuclides addressed:
226Ra
U
Pu 1
137Cs
t
Th "A"
Technology: Biorem.
"Tc
other
90Sr
Np
Media: GW, SW
Abstract: The majority of the radionuclides generated by
the nuclear fuel cycle can be removed during established
remediation processes. However among the long-lived, alpha-
emitting actinides neptunium(V) is recalcitrant to removal
from solution by physicochemical or bio technological meth-
ods. The latter include a biocrystallization process, based on
the enzymatic liberation of phosphate as a precipitating ligand
by a Citrobacter^., which was previously shown to precipitate
tetravalent actinides such as Th(IV) and Pu(IV) as their cor-
responding phosphates. Np(V) was reduced to a lower va-
lence (probably Np(IV)) by ascorbic acid or biologically, us-
ing the reductive capability of Shewanellaputrefadens, but re-
duction alone did not desolubilize Np. However Np(V) was
removed by the two organisms, S. putrefadens and Citrobacter
sp. in concert; bioreduction to Np(IV) by S'. putrefadens, to-
gether with phosphate liberation by the Citrobacter sp., per-
mitted bioprecipitative removal of 237Np as well as its daugh-
ter 233protactinium. Tests were made possible by a novel tech-
nique permitting actinide separation by paper chromatogra-
phy followed by quantification of the radioactive species us-
ing a phosphorlmager. This study has implications for the
development of methods to remove Np(V) from solution,
by the simple combination of two biotechnological methods,
which can succeed where chemical treatments are ineffec-
tive.
Website: http://pubs.acs.org/journals/esthag
45
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Radionuclide Biological
Remediation Resource Guide
Bioremediation
Articles 67-68
(66) Macaskie, LE, KM Bonthrone, P Yong and DT
Goddard. 2000.Enzymatically mediated bioprecipitation
of uranium by Citrobacter sp.: a concerted role for
exocellular lipopolysaccharide and associated phos-
phatase in biomineral formation. Microbiology 146:
1855-1867.
Radionuclides addressed:
226Ra
U *
137Cs
Pu
Th
Technology: Biorem.
99Tc
90Sr
other
Media: SW
Abstract: A Citrobacter sp. accumulated uranyl ion (UO22+)
via precipitation with phosphate ligand liberated by phos-
phatase activity. The onset and rate of uranyl phosphate depo-
sition were promoted by NH4+, forming NH4UO2PO4, which
has a lower solubility product than NaUO2PO4. This accel
decoupled the rate-limiting chemical crystallization process
from the biochemical phosphate ligand generation. This pro-
vided a novel approach to monitor the cell-surface-associated
changes using atomic-force microscopy in conjunction with
transmission electron microscopy and electron-probe X-ray
micro analysis, to visualize deposition of uranyl phosphate at
the cell surface. Analysis of extracted surface materials by 31P
NMRspectroscopy showed phosphorus resonances at chemi-
cal shifts of 0.3 and 2.0 p.p.m., consistent with monophos-
phate groups of the lipid A backbone of the lipopolysaccha-
ride (LPS). Addition of UO22+ to the extract gave a yellow
precipitate which contained uranyl phosphate, while addition
of Cd2+ gave a chemical shift of both resonances to a single
new resonance at 3 p.p.m. Acid-phosphatase-mediated crys-
tal growth exocellularly was suggested by the presence of acid
phosphatase, localizedby immunogold labelling, on the outer
membrane and on material exuded from the cells. Metal depo-
sition is proposed to occurvia an initial nucleation with phos-
phate groups localized within the LPS, shown by other work-
ers to be produced exocellularly in association with phos-
phatase. The crystals are further consolidated with additional,
enzymically generated phosphate in close juxtaposition, giv-
ing high loads of LPS-bound uranyl phosphate without loss
of activity and distinguishing this from simple biosorption,
or periplasmic or cellular metal accumulation mechanisms.
Accumulation of 'tethered' metal phosphate within the LPS
is suggested to prevent fouling of the cell surface by the accu-
mulated precipitate and localization of phosphatase
exocellularly is consistent with its possible functions in
homeostatis and metal resistance.
Website: http://mic.sgmjournals.org
(67) Smith, RW, DM Cosgrove, JLTaylor, Y Fujita, FS
Colwell,TL McLing. 2000. Remediation of metal con-
taminants by microbially mediated calcite precipitation.
Idaho National Engineering and Environmental Labo-
ratory, Idaho Falls, ID
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Biorem.
"Tc
90Sr *
other
Media: GW
Abstract: Radionuclide and metal contaminants such as 90Sr
are present beneath U.S. Department of Energy (DOE) lands
in both the groundwater (e.g., 100-N area at Hanford, WA)
and vadose zone (e.g., Idaho Nuclear Technology and Engi-
neering Center at the Idaho National Engineering and Envi-
ronmental Laboratory [INEEL]). In situ containment and
stabilization of these contaminants is a cost-effective treat-
ment strategy. However, implementing in situ containment
and stabilization approaches requires definition of the mecha-
nisms that control contaminant sequestration. We are investi-
gating the in situ immobilization of radionuclides or contam-
inant metals (e.g., 90Sr) by their facilitated co-precipitation
with calcium carbonate in groundwater and vadose zone
systems. Our facilitated approach relies upon the hydrolysis
of introduced urea to cause the acceleration of calcium
carbonate precipitation (and trace metal co-precipitation) by
increasing pH and alkalinity and liberating cations from the
aquifer matrix by exchange reactions.
H2NCONH2 + 3H2O ->2NH4+ + HCO; + OET
>X:2Ca + 2NH4+ -» 2>X:NH4 + Ca2+
Ca2+ +HCO; + OR- ->CaCO3(s) + H2O
where >X: is a cation exchange site on the aquifer matrix.
Subsurface urea hydrolysis is catalyzed by the urease enzyme,
which is produced in situ by native urea hydrolyzing
microorganisms. Because the precipitation process tends to
be irreversible and many western aquifers are saturated with
respect to calcite, the co-precipitated metals and radionuclides
will be effectively removed from the aqueous phase over the
long-term. Our ongoing research has shown that a) urea hy-
drolyzing microorganisms are ubiquitous in the Snake River
Plain Aquifer underlying the INEEL) b) urea hydrolysis and
calcite precipitation are linked, in laboratory and field settings,
and c) Sr^ is incorporated into calcite precipitated by urea
hydrolyzers with higher distribution coefficients than in abi-
otic systems. These experimental results and observations
have been embodied in a commercially available geochemical
and reactive transport computer code that allows field-scale
simulations of the urea hydro lysis-calcite precipitation pro-
cess. The mixed equilibrium-kinetic model accounts for urea
46
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Radionuclide Biological
Remediation Resource Guide
Bioremediation
Articles 68-69
hydrolysis by ureolytic bacteria and calcite precipitation/dis-
solution using kinetic expressions. Additionally, possible mi-
crobial nitrification and its associated consumption of dis-
solved oxygen and production of acid are accounted for us-
ing a kinetic expression. Cation exchange reactions and metal
partitioning into the precipitated calcite are treated as equi-
librium processes. Simulation of a hypothetical remediation
in the Snake River Plain Aquifer using mM levels of urea
shows that almost 1 mmole of calcite is precipitated per mmole
of hydrolyzed urea, with most of the precipitated cations being
derived from exchange of NH4+ with the aquifer matrix.
Because of the cation exchange reactions and the near ab-
sence of NH4+ in the groundwater, the long-term persistence
of the precipitated calcite is a function of the applied urea
concentration and the total cation exchange capacity of the
aquifer matrix. Our simulation results suggest that with ap-
propriate urea introduction strategies calcite precipitation can
provide for the long term in situ sequestration of radionu-
clides and metals.
Website: http//www.irna.org
(68) Wildung, RE, YA Gorby, KM Krupka, NJ Hess,
SW Li, AE Plymale, JP McKinley and JK Fredrickson.
2000. Effect of electron donor and solution chemistry
on products of dissimilatory reduction of technetium
by Shewanella putrefaciens. Applied and Envimnmen-
tal Microbiology 66: 2451 -2460.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Biorem.
