Distribution and Uptake of Copper, Chromium, Nickel, and Iron in Equisetum arvense and Equisetum hyemale Grown in Gold Mine Tailings

Abstract

Globally, the Equisetum genus has been identified as metal tolerant with characteristics useful for revegetating metal-contaminated sites and tailings. In this study, Equisetum arvense and Equisetum hyemale were propagated from wild stock and grown under greenhouse conditions to investigate their interactions with metals. Substrates were northern Canadian gold mine tailings, 10% v/v peat amended tailings, and a constructed control. Plant survival, above and belowground biomass, and metal content were measured after 14 weeks. Then, roots and stems were measured with synchrotron X-ray fluorescence imaging (XFI) to identify tissues involved in plant–metal interactions. Both species were tolerant of the tailings substrate, but E. hyemale had higher survival across all substrates and consistently low metal translocation (studied metal translocation factors ≤4.61–41.7%). XFI revealed E. hyemale excluded most metals at the root epidermis, and E. arvense used distinct root vasculature for Cu and Fe transport, giving direction to future mechanistic studies. E. hyemale’s survival and belowground metal accumulation make it more desirable for tailings revegetation than E. arvense. By cultivating Equisetum under field relevant conditions and using XFI on these species for the first time, this study describes the potential of these native boreal species for metal phytostabilization.