## 3 Results
### Metal(loid) Concentrations
#### 3.2.3 Correlation Analysis  
Moderate to strong positive correlations between organic matter content (LOI) and most metal(loid) concentrations, as well as between the metal(loid) concentrations themselves, were found for the Einsiedel Reservoir sediments (Table 5). Exceptions to these correlations were the concentrations of Cr, Fe and V, which were inversely negatively correlated with pH and positively correlated with electrical conductivity (Table 5, Figure S5). The strong negative correlation between Fe and pH can be described as an effect of Fe oxidation during drying of the Einsiedel Reservoir sediment samples. This tendency did not occur in the soils of the reservoir catchment because Fe was already largely oxidised in the soils. The strongest correlations between individual metal(loid)s were found between As, Cd, Co, Ni and Zn. In catchment soils, the positive correlations between the metal(loid)s themselves were less strong and frequent than in the reservoir sediments (Table 6). Stronger positive correlations between the organic matter content and metal(loid) concentrations were limited to As and Pb concentrations (Table 6, Figure S6). Positive correlations between Pb and organic matter were typical for forest soils, since atmospherically deposited As and Pb are preferentially accumulated in organic-rich topsoil layers [45]. In contrast, moderate and strong negative correlations existed between organic matter and concentrations of Ni and Co, consistent with Co and Ni having higher concentrations in subsoil layers, reflecting a geogenic origin or a migration from above. Clay content was positively correlated with As and Pb concentrations, while it was negatively correlated to Ni and Co. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Geogenic Background Values (Median) (mg/kg) for BSP Sediments (LfULG 2015 [43])**} \\ \cline{2-9}
**As** & **Cd** & **Cr** & **Cu** & **Hg** & **Ni** & **Pb** & **Zn** & **Co** & **V** \\ \hline
36 & 0.59 & 30 & 22 & 0.12 & 17 & 83 & 140 & 9.3 & 46 \\ \hline \multicolumn{9}{c}{Metal(loid) concentrations (median \(\pm\) average absolute deviation) in sediments of the BSP (mg/kg), \(n\)\(\pm\)**43**} \\ \cline{2-9}
**62.9 \(\pm\) 695** & **10.3 \(\pm\) 12.0** & **43.1 \(\pm\) 11.0** & **50.2 \(\pm\) 207** & **0.51 \(\pm\) 0.25** & 9.4 \(\pm\) 4.7 & **204 \(\pm\) 212** & **626 \(\pm\) 6264** & 6.4 \(\pm\) 2.7 & **57.0 \(\pm\) 11.2** \\ \hline \end{tabular}
\end{table} 
Table 4: Comparison of the geogenic background values for the Saxon topsoils on gneiss (land use: agriculture) [43] with the measured element concentrations in the sediments of the Berthelsdorf Smelter Pond (BSP). Values in bold exceeded the background concentrations. For BSP sediments, weak to moderate positive correlations were found between Cd, Cr, Ni and V concentrations and the amount of organic matter (Table 7, Figure S7). Weak to moderate negative correlations occurred between pH and the concentrations of As, Cd and Fe. Similar to the Einsiedel Reservoir sediments, moderate to strong positive correlations occurred between most of the investigated metal(loid)s. The strongest positive correlations occurred between the concentrations of Co, Cr, Ni and V, while the correlations between these elements and other metal(loid)s were noticeably lower (correlation coefficients \(<\) 0.6). Independently of this, the concentrations of As, Cd, Cu, Fe, Hg and Zn showed moderate to strong correlations (correlation coefficients \(\geq\) 0.59) with each other. \begin{table}