"Tc
90Sr
*
other
Media: GW
Abstract: To help provide a fundamental basis for use of
microbial dissimilatory reduction processes in separating or
immobilizing "Tc in waste or groundwaters, the effects of
electron donor and the presence of the bicarbonate ion on
the rate and extent of pertechnetate ion [Tc(VII)O4~] enzy-
matic reduction by the subsurface metal-reducing bacterium
Sheivanellaputrefadens CN32 were determined, and the forms
of aqueous and solid-phase reduction products were evalu-
ated through a combination of high-resolution transmission
electron microscopy, X-ray absorption spectroscopy, and ther-
modynamic calculations. When H2 served as the electron do-
nor, dissolved Tc(VII) was rapidly reduced to amorphous
Tc(IV) hydrous oxide, which was largely associated with the
cell in unbuffered 0.85% NaCl and with extracellular particu-
lates (0.2 to 0.001 (am) in bicarbonate buffer. Cell-associated
Tc was present principally in the periplasm and outside the
outer membrane. The reduction rate was much lower when
lactate was the electron donor, with extracellular Tc(IV) hy-
drous oxide the dominant solid-phase reduction product, but
in bicarbonate systems much less Tc(IV) was associated di-
rectly with the cell and solid-phase Tc(IV) carbonate may have
been present. In the presence of carbonate, soluble (<0.001
|om) electronegative, Tc(IV) carbonate complexes were also
formed that exceeded Tc(VII)O4 in electrophoretic mobility.
Thermodynamic calculations indicate that the dominant re-
duced Tc species identified in the experiments would be stable
over a range of Eh and pH conditions typical of natural wa-
ters. Thus, carbonate complexes may represent an important
pathway for Tc transport in anaerobic subsurface environ-
ments, where it has generally been assumed that Tc mobility
is controlled by low-solubility Tc(IV) hydrous oxide and ad-
sorptive, aqueous Tc(IV) hydrolysis products.
Website: http://aem.asm.Org/cgi/content/abstract/66/6/
2451
(69) Lloyd, JR, J Ridley, T Khizniak, NN Lyalikova, and
LE Macaskie. 1999. Reduction of technetium by
Desulfovibrio desulfuricans: biocatalyst characteriza-
tion and use in flowthrough bioreactor. Applied Envi-
ronmental Microbiology 65: 2691-2696.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Biorem.
"Tc
90Sr
if
other
Media: SW
Abstract: Resting cells of Desulfovibrio desulfuricans coupled the
oxidation of a range of electron donors to Tc(VII) reduc-
tion. The reduced technetium was precipitated as an insoluble
low-valence oxide. The optimum electron donor for the
biotrans formation was hydrogen, although rapid rates of re-
duction were also supported when formate or pyruvate was
supplied to the cells. Technetium reduction was less efficient
when the growth substrates lactate and ethanol were supplied
as electron donors, while glycerol, succinate, acetate, and
methanol supported negligible reduction. Enzyme activity was
stable for several weeks and was insensitive to oxygen. Trans-
mission electron microscopy showed that the radionuclide was
precipitated at the periphery of the cell. Cells poisoned with
Cu(II), which is selective for periplasmic but not cytoplasmic
hydrogenases, were unable to reduce Tc(VII), a result consis-
tent with the involvement of a periplasmic hydrogenase in
Tc(VII) reduction. Resting cells, immobilized in a flowthrough
membrane bioreactorand supplied with Tc(VII)-supplemented
solution, accumulated substantial quantities of the radionu-
clide when formate was supplied as the electron donor, indi-
cating the potential of this organism as abiocatalyst to treat
Tc-contaminated wastewaters.
Website: http://aem.asm.Org/cgi/content/abstract/65/6/
2691
47
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Radionuclide Biological
Remediation Resource Guide
(70) Lloyd, JR, GH Thomas, JA Finlay, JA Cole and LE
Macaskie. 1999. Microbial reduction of technetium by
Escherichia coli and Desulfovibrio desulfuricans: en-
hancement via the use of high-activity strains and ef-
fect of process parameters. Biotechnology and
Bioengineering 66:122-130.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Biorem.
"Tc
90Sr
*
other
Media: SW
Abstract: Escherichia coli and Desulfovibrio desulfuricans reduce
Tc(VII) (TcO4~) with formate or hydrogen as electron donors.
The reaction is catalyzed by the hydrogenase component of
the formate hydrogenlyase complex (FHL) of E. coli and is
associated with a periplasmic hydrogenase activity in D.
desulfuricans. Tc(VII) reduction in E. coli by H2 and formate
was either inhibited or repressed by 10 mM nitrate. By con-
trast, Tc(VII) reduction catalyzed by D. desulfuricans was less
sensitive to nitrate when formate was the electron donor, and
unaffected by 10 mM or 100 mM nitrate when H2 was the
electron donor. The optimum pH for Tc(VII) reduction by
both organisms was 5.5 and the optimum temperature was
40°C and 20°C for E. coli and D. desulfuricans, respectively. Both
strains had an apparent Km for Tc(VII) of 0.5 mM, but Tc(VII)
was removed from a solution of 300 nMTcO4~ within 30 h by
D. desulfuricans at the expense of H2. The greater bioprocess
potential of D. desulfuricans was shown also by the K for for-
mate (>25 mM and 0.5 mM for E. coli and D. desulfuricans,
respectively), attributable to the more accessible, periplasmic
localization of the enzyme in the latter. The relative rates of
Tc(VII) reduction for E. coli and D. desulfuricans (with H2) were
12.5 and 800 micromol Tc(VII) reduced/gbiomass/h, but
the use of an E. coli HycA mutant (which upregulates FHL
activities by approx. 50%) had a similarly enhancing effect on
the rate of Tc reduction. The more rapid reduction of Tc(VII)
by D. desulfuricans compared with the E. coli strains was also
shown using cells immobilized in a hollow-fiber reactor, in
which the flow residence times sustaining steady-state removal
of 80% of the radionuclide were 24.3 h for the wild-type E.
coli, 4.25 h for the upregulated mutant, and 1.5 h for D.
Website: http://www3.interscience.wiley.com/cgi-bin/
jhome/71002188
(71) Macaskie, L. Report on 1st Euroconference on
bacterial-metal/radionuclide interactions: basic re-
search and bioremediation. Environmental Microbiol-
ogy 1: 185-186.
Biore media tion
Articles 70-74
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Biorem.
"Tc
90Sr
other General
Media: Soil, GW, SW
Abstract: No abstract available.
(72) Selenska-Pobell, S and H Nitsche, eds. 1999. Bac-
terial-Metal/Radionuclide Interaction. Euroconference
of Forschungszentrum Rossendorf, Dresden, Ger-
many. 114 pp.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Biorem.
"Tc
other
Media: Soil
90Sr
*
General
GW, SW
Abstract: This issue contains five sessions about radionuclide-
bacteria interactions in the presence of metals like uranium
and transuranium elements in sediments.
Order Number: DE99749745, Report Number: FZR-252 ,
CONF-981226,
(73) Stephen, JR and SJ Macnaughton. 1999. Devel-
opments in terrestrial bacterial remediation of metals.
Current Opinion in Biotechnology 10: 230-233. *
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Biorem.
"Tc
other
Media: Soil
90Sr
General
SW
Abstract: Recent advances in understanding the role and ap-
plication of bacteria to the remediation of toxic metal and
radionuclide contaminated terrestrial environments have come
from several avenues. Novel species capable of mobilization
and immobilization of metal ions have been discovered.
Remediation of toxicity has been accelerated by nutrient
amendment, the use of chelating agents and novel methods
for phosphate amendment. Major advances in the use of natu-
ral and genetically engineered species for bioprotection and
remediation of organic co-contaminants have been reported.
Construction of wetland function continues to be developed
for containment and decontamination of wastewaters.
Website: http://www.sciencedirect.com/science/journal/
09581669
(74) Bahaj, AS, IW Croudace, PAB James, FD
Moeschler and PE Warwick. 1998. Continuous radio-
nuclide recovery from wastewater using magnetotactic
bacteria. Journal of Magnetism and Magnetic Materi-
al's184: 241 -244.
48
Review Article
-------
Radionuclide Biological
Remediation Resource Guide
Bioremediation
Articles 75-77
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Biorem.
"Tc
other
90Sr
General
Media: SW
Abstract: Magnetotactic bacteria (MTB) can be magnetically
removed and harvested from samples collected from ponds
and streams. This is achieved by placing a permanent magnet
at the sediment/water interface of a sample container. The
bacteria swim along field lines, accumulating at regions close
to the pole of the magnet. This is the basic principle of Ori-
entation Magnetic Separation (OMS), where the applied mag-
netic field is utilised to orientate the bacteria to swim in a
specific direction. This paper describes the use of MTB for
bio accumulation and radionuclide removal from wastewater
using an OMS system.
