TOOLBOX / BSLA
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Inorganic pollutants are naturally occurring
elements on the periodic table such as metals,
including lead and arsenic. Human activities such
as the burning of fossil fuels, industrial production
and extraction mining create releases of inorganic
pollutants into the environment, causing toxicity.
These are elements, so they cannot be degraded
and destroyed; in some instances, they can be
taken up and extracted by plants (ITRC, 2009).
However, despite what you may have read on the
internet about metals, phytotextraction of inorganic
contaminants on sites is quite difficult and usually
not worth attempting (Rock 2013). If extraction is
possible, the plants must be cut down and harvested
to remove the pollutant from a site (Chaney et al
2010). Instead of extraction and removal, plants and
their associated microbes may be used to stabilize
or change the state of an inorganic contaminant
to reduce exposure risk and danger to humans and
the environment. Interestingly, sunflowers used
for lead remediation continue to appear on the
internet and in landscape architecture publications
as a phytoremediation solution, even though this
practice essentially failed in field trials in the late
90s (Ulam, 2013). There is a lot of outdated science
that we landscape architects must be careful not to
misinterpret and apply. Instead we should team with
knowledgeable phytotechnology scientists.
ABOVE
Potential contaminants can be anticipated by site
program and landscape systems can be designed to
intercept contamination events before they occur.
For pollutants found in soils, plant-based treatment
technologies have been best utilized for the
treatment of organic contaminants and nitrogen
(Dickinson et al 2009). Inorganic contaminant
phytoremediation for removal of pollutants
from a site (other than nitrogen) has been less
successful. This generalization refers to soil-based
contamination and does not apply to remediation of
pollutants within water, since inorganics in water
can often be filtered out by various types of soil and
plant interactions and held within the soil matrix
(Kadlec and Wallace, 2009).
Integrating Phyto and Design
Phytotechnologies could play a larger role in
landscape design practice and in transforming
brownfields into developable parcels providing a
more sustainable choice for land planning. Twenty
percent of all real estate transfers in the United
States are brownfield sites, (Sattler et al, 2010) with
the current value of these lands in 2010 in the range
of two trillion US dollars. More than 16% of global
land areas, equivalent to about 52 million hectares,
are impacted by soil pollution worldwide (Anjum,
2014). The majority of traditional remediation
techniques are expensive and energy intensive in
their approach to quickly correct an environmental
Boston Society of Landscape Architects Fieldbook
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