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Page Title: Table 1. Types of Phytoreclamation Technology for Metal-Contaminated Soil Materials: Advantages and Disadvantages (U.S. Envir...
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Technical Note DOER-C3
May 1999
Table 1
Types of Phytoreclamation Technology for Metal-Contaminated Soil Materials:
Advantages and Disadvantages (U.S. Environmental Protection Agency (EPA)
1996)
Type of Phytoreclamation
Advantages
Disadvantages
Phytoextraction by trees
High biomass production
Potential for offsite migration and leaf
transportation of metals to soil surface
Potential for metal recovery
Metals are concentrated in plant biomass
and must be disposed of eventually
Phytoextraction by grasses
High accumulation
Low biomass production and slow growth
rate
Potential for metal recovery
Metals are concentrated in plant biomass
and must be disposed of eventually
Phytoextraction by crops
High biomass and increased
Potential threat to the food chain through
growth rate
ingestion by herbivores
Metals are concentrated in plant biomass
and must be disposed of eventually
Phytostabilization
No placement of contaminated
Remaining liability issues, including
biomass required
maintenance for indefinite period of time
(containment rather than removal)
Rhizofiltration
Readily absorbs metals
Applicable for treatment of water only
Potential for metal recovery
Metals are concentrated in plant biomass
and must be disposed of eventually
humus rich topsoil. In Stafford et al. (1991), earthworms were not shown to accumulate significant
amounts of cadmium from nonforested dredged material in the Times Beach, New York, CPF.
However, earthworms in the leaf-littered dredged material beneath volunteer cottonwood trees had
significantly elevated cadmium levels, indicating potential transfer to higher levels of the food
chain. These types of situations must be considered in the screening and selection process and, if
necessary, management strategies developed to minimize risks to the ecosystem. Control of
cottonwood trees and replacement with trees, such as red oak, that minimize uptake of metals would
be appropriate in the above example.
The processes and considerations for phytoreclamation of dredged material are complicated. A
simple, fast-screening tool is currently not available. However, a protocol to determine if phytore-
clamation of dredged material would be successful is now being developed. Each dredged material
will require that site/application-specific considerations and physical/chemical characteristics be
evaluated. In some cases, contaminated, freshwater dredged material may be phytoreclaimed soon
after dewatering with little to no modification. In other cases, modifications such as reduction in
soluble salts or chemical amendments may be necessary to enhance plant growth or increase the
plant availability of a given contaminant.
The plant pathways and phytoreclamation processes for each contaminant class are shown in
Table 2, and, as indicated by question marks, some of these processes are not fully understood.
4

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