Page 44 - Plant-Based Remediation Processes

2 Protocols for Applying Phytotechnologies in Metal-Contaminated Soils 31

Fig. 2.5 Energy crop demonstration site in the vicinity of make-shift copper/zinc smelters in
Fuyang valley (Zhejiang, China)

2. The capacity of the proposed crops or local natural vegetation species to grow on
the polluted soil after application of the additives, mainly concerning
phytotoxicity.
3. The price of the used additives in combination with the duration of their
effectiveness; generally unpolluted waste materials like compost, fly ash, etc.,
are considered the best option.
4. The longer term effectiveness of the proposed additives and the need to be
effective for a longer period (it is possible that the system on the longer term
does not need the additives any more).
5. The risk of food-chain contamination induced by the selected plant species.
6. The capacity of the selected plant species regarding their erosion mitigating
potential, with special emphasis on all-year effectiveness (perennial vs. non-
perennial).
7. The need of fertilizers and pesticides to sustain healthy growth of the selected
plant species.
The last five issues (3–7) are general characteristics of additives/plant species
and therefore can normally be assessed adequately on the basis of a literature check
and/or a very simple decision support system containing literature dataor simply
based on an expert opinion, which offers the advantage of integrating the different
issues.
Factors 1 and 2, however, are highly site specific and do need preliminary
laboratory tests. Such laboratory tests can be a simple series of solvent extractions
of the soil/additive mixture (with and/or without aging of the mixtures) especially
to chemically assess heavy metal mobility and plant-availability. A simple test to
assess potential phytotoxicity is the standard barley root elongation test (see