## 4 Discussion  
### Metal(loid)s in Reservoir Sediments  
The fine texture and the high concentrations of organic matter of the reservoir sediments generally favours a high sorption potential for metal(loid)s [46], which, however, was reduced by the acidic conditions in the BSP sediments. The differences in acidity between the two reservoirs may be influenced by intense weathering of the biotite engisses, biotite-two-feldspar graisses and quartzites in the BSP catchment area [25], which have been exposed to the surface longer than the rocks and soils of the Einsiedel Reservoir catchment. Although the pH of the BSP sediments was weakly correlated with Fe concentrations, which can be interpreted as an indication of acidification due to the oxidation processes during sediment drying [47], this process alone seems insufficient to explain the high acidity of the BSP samples. Since the maximum concentrations of As (34,661 mg/kg), Cd (124 mg/kg) and Zn (23,653 mg/kg) correspond to concentrations of raw ones, it is likely that the BSP sediments partially contained residual products of ore processing. Since \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline  & **As** & **Cd** & **Cr** & **Co** & **Cu** & **Fe** & **Hg** & **Ni** & **V** & **Zn** & **Pb** \\ \hline
**LOI** & **0.76** & - & - & **\(-\)0.82** & - & - & - & \(-\)0.62 & - & - & 0.92 \\
**pH** & - & - & - & 0.69 & - & - & - & - & - & - & - \\
**Electrical** & - & - & 0.60 & - & - & - & - & - & - & - \\
**conductivity** & - & - & - & 0.60 & - & - & - & - & - & - & - \\
**Clay content** & **0.74** & - & - & **\(-\)0.89** & - & - & - & \(-\)0.69 & - & - & **0.74** \\
**As** & & - & - & - & - & - & - & - & - & - & - & **0.84** \\
**Cd** & & & 0.59 & - & 0.62 & 0.58 & - & 0.63 & - & 0.58 & - \\
**Cr** & & & & - & - & 0.67 & - & - & **0.95** & - & - \\
**Co** & & & & & - & **0.76** & - & **0.90** & - & 0.69 & \(-\)0.63 \\
**Cu** & & & & & & - & - & - & - & 0.62 & 0.59 \\
**Fe** & & & & & & & - & **0.78** & - & **0.88** & - \\
**Hg** & & & & & & & & & \(-\)0.58 & - & - & - \\
**Ni** & & & & & & & & & & - & 0.63 & - \\
**V** & & & & & & & & & & & - & - \\
**Zn** & & & & & & & & & & & - \\ \hline \hline  & & & & & & & & & & & & & \\ \end{tabular}
\end{table} 
Table 6: Spearman correlations (rho values) in the soil samples from the Einsiedel Reservoir catchment (\(n=12\)). \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline  & **As** & **Cd** & **Cr** & **Co** & **Cu** & **Fe** & **Hg** & **Ni** & **Pb** & **V** & **Zn** \\ \hline
**LOI** & - & **0.46** & **0.55** & - & 0.31 & - & 0.33 & **0.41** & - & **0.51** & - \\
**pH** & \(-\)**0.63** & \(-\)0.36 & - & - & - & \(-\)0.39 & - & - & - & - & - \\
**Electrical** & 0.63 & 0.37 & - & - & 0.35 & 0.41 & - & - & - & - & 0.36 \\
**conductivity** & & & & & & & & & & & & \\
**As** & & 0.81 & - & - & 0.81 & 0.74 & 0.71 & - & 0.70 & 0.31 & 0.79 \\
**Cd** & & & 0.45 & 0.35 & 0.84 & 0.75 & 0.79 & 0.40 & 0.68 & 0.56 & 0.93 \\
**Cr** & & & & 0.90 & - & **0.48** & **0.41** & 0.92 & - & 0.94 & 0.40 \\
**Co** & & & & & - & 0.54 & 0.33 & 0.94 & - & 0.89 & 0.35 \\
**Cu** & & & & & & & & 0.74 & 0.72 & - & 0.93 & 0.41 & 0.89 \\
**Fe** & & & & & & & & 0.79 & 0.48 & 0.59 & 0.56 & 0.80 \\
**Hg** & & & & & & & & & & & & \\
**Ni** & & & & & & & & & & & & \\
**Pb** & & & & & & & & & & & & \\
**V** & & & & & & & & & & & & \\ \hline \hline  & & & & & & & & & & & & \\ \end{tabular}
\end{table} 
Table 7: Spearman correlations (rho values) in the sediments of the Berthelsdorf Smelter Pond (\(n=43\)). the local ones are often sulfidic [24], the low pH of the BSP sediments can be explained by the oxidation of sulfidic compounds [48]. In the case of sediment dredging, the high acidity of the BSP sediments favours the release of metal(loid)s, which means the sediments have a high potential to be a source of contaminants during removal. Metal(loid) enrichments in both reservoirs were assumed to be favoured by a relatively high geogenic background [49].