## 3 Results and Discussion
### Major and Trace Element Assessment in Soil
#### 3.2.2 Other Major and Trace Elements in Soil
In the first soil section, aluminum concentrations range from 36.3 to 51.0 g kg\({}^{-1}\), and in the second soil section, they range from 35.3 to 54.7 g kg\({}^{-1}\). The silicon content in the top 5 cm of soil is comparable to that of agricultural soil found in the TUL and SEN regions. The values  
Figure 6: Light element distribution and concentration in upper layers of agricultural soils in the Lower Danube Basin, determined by PIGE technique (g kg\({}^{-1}\) d.w.). range from 324.1 to 342.2 g kg\({}^{-1}\). In the second soil section, the silicon content ranges from 319.1 to 375.9 g kg\({}^{-1}\). The analysis of agricultural soils has shown a variable accumulation of Fe between soil layers and territorial distribution. In TUL, higher concentrations of Fe were observed at the depth of 5-30 cm, with values ranging from 32.9 to 41.9 g kg\({}^{-1}\) compared to the first layer, where the values vary between 27.2 g kg\({}^{-1}\) and 39.5 g kg\({}^{-1}\). However, soil sampled from site T-1 shows higher values in the 0-5 cm layer (40.719 \(\pm\) 4.316 g kg\({}^{-1}\) d.w.) compared to the underlying 5-30 cm layer (37.289 \(\pm\) 7.048 g kg\({}^{-1}\) d.w.). In SEN and VAD, higher concentrations of Fe were found in the upper 0-5 cm layer, with values ranging from 34.7 g kg\({}^{-1}\) to 39.4 g kg\({}^{-1}\) and from 34.5 g kg\({}^{-1}\) to 61.0 g kg\({}^{-1}\), respectively. In the 5-30 cm layer, the concentrations vary between 29.5 g kg\({}^{-1}\) and 37.4 g kg\({}^{-1}\) in SEN and between 28.7 and 38.8 g kg\({}^{-1}\) in VAD. According to [62], the average value of Fe in soil is 35 g kg\({}^{-1}\). The highest value of Fe concentration was recorded at sampling site V-2, at both depths, with values of 61.0 g kg\({}^{-1}\) and 55.8 g kg\({}^{-1}\), respectively. Titanium values are lower than the average concentration in soil presented in Table 4. In TUL, the values range between 3.6 g kg\({}^{-1}\) and 4.9 g kg\({}^{-1}\) in the first soil section and from 2.7 g kg\({}^{-1}\) to 5.3 g kg\({}^{-1}\) in the second soil section. In SEN, the concentration of Ti in the first layer ranges between 3.6 g kg\({}^{-1}\) and 6.6 g kg\({}^{-1}\), and in the second layer, the values are from 5.2 g kg\({}^{-1}\) to 6.4 g kg\({}^{-1}\). In VAD, the values vary between 3.4 g kg\({}^{-1}\) and 5.0 g kg\({}^{-1}\) in the first soil section and between 3.3 g kg\({}^{-1}\) and 4.9 g kg\({}^{-1}\) in the second soil section. Through PIGE technique, it was possible to identify fluorine, an extremely harmful element that negatively impacts ecosystems. Fluorine is typically associated with bone disease [69] and can disrupt the processes of photosynthesis and respiration in plants [70]. In most living organisms, the concentration of fluoride is less than 10 \(\mu\)g g\({}^{-1}\) d.w. [71]. According to [62], soils worldwide have an average fluoride content of 321 mg kg\({}^{-1}\), while the continental crust has a value of 625 mg kg\({}^{-1}\). In **the analyzed soils, fluoride exceeds the global average and the Romanian norms**. For instance, in TUL and SEN, fluoride content values range from 0.3 g kg\({}^{-1}\) to 0.4 g kg\({}^{-1}\) in both considered soil sections. The fluoride concentration in the soil from VAD territory is 0.3-0.5 g kg\({}^{-1}\), in both soil layers. Notably, sampling point V-2, located on the right side of the European road E87 in the Sendreni-Baldovinesti segment, has slightly higher fluoride concentrations at both depths compared to other sampling points on the territory of Vadeni. The main sources of soil contamination with fluoride are emissions from metallurgical activities and the use of phosphate fertilizers and pesticides [72].