Percentage (%) of Cd, Zn, Pb and As in shoot, root and iron plaque were based on the total amount of Cd, Zn, Pb and As measured.
All data were subjected to two-way analysis of variance (ANOVA) to test for significant differences resulting from the biochar
type and particle size treatments. Comparisons between means
were made using the Tukey-test (p < 0.05). Multiple linear regressions were used to examine relationships between heavy metal
concentrations in shoot and plant transfer coefficient, root length,
heavy metal concentrations in pore water (Cpw) and in iron plaque.
Statistical analysis was performed using the SPSS 16.0 software
(SPSS Inc., USA).