Website: http://www.sciencedirect.com/science/journal/
03048853
(75) Francis, AJ. 1998. Bioremediation of uranium con-
taminated soils and wastes. Pp. 340-346 In Uranium
mining and hydrogeology II. Merkel, B and C Helling,
eds. Koeln, Freibert, Germany.
Radionuclides addressed:
226Ra
U *
137Cs
Pu
Th
Technology: Biorem.
"Tc
other
90Sr
General
Media: Soil, SW
Abstract: Contamination of soils, water, and sediments by
radionuclides and toxic metals from uranium mill tailings,
nuclear fuel manufacturing and nuclear weapons production
is a major concern. Studies of the mechanisms of biotrans-
formation of uranium and toxic metals under various micro-
bial process conditions has resulted in the development of
two treatment processes: (i) stabilization of uranium and toxic
metals with reduction in waste volume and (ii) removal and
recovery of uranium and toxic metals from wastes and con-
taminated soils. Stabilization of uranium and toxic metals in
wastes is accomplished by exploiting the unique metabolic ca-
pabilities of the anaerobic bacterium, Clostridium sp. The ra-
dionuclides and toxic metals are solubilized by the bacteria
directly by enzymatic reductive dissolution, or indirectly due
to the production of organic acid metabolites. The radionu-
clides and toxic metals released into solution are immobilized
by enzymatic reductive precipitation, biosorption and redis-
tribution with stable mineral phases in the waste. Non-haz-
ardous bulk components of the waste such as Ca, Fe, K, Mg
and Na released into solution are removed, thus reducing the
waste volume. In the second process uranium and toxic met-
als are removed from wastes or contaminated soils by extract-
ing with the complexing agent citric acid. The citric-acid ex-
tract is subjected to biodegradation to recover the toxic met
als, followed by photochemical degradation of the uranium
citrate complex which is recalcitrant to biodegradation. The
toxic metals and uranium are recovered in separate fractions
for recycling or for disposal. The use of combined chemical
and microbiological treatment process is more efficient than
present methods and should result in considerable savings in
clean-up and disposal costs.
Report Number: CONF-980981
(76) Francis, AJ and CJ Dodge. 1998. Remediation of
soils and wastes contaminated with uranium and toxic
metals. Environmental Science & Technology 32:3993-
3998.
Radionuclides addressed:
226Ra
U *
137Cs
Pu
Th «
Technology: Biorem.
99Tc
90Sr *
other
Media: Soil, SW
Abstract: The presence of radionuclides and toxic metals in
soils and wastes due to nuclear related activities is a major
environmental concern. To restore the contaminated sites,
both the radionuclides and toxic metals must be removed.
We have developed a comprehensive method to remediate
contaminated soils and wastes with the removal and recovery
of uranium and toxic metals. The overall process consists of
three steps: extraction, biodegradation, and photodegradation.
Radionuclides and toxic metals are removed from contami-
nated soils and wastes by extracting them with citric acid, a
natural multidentate complexing agent. Citric acid forms dif-
ferent types of complexes with the transition metals and ac-
tinides that may involve the formation of bidentate, triden-
tate, binuclear, or polynuclear complex species. Several metal-
citrate complexes were readily biodegraded by Pseudomonas
fluorescens, resulting in the bioprecipitation and recovery of
the metals, whereas uranyl citrate, which is recalcitrant to bio-
degradation, upon exposure to light was photodegraded with
the precipitation of uranium as UO3 -xH2O. For example, ura-
nium was removed from contaminated soils and sludge with
>85% efficiency. Biodegradation followed by
photodegradation of the citric acid extract resulted in >99%
recovery of the extracted uranium. In addition, significant
amounts of Al, Ca, Co, Cr, Cu, Mg, Mn, Ni, Pb, Sr, Th, and
Zn were also removed during biodegradation of the extract.
In this process, the toxic metals and uranium are recovered
in separate fractions in concentrated form for recycling or
disposal.
Website: http://pubs.acs.org/journals/esthag
(77) Lloyd, JR, H-F Molting, VA Sole, K Bosecker and
LE Macaskie. 1998. Technetium reduction and precipi-
tation by sulfate-reducing bacteria. Geomicrobiology
Journal 15: 45-58.
49
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Radionuclide Biological
Remediation Resource Guide
Bio re media tion
Articles 78-80
Radionuclides addressed:
226Ra Pu
U Th
Technology: Biorem.
137Cs 90Sr
99Tc +
other
Media: SW
Abstract: Resting cells of the sulfate-reducing bacterium
Desulfovibrio desulfuricans ATCC 29577 were able to pre-
cipitate the radionuclide technetium, supplied as the
pertechnetate anion (TcO4~), under anaerobic conditions by
two discrete mechanisms. Sulfidogenic cultures, supplied with
sulfate and lactate as an electron acceptor and donor, respec-
tively, precipitated the radionuclide as an insoluble sulfide.
Using electron microscopy in combination with energy-dis-
persive x-ray analysis (EDAX), the precipitate was shown to
be extracellular, and contained S as the major element at a
fivefold stoichiometric excess to Tc as quantified by proton-
induced x-ray emission analysis (PIXE). With hydrogen sup-
plied as the electron donor, the pertechnetate anion was uti-
lized as an alternative electron acceptor in the absence of
sulfate. The radionuclide was removed from solution, but in
these cultures the precipitate was cell associated, with Tc as
the major element detected by PIXE (Tc:S ratio of 2:1). Re-
duction of the radionuclide in lieu of sulfate was confirmed
using XAS. Hydrogen uptake, coupled to metal reduction, was
also monitored manometrically, with 1 mol H2 used to reduce
1 mol TcO4~. The implications of these results on Tc mobility
in the environment are discussed, and possible biotechno-
logical uses of sulfate-reducing bacteria in bioremediation
programs to treat Tc-contaminated waters are highlighted.
Website: http://www.tandf.co.uk/journals/online/0149-
O451.asp
(78) Macaskie, LE and G Basnakova. 1998 Microbially-
enhanced chemisorption of heavy metals: A method
forthe bioremediation of solutions containing long-lived
isotopes of neptunium and plutonium. Environmental
Science & Technology 32: 184-187.
Radionuclides addressed:
226Ra pu ^
U Th
Technology: Biorem.
137Cs 90Sr
r »TC
other Np
Media: SW
Abstract: Immobilized cells of a Citrobacter sp. removed nep-
tunium and plutonium negligibly from solution using an es-
tablished technique that used biologically-produced phosphate
ligand (Pi) for metal phosphate bioprecipitation. Removal of
these transuranic radionuclides was enhanced by prior expo-
sure of the biomass to lanthanum in the presence of organo-
phosphate substrate to form cell-bound LaPO4. Polyacryla-
mide gel-immobilized cells removed little Np and Pu per se,
but preloaded LaPO4 promoted the removal of Np and Pu
upon subsequent challenge in a flowthrough column. Approxi-
mately 2 g of Np was loaded per 1 mL, column, when the
experiments were stopped after 10 mL, with maintenance of
approximately 90% removal of the input metal. Transuranic
element removal by this technique, generically described as
microbially-enhanced chemisorption of heavy
metals (MECHM), is via a hybrid of bio accumulative and
chemisorptive mechanisms.
Website: http://pubs.acs.org/journals/esthag
(79) Yong, Pand LE Macaskie. 1998. Bioaccumulation
of lanthanum, uranium and thorium, and use of a model
system to develop a method forthe biologically-medi-
ated removal of plutonium from solution. Journal of
Chemical Technology and Biotechnology 71:1 5-26.
Radionuclides addressed: | 137Cs 90Sr
226Ra Pu X 99Tc
U "K" Th «" other La
Technology: Biorem. Media: SW
Abstract: Removal of La3+, UO22+, and Th4+ from aqueous
solution by a Citrobacter sp. was dependent on phosphatase-
mediated phosphate release and the residence time in a plug-
flow reactor (PFR) containing polyacrylamide gel-immobilized
cells. In a stirred tank reactor (STR) lanthanum phosphate
accumulated on the biomass rapidly, in preference to uranium
or thorium phosphates. Thorium removal was not affected
by the presence of uranium but was promoted in the pres-
ence of lanthanum. Analysis of the accumulated polycrystal-
line material by X-ray powder diffraction (XRD) analysis and
proton induced X-ray emission (PIXE) suggested the forma-
tion of a mixed crystal of lanthanum and thorium phosphate.
