## 3 Results and Discussion
### Major and Trace Element Assessment in Crops
#### 3.5.1 Heavy Metals in Plants  
The concentration of Cd in _wheat_ ranges from 0.001 \(\pm\) 0.001 to 0.040 \(\pm\) 0.003 mg kg\({}^{-1}\) in the leaves and from 0.000 \(\pm\) 0.000 to 0.046 \(\pm\) 0.003 mg kg\({}^{-1}\) in the grains. The mean content of Cd in grains falls within the [93; 94] recommendations for all sampling sites. Reference [62] reports average values of Cd in wheat grains, grown under various conditions, of 4.5-270.0 mg kg\({}^{-1}\). Reference [96] shows that Cd accumulation in plants occurs in the order root > stem > grain when applying Cd treatments in different concentrations to the soil in wheat and corn. The present study confirms the higher accumulation in leaves than in grains (site S-1), but higher concentration in the grains than in the leaves (sites T-1, T-2). Therefore, careful monitoring of this crop is required due to the tendency of transfer of Cd in grains. In _corn_, the mean content of Cd is from 0.056 \(\pm\) 0.002 to 0.093 \(\pm\) 0.001 mg kg\({}^{-1}\) in the leaves and from 0.003 \(\pm\) 0.001 to 0.012 \(\pm\) 0.001 mg kg\({}^{-1}\) in the grains. These values fall within the maximum permissible limit recommended by [92; 93]. Reference [96] shows that Cd accumulates in large quantities in the root and stem at increasingly high concentrations of Cd in the soil, unlike the grain, which makes corn able to be used as a hyperaccumulator in polluted areas, without posing risks to consumers, provided that the contaminated tissues are not used for animal feed. In _sunflower_, Cd content ranges in the limits 0.171 \(\pm\) 0.005-0.361 \(\pm\) 0.007 mg kg\({}^{-1}\) in the leaves and 0.114 \(\pm\) 0.001-0.400 \(\pm\) 0.004 mg kg\({}^{-1}\) in the seeds. The values do not exhibit the MPLs for Cd, as established by [92] and [93]. Reference [89] shows that sunflower accumulates Cd more in the root, and the concentration of this element in the plant decreases in the order root > stem > leaves. At the same time, the study of [97] on the ability of sunflower to phytoextract Cd shows that it is a good hyperaccumulator of this element, especially at the root level. In _wheat_, Co content lies in the range of 0.030 \(\pm\) 0.002-0.563 \(\pm\) 0.015 mg kg\({}^{-1}\) in the leaves and 0.009 \(\pm\) 0.001-0.062 \(\pm\) 0.005 mg kg\({}^{-1}\) in the grains. The highest concentration of Co in leaves was found at sampling site S-1, located near the slag dump. In _corn_, the concentration of Co ranges from 0.038 \(\pm\) 0.001 to 0.050 \(\pm\) 0.003 mg kg\({}^{-1}\) in the leaves and 0.003 \(\pm\) 0.001-0.008 \(\pm\) 0.001 mg kg\({}^{-1}\) in the grains. The pattern of cobalt accumulation in _sunflowers_ mirrors that observed in wheat and corn. In this case, Co level ranges from 0.021 \(\pm\) 0.002 to 0.128 \(\pm\) 0.011 mg kg\({}^{-1}\) in the leaves and from 0.010 \(\pm\) 0.001 to 0.047 \(\pm\) 0.004 mg kg\({}^{-1}\) in the seeds. In Europe, no maximum threshold has been established for the concentration of cobalt in cereals and sunflower seeds. The present study shows that Co accumulates in the order of leaf > cryopses/achenes. Other studies have reported the following concentrations of Co in crop plants: 0.14-0.49 mg kg\({}^{-1}\) in wheat grains [98; 99] and 0.15-0.24 mg kg\({}^{-1}\) in corn grains [98; 100]. The results on _wheat_ sections found that Cr concentration tends to be higher in the leaves (0.649 \(\pm\) 0.055 to 2.707 \(\pm\) 0.093 mg kg\({}^{-1}\)). In grains, the concentration was from 0.100 \(\pm\) 0.004 to 0.801 \(\pm\) 0.050 mg kg\({}^{-1}\). The highest concentrations of Cr were found in sampling sites T-2 (TUL), S-1 (SEN), and V-1, (VAD). The results suggest that the concentration of Cr in different parts of the wheat plant is influenced by the ecological conditions in which the plants grow.