*2.8. Statistical Analysis*

The software SPSS® v22.0 from IBM Corp. was used to perform a correlation analysis between the content of each metal in the different sites and the several years studied. Principal component analysis (PCA) was carried out with Varimax rotation with Kaiser normalization, in order to verify the existence of relationships between metal contents in soils analyzed in different city sites over the studied years [37].

#### **3. Results and Discussion**
