## 3 Results and Discussion  
### Pollutant Contents in Soils  
Figure 1 summarizes the PAH contents in the soils. The sum of PAH contents varied in a wide range between 0.5 and 23.3 mg/kg. This result confirms our previous findings, where [PERSON] et al. [33] found at differing sampling sites in Litvinov City that the sum of PAHs varied between 0.5 and 10.8 mg/kg. To assess the soil PAH levels, the public notice characterizing the conditions for the protection of agricultural soil quality in the Czech Republic [39] was used. However, the soils analyzed were not agricultural soils. According to this document, the preventive value of the sum of PAHs representing elevated soil PAH contents, but without any imminent environmental risk, is 1 mg/kg. The only PAH levels not exceeding this limit were found at the Nova Voda sampling area. On the contrary, the highest PAH contents were identified in the Mine Pavel area (Figure 2A). However, the indicative value of the sum of PAHs that can directly threaten human and animal health (i.e., 30 mg/kg) was not exceeded. However, the indicative value for sole benzo(a)pyrene (i.e., 0.5 mg/kg) was substantially exceeded at the Mine Pavel area, reaching up to 1.84 mg/kg. Thus, the potential adverse effect of the pollution level on the biota in this sampling area cannot be excluded. The predominant PAHs, representing 19% and 15% of the total PAH content in soils, were fluoranthene and pyrene (Supplementary Figure S1). The extensive monitoring provided by [PERSON] et al. [40] in South Korea showed fluoranthene and pyrene as the most abundant compounds, regardless of different sampling areas and variable PAH contents. Figure 1: The contents of the individual PAHs in the soils regardless of the sampling site. Figure 2: Total contents of PAHs (**A**) and PCBs (**B**) in the soils according to the individual sampling sites. As reviewed by [PERSON] et al. [41], so-called diagnostic ratios can be used to identify the origin of the PAH contamination based on the comparison of the relative concentrations of the individual PAHs. These ratios can allow us to qualitatively distinguish petrogenic and pyrogenic sources of PAHs, where the petrogenic source of PAHs in soils is typical for coal mining areas, and the pyrogenic sources are related to emissions from coal power plants [42; 43]. However, the results of our previous investigations were not unambiguous [33]. For instance, the phenanthrene/anthracene ratio indicated a pyrogenic source of PAHs, including the Mine Pavel site, where the more petrogenic origin of the pollution was expected. On the contrary, the fluoranthene/pyrene ratio indicated the pyrogenic origin of the pollution in the whole sampling area [33]. Therefore, these results indicate multiple sources of soil PAHs in the investigated area, where there is no possibility of distinguishing the impacts of the individual potential pollution sources. The soil PAH contents can be related to the soil's physicochemical parameters. Table 1 shows the main characteristics of the sampled soils, documenting the wide range of all the determined parameters. Moreover, the low level of one parameter at the particular sampling site does not mean the low levels of the other measured characteristics. These results were expected because of the big diversity among the individual sampling points, covering meadows, city parks, and forested areas. Except for the Mine Pavel soil, characterized by a pH of 6.8, the other sampling sites showed acidic soil pH, with the lowest level reaching 3.5 at the Nova Voda location. Numerous investigations confirmed that faster mineralization of soil organic matter at higher pH levels results in faster biodegradation of PAHs [44; 45; 46; 47]. Therefore, a negative correlation between soil pH and total PAH contents is expected. However, Supplementary Table S3 indicates the opposite pattern, where a significant (\(p<0.05\)) [PERSON]'s correlation coefficient \(\rho=0.66\) characterizes the relationships between soil pH and total PAH contents.