A standard statistical analysis (mean, median, quartiles, standard deviation, etc.) was carried out to describe soil properties and heavy metals contents. Standardised concentrations were further processed by a PCA to study heavy metal correlations and to reduce the dimensionality
of the dataset. Principal components were retained in the analysis based on their eigenvalues. Components' scores were calculated for each plot to subsequently compute correlation coefficients
with the physical and chemical soil variables. Interpretation of principal components was assisted by correlation circles.