Distribution of metals in soils and relationships among fractions by principal component analysis

A sequential extraction procedure (speciation procedure) was proposed with the aim of determining the distribution of Pb, Co, Ni, Cu, Zn, Mn, Fe, Cd and Cr among the different fractions of soil samples taken in three locations; two in rural areas and one in an industrial area. These results provided information about the main fractions where these metals were accumulated in the soils studied. Principal component analysis was used as a method for data treatment to establish general relationships among metal amounts accumulated in the different fractions and general soil properties, which were expected to govern the metal distribution pattern. On the basis of the results obtained from the position maps of variables and samples, the carbonate content was the soil property with the greatest number of statistically significant correlations with metal contents in fractions, so it can be considered as a relevant parameter in the distribution of some metals such as Pb, Ni, Zn and Cu in the soils.