## 3 Results and Discussion  
### Spatial Assessment of Heavy Metals in Surface Water and Sediment  
The concentration of heavy metals in surface water among all samples indicated Cu (26.9 \(\pm\) 2.3) and Ni (21.2 \(\pm\) 3.9) as the most dominant heavy metals (Figure 1a), whereas in sediments, it was Zn (174.3 \(\pm\) 10.9) and Cr (97.05 \(\pm\) 5.4) (Figure 1b). The data suggest a noticeable increase in the concentrations of most heavy metals in sediments and surface water from Sample 1 to Sample 10, indicating a possible contamination gradient across the sampled area. Notably, the levels of Cu and Ni for surface water and As and Cd for sediments increased significantly from Sample 1 to Sample 10. Heavy metal concentrations, including Arsenic, Cadmium, Copper, Nickel, Mercury, and Zinc, exhibited notable differences across the surface water samples, as indicated by the analysis of variance (ANOVA) results (\(p\) < 0.05) (Table 2). Heavy metal concentrations, including Arsenic, Chromium, Copper, and Zinc, exhibited notable differences across the sediment samples, as indicated by the analysis of variance (ANOVA) results (\(p\) < 0.05) (Table 3). These variations suggest spatial heterogeneity in heavy metal distribution across the sampled area. This could indicate an external source of contamination, possibly due to anthropogenic activities, such as industrial discharges, agricultural runoff, or improper disposal of hazardous waste [2; 36; 37]. The dominance of Cu and Ni could be due to stormwater and agricultural runoff, particularly from roads, and the use of copper-containing pesticides and fertilizers in agriculture can lead to Copper in river water. Nickel can also be found in certain fertilizers [2; 25; 38]. Since this tributary is exposed to agricultural runoff, this could possibly explain why Cu and Ni were found to be dominant. The hierarchy of heavy metal concentration in surface water is as follows: Cu > Ni > Zn > Cr > Pb > As > Cd > Hg. For sediments, it is the following: Zn > Cr > Cu > Ni > Pb > As > Cd > Hg. A medium coefficient of variation (CV) was observed for Ni (21.7) and Zn (19.5) in surface water (Figure 2), while for sediments, it was observed for Cu (16.88), Ni (17.9), Pb (16.2), and As (15.58) (Figure 3). The medium variations of heavy metal concentrations found in the surface water and sediments indicated potential variations in their origins, possibly influenced significantly by human or anthropogenic activities [39; 40]. All the other heavy metals had a CV of <15, indicating no minor or significant changes in heavy metal variation. Figure 1: (a) Heavy metal concentrations in surface water. (b) Heavy metal concentrations in sediments. \begin{table}
\begin{tabular}{l l l} \hline \hline
**Surface Water** & \
\begin{tabular}{l} **Range (Sample 1 to** \\ **Sample 10**) \\ \end{tabular} &
\begin{tabular}{l} **Mean \(\pm\) SD (Mean of Combining** \\ **Data Sample 1 to Sample 10**) \\ \end{tabular} \\ \hline
**Arsenic** & 4.066–6.900 & 5.452 \(\pm\) 0.658 e \\
**Cadmium** & 0.600–0.980 & 0.712 \(\pm\) 0.079 f \\
**Copper** & 21.790–32.880 & 26.276 \(\pm\) 3.416 a \\
**Lead** & 6.652–11.791 & 8.688 \(\pm\) 1.214 d \\
**Chromium** & 7.746–10.433 & 8.934 \(\pm\) 0.709 d \\
**Nickel** & 12.694–29.244 & 20.747 \(\pm\) 4.877 b \\
**Mercury** & 0.150–0.215 & 0.177 \(\pm\) 0.150 f \\
**Zinc** & 11.675–24.330 & 16.316 \(\pm\) 3.496 c \\ pH & 7.3–8.1 & 7.6 \(\pm\) 0.2 C \\
**Temperature** & 15.0–15.7 & 15.4 \(\pm\) 0.2 B \\
**TSS** & 22.0–46.0 & 36.1 \(\pm\) 6.18 A \\
**TN** & 2.1–3.3 & 2.69 \(\pm\) 0.29 D \\
**COD** & 32.6–45.6 & 36.91 \(\pm\) 3.80 A \\
**TP** & 0.13–0.18 & 0.15 \(\pm\) 0.01 E \\
**Chl\(\alpha\)** & 2.4–3.8 & 3.07 \(\pm\) 0.38 D \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Results from ANOVA display the distribution of a heavy metal among all surface water samples. Groups with the same letter are not statistically significant. Figure 2: Coefficient of variation among the samples in surface water and sediments.