Gardening In The City.
Thinking about growing vegetables in your city? Go for
it. Research at the University of Toronto suggests that with
a few exceptions, vegetables grown in a city environment are
generally safe to eat.
For almost two years Clare Wiseman, a professor at the
Center for Environment has been assessing the fate of
traffic-related trace metal emissions and their uptake by
plants grown in Toronto. She and her team of volunteers grew
a variety of vegetables and herbs in areas of high and low
volume traffic, within the city. The produce included Swiss
chard, beets, eggplants and oregano. They measured the
levels of a wide range of potentially hazardous metals
(including cadmium and lead) absorbed by the soils and the
produce.
Wiseman found that despite some "hot spots", the amounts
of metals found in most of the herbs and vegetables were
within acceptable limits (with the exception of lead levels
in oregano and cadmium in eggplant grown close to
traffic).
Interestingly, it was found that the so-called "organic
triple mix soil" from a local garden supplier tested higher
for most trace metals, including cadmium, than the
pre-existing soil it was intended to replace. It was also
found that the plants grown in the organic triple mix soil
readily took up more available metals compared to the plants
grown in the unremediated soil. It appears that metal uptake
by plants is strongly influenced by soil age and that trace
elements are more likely to become tightly bound to soil
constituents over time, making them less soluble and
available for uptake.
Considering these findings Wiseman suggests that most
gardeners save themselves money by simply planting in
existing soils in their own backyards. She also advises
urban gardeners to continue gardening but to try to avoid
roadside locations. Fruits and vegetables she says, should
always be washed thoroughly.
Andrew Motrovica, Roadside Harvest, University of Toronto
Magazine, Spring 2012.
From exhaust pipe to plants: tracking the fate of trace
metal emissions in roadside gardens in Toronto,
The Center For Environment, University of Toronto,
http://www.environment.utoronto.ca/Research/FacultyResearch/ContinuingResearch.aspx
|