ObjectiveThis study aims to investigate the accumulation characteristics of different heavy metals in all parts of Populus alba 'Berolinensis'.

MethodWe analyzed the bio-accumulation amount and bio-concentration factor (BCF) of roots, stems and leaves to cadmium (Cd), zinc (Zn) and lead (Pb) after treating the soil with three concentrations of each heavy metal. For Cd, we used 0.5, 1.5 and 2.5 mg/kg; for Zn we used 300, 500 and 700 mg/kg; and for Pb, the concentrations were 300, 500 and 700 mg/kg.

ResultOur results showed that the bio-accumulation amounts of Cd, Zn and Pb in roots, stems and leaves were all significantly positively correlated with corresponding heavy metal content in the soil (P < 0.01). High concentration treatment of Cd resulted in the BCF of all the plant parts in response to Cd to be lower than those for low treatment concentrations; The BCF of leaves to Zn in high concentration treatment of Zn and the BCF of leaves to Pb in high concentration treatment of Pb were lower than those in low treatment concentrations. The BCF for roots and stems of Zn was not sensitive to the Zn treatment concentrations, whereas the BCF of roots and stems to Pb was dependent on Pb treatment concentrations. The bio-accumulation amount of Cd in all plant parts did not show any clear trends. The BCF of Cd among all parts showed no differences in response to the lowest concentration, but the BCF of the roots was significantly lower than those of the stems and leaves under the highest concentration (P < 0.05). The bio-accumulation amount and BCF of leaves, roots, stems for Zn in the low concentration treatment group, and of roots, leaves, stems in the high concentrations treatment groups decreased in turn. The bio-accumulation amounts and BCF of Pb in roots for all Pb concentrations applied were higher than those of the stems and leaves (P < 0.05).

ConclusionThe above results indicated that the concentrations of Cd, Zn and Pb in soil caused different, specific accumulations of these three heavy metals in Populus alba 'Berolinensis' roots, stems, and leaves. With regard to accumulation in all three parts of the Populus alba 'Berolinensis' plants, for Cd the enrichment thresholds of stems and leaves were higher than those of roots. For Zn, the accumulation results showed a trend of leaf > stem > root at low treatment concentrations and a different trend of root > leaf > stem at moderate and high treatment concentrations. For Pb, the accumulation was always greatest in the roots.