## 4 Conclusions  
In the framework of characterization and remediation strategies of potentially contaminated sites, this work tested the effectiveness of different PSS methods and combined them with pedological investigation in order to facilitate spatial variability assessment of the physical and chemical degradation phenomena affecting soil in an industrial site in southern Italy. The use of the EMI and ARP techniques--provided by the Italian regulatory body for potentially polluted sites with unknown spatial distribution of contaminants--in combination with \(\gamma\)-rays and ultrasound penetrometry surveys proved very effective for the identification of HZs. This was verified and validated through the use of pXRF for elemental analyses. Moreover, the detailed pedological characterization enabled us to identify high variability in the in-depth soil stratigraphy, as well as extensive soil physical degradation and PTE (mainly Pb, As, Cd) contamination from the soil surface down to variable soil depths. The validation analysis, obtained using pXRF spectrometry, and the high consistency between \(\gamma\)-rays and pXRF maps, demonstrated that the most successfully applied technique in this study was \(\gamma\)-rays spectrometry. This supported the use of natural and artificial radioactivity-based methodologies as proxy for the fast, noninvasive identification of soil degradation and pollution spatial variability.  
Therefore, a multi-sensor approach must be increasingly considered a powerful tool for the fast identification of HZs in degraded environments. It offers the tangible opportunity to address targeted prevention and remediation strategies. This study confirmed and highlighted the fact that site-specific investigation strategies must be tuned every time environmental studies are faced. A priori, neither the best performing or the most suitable proximal sensors exist; only the use of combined techniques based on different physical principles associated with pedological surveys will enable researchers to describe, as closely as possible, the real extent and variability, both in space and depth, of soil degradation phenomena.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app12083993/s1](https://www.mdpi.com/article/10.3390/app12083993/s1)]([https://www.mdpi.com/article/10.3390/app12083993/s1](https://www.mdpi.com/article/10.3390/app12083993/s1)). Table S1. (**A**) Pearson correlation coefficients between elements measured on the regular grid at a depth of 0-10 cm by pXRF (Fe, K, Pb, Ti, Mn, Sr, Sb, Cu, Zn, Zr, Sn, Rb, As, Cd, V, Cr, Ni, Nb, Th), and \(\gamma\)-rays (dose rate) and cone index data (CI); (**B**) Pearson correlation coefficients between elements measured on the regular grid at a depth of 10-45 cm by pXRF (Fe, K, Pb, Ti, Mn, Sr, Sb, Cu, Zn, Zr, Sn, Rb, As, Cd, V, Cr, Ni, Nb, Th), and \(\gamma\)-rays (dose rate) and cone index data (CI).  
Conceptualization, S.V., F.T., G.L. and P.M.; Methodology, S.V., F.T. and P.M.; Software, A.A. and F.A.M.; Validation, S.V., F.T., G.L. and P.M.; Formal Analysis, A.A., R.D.M., P.M. and S.V.; Investigation, A.A., S.V., R.D.M. and F.T.; Resources, F.T.; Data Curation, S.V., A.A. and F.A.M.; Writing--Original Draft Preparation, S.V. and F.T.; Writing--Review & Editing, S.V. and F.T.; Visualization, A.A., F.A.M. and S.V.; Supervision, S.V. and F.T.; Project Administration, F.T.; Funding Acquisition, F.T. All authors have read and agreed to the published version of the manuscript.  
This research activity was funded by the agreement between ECOBAT S.p.a. and CIRAM--University of Naples Federico II, an Italian funding programme after-LIFE11/ENV/IT/275 EcoRemed project (2012-2017): Implementation of eco-compatible protocols for agricultural soil remediation in Litorale Domizio Agro Aversano NIPS.  
The authors declare no conflict of interest.