## 3 Results and Discussion
### Major and Trace Element Assessment in Crops
#### 3.5.1 Heavy Metals in Plants
The findings of our study reveal that the concentration of nickel exhibits a higher presence in the _wheat_ leaves in comparison to the caryopses. The average Ni concentration in the leaves ranges from 0.771 \(\pm\) 0.047 to 4.130 \(\pm\) 0.235 mg kg\({}^{-1}\), while in the caryopses it ranges from 0.400 \(\pm\) 0.034 to 1.164 \(\pm\) 0.115 mg kg\({}^{-1}\). Similarly, for _corn_, the average Ni concentration is higher in the leaves compared to the caryopses. The average Ni concentration in the leaves ranges from 0.885 \(\pm\) 0.094 to 1.147 \(\pm\) 0.001 mg kg\({}^{-1}\) d.w. and in the caryopses, it ranges from 0.094 \(\pm\) 0.065 to 0.718 \(\pm\) 0.034 mg kg\({}^{-1}\) d.w.  
On the other hand, in the case of _sunflowers_, the Ni concentration is higher in the seeds than in the leaves. The mean Ni content in the achenes ranges from 3.797 \(\pm\) 0.106 to 6.816 \(\pm\) 0.144 mg kg\({}^{-1}\) d.w., while in the leaves, it ranges from 0.511 \(\pm\) 0.023 to 5.005 \(\pm\) 0.445 mg kg\({}^{-1}\) d.w. It is worth noting that there are no established maximum allowed values for Ni in cereals and oilseeds in EU. The results obtained in this analysis indicate that the Ni concentration in the analyzed plants is below the recommended threshold, as is mentioned in Table 12.  
The analytical results of this work revealed that Pb accumulation in _wheat_ leaves is higher than in caryopses, with values ranging from 0.714 \(\pm\) 0.052 to 1.413 \(\pm\) 0.008 mg kgfor the leaves and 0.026 \(\pm\) 0.002 to 0.640 \(\pm\) 0.059 mg kg\({}^{-1}\) for the cryopges. The average concentrations for cryopses exhibit the MPLs according to [92] and [93]. Similarly, the mean concentrations of Pb in _corn_ are elevated in the leaves, with levels ranging from 0.774 \(\pm\) 0.035 to 1.461 \(\pm\) 0.039 mg kg\({}^{-1}\), in comparison to the levels found in the cryopsis, where they vary from 0.051 \(\pm\) 0.003 to 0.217 \(\pm\) 0.015 mg kg\({}^{-1}\). Notably, the average values of Pb at the T-3 site (TUL) exceed the permissible limit of 0.20 mg kg\({}^{-1}\). However, for all caryposis samples, the lead level is below the values recommended by [94]. According to [101], lead accumulation is usually higher in the roots than in the leaves and grains. Regarding _sunflower_ sections, two distinct situations were found. In the TUL territory, our study revealed higher Pb accumulation in the leaves, with average concentrations ranging from 0.805 \(\pm\) 0.036 to 0.955 \(\pm\) 0.030 mg kg\({}^{-1}\), than in the achenes, where average values were between 0.314 \(\pm\) 0.014 and 0.372 \(\pm\) 0.034 mg kg\({}^{-1}\). The concentration of Pb in the achenes of SEN and VAD territories is notably higher compared to that in the leaves. In the achenes, the average values range from 0.646 \(\pm\) 0.400 to 1.542 \(\pm\) 0.140 mg kg\({}^{-1}\), while in the leaves, the values range from 0.007 \(\pm\) 0.001 to 0.011 \(\pm\) 0.001 mg kg\({}^{-1}\). The mean Pb concentration in the seeds collected from the three targeted ATUs exhibits the MPLs according to [92] and [93], as well as the limit mentioned by [94]. However, [97] revealed that sunflowers are good accumulators of this element, and [102] concluded that the quality of the obtained oil does not exceed food safety regulations, despite the high content of Pb extracted by the plant. Reference [101] suggests that lead transfer in sunflower sections occurs in the order root > stem > leaves > achenes, which is confirmed by the present study for the TUL territory, while for SEN and VAD, the situation is the opposite. In _wheat_, it was found that the caryopsis had a tendency to accumulate more zinc than the leaves. The concentration of zinc in caryopses ranged from 47.584 \(\pm\) 1.570 to 69.420 \(\pm\) 0.417 mg kg\({}^{-1}\), while in the leaves it varied between 31.842 \(\pm\) 0.0318 and 66.389 \(\pm\) 1.129 mg kg\({}^{-1}\). It was observed that the concentration of zinc in caryopses was below the MPLs mentioned in [94]. In _corn_, it was found that the leaves accumulated more zinc than the caryopsis.