## 3 Results and Discussion
### Pedological and Chemical Properties of the Homogeneous Zones (HZs)  
A pedology-based approach was applied for the characterization of the HZs identified by the geophysical, spectrometric (\(\gamma\)-rays dose rate) and ultrasound penetrometry surveys. Five representative soil profiles (P1, P3, P4, P5 and P7) (Figure 6) were used to focus on the pedological properties of the 5 identified HZs: for site 1, P1 in HZ1 and P3 in HZ2; for site 2, P4 in HZ3, P5 in HZ4a and P7 in HZ4b. Two additional profiles were also performed: P2 on the boundary between HZ1 and HZ2, and P6 in the southern part of HZ3. Soil morphological and chemical properties are reported in Table 3A,B. Field morphological descriptions of the profiles showed massive hard structures in the surface horizons of all the soil profiles. In particular, P1, P2, P4 and P5 showed massive structure to a depth of 80-110 cm, while P3 and P6 were massive until 25-35 cm and P7 was not massive at all. Moreover, the profiles had generally common (5-15%) coarse fragments on the surface that decreased with depth, except for P1, which had abundant (21-26%) coarse fragments in the first 105 cm, formed by landfill materials (HZ1), and P7, which showed only volcanic clats (pumices and scoria) below 65 cm. Few or no roots were detected in the soil profiles, except for P4 and P7, in which common roots were found in the topsoil and few roots were found up to 180 and 100 cm, respectively. Then, different soil colors characterized the soil profiles: (i) in site 1, P1 was the only profile showing mainly olive (5Y) colors, while both P2 and P3 were olive brown (2.5Y), except for the deepest horizon (175-185+) of P2, which turned to yellowish brown (10 YR); (ii) in site 2, P4, P5 and P6 were olive brown until 70 or 95 cm and yellowish brown in the deeper buried horizons, while P7 was yellowish brown starting from the topsoil. It is known that ancient Andosols and anodic soils of Campania volcanic landscapes typically show sequences of buried yellowish brown soils, due to the presence of organo-mineral complexes, poorly ordered iron oxides (including ferrihydrite) and short-range ordered clay minerals [40; 41]. PTE contamination (as later shown in Table 4) was found only for olive and olive brown colored soil horizons, and never for yellowish brown horizons even when they formed the topsoil. Therefore, the soil color seemed to represent a good covariate of other soil properties (such as soil structure or clats abundance) that could be used for fast surveys aiming to discriminate between allochthonous anthropogenic (polluted) and autochthonous volcanic sources. Anthropic discontinuous 'Cu layers at low depths (50-60 cm), made by abundant (approximately 70%) cement clasts for a thickness of approximately 20-25 cm or thin (6-7 cm) Cm massive calcareous layers, were found in P4 and P5, respectively; in both cases, they covered hardened compacted horizons. The caret symbol (\") is a prefix that indicates horizons and layers formed in human-transported material. Indeed, presumably this material has been moved horizontally onto a pedon from a source area outside of that pedon by purposeful human activity, usually with the aid of machinery or hand tools. The \"u\" suffix indicates the presence of objects or materials that have been created or modified by humans, typically for a practical purpose in habitation, manufacturing, excavation, or construction activities [52]. Therefore, these C layers were supposed to be the remnant of ancient, buried worksite trails for moving vehicles in the industrial site, which caused strong compaction of the underlying soil structure. Close to both P4 and P5, buried trails were identified in the archive picture from 1998 (Figure 3B), and these were already identified in the ARP maps (Figure 2A,B) as red zones.