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Freshwater Management
Series No. 7
Phytotechnologies
A Technical
Approach in Environmental Management
IV. Important
Considerations For The Application of Phytotechnologies >
A. Site Characterization
A complete site characterization is essential for the application of phytotechnologies.
Characterization should include an evaluation of surface features, structures
and buried services to determine whether the site is amenable to a phytotechnology application. Site characterization should provide data on the following:
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Site description |
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Geological data |
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Hydrogeologic data |
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Aquifer characteristics |
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Soil conditions |
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Air quality |
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Climatic conditions |
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Geochemical data |
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Microbiology |
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Presence and distribution of contaminants (if any) |
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Risk assessment. |
Assessment of available data should include an analysis of the sufficiency
and validity of the data in relation to the proposed phytotechnology application.
As part of the site characterization, agronomic studies should be conducted
to determine if site conditions will support plant growth. Soil samples should
be collected and analyzed for soil parameters influencin g plant growth, including
soil pH, soil fertility and nutrient content, soil structure, soil texture,
soil temperature, and soil depth. Saline groundwater conditions may adversely
affect plant growth of some species of plants. The site soils should be amended
as necessary to optimize plant growing conditions. The need for an irrigation
system should also be determined.
B. Plant Selection
Native, non-agricultural plants are generally preferred for phytotechnology
applications. In most applications, plants that are adapted to local conditions
will have better chances of success than non-adapted plants. The use of mixed
species of vegetation can also lead to greater chances of success than the
use of monocultures. Care should be taken not to introduce specie s of plants
that are invasive or a nuisance. In cases where the spread of a plant is undesirable,
the plants should be selected to prevent reproduction.
The long term establishment of vegetation at a site is dependent on the project
goals and the future intended use of the site. For phytotechnology applications
involving little or no maintenance at a given site, it is likely that there
will be a succession of plants. If so, this succession could be planned when
considering types and timing of vegetation. Plant rotation could be important
when short-lived vegetation is used that does not meet overall objectives or
for vegetation that should not be replanted in the same place.
C. Modelling
Models are essentially a simplified picture of reality that can be used to
help solve problems. The use of modelling in the environmental field has developed
rapidly during the last two decades due to:
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The development of computer technology, which can handle
very complex mathematical systems, |
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A better understanding of pollution problems, including the
recognition that complete elimination of pollution (or “zero discharge”)
is not feasible, but that proper pollution control within the limitations
of available financial resources requires serious consideration of the
potential impacts of pollution on ecosystems, |
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Increasing knowledge regarding the quantitative relationships
in ecosystems, and between the various ecological properties and environmental
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Ecosystem models can be considered a synthesis of what we know about the ecosystem,
or a component of the ecosystem, with reference to a given problem. It is therefore
not surprising that ecological models have been used increasingly as a tool
to understand the properties of the ecosystem. The principal advantages of
models are that they can be used to survey complex systems, reveal system properties
and gaps in our knowledge, and help establish research priorities. Models are
useful in tests of scientific hypotheses because they can simulate real conditions,
which can then be compared with actual observations.
Modelling may be necessary to optimize the phytotechnology application or
to predict behavior. For example, plant uptake models may be used to predict
the rate at which a contaminant will be degraded within a plant. Similarly,
ecosystem models can be used to understand the relationships between the physical
and biological components of phytotechnologies as part of the overall ecosystem.
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