Nine soils were perfectly clustered into four groups, differentiated by
the concentrations of Cd, Pb, Cu, and Zn in leachates according to results
from 2-D HCA heat map and PCA. Therefore, two soil treatments of S5
and S6, clustered in respective Group 4 and 1, showing significantly different
concentrations of heavy metals in leachates, were further chosen
to study the speciation transformation of heavy metals.