Where there's a willow, there's a way: City using saplings to decontaminate land
The City of Montreal is trying out a new way to decontaminate industrial land: planting willow trees.
Their roots have the ability to remove oil and toxic materials from the ground.
Up until now, the city’s only option to clean the soil was to truck it away – like they did on a lot just a stone’s throw away from Pointe-Aux-Trembles oil refinery, where four hectares of land are unfit for a park or a housing development.
There are a few plants, but the lot is mostly occupied by gravel, residue patches – like from oil – and other contaminants.
But willow trees, once planted, grow relatively quickly and act as a natural decontaminant for the soil.
“There’s a large variety of willow trees, willow shrubs, and we prefer to work with those plants because they can suffer,” explained Michel Labreque, an associate professor of science and biology at Universite de Montreal. “They can resist the kind of conditions we find here.”
Scientists have observed the willows’ ability to process and destroy contaminants through their roots in a lab setting.
This is the first time they’re trying it in the field – but a full decontamination using willows could take up to 15 years.
The borough of Pointe-aux-Trembles is trying to rehabilitate several contaminated areas, so it agreed to fund the project.
“This is a new technology – sustainable technology, green tech – it’s very interesting,” said Chantal Rouleau, mayor of RDP-Pointe-aux-Trembles.
It’s also labour intensive. The workers are all environmental professionals, who have to clear weeds around the willows they’ve just planted.
Even if willows are tough, scientists say there’s a limit to the level of pollution they can endure.
“If it would be too contaminated, the plants wouldn’t be able to grow that well,” Labreque added.
If the decontamination is successful, as expected, the team hopes to try it on other polluted sites across the country – nature’s way of cleaning up a very big mess.