Evaluation of Populus and Salix Continuously Irrigated with Landfill Leachate I. Genotype-Specific Elemental Phytoremediation

Abstract

There is a need for the identification and selection of specific tree genotypes that can sequester elements from contaminated soils, with elevated rates of uptake. We irrigated Populus (DN17, DN182, DN34, NM2, NM6) and Salix (94003, 94012, S287, S566, SX61) genotypes planted in large soil-filled containers with landfill leachate or municipal water and tested for differences in inorganic element concentrations (P, K, Ca, Mg, S, Zn, B, Mn, Fe, Cu, Al, Na, and Cl) in the leaves, stems, and roots. Trees were irrigated with leachate or water during the final 12 wk of the 18-wk study. Genotype-specific uptake existed. For genera, tissue concentrations exhibited four responses. First, Populus had the greatest uptake of P, K, S, Cu, and Cl. Second, Salix exhibited the greatest uptake of Zn, B, Fe, and Al. Third, Salix had greater concentrations of Ca and Mg in leaves, while Populus had greater concentrations in stems and roots. Fourth, Populus had greater concentrations of Mn and Na in leaves and stems, while Salix had greater concentrations in roots. Populus deltoides × P. nigra clones exhibited better overall phytoremediation than the P. nigra × P. maximowiczii genotypes tested. Phytoremediation for S. purpurea clones 94003 and 94012 was generally less than for other Salix genotypes. Overall, concentrations of elements in the leaves, stems, and roots corroborated those in the plant–sciences literature. Uptake was dependent upon the specific genotype for most elements. Our results corroborated the need for further testing and selecting of specific clones for various phytoremediation needs, while providing a baseline for future researchers developing additional studies and resource managers conducting on-site remediation.

KEY WORDS:

• remediation
• uptake
• poplar
• willow
• heavy metals
• salts
• nutrients

ACKNOWLEDGMENTS

We thank Jud Isebrands (Environmental Forestry Consultants, LLC) and Don Riemenschneider (USFS) for advice when planning and executing the study, along with Timothy Volk (SUNY ESF) for supplying the Salix cuttings. We are indebted to Jill Zalesny (Iowa State University) for pivotal discussions about the interactions among soil science, plant physiology, and plant genetics. In addition, we are grateful to Steven Rock (US EPA) for insightful technical reviews and suggestions. Also, we appreciate review of earlier versions of the manuscript from: Robert Bridges, Mark Coleman, David Coyle, Deahn Donner, Neil Nelson, Adam Wiese, and Jill Zalesny.

Notes

^a Concentrations of P, Zn, Cu, and Al were not available. Note: Min = minimum, Max = maximum, SE = standard error.

^a Not significant at α = 0.05.

^a Interpretation: use Populus clone DN17 or Salix clone SX61 for uptake and translocation of Mn into the leaves (the Populus genus is significantly better). Asterisks (∗) indicate the significantly greater genus at α = 0.05, while dashed lines (—) indicate a lack of an advantage for either genus.