La3+, UO22+, and Th4+ are analogues of the corresponding
UO22+ species of Pu3+, PuO22+, and Pu4+. The La/U/Th model
system was used to identify some potential problems in the
bioremediation of wastes containing plutonium and to de-
velop a method for the biologically-mediated removal of plu-
tonium from solution, in a test solution of 239Pu "spiked"
with a 241Pu tracer.
Website: http://www3.interscience.wiley.com/cgi-bin/
jhome/2517
(80) Bird, GAand W Schwartz. 1996. Effect of microbes
on the uptake of 60Co, 85Sr, 95Tc, 131I and 134Cs by de-
composing elm leaves in aquatic microcosms.
Hydrobiologia 333: 57-62.
Radionuclides addressed: 137Cs 90Sr
226Ra Pu 99Tc
U Th other Multiple
Technology: Biorem. Media: SW
50
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Radionuclide Biological
Remediation Resource Guide
Bioremediation
Articles 81-83
Abstract: We used decomposition of elm leaf discs as a model
system to determine the uptake of 60Co, 85Sr, 95Tc, 131I and
134Cs from freshwater by detritus and the role of microbes in
this process. Two treatments were used: a microbially enhanced
(ME) treatment and a microbially inhibited (MI) treatment.
The ME treatment involved the addition of a microbial in-
oculum, collected from a beaver pond, and nutrients (5 mg P
I1 as K2HPO4 and 20 mg N I4 as ((NH^SCg to the water to
enhance microbial growth. The MI treatment involved
sterlizing the leaf discs and water with gamma irradiation (1.7
Gy s"1 for 4 h) and the addition of a fungicide (100 mg I"1 of
nystatin) and bactericide (3.0 mgl4 each of streptomycin and
penicillin) to the water. The 60Co, 95Tc, 131I, and 134Cs concen-
trations of the elm leaf discs were greater (P<0.05) in the
ME treatment than the MI treatment, whereas the 85Sr con-
centration was higher in the MI treatment. The increase in
the 95Tc, 131I, and 134Cs concentration of leaf discs with time
in the ME treatment suggests microbes played an important
role in uptake. Uptake of these radionuclides by the leaf discs
points to the potential importance of detritus in the accumu-
lation of radionuclides. This could subsequently result in the
transfer of radionuclides to higher trophic levels by the detri-
tus-food web.
(81)Gadd, GM. 1996. Influence of microorganisms on
the environmental fate of radionuclides. Endeavor 20:
150-156.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Biorem.
"Tc
other
90Sr
General
Media: Soil, GW, SW
Abstract: Microorganisms have a significant influence on the
environmental fate of radionuclides in aquatic and terrestrial
ecosystems with a multiplicity of physico-chemical and bio-
logical mechanisms effecting changes in mobility and specia-
tion. Physico-chemical mechanisms of removal include asso-
ciation with extracellular materials, metabolites and cell walls
which are features of living and dead organisms. In living
cells, some physico-chemical processes are reversible, influ-
enced by metabolism and changing environmental conditions.
Metabolism-dependent mechanisms of radionuclide immo-
bilization include sulphide precipitation, transport and intra-
cellular compartmentation and/or sequestration by proteins
and peptides. In addition, chemical reduction to less soluble
forms can result in immobilization. Microbial processes in-
volved in radionuclide solubilization include autotrophic and
heterotrophic leaching, and complexation by siderophores and
other metabolites. Such mechanisms are important compo-
ents of biogeochemical cycles for radionuclides and should bf
considered in any analyses of environmental radionuclide con
tamination. In addition, several microorganism-based bio-
ntechnologies are receiving interest as potential treatment
methods.
Website: http://www.sciencedirect.com/science/journal/
01609327
(82) White, C, SC Wilkinson and GM Gadd. 1995. The
role of microorganisms in biosorption of toxic metals
and radionuclides. InternationalBiodeterioration & Bio-
degradation 35:17-40.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Biorem.
"Tc
other
Media: Soil
90Sr
General
GW,SW
Abstract: A multiplicity of physico-chemical and biological
mechanisms determine the removal of toxic metals, metal-
loids and radionuclides from contaminated wastes. Physico-
chemical mechanisms of removal, which may be encompassed
by the general term "biosorption", include adsorption, ion
exchange and entrapment which are features of living and
dead biomass as well as derived products. In living cells,
biosorption can be directly and indirectly influenced by me-
tabolism. Metabolism-dependent mechanisms of metal re-
moval which occur in living microorganisms include metal
precipitation as sulphides, complexation by siderophores and
other metabolites, sequestration by metal-binding proteins and
peptides, transport and intracellular compartmentation. In
addition, transformations of metal species can occur result-
ing in oxidation, reduction or methylation. For metalloids such
as selenium, two main transformation mechanisms are the
reduction of oxyanions to elemental forms, and methylation
to methylated derivatives which are volatilized. Such mecha-
nisms are important components of natural biogeochemical
cycles for metals and metalloids as well as being of potential
application for bioremediation.
Website: http://www.sciencedirect.com/science/journal/
09648305
(83) Rusin, PA, L Quintana, JR Brainard, BA
Strietelmeier, CD Tait, SA Ekberg, PD Palmer, TW
Newton and DL Clark. 1994. Solubilization of pluto-
nium hydrous oxide by iron-reducing bacteria. Env;-
ronmental Science & Technology 28:1686-1690.
Radionuclides addressed:
226Ra
U
Pu 1
137CS
^
Th
Technology: Biorem.
"Tc
90Sr
other
Media: Soil
51
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Radionuclide Biological
Remediation Resource Guide
Bioremediation
Articles 83-83
Abstract: The removal of plutonium from soils is challeng-
ing because of its strong sorption to soils and limited solubil-
ity. Microbial reduction of metals is known to affect the spe-
ciation and solubility of sparingly soluble metals in the envi-
ronment, notably iron and manganese. The similarity in re-
duction potential for alpha-FeOOH(s) and hydrous PuO2(s)
suggests that iron-reducing bacteria may also reduce and solu-
bilize plutonium. Bacillus strains were used to demonstrate
that iron-reducing bacteria mediate the solubilization of hy-
drous PuO2(s) under anaerobic conditions. Up to apprx 90%
of the PuO2 was biosolubilized in the presence of nitrilotriacetic
acid (NTA) within 6-7 days. Biosolubilization occurred to alesser
extent (apprx 40%) in the absence of NTA. Little PuO2 solubili-
zation occurred in sterile culture media or in the presence of a
non-iron-reducing Escherichia coli. These observations suggest
a potentially attractive, environmentally benign strategy for the
remediation of Pu-contaminated soils.
Website: http://pubs.acs.org/journals/esthag
52
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Radionuclide Biological
Remediation Resource Guide
(84)Steiner, M, I Linkovand SYoshida. 2002. The role
of fungi in the transfer and cycling of radionuclides in
forest ecosystems. Journal of Environmental Radio-
activity 58:217-241.*
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Fungi
99Tc
other
90Sr
General
Media: Soil
Abstract: Fungi are one of the most important components
of forest ecosystems, since they determine to a large extent
the fate and transport processes of radionuclides in forests.
They play a key role in the mobilization, uptake and translo-
cation of nutrients and are likely to contribute substantially
to the long-term retention of radiocesium in organic hori-
zons of forest soil. This paper gives an overview of the role
of fungi regarding the transfer and cycling of nutrients and
radionuclides, with special emphasis on mycorrhizal symbio-
sis, Common definitions of transfer factors, soil fungus and
soil green plant, including their advantages and limitations,
are reviewed. Experimental approaches to quantify the
bio availability of radionuclides in soil and potential long-term
change are discussed.
Website: http://www.sciencedirect.com/science/journal/
0265931X
(85) Dhami, PS, R Kannan, V Gopalakrishnan, A
Ramanujam, S Neeta and SR Udupa. 1998. Sorption
of plutonium, americium and fission products from re-
processing effluents using Rhizopus arrhizus. Biotech-
nology Letters 20: 869-872.
Radionuclides addressed:
226Ra
U
Pu 1
»7CS
\
Th
Technology: Fungi
»Tc
other
90Sr
Multiple
Media: SW
Abstract: Rhizopus arrhizus biomass removed more than 95%
of 239Pu, 241Am, 95Zr, 144Ce and 152+154Eu from different waste
streams generated in Purex as well as Truex processes after
suitable adjustment of pH.
