## 4 Discussion
\begin{table}
\begin{tabular}{l c c c c c} \hline \hline \multirow{2}{*}{**Site**} & \multirow{2}{*}{**Source**} & \multicolumn{4}{c}{**Concentration in Bqkg\({}^{-1}\)**} \\ \cline{3-6}  & & \({}^{226}\)Ra(\({}^{238}\)U) & \({}^{228}\)Ac(\({}^{232}\)Th) & \({}^{40}\)K & \({}^{137}\)Cs \\ \hline The study & Current study & 7.80 & 6.27 & 146.00 & 10.59 \\ \hline POLAND & [2] & 25.20 & 24.70 & 410.00 & - \\ \hline North Europe & [2] & 32.08 & 27.42 & 522.67 & - \\ \hline West Europe & [2] & 40.22 & 37.50 & 547.67 & - \\ \hline East Europe & [2] & 34.90 & 33.09 & 462.12 & - \\ \hline South Europe & [2] & 28.34 & 26.40 & 332.67 & - \\ \hline Republic of Srpska & [47] & 47.00 & 41.00 & 536.00 & 26.00 \\ (Bosnia and Herzegovina) & & 44.70 & 42.30 & 542.00 & 30.80 \\ \hline Region of Croatia & [49] & 61.00 & 60.00 & 418.00 & - \\ \hline Novi Sad, Republic of Serbia & [50] & 37.00–55.00 & 45.00–55.00 & 570.00–730.00 & 5.49 \\ \hline Parks in Lithuania & [51] & 14.50 & 5.470 & 348.07 & 13.27 \\ \hline Shatsk National Natural Park, Ukraine & [44] & 6.00–9.00 & 6.00–9.00 & 106.00–148.00 & about 25.00 \({}^{*}\) \\ \hline Worldwide average & [2] & 32.00 & 45.00 & 412.00 & - \\ \hline \hline \end{tabular} \({}^{*}\) to 10 cm soil depth.  
\end{table} 
Table 4: Comparison of current results of natural radionuclides concentrations with data available in the literature. The calculated values of absorbed gamma dose rates in the Poleski National Park are close to values noted in Poland but are lower than those in East Europe and worldwide average (Table 4). In studies conducted in the Czech Republic, Switzerland, Republic of Serbia, and Bosnia and Herzegovina, the average absorbed doses were higher from about 40 to 66% than the values obtained for the Poleski Park Narodowy. Only in parks in Lithuania, the value was lower by about 48%. It looks different in the case of annual effective dose (Table 5). The annual effective dose calculated for the Poleski Park Narodowy is significantly higher than the worldwide value (250%) and the values calculated for the Republic of Serbia, parks in Lithuania, Czech Republic, Bosnia and Herzegovina (from 30 to 333%). Only in Switzerland, the value was significantly higher. The degree of soil degradation due to contamination with heavy metals largely depends on the properties of the soil. In general, trace metals in cationic forms are strongly absorbed at the surface level of the soil profile. The absolute content of a given heavy metal in the soil is a sufficient criterion to assess the degree of contamination of the soil environment with a given element. Such an assessment is often carried out on an agricultural land and is very important when assessing the amount of a toxic compound that may enter the biogeochemical cycle, and thus may reach the end consumer, which is humans. The conducted research allows evaluating the examined soils as not contaminated with chromium Cr, nickel Ni, and copper Cu. The soils of the Poleski National Park contain increased lead Pb concentrations and are highly contaminated with cadmium Cd. Cadmium Cd concentrations in the soils of the Poleski National Park are higher than in the areas more exposed to the anthropogenic impact [59]. Research has shown that protected areas such as parks are recipients of pollutants containing heavy metals that accumulate in the soils. The accumulation of heavy metals in the soil of the Poleski National Park may be related to the quality of plant communities, especially conifers, which have the ability to accumulate heavy metals in needles [60]. The obtained results were consistent with the research of other scientists [61; 62; 63]. Another basic source of pollution of the soils of the Poleski National Park with heavy metals are anthropogenic activities. These protected ecosystems have received pollutants in the gaseous or aerosol form, transported from long distances [64]. The emission of pollutants rich in heavy metals by aero position contributes to the contamination of National Parks [64; 65; 66].