*3.3. Principal Component Analysis*

The results of PCA for pseudo-total metal concentrations in soils are shown in Tables 3 and 4. Four principal components (PC) with eigenvalues higher than 1 (before and after rotation) were extracted. The total variance explained by these four components is nearly 78%. In the rotated matrix, Ti, V, Fe (with positive loadings) and As and Hg (with negative loadings) are associated in a first component (PC1), which explains 24.8% of the variance. A second component (PC2), which combines Ni, Cr, and Co (all with positive loadings), and explaining 22.0% of variance, was identified. The third component (PC3) combines Pb, Zn, Cd, and Cu, accounting for 19.0% of variance. The fourth component (PC4) includes only Mn and accounts for 11.8% of variance.
