Phytoextraction of soil trace elements by willow during a phytoremediation trial in Southern Québec, Canada

ABSTRACT

The phytoextraction of the trace elements (TEs) As, Cd, Cu, Ni, Pb, and Zn by willow cultivars (Fish Creek, SV1 and SX67) was measured during a 3-year field trial in a mildly contaminated soil. Biomass ranged from 2.8 to 4.4 Mg/ha/year at 30,000 plants/ha. Shoots (62%) were the main component followed by leaves (23%) and roots (15%). Biomass was positively linked to soluble soil dissolved organic carbon, K, and Mg, while TEs, not Cd and Zn, had a negative effect. The TE concentration ranking was: Zn > Cu > Cd > Ni, Pb > As, and distribution patterns were: (i) minima in shoots (As, Ni), (ii) maxima in leaves (Cd, Zn), or (iii) maxima in roots (Cu, Pb). Correlations between soil and plant TE were significant for the six TEs in roots. The amounts extracted were at a maximum for Zn, whereas Fish Creek and SV1 extracted more TE than SX67. More than 60% (91–94% for Cd and Zn) of the total TE was in the aboveground parts. Uptake increased with time because of higher biomass. Fertilization, the selection of cultivars, and the use of complementary plants are required to improve productivity and Cd and Zn uptake.

KEYWORDS:

• phytoremediation
• phytoextraction
• willows
• trace elements

Acknowledgments

The contribution of Julien Arsenault, Joanie Labonté, Julie Labonté, Richard LaBrie, Catherine Mercier, Gilbert Tremblay and Audrey Veillette to field and laboratory work is sincerely acknowledged. The authors thank Defence Research and Development Canada for providing them the access to their landfill site.

Funding

The authors acknowledge funding by the GenoRem Project, which is primarily financed by Genome Canada and Genome Quebec, and by a Discovery grant from the Natural Sciences and Engineering Research Council of Canada to FC.