Website: http://www.kluweronline.com/issn/0141-5492/
contents
Other
Articles 84-87
(86) Gadd, GM, MM Gharieb, LM Ramsay, JASayer,
AR Whatley and C White. 1998. Fungal processes for
bioremediation of toxic metal and radionuclide pollu-
tion. Journal of Chemical Technology and Biotechnol-
ogy 71:364-366. *
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Fungi
"Tc
other
Media: Soil
90Sr
General
SW
Abstract: No abstract available.
Website: http://www3.interscience.wiley.com/cgi-bin/
jhome/2517
(87) Haas, JR, EH Bailey and OW Purvis. 1998.
Bioaccumulation of metals by lichens: uptake of aque-
ous uranium by Peltigera membranacea as a function
of time and pH. American Mineralogist 83:1494-1502.
Radionuclides addressed:
226Ra
U *
137Cs
Pu
Th
Technology: Lichens
"Tc
90Sr
other
Media: Soil,
SW
Abstract: Uranium sorption experiments were carried out at
approx. 25 degrees C using natural samples of the lichen
Peltigera membranacea. Thalli were incubated in solutions
containing 100 ppm U for up to 24 h at pH values from 2 to
10. Equilibrium sorption was not observed at less than approx.
6 h under any pH condition. U sorption was strongest in the
pH range 4-5, with maximum sorption occurring at a pH of
4.5 and an incubation time of 24 h. Maximum U uptake by P.
membranacea averaged approx. 42 000 ppm, or approx. 4.2 wt%
U. This appears to represent the highest concentration of
biosorbed U, relative to solution U activity, of any lichen re-
ported to date. Investigation of post-experimental lichen tis-
sues using electron probe microanalysis (EPM) reveals that U
uptake is spatially heterogeneous within the lichen body, and
that U attains very high local concentrations on scattered ar-
eas of the upper cortex. Energy dispersive spectroscopic
(EDS) analysis reveals that strong U uptake correlates with P
signal intensity, suggesting involvement of biomass-derived
phosphate ligands or surface functional groups in the uptake
process.
Website: http://www.minsocam.org/MSA/AmMin/
AmMineral.html
*-
= Review Article
-------
Radionuclide Biological
Remediation Resource Guide
(88) McLean, J, OW Purvis, BJ Williamson and EH
Bailey. 1998. Role for lichen melanins in uranium
remediation. Nature 391: 649-650.
Radionuclides addressed:
226Ra
U *
137Cs
Pu
Th
Technology: Lichens
"Tc
90Sr
other
Media: Soil
Abstract: Lichens are successful colonizers in extreme ter-
restrial habitats world-wide, including metalliferous environ-
ments. Their ability to accumulate metals has led to their use
in monitoring radionuclide fall-out from Chernobyl and ura-
nium uptake from dust resulting from mining. Here we re-
port for the first time a lichen growing directly on uranium
minerals and uranium being concentrated within its tissues.
Our study suggests that melanin-like pigments, substances
previously unreported within lichens, are involved.
Website: http://www.nature.com/nature
(89) Brady, PV and DJ Borns. 1997. Natural attenua-
tion of metals and radionuclides. Sandia National
Laboratoy, Albuquerque, NM. 250 pp.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Attenuation
"Tc
other
90Sr
General
Media: Soil, GW
Abstract: Natural attenuation is increasingly applied to
remediate contaminated soils and ground waters. Roughly 25%
of Superfund groundwater remedies in 1995 involved some
type of monitored natural attenuation, compared to almost
none five years ago. Remediation by natural attenuation (UNA)
requires clear evidence that contaminant levels are decreas-
ing sufficiently over time, a defensible explanation of the at-
tenuation mechanism, long-term monitoring, and a contin-
gency plan at the very least. Although the primary focus of
implementation has to date been the biodegradation of or-
ganic contaminants, there is a wealth of scientific evidence
that natural processes reduce the bio availability of contami-
nant metals and radionuclides. Natural attenuation of metals
and radionuclides is likely to revolve around sorption, solu-
bility, biologic uptake and dilution controls over contaminant
availability. Some of these processes can be applied to ac-
tively remediate sites. Others, such as phytoremediation, are
likely to be ineffective. RNA of metals and radionuclides is
Other
Articles 88-91
likely to require specialized site characterization to construct
contaminant and site-specific conceptual models of contami-
nant behavior. Ideally, conceptual models should be refined
such that contaminant attenuation can be confidently predicted
into the future. The technical approach to RNA of metals
and radionuclides is explored here.
Order Number: DE98001672/XAB; Report No: SAND-
97-2727, CONF-9706209-SUMM
(90) Gray, SN. 1997. Fungi as potential bioremediation
agents in soil contaminated with heavy or radioactive
metals. Biochemical Society Transactions 26: 666-
670. *
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Fungi
"Tc
90Sr
other
Media: Soil
Abstract: The origin and impact of heavy metal and radionu-
clide pollution in soil is discussed and the accumulation of
heavy metals and radioactive metals by fungi, particularly the
translocation and accumulation of radiocaesium, zinc and
cadmium by filamentous fungi are examined and their appli-
cation to bioremediation is discussed. It is concluded that fungi
have a significant potential as bioremediation agents in metal-
contaminated soil.
(91) Linkov, I, WR Schell, E Belinkaia and B Morel.
1996. Application of a dynamic model for evaluating
radionuclide concentration in fungi. Pp. 752-754 In
IRPA9:1996 International Congress on Radiation Pro-
tection Proceedings. Duftschmid, KE, ed. Berger, Horn,
Austria.
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Fungi
"Tc
other
90Sr
General
Media: Soil
Abstract: Global fallout from nuclear weapon tests in the
1960s revealed the potential of fungi as an enhanced accumu-
lator of radioactivity. Data derived from Chernobyl fallout
sampling has shown fungi to be a major accumulator of
radiocaesium and an important food-chain contributor to the
human radiation dose. Fungi can significantly affect the ra-
54
Review Article
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Radionuclide Biological
Remediation Resource Guide
Other
Articles 92-94
dionuclide cycling in forests. According to experimental data
and estimations, forest micro flora, particularly fungi mycelia,
could retain up to 40% of radiocaesium. This paper illus-
trates the application of the dynamic model FORESTPATH
to evaluate the contamination dynamics in fungi and the rela-
tive importance of fungal species for forest cycling. Only a
few studies have been made to model fungi contaminated by
radionuclides and these utilize Transfer Factors to describe
soil-to-fungi uptake of radionuclides. Such an approach has
serious limitations, since equilibrium conditions and speci-
fied soil sampling depths must be assumed. The
FORESTPATH model uses rate of uptake and residence half-
times for radionuclides to describe this process. The model
was applied to describe radionuclide dynamics in fungi for
the case of chronic deposition and for the accidental release
of radionuclides. Experimental measurements of fallout from
nuclear weapon tests and from the Chernobyl accident were
used to test the FORESTPATH predictions.
(92) Riesen, TK and I Brunner. 1996. Effect of
ectomycorrhizae and ammonium on 134Cs and 85Sr
uptake into Picea abies seedlings. Environmental Pol-
lution 93: 1-8.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Fungi
99Tc
90Sr
other 134Cs, ssSr
Media: Soil
Abstract: Microorganisms play an important role in the fixa-
tion of radionuclides in forest soils. In particular, fungi have
the capacity to absorb and translocate radionuclides. The role
of the ectomycorrhizal fungus Hebeloma crustuliniformein
the uptake of radiocaesium (134Cs) and radiostrontium (85Sr)
into seedlings of Norway spruce ( Picea abies) was investi-
gated in a pouch test system. Inoculated and non-inoculated
seedlings; seedlings inoculated during 8 and 15 weeks; seed-
lings exposed during 2 and 3 weeks to the radioactive solu-
tion; and seedlings grown under low and high ammonium
conditions prior to the application of the radionuclides were
compared. The final 134Cs and 85Sr activity was determined in
fine-roots, main-roots, stems and needles. The results showed
that ectomycorrhizae reduced the uptake of 134Cs and S5Sr.
The degree of ectomycorrhization was of crucial importance
and seemed to be governed by the period during which
ectomycorrhizae were allowed to develop and by the ammo-
nium concentration in the nutrient solution. The radionuclide
uptake increased with increasing exposure time. Both radio-
nuclides were predominantly accumulated in fine-roots. How-
ever, needles proved to describe best the result of net root
uptake and translocation to the shoot. The uptake- and trans-
location-rates of 85Sr were smaller than those of 134Cs. It is
assumed that the translocation is coupled with the intensity
of water fluxes through the xylem and that 85Sris more readily
adsorbed into mycelium or plant tissue relative to 134Cs. The
effect of high ammonium growth conditions was overcome
by the effect of ectomycorrhization, except in needles with a
very large biomass which behaved as a strong sink and led to
a high accumulation of 134Cs.
