Montreal Researchers Use Willows to Decontaminate Polluted Soil, Groundwater

MONTREAL —In an east-end Montreal neighbourhood, a polluted piece of former industrial land has become a garden.

Willows sway in the breeze, creating a pleasant green space as the plants slowly reverse decades of industrial activity that has left the chemical-soaked soil of the Pointe-aux-Trembles site too contaminated to use.

The trees are part of a four-year natural decontamination project by the city and the Universite de Montreal that uses the tall plants to rehabilitate former industrial “brownfields” that are left abandoned because they’re too expensive to redevelop.

Michel Labrecque, the head of research at the Montreal Botanical Garden and a biological sciences professor, said willows are “an excellent material” for decontamination because they’re hardy, fast-growing, can survive Quebec winters and thrive in even the most polluted soil.

“I put willows in soil where there was some pollution and saw they were performing quite well, even when the soil was not only polluted by contaminants, but also poor and with a lack of organic materials,” he said.

As they grow, they absorb the pollutants in the soil, while their roots produce micro-organisms that further break down the chemical compounds that can’t be absorbed.

The contaminants become concentrated in the plants’ leaves and branches, which are then cut off and usually burned.

Labrecque said the method is favourable to traditional “dig and dump” methods of decontamination, which involve excavating and removing the polluted soil without removing any chemicals.

Xavier Lachapelle-Trouillard, who recently completed a Masters’ from Polytechnique University, said the same thing Labrecque mentioned about how using willows to treat soil has the advantage of being environmentally-friendly, low-maintenance and much cheaper than traditional methods. But, they can take much longer to work and use much more space.

Labrecque said if the project in Montreal’s East End is allowed to continue, the city-owned land should be ready for new building after between five and 15 years.

The question, he said, is whether the citizens will want to give up their green oasis.

“The citizens really like it the way it is, so a challenge we face is that people like it as a green zone,” he said.

Edited by The Epoch Times for brevity