DC, October 21, 2004 (ENS): Pumpkins and zucchinis
have the ability to remove DDT from soil, a chemist
at the Royal Military College of Canada has found.
A greenhouse study by chemist Dr. Ken Reimer and his
team suggests that phytoremediation with these plants
is a environmentally friendly technique for cleaning
up sites contaminated with DDT, PCBs and other harmful
Once they have taken up the contaminants, the pumpkins
would not be eaten. The pumpkins would be allowed to ripen
and then composted with their vines to reduce their volume
before they are disposed of in landfills or incinerated.
"Our research has shown that members of the Cucurbita
pepo species, including pumpkins, are particularly effective
in this regard," Reimer says. "Phytoremediation
offers a green solution to cleaning up contaminated
The report is scheduled to appear in the November 15
edition of "Environmental Science & Technology,"
a peer-reviewed journal of the American Chemical Society
headquartered in Washington, DC.
DDT was applied widely as an insecticide in North America
until it was banned in 1972. Some developing nations
still use DDT for protection against typhus and malaria,
and it endures for long periods of time in the environment,
posing a potential health threat to humans and animals.
Persistent organic pollutants like DDT, PCBs and dioxins
are difficult to remove from soils because they are
not water soluble, and the difficulty increases with
the passage of time. To clean up contaminated sites,
it has been necessary to excavate the soil and place
it in a landfill or burn it in a high temperature incinerator.
Reimer and his coworkers, Alissa Lunney and Barbara
Zeeb, conducted a greenhouse study of five plant species:
rye grass, tall fescue, alfalfa, zucchini and pumpkin.
The researchers used soil from a site in the Canadian
Arctic where DDT had been sprayed to protect workers
"The cold temperatures meant that the contamination
was virtually identical to the technical grade DDT mixture
that had originally been used," Reimer says. The
researchers were able to examine the ability of the
test plants to remove DDT from soil that had been contaminated
for several decades.
Pumpkins took up the largest amount of DDT, while another
member of the Cucurbita pepo species, zucchini, came
in second at about half the pumpkins’ accumulation.
While the technique is not likely to replace traditional
methods any time soon, Reimer says, phytoremediation
could offer an inexpensive and environmentally friendly
alternative, especially in small communities and developing
countries where money is an obstacle to cleanup.