Website: http://www.sciencedirect.com/science/journal/
02697491
(93) Singleton, I and JM Tobin. 1996. Fungal interac-
tions with metals and radionuclides for environmental
bioremediation. Pp. 282-298 In British Mycological
Society Symposium; Fungi and Environmental Change.
Frankland, JC, N Magan and G Gadd, eds. Cambridge
University Press, Cambridge, UK.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Fungi
99Tc
other
90Sr
General
Media: Soil
Abstract: No abstract available.
(94) Wilde, EW, JC Radway, J Santo-Domingo, RG
Zingmark and MJ Whitaker. 1996. Bioremediation of
aqueous pollutants using biomass embedded in hy-
drophilic foam. Oak Ridge Institute for Science and
Education, Tennessee. 261 pp.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Biomass
"Tc
90Sr
*
other
Media: SW
Abstract: The major objective of this project was to exam-
ine the potential of a novel hydrophilic polyurethane foam as
an immobilization medium for algal, bacteria, and other types
of biomass, and to test the resulting foam/biomass aggre-
gates for their use in cleaning up waters contaminated with
heavy metals, radionuclides and toxic organic compounds.
Initial investigations focused on the bioremoval of heavy
metals from wastewaters at SRS using immobilized algal bio-
mass. This effort met with limited success for reasons which
included interference in the binding of biomass and target
55
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Radionuclide Biological
Remediation Resource Guide
Other
Articles 95-96
metals by various non-target constituents in the wastewater,
lack of an appropriate wastewater at SRS for testing, and the
unavailability of bioreactor systems capable of optimizing
contact of target pollutants with sufficient biomass binding
sites. Subsequent studies comparing algal, bacterial, fungal,
and higher plant biomass demonstrated that other biomass
sources were also ineffective for metal bioremoval under the
test conditions. Radionuclide bioremoval using a Tc-99 source
provided more promising results than the metal removal stud-
ies with the various types of biomass, and indicated that the
alga Cyanidium was the best of the tested sources of biomass
for this application. However, all of the biomass/foam ag-
gregates tested were substantially inferior to a TEVA resin
for removing Tc-99 in comparative testing. The authors also
explored the use of hydrophilic polyurethane foam to embed
Burkholderia cepacia, which is an efficient degrader of trichlo-
roethylene (TCE), a contaminant of considerable concern at
SRS and elsewhere. The embedded population proved to be
incapable of growth on nutrient media, but retained respira-
tory activity. Lastly, the degradative capabilities of embedded
G4 were examined. Phenol- or benzene-induced bacteria re-
tained the ability to degrade TCE and benzene. The authors
were successful in inducing enzyme activity after the organ-
isms had already been embedded.
(95) Andrews, AM and RDugan. 1995. Assessment of
Bioremediation Technologies: Focus on Technologies
Suitable for Field-Level Demonstrations and Applicable
to DOD Contaminants. Institute for Defense Analyses,
Alexandria, VA. 116 pp.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Multiple
99Tc
90Sr
other General
Media: Soil,
SW
Abstract: Bioremediation is a viable, cost-effective treatment
for environmental contaminants. Research activities continue
to uncover new bioremediation technologies, increasing the
need for field-level demonstrations. The goal of this study is
to identify bioremediation technologies that have demon-
strated viability in laboratory or pilot studies, but require ad-
ditional field demonstrations to determine the capabilities and
limitations of the technology. In selecting technologies that
would be of interest to the DOD, the service-identified re-
search and development priorities for cleanup were consid-
ered, and those contaminants amenable to bioremediation
were identified. These contaminants included halogenated and
non-halogenated hydrocarbons, energetics, and inorganics.
Technologies that are promising at either laboratory or pilot
scales and are in need of demonstrations for validation under
field conditions include bioreactors for the treatment of en-
ergetics, in situ anaerobic/aerobic sequential treatment of
chlorinated hydrocarbons, constructed wetlands, and white rot
fungus. We strongly recommend the first three technologies
as candidates for field-level demonstrations; the fourth we
recommend less enthusiastically. Beyond our primary recom-
mendations, we make note of two other technologies of in-
terest: microbial mats and systems capable of assessing and
monitoring bioremediation activities.
Order Number: NTIS/AD-A301 147/5
(96) Garnham, GW, SVAvery, GACodd and GM Gadd.
1994. Interactions of microalgae and cyanobacteria
with toxic metals and radionuclides. Pp. 289-293 In
Changes in Fluxes in Estuaries: Implications from Sci-
ence to Management. Dyer, KR and RJ Orth, eds.
Olsen and Olsen, Fredensborg, Denmark.
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Biomass
"Tc
90Sr
*
other 60Co
Media: SW
Abstract: Accumulation of metals/ radionuclides by
microalgae and cyanobacteria may consist of two phases:
metabolism-independent binding to cell walls/extracellular
polysaccharide (biosorption) followed or accompanied by in-
tracellular uptake which may be energy-dependent. Chlorella
salina and Synechocystis PCC 6803 exhibit both uptake mecha-
nisms for cobalt, manganese, zinc and caesium; Chlorella
emersonii and Synechocystis PCC 6803 only exhibit a
biosorptive phase for technetium. Both phases can be affected
by environmental factors, e.g. changes in pH, salinity, nutri-
tional regime and suspended clay minerals. C. salina exhibits
multiphasic kinetics for cobalt, manganese and zinc uptake,
with a high-affinity mechanism ensuring essential metabolic
requirements. Cellular distribution analysis revealed that large
amounts of metals/ radionuclides (except Cs+) are bound to
cell walls and to an insoluble intracellular fraction, possibly
polyphosphates and/or metal-binding peptides. For Co2+,
Mn2+, Zn2+, and Cs+ the vacuole appeared to play an impor-
tant role in intracellular compartmentation in microalgae.
Accumulation of Cs+ was via monovalent transport systems
for K+ and/or NH4+ and was highly dependent on external
Na+ and K+ concentrations.
Book Number (ISBN): 87-85215-22-87-85215-22-8
56
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Radionuclide Biological
Remediation Resource Guide
Other
Articles 97-100
(97) Tobin, JM, C White and GM Gadd. 1994. Metal
accumulation by fungi: applications in environmental
biotechnology. Journal of Industrial Microbiology and
Biotechnology 13: 126-130.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Fungi
"Tc
90Sr
other General
Media: SW
Abstract: Fungi accumulate metal and radionuclide species
by physicochemical and biological mechanisms which include
extracellular binding by metabolites and biopolymers, bind-
ing to specific polypeptides and metabolism-dependent ac-
cumulation. Biosorptive processes have the greatest potential
in environmental biotechnology applications. Biosorption
consists metabolism-independent accumulation of com-
pounds interactions. The biosorptive capacity of the biomass
can be manipulated by a range of physical and chemical treat-
ments with immobilized biomass retaining its biosorptive
properties whilst possessing a number of advantages for pro-
cess applications. Native or immobilized biomass has been
used in fixed-bed, airlift, or fluidized bed bioreactors. After
biosorption metal/radionuclide species are removed for rec-
lamation and the biomass regenerated by simple chemical
treatments.
(98) Gadd, GM and C White. 1992. Removal of tho-
rium from simulated acid process streams by fungal
biomass: potential for thorium desorption and reuse of
biomass and desorbent. Journal of Chemical Technol-
ogy and Biotechnology 55: 39-44.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th "A"
Technology: Fungi
»Tc
90Sr
other
Media: SW
Abstract: No abstract available.
(99) Guillitte, O, A Fraiture and J Lambinon. 1990. Soil-
fungi radiocesium transfers in forest ecosystems. Pp
468-476 In Transfer of Radionuclides in Natural and
Semi-natural Environments. Desmet, G and P
Nassimbeni, eds. ElsevierApplied Science, London,
UK.
