## 3 Results and Discussion
### Trace Elements Content
[35], Al is highly bio-excluded by King Bolete, although [PERSON] et al. [36] even determined 1200 mg kg\({}^{-1}\) DW in _Boletus edulis_. In the case of Fe content, it was reported that other mushroom species found Fe better than _Boletus edulis_[35] and the highest reported Fe content was 340 mg kg\({}^{-1}\) DW [36]. Nevertheless, in the case of purchased mushrooms, it is impossible to clearly indicate the cause of this surprising bioaccumulation. Furthermore, clustering analysis was performed based on the element contents in dried samples (Figure 6a) and water extracts (Figure 6b). Based on the provided dendrogram in Figure 6, the outliers were Sample 5 in the dried sample and Sample 3 in water extracts because they had the highest concentration in all detected metals. The samples with the lowest element concentrations were clustered together, i.e., samples no. 1 and 2 \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Elements**} & \multirow{2}{*}{**Fraction**} & \multicolumn{8}{c}{**Samples (mg kg\({}^{-1}\) DW)**} \\ \cline{3-8}  & & **1** & **2** & **3** & **4** & **5** & **6** \\ \hline \multirow{3}{*}{Al} & Total & 2.34 & 4.24 & 44.9 & 107 & 542 & 58.3 \\  & Water & 1.00 & 0.85 & 3.23 & 5.28 & 7.18 & 2.14 \\  & \% & 43 & 20 & 7.2 & 4.9 & 1.3 & 3.7 \\ \hline \multirow{3}{*}{Cr} & Total & \textless{}0.01 & \textless{}0.01 & \textless{}0.01 & 0.01 & 0.01 & 0.05 & \textless{}0.01 \\  & Water & \textless{}0.01 & \textless{}0.01 & \textless{}0.01 & \textless{}0.01 & \textless{}0.01 & \textless{}0.01 & \textless{}0.01 \\  & \% & - & - & - & - & - & - \\ \hline \multirow{3}{*}{Cu} & Total & 26.0 & 36.3 & 15.7 & 9.37 & 9.92 & 11.7 \\  & Water & 5.41 & 8.34 & 15.3 & 4.63 & 4.02 & 3.47 \\  & \% & 21 & 23 & 97 & 49 & 41 & 30 \\ \hline \multirow{3}{*}{Fe} & Total & 10.9 & 16.0 & 55.7 & 106 & 741 & 98.6 \\  & Water & \textless{}0.01 & \textless{}0.01 & 7.18 & \textless{}0.01 & 0.92 & \textless{}0.01 \\  & \% & - & - & 13 & - & 0.1 & - \\ \hline \multirow{3}{*}{Ni} & Total & 0.39 & 0.98 & 1.74 & 0.61 & 1.12 & 0.43 \\  & Water & \textless{}0.01 & 0.20 & 1.23 & 0.23 & 0.23 & 0.24 \\  & \% & - & 21 & 70 & 38 & 20 & 56 \\ \hline \multirow{3}{*}{Zn} & Total & 76.8 & 83.2 & 91.4 & 46.5 & 23.6 & 78.7 \\  & Water & 16.0 & 5.65 & 73.7 & 8.54 & 12.9 & 21.4 \\ \cline{1-1}  & \% & 21 & 6.8 & 81 & 18 & 55 & 27 \\ \hline \hline \end{tabular} \(<\)0.01—below the limit of detection; DW—dry weight; Total—element content in acid digests; Water—element content in water extracts, %—water-extractable percentage of total element content.  
\end{table} 
Table 3: Selected trace elements content in six mushroom sample extracts (_n_ = 3). in the dried samples and no. 2, 4, and 5 in water extracts. In general, the dendrograms show a different pattern, which indicates that the relation of elements contents in dried samples and in water extracts varies from one sample to another. The differences were mainly due to the variation in the extraction coefficient of each sample. The content of water-extractable elements ranged from 1.9% (Sample 5) to 48% (Sample 3) of the total content of these elements in the dry samples. However, the Euclidian distance in Figure 6a,b ranged 0-1000 and 0-100 in the dendrograms, respectively. This value represents that the average extractable elements from dried samples to the solvent was roughly 10%.