## 3 Results and Discussion
### Assessment of Contamination Parameters
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multicolumn{1}{c}{} & \multicolumn{6}{c}{**TE Concentrations (ppm)**} \\ \hline
**TE** & **This Study** & **Lomié** & **Meiganga** & **Dosheng** & **Douala** & **Nigeria** & **China** & **Burkina** & **Niger** \\ \hline Ba & 89 & 175 & - & 147 & - & - & - & - & - \\ Cr & 110 & 903 & 122 & 186 & 89 & 25 & 22 & 5 & 16 \\ Mn & 292 & 421 & - & - & 551 & 146 & - & - & - \\ Fe & 42,005 & 126,343 & - & - & 7 & 784 & - & - & - \\ Co & 17 & - & - & 23 & 5 & 4 & - & - & - \\ Ni & 52 & 189 & 169 & 64 & 43 & 20 & 10 & 1 & 8 \\ Cu & 22 & 36 & 192 & 8 & 96 & 39 & 19 & 10 & 17 \\ Zn & 61 & 35 & - & 67 & 421 & 10 & 82 & 40 & - \\ Ga & 22 & 18 & - & 59 & - & - & - & - & - \\ Pb & 31 & 16 & 6 & 18 & 302 & 71 & 41 & 1 & 1 \\ Zr & 651 & 264 & - & 2209 & - & - & - & - & - \\ Nb & 57 & - & - & - & - & - & - & - \\ Y & 17 & 9 & - & 33 & - & - & - & - & - \\ Ti & 13,004 & - & - & - & - & - & - & - \\ V & 96 & - & - & - & - & - & - & - & - \\ Br & 7 & 10 & - & - & - & - & - & - & - \\ References & - & [8] & [9] & [57] & [60] & [41] & [7] & [55] & [56] \\ \hline \hline \end{tabular}  
* significant enrichment.  
\end{table} 
Table 5: Average TE concentrations in this study compared to other reported studies. Igoo values of the trace elements taken into account in our study are all below 0 except for those of Pb, Zr, Nb, and Ti, which are between 0 and 1. The results indicate there is no soil contamination by TE in the study area and found that indirect human activities are linked to the buildup of oligo-elements in soil, sediments, and water. The box plots in Figure 2 show the results of the Igeo and CF evaluations for the trace elements examined in the soil. The values of Ei and RI for Cr, Mn, Ni, Cu, Zn, and Pb elements are shown in Table 7. The results of the ecological risk index of the soil contamination with trace elements show the mean values of the individual environmental risk index (Ei) ranging from the lowest value (0.41) for the Mn to the highest value (8.76) for the Pb. Individual risk indices imply \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multicolumn{6}{c}{**Ei**} & \multirow{2}{*}{**RI**} \\ \cline{2-2} \cline{5-8}  & & & & & & & \\ \cline{2-2} \cline{5-8}
**ID** & **Cr** & **Mn** & **Ni** & **Cu** & **Zn** & **Pb** & \\ \hline A1 & 3.16 & 0.24 & 6.01 & 3.51 & 0.64 & 8.43 & 21.99 \\ A2 & 2.49 & 0.45 & 6.15 & 5.91 & 0.75 & 9.15 & 24.91 \\ A3 & 2.34 & 0.62 & 3.74 & 2.60 & 1.51 & 7.55 & 18.36 \\ A4 & 2.01 & 0.44 & 5.32 & 3.72 & 0.60 & 8.13 & 20.21 \\ A5 & 2.55 & 0.49 & 4.11 & 3.60 & 0.57 & 7.90 & 19.22 \\ A6 & 3.43 & 0.63 & 2.91 & 7.58 & 0.77 & 6.35 & 21.67 \\ A7 & 2.04 & 0.19 & 1.56 & 1.38 & 0.49 & 3.68 & 9.34 \\ A8 & 2.13 & 0.82 & 2.97 & 2.54 & 0.51 & 5.48 & 14.45 \\ A9 & 2.46 & 0.60 & 4.18 & 2.88 & 0.47 & 5.80 & 16.38 \\ A10 & 2.67 & 0.31 & 4.90 & 3.59 & 0.65 & 8.23 & 20.34 \\ A11 & 2.28 & 0.26 & 4.89 & 4.27 & 0.71 & 7.78 & 20.18 \\ A12 & 2.45 & 0.26 & 4.51 & 2.77 & 0.51 & 7.90 & 18.39 \\ A13 & 2.52 & 0.09 & 2.10 & 0.26 & 0.36 & 4.70 & 10.03 \\ A14 & 2.48 & 0.10 & 2.35 & 0.68 & 0.39 & 4.90 & 10.90 \\ A15 & 2.88 & 0.40 & 5.19 & 3.57 & 1.21 & 13.63 & 26.88 \\ A16 & 5.94 & 0.50 & 2.76 & 4.31 & 0.90 & 27.80 & 42.22 \\ A17 & 2.53 & 0.31 & 4.55 & 3.52 & 0.83 & 8.10 & 19.85 \\ A18 & 2.37 & 0.26 & 5.73 & 4.28 & 0.59 & 8.43 & 21.65 \\ A19 & 2.16 & 0.51 & 4.72 & 3.53 & 0.53 & 7.98 & 19.43 \\ A20 & 1.72 & 0.07 & 1.51 & 0.14 & 0.34 & 4.03 & 7.82 \\ A21 & 2.29 & 0.80 & 4.14 & 3.42 & 1.56 & 22.85 & 35.06 \\ A22 & 2.26 & 0.41 & 5.02 & 2.96 & 0.73 & 7.75 & 19.12 \\ A23 & 1.62 & 0.45 & 4.14 & 2.99 & 0.56 & 5.85 & 15.61 \\ A24 & 2.16 & 0.72 & 5.18 & 2.84 & 0.70 & 7.90 & 19.51 \\ A25 & 2.51 & 0.33 & 4.12 & 2.58 & 0.65 & 8.75 & 18.94 \\ Mean & 2.54 & 0.41 & 4.11 & 3.18 & 0.70 & 8.76 & 19.70 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Potential Ecological Risk Index (RI). Figure 2: Box plot of CF (**left**) and Igoo (**right**).