Radionuclides addressed:
226Ra pu
U Th
Technology: Fungi
137Cs 90Sr
"Tc
other General
Media: Soil
Abstract: The search for soil to fungi radionuclide transfer
must take into account macromycetes characteristics and, in
particular, the fact that is it impossible to determine in situ
the soil part in which the mycelium is located. This study shows
that fallout from the Chernobyl nuclear accident made it pos-
sible to accurately estimate the depth at which mycelium de-
velopment occurs and, therefore, to identify factors from the
soil layers that are actually colonized by fungi. It is proven
that this calculation method
of transfer factors provides a
more suitable approach to the response of fungal species to
radionuclides and greater reliability when interpreting trans-
fers in space and time.
(100) Roemmelt, R, L Hiersche, G Schaller and E
Wirth. 1990. Influence of soil fungi (basidiomycetes)
on the migration of 134+137Cs and 90Sr in coniferous for-
est soils. Pp. 152-160 In Transfer of Radionuclides in
Natural and Semi-natural Environments. Desmet, G
and P Nassimbeni, eds. ElsevierApplied Science, Lon-
don, UK.
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Fungi
99Tc
other
90Sr *
134Cs
Media: Soil
Abstract: During the first three years after the Chernobyl
event high 134+137Cs activities in fruitbodies of basidiomycetes
have been measured. A decline of activities with time has not
yet been observed. The activities are considerably higher com-
pared to agricultural products from the same area. In order
to study the movement of radiocesium in coniferous forest
sites, the activities in soil, fungi, and plants have been mea-
sured. Based on these results a model to describe the cesium
cycling in coniferous forest ecosystems is proposed with spe-
cial emphasis on the influence of soil fungi and plants on the
migration of cesium. As measurements of 90Sr in forest eco-
systems are rare this nuclide has been included in the investi-
gations.
57
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Radionuclide Biological
Remediation Resource Guide
Other
Article 101
(101) White C and GMGadd. 1990. Biosorption of ra-
dionuclides by fungal biomass. Journal of Chemical
Technology and Biotechnology 49: 331 -343
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th "A"
Technology: Fungi
"Tc
90Sr
other
Media: SW
Abstract: Four kinds of bioreactor were evaluated for tho-
rium removal by fungal biomass. Static-bed or stirred-bed
bioreactors did not give satisfactory thorium removal prob-
ably because of poor mixing. An air-lift bioreactor removed
approximately 90-95% of the thorium supplied over extended
time periods and exhibited a well-defined breakthrough point
after biosorbent saturation. The air-lift bioreactor promoted
efficient circulation and effective contact between the tho-
rium solution and the mycelial pellets. Of several fungal spe-
cies tested, Rhizopus arrhizus and Aspergillus niger were the
most effective biosorbents with loading capacities of 0.5 and
0.6 mmol gl respectively (116 and 138 mg g4) at an inflow
thorium concentration of 3 mmol dnr3. The efficiency of
thorium biosorption by A. niger was markedly reduced in the
presence of other inorganic solutes while thorium biosorption
by R. arrhizus was relatively unaffected. Air-lift bioreactors
containing R. arrhizus biomass could effectively remove tho-
rium from acidic solution (1 mol dnr3 HNO,) over a wide
range of initial thorium concentrations (0.1-3 mmol dnr3).
The biotechnological application and significance of these
results are discussed in the wider context of fungal biosorption
of radionuclides.
Website: http://www3.interscience.wiley.com/cgi-bin/
jhome/2517
Lichen growing on a tree trunk.
Photo: National Oceanic and Atmospheric Administration
A microbial mat remediating contaminants.
58
Photo: Dr. Victor Ibeanusi
-------
Future Research Opportunities
When there is caution about innovation, it takes a considerable amount of time for emerging
technologies to become accepted into the mainstream of activities. This was true for
phytotechnology and bioremediation, which were not fully understood two decades ago.
However, through research and funding, both technologies have emerged as major
alternatives to conventional remediation modalities for environmental cleanups.
As this guide was being prepared, studies that involved the use of shellfish and microbial
mats were reviewed and seemed to be potential options for future biotechnology. A few of
the abstracts that described these areas are included on pages 60-62. Although the abstracts
did not meet the criteria set for this current guide, perhaps, by including them, new
opportunities for future research and field tests in these areas may be explored.
59
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Radionuclide Biological
Remediation Resource Guide
Future Research Opportunities
Articles 1-3
(1) Copplestone, D, D Jackson, RG Hartnoll, MS
Johnson, P McDonald, and N Wood. 2004. Seasonal
variations in activity concentrations of "Tcand 137Cs in
the edible meat fraction of crabs and lobsters from the
central Irish Sea. Journal of Environmental Radioac-
tivity 73:29-48.
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Shellfish
"Tc
90Sr
*
other
Media: SW
Abstract: Discharges of most radionuclides into the Irish
Sea from the BNFL site at Sellafield have decreased over the
past 20 years or so. For a few radionuclides, however, dis-
charges have peaked more recently. Notably, operation of the
Enhanced Actinide Removal Plant (EARP) since 1994 has
led to an increase in discharges of "Tc, as a result of the
treatment of previously stored waste, with consequent in-
creases in "Tc activity concentrations in a number of marine
species, particularly in crustaceans such as lobsters. Previous
research has considered the significance of factors such as
sex and body weight on radionuclide concentrations. The
current project set out to investigate whether seasonal varia-
tions in radionuclide concentrations in crabs and lobsters
occur, with particular emphasis on the dynamics of "Tc and
137Cs. Organisms were obtained from a site off the Isle of
Man, where radionuclide concentrations were measurable but
the site was sufficiently distant from Sellafield that the radio-
nuclides were well mixed in the water column and not likely
to be influenced by the pulsed nature of discharges of "Tc.
Crab and lobster samples were collected monthly, between
February 2000 and February 2001. Fifteen or 16 individuals
(evenly split as male and female) of each species were col-
lected on each occasion. Seawater samples were also collected
over the 12- month period. Activity concentrations of "Tc in
the edible meat fraction (both brown and white meat) ranged
from 0.23 to 2.46 Bq kg1 (fresh weight (fw)) in crabs and 124
to 216 Bq kg1 (fw) in lobsters, with no observed seasonal
variations. Activity concentrations of 137Cs in both crab and
lobster were lower, ranging from <0.16 to 0.85 Bq kg4 for
crab meat (fw) and <0.3 to 3.3 Bq kg1 for lobster meat (fw).
A statistically significant increase in activity concentrations
of 137Cs in the meat was observed in the summer months for
both crab and lobster. The cause has not been investigated
but may be related to the laying down of energy reserves
during the active feeding period over the summer. At all times,
uptake of "Tc is higher in the brown meat fraction of both
crabs and lobsters, whilst 137Cs is more uniformly distributed.
These results are used to discuss the implications for sam-
pling and monitoring programmes.
Website: http://www.sciencedirect.com/science/journal/
0265931X
(2) Bustamante, P, P Germain, G Leclerc and P
Miramand. 2002.Concentration and distribution of 210Po
in the tissues of the scallop Chlamys varia and the
mussel Mytilus edulis from the coasts of Charente-
Maritime (France). Marine Pollution Bulletin 44: 997-
1002.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Shellfish
"Tc
other
90Sr
210p0
Media: SW
Abstract: Polonium-210 (210Po) has been analysed in the soft
parts of two bivalves species, the scallop Chlamys varia and
the common mussel Mytilus edulis, from the Bay of La Roch-
elle and Re Island, on the French Atlantic coast. Between those
sites, the highest 210Po concentrations have been found in
whole scallop soft parts from La Rochelle, reaching 1181 plus
or minus 29 Bq kg4 dry weight (dwt), a size effect being re-
lated to the highest 210Po concentration in the smallest scal-
lops. The results show a significant difference in concentra-
tions for similar size individuals between species in each site
(C. varia > M. edulis) and between sites for each species (Re
Island > Bay of La Rochelle). Very high 210Po concentrations
have been found in the digestive gland of C. varia, ranging
3150-4637 Bq kg1 dwt. Thus, the digestive gland contains up
to 60% of the radionuclide. Subcellular investigations have
shown that approximately 40% of the 210Po contained in the
digestive gland is in the cytosolic fraction, suggesting a high
bio availability of the 210Po from this fraction to the trophic
upper level. Calculations will show that approximately 4 kg
of scallops flesh intake would be necessary to reach the an-
nual incorporation limit of 1 mSv.
Website: http://www.sciencedirect.com/science/journal/
0025326X
(3) Rapiejko, A, R Rosson, J Lahr, R Garcia and B
Kahn.2001. Radionuclides in Peconic River fish, mus-
sels, and sediments. Health Physics 81: 698-703.
