## 3 Results and Discussion
### PXRF (Portable X-ray Fluorescence): Spatial Survey
Hot spots of Cd contamination (in the range 100-200 mg/kg) were principally concentrated in site 1, in both HZ1 and HZ2, and a similar trend was observed for site 2 where some hot spots of Cd were found in proximity to the removed waste hills (in HZ3 and HZ4a) (Figure 7A). In correspondence with HZ4b, considerably lower concentrations of Cd were detected, with areas reaching levels below CSC2 and CSC1. However, contamination levels generally decreased with depth, although strong Cd concentrations persisted in HZ1. Meanwhile, the less contaminated areas in HZ4b grew larger with depth (Figure 7B). Concerning Pb distribution: all of site 1 was widely and strongly contaminated, with measured values exceeding the CSC3 by ten to thirty times (Figure 7C). High consistency was found between Pb and Cd distribution for both sites 1 and 2. With depth (Figure 7D), weak decreases of Pb contamination were observed, as well as an increased extension of the less contaminated area in HZ4b. The spatial distribution of As (Figure 7E) was similar; it was highly concentrated in site 1, with the highest concentrations in the southern part of HZ1, as well as in HZ3 and partially in HZ4a, while As concentrations below CSC1 and CSC2 were found mainly in HZ4b. In both site 1 and site 2, decreased As concentrations were detected with depth (Figure 7F). Bivariate Pearson correlation analysis was applied to penetrometry (CI), \(\gamma\)-rays dose rate and pXRF measurements (Table S1A,B). CI values in the first 10 cm showed significant correlation coefficients (at 0.05 level, two-tails), with only Pb (0.293 *), Zn (0.293 *) and Sn (0.292 *) measured in the 0-10 cm of depth, suggesting that the more hardened the soil  
\begin{table}
\begin{tabular}{l c c c c c c c c c c c c c c c c c c c} \hline \hline  & **As** & **Cd** & **Cr** & **Cu** & **Ni** & **Pb** & **Sn** & **Zn** & **V** & **Mn** & **Nb** & **Rb** & **Sr** & **Sb** & **Th** & **Ti** & **Zr** & **Ca** & **Fe** & **K** \\  & & & & & **mg/kg** & & & & & & & & & & & & & & **g/kg** & & \\ \hline
**0-10 cm** & & & & & & & & & & & & & & & & & & & & & & \\ N. cases & 91 & 91 & 120 & 120 & 118 & 120 & 107 & 120 & 120 & 120 & 119 & 120 & 120 & 101 & 120 & 120 & 120 & 120 & 120 & 120 \\ Mean & **69** & **74** & 60 & 335 & 35 & **9456** & 178 & 226 & 115 & 1055 & 59 & 252 & 533 & **229** & 39 & 3126 & 386 & 32.8 & 38.0 & 29.2 \\ St. Dev. & 45 & 41 & 12 & 448 & 21 & 7888 & 195 & 118 & 9 & 111 & 6 & 25 & 45 & 148 & 6 & 338 & 36 & 19.7 & 7.7 & 4.8 \\ Min & **21** & **16** & 38 & 55 & 15 & 27 & 91 & 93 & 589 & 28 & 96 & 328 & 30 & 19 & 1991 & 174 & 17.9 & 27.0 & 15.9 \\ Max & **230** & 185 & 125 & **3382** & **201** & **45310** & **1682** & 969 & 150 & 1402 & 77 & 368 & 670 & **854** & 54 & 4453 & 242.7 & 100.7 & 44.9 \\ Coef. Var. & 64 & 56.0 & 19.7 & 133.7 & 59.7 & 83.4 & 109.4 & 52.4 & 8.2 & 10.5 & 10.2 & 9.8 & 8.4 & 64.6 & 15.6 & 10.8 & 9.3 & 60.1 & 20.1 & 16.4 \\ \% & & & & & & & & & & & & & & & & & & & & & \\ Skewness & 1.3 & 0.5 & 2.7 & 4.7 & 5.5 & 1.2 & 5.3 & 3.7 & 0.5 & \(-\)0.1 & \(-\)1.7 & \(-\)1.8 & \(-\)0.4 & 1.3 & \(-\)0.5 & 0.1 & \(-\)2.5 & 8.1 & 5.2 & 0.3 \\ Kurtosis & 1.6 & \(-\)0.6 & 13.6 & 25.7 & 41.7 & 2.6 & 36.0 & 19.7 & 0.5 & 1.9 & 9.8 & 17.2 & 3.8 & 3.2 & 0.9 & 0.7 & 12.5 & 77.0 & 38.7 & \(-\)0.3 \\
**10-40 cm** & & & & & & & & & & & & & & & & & & & & \\ N. cases & 98 & 59 & 98 & 98 & 94 & 98 & 76 & 98 & 98 & 98 & 98 & 98 & 73 & 98 & 98 & 98 & 98 & 98 & 98 \\ Mean & **56** & **57** & 56 & 217 & 29 & **5781** & 132 & 184 & 118 & 1111 & 59 & 257 & 550 & **166** & 40 & 3269 & 398 & 31.2 & 35.8 & 31.3 \\ St. Dev. & 40 & 39 & 9 & 184 & 11 & 6241 & 122 & 70 & 9 & 116 & 5 & 20 & 43 & 130 & 6 & 332 & 33 & 10.9 & 3.6 & 4.3 \\ Min & 18 & 16 & 38 & 42 & 15 & 100 & 25 & 94 & 86 & 813 & 41 & 173 & 409 & 32 & 19 & 2234 & 290 & 19.5 & 27.0 & 19.9 \\ Max & **211** & **200** & **82** & **899** & **203** & **2019** & **772** & 399 & 140 & 1301 & 74 & 301 & 668 & **578** & 3682 & 492 & 112.2 & 49.1 & 39.6 \\ Coef. Var.