Page 46 - Plant-Based Remediation Processes

2 Protocols for Applying Phytotechnologies in Metal-Contaminated Soils 33

the end can be effectively eliminated. To add a standard ecotoxicology test as a
monitoring tool as an integrated part of a phytoextraction project may help to
lead to technology acceptance. Research reports and reports on feasibility
studies should not only focus on plant accumulation and translocation data but
also on an effective reduction of different heavy metal fractions in the soil; they
should also provide sound heavy metal mass balances to show that no leaching
and other losses occurred.
• Decision Support Tools are not commonly used to help decision-making on
which approach is the most appropriate for a specific polluted site. Some tools
mainly focus on “hard technology” (e.g., DARTS developed by ICS-UNIDO)
and do not specifically deal with phytotechnologies. To improve the use of such
a specific Decision Support Tool to decide upon the best approach when
phytotechnologies already have been selected for remediation, has to be further
developed, to include a database for calibration and validation based on real
experimental phytoremediation field trials.
• An agreement on a regulatory base for the use of remediation techniques which
only reduce the concentration of heavy metal fraction which pose the major
human health and ecosystem risks still has to be developed in many countries.
The scientific community already agrees upon the need to do so. Such a
regulatory basis will greatly facilitate the introduction of phytotechnologies as
an accepted method to reduce risks caused by heavy metals in soils. It will also
avoid that phytotechnologies are used where and when they are not appropriate
and, on the contrary, avoid situations where more invasive and expensive
technologies are used where phytotechnologies represent a better option.
Major hurdles for the successful use of remediation approaches based on reduc-
tion of bioavailable heavy metal fractions in the soil, which include
phytotechnologies, continue to be mainly political and regulatory rather than
scientific.
• Regarding phytostabilization, the need of a regulatory framework is even more
pressing than in the case of phytoextraction. The reason is that in phytoextraction
the bioavailable heavy metal fraction in the soil is effectively removed, which
satisfies regulators and public opinion. This is not the case with phytosta-
bilization. Introducing phytostabilization on a broader scale should focus on
the following issues:
– Stressing the need of doing something to stop/reduce the transport of heavy
metals from extending extremely polluted sites to cleaner adjacent environ-
mental compartments. Emphasizing that hard technological clean-up is no
option, due to extreme costs and emphasizing that dig and dump is not a
sustainable solution.
– Putting emphasis on the fact that there are no other options (except capping in
combination with clean-up of groundwater) than phytostabilization and
revegetation to improve the situation of extremely polluted extended sites.
– Promoting the possibility of making phytostabilization economically sustain-
able on the longer run by using perennial non-food crops like deep-rooting