## 2 Materials and Methods
### Pollution and Health Risk Assessment
#### 2.4.1 Pollution Indices
Soil contamination was classified as follows: PI\({}_{i}\) \(<\) 1--uncontaminated (Class 1); 1 \(<\) PI\({}_{i}\) \(<\) 2--low contaminated (Class 2); 2 \(<\) PI\({}_{i}\) \(<\) 3--moderate contaminated (Class 3); 3 \(<\) PI\({}_{i}\) \(<\) 5--high contaminated (Class 4); and PI\({}_{i}\) \(>\) 5--very high contaminated (Class 5) [40]. The _Potential Ecological Risk Index_ (PERI), introduced by [43], expresses the probability of the occurrence of an ecological risk due to contamination with toxic or potentially toxic elements. This index was calculated with formula (Equation (4)) [43], and its values are classified after the following scale of interpretation: low potential ecological risk (PERI \(<\) 150), moderate potential ecological risk (150 \(\leq\) PERI \(<\) 300), high potential ecological risk (300 \(\leq\) PERI \(<\) 600), and very high potential ecological risk (PERI \(\geq\) 600) [43]. \[\text{PERI}=\sum_{i=1}^{n}\text{E}_{r}^{i} \tag{4}\]  
where \(n\) is the number of elements, and \(E_{r}^{i}\) is the potential ecological risk of the metal \(i\), which is calculated with Equation (5). \[\text{E}_{r}^{i}=\text{T}_{r}^{i}\cdot\text{Pi}_{i} \tag{5}\]  
where \(\text{T}_{r}^{i}\) is the toxic response caused by the exposure of metal \(i\). According to [43], \(\text{T}_{r}^{i}\) values (mg kg\({}^{-1}\)) are as follows: \(\text{T}_{r}^{Cd}\)--30, \(\text{T}_{r}^{Cu}\)--5, \(\text{T}_{r}^{Pb}\)--5, \(\text{T}_{r}^{Cr}\)--2, \(\text{T}_{r}^{Zn}\)--2, and \(\text{T}_{r}^{Ni}\)--5. According to [9; 40], the ecological risk can be classified as follows: low ecological risk (\(\text{E}_{r}^{i}<\) 40), medium ecological risk (40 \(<\text{E}_{r}^{i}<\) 80), considerable ecological risk (80 \(<\text{E}_{r}^{i}<\) 160), high ecological risk (160 \(<\text{E}_{r}^{i}<\) 320), and very high ecological risk (E\({}_{r}^{i}>\) 320). The _Contamination Severity Index_ (CSI), developed by [44] to assess the degree of soil pollution with HMs, was calculated using the formula provided by [40; 45] (Equation (6)). \[\text{CSI}=\sum_{i=1}^{n}\text{W}_{t}\left[\left(\frac{\text{C}_{i}}{\text{ ERI}_{i}}\right)^{\frac{1}{2}}+\left(\frac{\text{C}_{i}}{\text{ERM}_{i}}\right)^{2}\right] \tag{6}\]  
where \(\text{W}_{t}\) is the calculated weight of the metal, \(\text{C}_{i}\) refers to the concentration of the metal i in soil, \(\text{ERI}_{i}\) represents the value at which the impact on living organisms of the metal is low, while \(\text{ERM}_{i}\) is the value at which the impact on living organisms of the metal is medium. Table 2 displays the HM weight values, as well as \(\text{ERM}_{i}\) and \(\text{ERI}_{i}\) values. The classification of soil contamination into contamination classes, as per the CSI, is based on the contamination intensity classes defined by [40]. These classes serve as an indicator of the severity of soil pollution present within a given area. The classes are defined as follows: Class 1 (\(<\)0.5)--uncontaminated soil; Class 2 (0.5-1.0)--very low level of soil contamination; Class 3 (1.0-1.5)--low level of soil contamination; Class 4 (1.5-2.0)--low to moderate level of soil contamination; Class 5 (2.0-2.5)--moderate level of soil contamination; Class 6 (2.5-3.0)--moderate to strong level of soil contamination; Class 7 (3.0-4.0)--high level of soil contamination; Class 8 (4.0-5.0)--very high level of soil contamination; and Class 9 (\(>\)5.0)--excessive level of pollution. The _mean Effect Range Median quotient_ (\(\text{mERM}_{\text{Q}}\)) was calculated according to [45] as Equation (7). \[\text{mERM}_{\text{Q}}=\frac{\sum_{i=1}^{n}\frac{\text{C}_{i}}{\text{ERM}_{i}}} {n} \tag{7}\]  
where \(Ci\) refers to the concentration of metal \(i\) in soil, \(ERM\)i is the value at which the impact on living organisms of the metal is medium, and \(n\) is the number of elements.