## 3 Results and Discussion
### Spatial Distribution of Parameters Obtained by Geophysical Sensors
\begin{table}
\begin{tabular}{c c c c c c c} \hline  & \multicolumn{3}{c}{**ARP**} & \multicolumn{3}{c}{**PROFILER**} \\
**ERa VOIE1** & \multicolumn{1}{c}{**ERA VOIE2**} & \multicolumn{1}{c}{**ERA VOIE3**} & \multicolumn{1}{c}{**ECa 15**} & \multicolumn{1}{c}{**ECa 10**} & \multicolumn{1}{c}{**ECa 5**} \\ \cline{2-7}  & \multicolumn{3}{c}{**\(\Omega\cdot\)m**} & \multicolumn{3}{c}{**KHz**} \\ \hline N. cases & 162,612 & 163,717 & 163,788 & 6441 & 6354 & 6146 \\ Mean & 113.5 & 98.4 & 88.2 & 17.7 & 17.5 & 17.1 \\ St. Dev. & 96.6 & 67.2 & 48.7 & 5.2 & 6.0 & 6.8 \\ Min & 1.1 & 1.2 & 2.4 & 1.1 & 0.0 & 0.1 \\ Max & 738.9 & 699.2 & 719.2 & 49.7 & 49.9 & 50.0 \\ Coef. Var. \% & 85.1 & 68.3 & 55.2 & 29.2 & 34.4 & 39.4 \\ Skewness & 2.66 & 3.51 & 3.72 & 1.18 & 1.19 & 0.84 \\ Kurtosis & 8.37 & 6.25 & 4.12 & 4.83 & 4.87 & 3.21 \\ \hline  & \multicolumn{3}{c}{**DUALEM**} \\  & \multicolumn{3}{c}{**ERa PRP2**} & \multicolumn{1}{c}{**ERa PRP4**} & \multicolumn{1}{c}{**ERA PRP6**} & \multicolumn{1}{c}{**ERA HCP2**} & \multicolumn{1}{c}{**ERA HCP4**} & \multicolumn{1}{c}{**ERA HCP6**} \\ \cline{2-7}  & \multicolumn{3}{c}{**\(\Omega\cdot\)m**} \\ \hline N. cases & 36,688 & 36,278 & 35,780 & 35,285 & 36,504 & 36,618 \\ Mean & 94.8 & 105.0 & 77.9 & 90.7 & 79.9 & 70.7 \\ St. Dev. & 27.8 & 27.0 & 15.4 & 24.4 & 19.5 & 17.9 \\ Min & 20.2 & 46.9 & 36.4 & 34.1 & 27.5 & 23.1 \\ Max & 185.2 & 185.2 & 122.0 & 161.3 & 131.6 & 119.0 \\ Coef. Var. \% & 29.3 & 25.7 & 19.8 & 26.9 & 24.4 & 25.3 \\ Skewness & 0.58 & 0.70 & 0.55 & 0.59 & \(-\)0.08 & \(-\)0.22 \\ Kurtosis & \(-\)0.39 & \(-\)0.12 & \(-\)0.07 & 0.00 & \(-\)0.03 & 0.07 \\ \hline \end{tabular}
\end{table} 
Table 1: Descriptive statistics on ARP, PROFILER EMP and DUALEM data of geophysical surveys. ERa = apparent electrical resistivity; Eca = apparent electrical conductivity. Figure 4: ECa maps (in mS/m) obtained from the PROFILER survey at (**A**) 15 KHz and (**B**) 7 KHz. Figure 3: Archive pictures of the site in 1998 (**A**), 2006 (**B**) and 2011 (**C**). In both maps, two main HZs were identified in site 1: one in the western part (blue color), along the step and overlapping the previously identified HZ1, showing the highest ECa values of the site (19-28 mS/m), and another in the eastern part (red color), characterized by low ECa values (15-9 mS/m), formerly occupied by waste heaps and comprising HZ2. In site 2, a jeopardized pattern of ECa values added great difficulty to the identification of HZs, although a small HZ (i.e., HZ3) with N-S strip shape and middle values (16-19 mS/m) was recognized in the western part (green color, Figure 4A), while middle-low values (16-10 mS/m) were found in the mid-eastern part of site 2 (red color). Therefore, through comparison of all the geophysical maps, high consistency arose for the two HZs of site 1 (HZ1 and HZ2) and the two HZs of site 2 (HZ3 and HZ4). However, the HZs were better defined in the maps of the ARP and DUALEM surveys (Figure 2), which were carried out in the phase preceding the rearrangement works of the site, compared with the PROFILER EMP maps (Figure 4) obtained by the survey carried out after the waste displacement. The effect of the site works on the geophysical signal showed by the PROFILER EMP maps was more evident in site 2, where the random distribution of the wastes on the soil surface very likely produced new geophysical anomalies. Therefore, the results of the geophysical surveys by measurement of soil ERA and ECa enabled the identification of field heterogeneity due to deep in situ soil reworking and/or presence of polluted materials. Indeed, ERA and ECa are key parameters for understanding high spatial resolution soil geography, since they are strongly affected by physical, chemical and hydrologic properties, including soil moisture [55], soil compaction, coarse fragments and clay content [56; 57], salinity [58] and carbonate content [59]. ECa maps represent the combined results of the spatial variability of the soil properties, but the effect produced by a single property is impossible to identify.