## 3 Results and Discussion
### Correlation and Principal Component Analysis  
[PERSON]'s correlation analysis of soil heavy metals (Table 9) showed statistically significant strong positive correlations >0.90 between Pb at 5 cm and 15 cm, Zn at 5 cm and 15 cm, and Cd at 5 cm and 15 cm. A strong correlation was observed between metals at different depths. However, the variation in the heavy metal concentrations in the investigated soil samples was correlated in each field. There were also strong correlations between Zn (5 and 15 cm), Pb (5 and 15 cm), and Cd (5 and 15 cm), with the correlation coefficients ranging from 0.78 to 0.85. [PERSON]'s correlation analysis of the different parts of the sweet potato plants is shown in Table 10. There were significant positive correlations between the Pb (tuber) and Zn (tuber) at 0.95, Pb (tuber) and Cd (tuber) at 0.79, Zn (tuber) and Cd (tuber) at 0.83, Zn (leaves) and Cd \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Location**} & \multicolumn{3}{c}{\(I_{geo}\)} & \multicolumn{3}{c}{\(E_{r}\)} & \multirow{2}{*}{**References**} \\ \cline{2-2} \cline{4-7}  & **Pb** & **Zn** & **Cd** & **Pb** & **Zn** & **Cd** \\ \hline Belgrade, Serbia & 3.3 & 3.2 & 1.8 & 4 & 2 & 63 & [PERSON] et al. [57] \\ \hline Southeast Coast, Jamaica & \(-0.05\) & \(-1.70\) & nd & 0.4 & 0.6 & nd & [PERSON] et al. [59] \\ \hline Guangzhou, China & 0.46 & 2.26 & 2.70 & 8.60 & 10.70 & 200.48 & [PERSON] et al. [58] \\ \hline Drama district, northern Greece & 0.70 & \(-0.30\) & 1.10 & 31.50 & 1.90 & 139.29 & [PERSON] et al. [60] \\ \hline Central Andes, Peru & \(-0.56\) & \(-0.53\) & \(-2.47\) & 8.25 & 1.08 & 8.14 & [PERSON] et al. [61] \\ \hline Konya, Turkey & \(-0.30\) & \(-1.05\) & \(-0.41\) & 5.29 & 0.98 & 24.32 & [PERSON] et al. [24] \\ \hline Shymkent, Kazakhstan & 5.33 & 8.80 & 5.28 & 3.55 & 1.94 & 32.10 & This study \\ \hline \hline \end{tabular} \(I_{geo}\) is the HM geoaccumulation index; \(E_{r}\), individual HM potential ecological risk index.  
\end{table} 
Table 7: Comparison of the ecological assessment in soil samples with other studies from industry sites. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & & **Field** & **Pb** & **Zn** & **Cd** \\ \hline  & & Field 1 & 10.50 & 18.08 & nd \\  & Tuber & Field 2 & 9.12 & 35.77 & 0.30 \\  & & Field 3 & 6.36 & 0.85 & 0.081 \\  & & Field 1 & 1.70 & 12.18 & nd \\  & Aerial parts (leaves) & Field 2 & 4.22 & 17.72 & nd \\  & & Field 3 & 6.01 & 1.34 & 0.33 \\ \hline \hline \multirow{2}{*}{Translocation coefficient} & & Field 1 & 0.08 & 0.11 & nd \\  & Aerial parts/roots & Field 2 & 0.22 & 0.14 & nd \\  & & Field 3 & 0.95 & 0.63 & 2.31 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Bioconcentration and translocation factors in sweet potato. (leaves) at 0.99, Pb (leaves) and Cd (leaves) at 0.96, and Pb (leaves) and Cd (leaves) at 0.98. Strong correlations between the different parts of the sweet potato plants were noted. In our research, PCA was used to conduct a multidimensional analysis of the influence of the concentration of heavy metals as dependent variables. In Figure 5, PCA explained 98.46% of the total variation, with p1 for 90.71% and p2 for 7.75%. The PCA plot revealed several groups, with six dependent variables distinguishing each group. Point 1 and Field 3 soils were close together because of their higher Zn concentration. The control, Point 2, and Fields 1 and 2 had lower concentrations of HMs. The mine tailings sample was dependent on higher concentrations of Pb and Cd. In the PCA results in Figure 5, the scores for the sweet potato tubers were mainly related to higher concentrations of metals. The results indicated that factors extracted 50.97% from the soils and 49.88% from the sweet potatoes of the total variances. In addition, the loadings showed that Pb (5 cm), Pb (15 cm), Pb (leaves), Zn (leaves), and Cd (leaves) were higher, at 96%, 96%, 92%, 97%, and 99%, respectively.