Phytoremediation capacity of hybrid aspen at sites affected by industry and agriculture

Abstract

Abstract Fast-growing Populus spp. are well-acknowledged to restore contaminated soils from heavy metals in industrial areas. Thus far, there is no knowledge about the phytoremediation capacity of Populusspp. plantations in hemiboreal conditions to restore industrially polluted areas. The objective of this study was to assess the soil contamination rate of heavy metals (As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb and Zn) and their uptake by trees in mature hybrid aspen (Populus tremula× Populus tremuloides Michx.) plantations at different industrial pollution (e.g. cement factory, thermal power plants, oil shale mining) levels and soil restoration methods. In total, 65 soil samples from the 0–10 cm topsoil layer, 39 wood samples and 39 bark samples were collected. Ingrowth cores were cut to separate wood developed to early and late ages. Soil pollution with heavy metals was determined in all studied plantations. Our study showed that tree growth was affected by soil pH and C:N ratio rather than the heavy metal concentration in the soil. Cd differs from other metals and accumulates less in wood and more in bark. A direct influence of wood age was confirmed; heavy metal (Cd, Cr, Cu, Fe, Mn, Ni and Zn) content in the old wood (formed 11–21 years ago) was higher than in young wood (formed during the last 10 years). The highest amounts of metals would be removed with felling on former agricultural soils with higher biomass, although wood on poorly growing stands in quarry spoil contained higher metal concentrations.