## 4 Results
### Severity of Stream Sediment Contamination by Metals  
The CF, PLI, Igeo, and EF were used to assess the severity of metal contamination of the sediment (Tables 4 and 5). V shows CF values ranging from 2.57 to 3.40 in samples K1 to K3, corresponding to moderate to considerable contamination [44, 62]. In contrast, most other metals (such as Pb, Tl, Th, and U) have CF values below 1, suggesting low contamination and dominance of natural background levels [55]. The Pollution Load Index (PLI), calculated as the geometric mean of the CF values for V, Cr, Co, Ni, Cu, Zn, Pb, Tl, Th, and U (normalised to UCC values), provides an integrated assessment of sediment quality. According to [PERSON] et al. [45], PLI \(>\) 1 indicates pollution, PLI \(=\) 1 represents baseline levels, and PLI \(<\) 1 suggests no pollution [45]. Among the analysed samples, K15 (PLI \(=\) 1.05) slightly exceeds the baseline value, indicating slight pollution. Samples K4 and K14 exhibit PLI values of 0.90 and 0.88, respectively, which are below the pollution threshold, indicating no pollution or low contamination. All remaining samples have PLI values \(<\) 1, reflecting generally low contamination levels in the study area (Figure 5). According to the geo-accumulation index (Igeo) values, Cr exhibited the highest pollution level with a value of 3.34 in sample K8, indicating moderate contamination. Cu and Zn also showed moderate pollution, with maximum Igeo values of 2.36 and 2.13, respectively, observed in sample K4. V showed slight to moderate pollution (Igeo \(=\) 1.18) in sample K1, while Co indicated slight pollution (Igeo \(=\) 0.46) in K1. Conversely, Ni exhibited the highest value of \(-\)0.22 in sample K4, suggesting no pollution. Pb, Tl, Th, and U had Igeo values \(\leq\) 0 across all samples, indicating no contamination  
Figure 4: The hierarchical clustering results for sediment samples are shown in the dendrogram. Annotated dendrogram of sediment samples (with cluster assignments). \begin{table}
\begin{tabular}{l c c c c c c c c c} \hline
**Cluster** & **V** & **Cr** & **Co** & **Ni** & **Cu** & **Zn** & **Pb** & **T1** & **Th** & **U** \\ \hline
1 (_n = 6_) & 160.00 & 345.67 & 16.87 & 40.25 & 39.70 & 93.35 & 6.91 & 0.09 & 1.67 & 0.78 \\
2 (_n = 3_) & 299.33 & 115.67 & 31.50 & 39.43 & 49.10 & 49.40 & 3.73 & 0.04 & 0.96 & 0.32 \\
3 (_n = 6_) & 152.00 & 127.17 & 25.20 & 48.30 & 157.17 & 351.50 & 5.53 & 0.04 & 1.34 & 0.49 \\ \hline \end{tabular}
\end{table} 
Table 3: Average metal concentrations (ppm) for each cluster. Below are the EF values calculated based on the Sc reference element and UCC background values. The EF values indicate varying degrees of metal contamination across the sediment samples. Cr exhibited very high enrichment in sample K8 (EF = 15.95), suggesting a potential for severe pollution. Cu and Zn showed high enrichment (EF > 2.5), particularly in samples K4 through K10. In contrast, Pb, Tl, Th, and U displayed low enrichment levels (EF < 0.4), indicating minimal anthropogenic influence. V, Co, and Ni were generally within the range of natural background levels to slight enrichment (EF \(\approx\) 0.8-1.7), suggesting a predominantly geogenic origin with limited contamination.