# Land Suitability Mapping Using Geochemical and Spatial Analysis Methods
## 4 Results and Discussion
### Land Evaluation Suitability for Various Types of Use Based on Screening Values  
#### 4.3.1. Cadmium  
All the sampling sites in Ioannina plain present Cd content in soil lower than the CCME (R) and the residential soil screening level (RS) established by the EPA (Figure 7A),  
Figure 6: Graduated symbol plots of Co content in soil of Ioannina plain concerning land uses (**A**) and geology (**B**).  
suggesting that there is no potential risk for residents. In contrast, all the sampling sites present Cd concentration in soil higher than the EPA's plant-avian-mammalian screening level (Figure 5B). In a research study conducted in Kontodespoti-Makrimalli area (Evia island, Greece) following the August 2019 wildfire, it was revealed that Cd content in burned topsoil and ash exceeds the EPA (P,A,M) screening level [35]. In the 54.2% (8.0 km\({}^{2}\)), 52.7% (41.0 km\({}^{2}\)), 60% (3.9 km\({}^{2}\)) and 83.8% (1.3 km\({}^{2}\)) of the urban, agricultural, shrubby-vegetated and wetlands land use, the Cd content in soil of the study area is well above the soil guideline values for agricultural land use established by the CCME (A) (Figures 7A and 8A). All the sampling sites at the area studied present Cd content in soil lower than the EPA (RS) and CCME (R) (Figure 6A).  
Figure 8: Suitability map comparing Cd content in soil of the study area to: (**A**) CCME (A); and (**B**) DEC (EI).  
Figure 7: Boxplots for (**A**) Cd and (**B**) Co, comparing element concentration to guideline established by the literature (EPA, CCME and DEC). EPA (RS): Residential soil regional screening level, EPA (P,A,M): plant-avian-mammalian screening level, EPA (A,M): avian-mammalian screening level, CCME (A): soil quality guideline for agricultural land use, CCME (R): soil quality guideline for residential land use; DEC (EI): ecological investigation level.  
The median value of Cd in soil samples of agricultural and urban land use of the area studied is higher than the CCME (A) (Figure 8A). Cadmium content in soil exceeding the DEC (EI) is observed in the 15.7% (2.3 km\({}^{2}\)), 9.2% (7.2 km\({}^{2}\)), 19.1% (1.2 km\({}^{2}\)) and 57% (0.9 km\({}^{2}\)) of the urban, agricultural, shrubby-vegetated and wetlands areas, respectively (Figure 8B).  
The most common effects of Cd on vegetables include a decrease in the number of leaves, a change in root morphology, a reduction in seed germination, a reduction in fruit production and a reduction in the absorption of nitrate [72; 73; 74]. The common adverse effects of Cd-contaminated vegetables on human health are lung damage and changes in skeletal formation, toxicity to kidneys, endocrine disrupting and irritation of the gastrointestinal system [72; 75; 76], while the consumption of various types of vegetables controls the level of toxicity of Cd in humans [72]. According to [PERSON] [77], human exposure also occurs by inhalation of dust derived from Cd contaminated soil. Moreover, chronic inhalation of Cd may cause lung cancer [78]. According to [PERSON] [79], the general toxicity of Cd to plants is moderate. Furthermore, 3 mg Cd kg\({}^{-1}\) in the plants' tissue depressed growth [80]. If Cd compounds are adsorbed by plants that play a significant role in the food chain; they can accumulate in various human organs [43]. Cadmium poses high threats to human health, soil quality and food safety [81; 82].  
Moreover, cigarette smoke is considered an important source of Cd exposure [43]. Cadmium tends to accumulate in humans' liver and kidney [46; 80]. Human exposure to Cd compounds may pose a serious health risk [81; 82]. The main organ to be affected by Cd in long-term exposure is the kidneys. The biological half-life of Cd ranges from 10 to 30 years [47].