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

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.