To determine if naturalized comfrey (Symphytum officinale), which is easily grown in tropical climates where farmers can produce multiple crops per year, will absorb metals from contaminated soils. Comfrey is a perennial plant with large foliage, a deep root system, is very resilient to diverse conditions and is easy to cultivate, growing rapidly and covering large areas at a time, which would make it an ideal crop for developing countries.


In order to determine if some of the most toxic or abundant metals were absorbed, commercial black soil was spiked with several concentrations of water soluble salts of metals such as Nickel (Ni), Chromium (Cr) Iron (Fe) and Zinc (Zn). Plants were grown in artificial conditions at Vale’s Greenhouse in Copper Cliff and at the end of the growing period, samples from roots, stem and leaves were tested for metal concentration levels.


Comfrey (Symphytum officinale) successfully absorbed chromium, iron and zinc onto the root system and nickel onto the leaves and root system confirming proof of principle. Use of Comfrey in developing countries where tailings waste have left a footprint, may offer local farmers an economic and environmental benefit. Farmers can not only remove and process metals for economic gain but the residue biomass can also be converted into energy to produce electricity. Furthermore, research unveiled which cyclic peptides were used to capture metals. This led to a further study into the possibility of artificially creating cyclic peptides for use in remediation.


  • Gerardo Ulibarri, Laurentian University
  • 1-705-675-1151 x 2107

Solution team

  • Douglas Morrison, CEMI
  • Nohaiah Aldarini (MSc), Laurentian University
  • Josee Bertrand (MSc), Laurentian University