## 3 Results
### Spatial Distribution and Migration Activity of Heavy Metals in Bottom Sediment  
The spatial distribution and migration activity of heavy metals in the bottom sediment of the Kapshagay Reservoir water area are shown in Figures 3-6. To visualize this process, map models were prepared using the Surfer software product in the water-bottom sediment system, which plays a significant role in the assessment of the ecological conditions of the reservoir. In the created model maps, small tributary rivers for reservoir pollution were also considered. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Parameters** & **Zn** & **Cu** & **Pb** & **Cd** \\ \hline Background [65] & 83.0 & 47.0 & 16.0 & 0.13 \\ Concentration & 33.6 & 0.23 & 5.18 & 0.46 \\ \(Kc\) & 0.40 & 0.005 & 0.32 & 3.54 \\ \hline \(Zc\) & & & 1.26 & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Calculation of the pollution level of the bottom sediment. Figure 3 shows an increase in copper concentration from 0.36 to 0.38 mg/kg in the bottom sediment at the mouths of Kaskelen and Turgen rivers and up to 4.4 and 4.7 mg/L in the water in the upper reaches of the reservoir. The data in the Cu-water and Cu-bottom sediment systems have a strong positive relationship, R\({}^{2}\) = 0.85, which indicates a regression of sediment pollution from water pollution by this metal. The deposition of copper in the bottom sediment can be traced at the mouths of the rivers, i.e., from the northern shore and near the dam part of the reservoir to the southern shore, whereby a decrease in pollution activity of this metal is observed. The concentration of this metal increases in the upper reaches of the reservoir to 4.7 mg/L, while in the direction of the dam part, it gradually decreases to 0.6 mg/L, apparently already being deposited in the bottom sediment, because sedimentation of the main mass of sediments brought by the Iii River occurs as the water mass moves to the central and near-dam parts of the reservoir. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Pollution Level** & \(\mathbf{Z_{c}}\) & **Sanitary and Toxicological Danger** & **Content of Toxic Elements in Water** \\ \hline Low & 10 & Acceptable & Mostly within background limits \\ \hline Middle & 10–30 & Moderate & Many are higher relative to the background; some occasionally reach MPC \\ \hline High & 30–100 & Dangerous & Many elements are above the background; some exceed MPC \\ \hline Very high & 100–300 & Very dangerous & Many are many times higher than the background; some consistently exceed MPC \\ \hline Extremely high & \textgreater{}300 & Extremely dangerous & Mostly many times higher than the background; many consistently exceed the MPC \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Indicative scale by pollution index \(\mathbf{Z_{c}}\) for water pollution assessment [69] with the help of heavy metal concentrations in bottom sediment. Figure 3: Spatial distribution of copper in water and bottom sediment of the Kapshagay Reservoir. (**a**) Water—ug/L, (**b**) bottom sediment—mg/kg. (authors [PERSON], [PERSON]). Figure 4: Spatial distribution of zinc in water and bottom sediment of the Kapshagay Reservoir. (**a**) Water—\(\mu_{\text{g}}/\text{L}\); (**b**) bottom sediment—mg/kg. (authors [PERSON], [PERSON].) Figure 5: Spatial distribution of lead in water and bottom sediment of the Kapshagay Reservoir. (**a**) Water—\(\mu_{\text{g}}/\text{L}\); (**b**) bottom sediment—mg/kg. (authors [PERSON], [PERSON].) Zinc concentration varies from 30 to 37 mg/kg in the bottom sediment throughout the whole reservoir water area, with deposition occurring in the area of the Turgen River confluence (Figure 4). Zinc deposition in the bottom sediment is also high, reaching up to 34-35 mg/kg, respectively, in the runoff areas of the Kaskelen and Shengeldy rivers. In the water of the reservoir, a high zinc concentration can be traced in the confluence zone of the Kaskelen River and in the dam part. In the Zn-water and Zn-bottom sediment systems, the regression has an inverse relationship R\({}^{2}=-0.78\).