## 3 Results and Discussion
### \(\gamma\)-rays Spectrometry and Penetrometry Surveys  
By preliminary random soil surveys using of a hand auger, valuable signs of soil physical degradation (such as massive soil structures, the presence of dense/hard layers and coarse fragments starting from the toposit) were identified throughout the site. Therefore, two additional PSS, including \(\gamma\)-rays spectrometry and ultrasound penetrometry, were applied, due to their high sensitivity to mineralogical and physical soil property variation. The data were used in combination with the ARP and EMI to define the HZs. Descriptive statistics of data are reported in Table 2. Potassium content ranged from 2.0% to 3.6%, U from 5.6 to 10.4 mg/kg and Th from 13.1 to 23.0 mg/kg. The \(\gamma\)-rays dose rate ranged from 60.4 to 121.9 nGy/h (Table 2). Pearson correlation coefficient underlined two significant tail correlations between \(\gamma\)-rays dose rate and the single elements (\(\gamma\)-rays dose rate vs. K = 0.798, vs. U = 0.685, vs. Th = 0.849), indicating that all these elements contributed to the radionuclide emission activity of the studied soils. Compared with measurements obtained from Vesuvius soils 20 km away as the crow flies (unpublished data), the studied area showed much lower values of K, U, Th and dose rate (in Vesuvius soils, K ranged from 3.9% to 5.1%, U from 24.1 to 31.66 mg/kg, Th 12.8 to 20.3 mg/kg and \(\gamma\)-rays dose rate from 233.5 to 279.0 nGy/h), very likely due to the dilution effect created by mixing with allochthonous wastes. Indeed, the natural origin of K, U and Th was reported in the literature in the volcanic soils of the Phlegrean Fields, Mt. Roccamonfina volcano area and Nola-Pomigliano area (north of Mt. Somma-Vesuvius volcano) [60; 61]. The common origin was confirmed by the significant correlation between K and Th (0.757) in the studied site. The georeferenced grid of the measurement points is shown in Figure 5A. Based on the data probability distribution, five classes of values were used to map the \(\gamma\)-rays dose rate variability (Figure 5B). Two main HZs were identified in site 1 (yellow and light green areas) with intermediate-low (78-100 nGy/h) and intermediate-high (100-117 nGy/h) values, respectively. Three HZs were identified for site 2 (red-orange, mainly yellow, and green areas), characterized by the lowest (60-90 nGy/h), intermediate (78-105 nGy/h) and the highest (117-122 nGy/h) values of \(\gamma\)-rays dose rate. By comparison of the \(\gamma\)-rays dose rate with the ARP and EMI maps (Figures 2 and 4), consistency was found in site 1 between the zone of intermediate-low \(\gamma\)-rays (Figure 5B) and HZ1, as well as between the intermediate-high \(\gamma\)-rays values and HZ2. For site 2, the lowest values of \(\gamma\)-rays dose rate were measured in HZ3, identified by the ARP and EMI surveys (Figures 2 and 4), while two subzones were defined for HZ4 (i.e., HZ4a and HZ4b). These were marked by intermediate and high \(\gamma\)-rays dose rates. As reported in the literature, higher levels of radionuclide activity concentrations are associated with igneous rocks, such as granite, and lower levels are associated with sedimentary rocks [62]. In particular, [PERSON] [63] demonstrated that the highest absorbed \(\gamma\)-rays dose rates for the Isparta plain (526.28 nGy/h) were in connection with Golcuk volcanics, while the lowest (18.70 nGy/h and 22.03 nGy/h) were found in the Davraz and Sobu limestones. Therefore, in our study, the areas where mainly autochthonous volcanic soils occurred, due to minimal soil/waste mixing processes, were expected to have higher \(\gamma\)-rays dose rate values. Additionally, thicker carbonate layers and higher coarse carbonate fragments content in the soil (or the presence of allochthonous nonvolcanic materials) were expected to correlate with lower \(\gamma\)-rays dose rates, despite the level of soil contamination.