Radionuclides addressed:
226Ra
U *
137Cs *
Pu
Th
Technology: Shellfish
"Tc
other
90Sr
60Co, 241Am
Media: SW
Abstract: For regulatory oversight and quality control of
Comprehensive Environmental Response, Compensation, and
Liability Act (CERCLA) actions, fish, mussels, and sediments
60
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Radionuclide Biological
Remediation Resource Guide
Future Research Opportunities
Articles 4-6
were analyzed from the Peconic River system on Long Is-
land, NY, downstream of the Brookhaven National Labora-
tory, as well as from control locations. The analyses were for
photon-emitting radionuclides (notably s°Co and 137Cs), ura-
nium, plutonium, and americium. Sediments were cored in 4
sections to 0.37 m depth, whole fish were analyzed, and mus-
sels were separated into flesh and shells. Radioisotopes of
the cited elements were detected in sediment, some of the
fish contained 137Cs, 241Am, and uranium, and mussel flesh
contained 137Cs and uranium. All of the 60Co, 233U, and en-
riched uranium, and some of the 137Cs and 241Am, can most
likely be attributed to Brookhaven National Laboratory. The
other radionuclides (and some of the 137Cs and 241Am) are
believed to have either fallout or nature as their origin. The
New York State Department of Health (NYSDOH) evalu-
ated the radiological data in terms of adverse health implica-
tions due to consumption of fish with the levels of reported
radioactivity. The NYSDOH determined that the added ra-
diation doses likely to result from eating this fish are a small
fraction of the radiation dose that normally results from ra-
dionuclides present in the body from natural sources.
Website: http://www.health-physics.com
(4) Balint, PJ. 1999. Marine biotechnology: a proposal
for regulatory reform. Politics and the Life Sciences
18:25-30.
Radionuclides addressed:
226Ra
U
137Cs
Pu
Th
Technology: Shellfish
"Tc
90Sr
other General
Media: SW
Abstract: Biotechnology companies are developing transgenic
fish, shellfish, and microorganisms to supplement conven-
tional marine aquaculture and aid in the bioremediation of
polluted coastal waters. These products may be ready for open-
environment field trials or commercial applications within two
to four years. Regulatory authority in the field of marine bio-
technology is poorly defined and ill prepared, however, and
the science base presently available is not adequate to sup-
port credible ecological risk assessment of genetically engi-
neered marine organisms. In response, I offer two specific
public policy recommendations: (1) an accelerated program
of basic and applied research in marine ecology underwritten
by a combination of government and private funds, and (2)
the creation of a dedicated unit within the National Marine
Fisheries Service responsible for regulatory oversight of
transgenic marine organisms. If implemented, these reforms
will encourage development in the marine biotechnology in-
dustry while laying the groundwork for appropriate ecologi-
cal risk assessment and management.
Website: http://www.politicsandthelifesciences.org
(5) Hutchins, DA, L Stupakoff, S Hook, SN Luoma and
NS Fisher. 1998. Effects of Arctic temperatures on
distribution and retention of the nuclear waste radio-
nuclides 241Am, 57Co, and 137Cs in the bioindicator bi-
valve Macoma balthica. Marine Environmental Re-
search 45: 17-28.
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Shellfish
"Tc
other
90Sr
57Co, 241Am
Media: SW
Abstract: The disposal of radioactive wastes in Arctic seas
has made it important to understand the processes affecting
the accumulation of radionuclides in food webs in coldwater
ecosystems. We examined the effects of temperature on ra-
dionuclide assimilation and retention by the bioindicator bi-
valve Macoma balthica using three representative nuclear waste
components, 241Am, 57Co, and 137Cs. Experiments were de-
signed to determine the kinetics of processes that control
uptake from food and water, as well as kinetic constants of
loss. 137Cs was not accumulated in soft tissue from water dur-
ing short exposures, and was rapidly lost from shell with no
thermal dependence. No effects of temperature on 57Co as-
similation or retention from food were observed. The only
substantial effect of polar temperatures was that on the as-
similation efficiency of 241Am from food, where 10% was as-
similated at 2 degree C and 26% at 12 degree C. For all three
radionuclides, body distributions were correlated with source,
with most radioactivity obtained from water found in the shell
and food in the soft tissues. These results suggest that in gen-
eral Arctic conditions had relatively small effects on the bio-
logical processes which influence the bioaccumulation of ra-
dioactive wastes, and bivalve concentration factors may not
be appreciably different between polar and temperate waters.
Website: http://www.sciencedirect.com/science/journal/
01411136
(6) McDonald, P, MS Baxter and SW Fowler. 1993.
Distribution of radionuclides in mussels, winkles and
prawns. Parti. Study of organisms under environmen-
tal conditions using conventional radio-analytical tech-
niques. Journal of Environmental Radioactivity 18:181-
202.
61
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Radionuclide Biological
Remediation Resource Guide
Future Research Opportunities
Article 7
Radionuclides addressed: | 137Cs "W"
226Ra
U
Pu «
Th
Technology: Shellfish
99Tc
other
90Sr
Multiple
Media: SW
Abstract: Mussels (Mytilus edulis) and winkles (Littorina
littorea), collected from Ravenglass, Cumbria, England in the
vicinity of the British Nuclear Fuels pic nuclear reprocessing
plant at Sellafield, and prawns (Palaemon serratus), landed
nearby at Whitehaven, have been investigated to determine
the distributions of alpha-emitting (210Po, 238Pu, 239+240Pu,
241 Am) and gamma-emitting (95Nb, 95Zr, 103Ru, 106Ru, 137Cs,
241 Am) radionuclides in their tissues and organs. Ravenglass
mussels exhibited 239+240pu concentrations ranging from 43
Bq/kg dry in muscle tissue to 1658 Bq/kg dry in byssal threads,
the corresponding 137Cs range being 131-1340 Bq/kg. Al-
though 210Po concentrations were not determined in byssal
threads, muscle tissue still displayed the lowest polonium con-
centration (124 Bq/kg), whilst the viscera (containing diges-
tive gland, stomach and kidneys) contained the highest (596
Bq/kg). Subsequent concentration factor estimates for 137Cs,
210Po and 239+240pu in the total soft parts of Ravenglass mus-
sels were, respectively, 9, 25 800 and 1400. In Cumbrian
winkles, nuclide concentrations ranged for 239+240Pu, from 18.5
Bq/kg dry (muscle tissue) to 457 Bq/kg dry (pallial complex);
for 137Cs, from 103 (foot tissue) to 1495 Bq/kg (pallial com-
plex) and for 210Po, from 12.2 (muscle tissue) to 145 Bq/kg
(digestive gland). Total soft part concentration factors (CFs)
were calculated to be 16 for 137Cs, 5500 for 210Po and 5700 for
239+240Pu.
Website: http://www.sciencedirect.com/science/journal/
0265931X
(7) Whitehead, NE, S Ballestra, E Holm and L Huynh-
Ngoc. 1988. Chernobyl radionuclides in shellfish. Jour-
nal of Environmental Radioactivity!: 107-121.
Education, Tennessee. 261 pp.
Radionuclides addressed:
226Ra
U
137Cs *
Pu
Th
Technology: Shellfish
"Tc
other
90Sr
Multiple
Media: SW
Abstract: Radionuclides from the Chernobyl accident arrived
at Monaco on 30 April, 1986. A sample of Mytilus
galloprovincialis collected six days later showed near-maxi-
mum levels of most radionuclides. Monitoring continued for
seven months thereafter, peak concentrations being transiently
as high as 480 Bq kg1 (all soft parts, wet weight) for 103Ru.
Other radionuclides detected included 132Te, 129mTe, 1311,106Ru,
134Cs, 137Cs, 110mAg, 140Ba, 125Sb, 95Nb and 141Ce. Biological half-
lives for elimination in this environment were generally around
10 days or longer and most elimination curves contained a
number of components. Radionuclide contents of the mus-
sels were predicted quite accurately from concentrations ob-
served on air filters collected simultaneously, but were not
satisfactorily explained relative to total radionuclide concen-
trations in the seawater even three days after peak air filter
activities. The use of concentration factors from the litera-
ture did not improve the latter predictions. This suggests that
the radionuclides were absorbed very rapidly from the fallout
particles, rather than from radionuclides first solubilised from
particles. Patella lusitanica specimens contained activities about
20-50 times higher than those in the mussels.
Website: http://www.sciencedirect.com/science/journal/
0265931X
Zebra mussels, an invasive species in the US, have potential as future remediation tools.
Photo: United States Geological Survey
62
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