## 3 Results
### Principle Component Analysis (PCA) of the Organic and Inorganic Pollutants  
In the present evaluation, the parameters listed in Table 9 were used as input variables for the principle component analysis. As a result of the PCA, three principle components were extracted, the rotated charges of which are shown in Table 9. Principle component 1 already explains 37% of the total variance. Principle component 2 explains another 20% and principle component 3 another 19%. In total, 76% of the total variance of all the parameters considered is explained.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**DDx** & **As** & **Cd** & **Cr** & **Cu** & **Ni** & **Pb** & **Zn** \\ \hline
**NFSI-1** & & 0.32 & 0.40 * & 0.51 ** & 0.46 ** & 0.59 ** & 0.45 ** \\
**NFSI-2** & 0.24 & 0.28 & 0.39 * & 0.38 * & 0.40 * & 0.54 ** & 0.03 \\ \hline \hline \end{tabular}
\end{table}
Table 8: Correlation coefficients between DDx concentrations (sum of DDT and its metabolites) and the As, Cd, Cr, Cu, Ni, Pb and Zn concentrations in the humus layer of the Brandenburg NFSI locations differentiated for data of NFSI-1 (n = 36) and NFSI-2 (n = 50); significance: * \(p\) < 0.05, ** \(p\) < 0.01.  
Figure 5: Percentage cumulative frequency distribution of the DDx concentrations (DDT and metabolites) of the nationwide NFSI sample in humus layer and 0–5 cm depth; plots of the NFSI in Brandenburg are indicated by green circles.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Parameter** & \multicolumn{4}{c}{**Principle Component**} \\ \cline{2-5}  & **1** & **2** & **3** \\ \hline
**HCB [ng/g]** & 0.90 & & & \\
**As [ppm]** & 0.89 & & & \\ Cr [ppm] & 0.86 & & & \\
**PAH\({}_{16}\) [ng/g]** & 0.82 & & & \\
**Ni [ppm]** & 0.69 & 0.52 & & \\
**Pb [ppm]** & 0.56 & 0.53 & 0.44 \\ Zn [ppm] & & & 0.82 & \\ Cd [ppm] & 0.49 & 0.74 & & \\ Cu [ppm] & 0.60 & 0.61 & & \\ DDx [ng/g] & & & & 0.80 \\
**Dieldrin [ng/g]** & & & & 0.70 \\
**PCB\({}_{6}\) [ng/g]** & 0.41 & 0.48 & 0.64 \\
**HCH [ng/g]** & 0.45 & & & 0.58 \\ \hline \hline \end{tabular}
\end{table}
Table 9: Correlation coefficients between organic and inorganic pollutants in the humus layer and the first three factors resulting from principle component analysis after Varimax rotation with Kaiser normalization (NFSI-2, n = 50).  
Table 9 shows that principle component 1 is mainly charged by the organic pollutants HCB and PAH and the elements As and Cr. In addition, there are weaker relationships, especially with Ni, Pb and Cu. PCB and HCH are of minor importance and the pesticides DDx and Dieldrin play no role. In contrast, principle component 2 primarily represents the Zn and Cd concentration and, to a lesser extent, Cu, Pb, Ni, and PCB. Principle component 3 is significantly charged by the pesticides DDx and Dieldrin. In addition, it receives a weak charge from PCB and HCH, and the Pb concentration also shows a positive relationship to this principle component. Thus, all three principle components are influenced to the same extent by the Pb concentration and PCB concentrations. Their accumulation is therefore rather unspecific and can occur on all sites contaminated in any way by anthropogenic inputs.