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.
Keywords: Poplar; brownfield; clone selection; heavy metals; phytoremediation.
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.