**3. Results**

#### *3.1. PTE Concentrations*

The concentrations of pseudo-total and Mehlich-3 extractable and acid-oxalate extractable PTEs are presented in Table 1.

The Kolmogorov–Smirnov (K–S) test showed normal distributions for pseudo-total As, Mn, Ti, and V, Mehlich-3 Fe and Mn, and acid-oxalate Cu and Hg. The distribution was not normal for the remaining concentrations. Consequently, the Spearman's correlations were determined.

Pseudo-total andMehlich-3 extractable metal concentrations were significantly correlated (p < 0.01) for all elements except Fe, As, and Hg. However, the proportions extracted by Mehlich-3 reagent varied widely among elements. The metal extracted by the Mehlich-3 reagent was a negligible fraction of the pseudo-total metal in the cases of Ti (0.11%) and V (0.07%). This fraction was also very low for Fe (0.66%), As (1.02%), Hg (1.29%), and Cr (1.33%). On the contrary, high fractions of Cd and Pb (30%), Mn (22%), Zn and Cu (18%) were extracted by Mehlich-3 reagent. Intermediate values were found for Co (13%) and Ni (6%).

Acid-oxalate concentrations correlated to pseudo-total concentrations (p < 0.01) for Co, Cr, Fe, Mn, and Pb, and to Mehlich-3 concentrations (p < 0.05) for Co, Cr, Cu, Mn, Ni, and Pb.

**Table 1.** Concentrations of potentially toxic elements (PTEs) for the 35 soils studied: average ± standard deviation, along with world soil average and maximum allowable concentrations (MAC) for agricultural soils according to Kabata-Pendias [27] (see also Table S1).


The percentage of metal extracted by acid oxalate, referred to the pseudo-total metal, was very high in the case of Hg, with an average value of 32% and a maximum value of 96%. The extractions were high for Co, Mn, and Zn (with average values of 10, 11, and 12%, respectively, referring to the pseudo-total concentration). For the other metals, the extraction percentages were low, with average values of less than 3%.
