Field assessment of trace element phytoextraction by different Populus clones established on brownfields in southern Quebec (Canada)

Abstract

Fast-growing hybrid poplars have been tested for their potential to remove trace elements (TE) from polluted soil in several temperate regions. Despite their potential, they have rarely been tested in countries with a cold temperate climate. The current study screened four different Populus hybrids for phytoextraction of four TEs (i.e., As, Cu, Pb, and Zn) on an abandoned brownfield site in southern Quebec (Canada). The main results showed that under the current experimental conditions, the most important traits determining the actual phytoextraction rate are Biological Concentration Factor (BCF) and TE accumulation in the aboveground biomass, rather than biomass productivity. Although the overall performance of the chosen hybrids was rather poor, the presence of poplar stands enhanced the movement of mobile contaminants in soil, which led to an increase in their concentration in the root zone. This aspect suggests possible strategies for using these plants with high transpiration rates in future phytoremediation projects, including either possible rotation with more effective TE phytoextractor plants (e.g., hyperaccumulators) that can remove high TE amounts that have migrated from the deeper soil layers following poplar plantation, or phytostabilization.

NOVELTY STATEMENT

Although the use of fast-growing woody species is commonly reported as a feasible option for the phytoextraction of TEs in temperate climates, most available information pertains to only a few species, mostly willows. This is one of the few studies reporting the results of a field test carried out in a cold temperate region, in which different poplar hybrid clones were tested for their potential in TEs phytoextraction. This research determined that although the studied poplar genotypes have no potential under these experimental conditions, the increase in TE concentration observed in the rhizosphere after two years suggests possible alternative phytoremediation strategies (phytostabilization) for managing polluted sites in cold temperate climates.

Keywords:

• Poplar
• phytoremediation
• brownfield
• clone selection
• heavy metals

Acknowledgments

Our thanks to Noémie Legault for assistance in maintaining the plantations and collecting soil and plant samples, and to Patrick Benoist for data management. We are grateful to the Quebec Ministry of Forests, Wildlife, and Parks for providing us with the poplar cuttings. Thanks also to Karen Grislis for critical review of the manuscript. The authors wish to thank the four anonymous reviewers for their positive and constructive comments during the revision process.

Author contributions

M.L.: conceptualization, methodology, formal analysis, investigation, supervision, project administration, and funding acquisition. W.G.N.: writing—original draft, writing—reviewing and editing, and visualization.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Additional information

Funding

This study was supported by the Federation of Canadian Municipalities (FCM), under the grant “Use of phytoremediation to revitalize former industrial sites in eastern Montreal” and by the Economic Development Division of the City of Montréal.