## 3 Results
### Multivariate Analysis of Physicochemical Quality of the Waters  
#### 3.3.1 Correlation and Principal Component Analysis (PCA)  
The Kaiser-Meyer-Olkin (KMO) value was 0.744, and the sphericity test of Bartlett was significant (\(p<0.0001\)). These results indicate that the PCA data were moderately adequate (0.7 < KMO < 0.79) for PCA and presented a homogeneity of variance, allowing multivariate analyses). Thereby, the variables studied exhibited positive Pearson correlations (Table 5). Significant and positive correlations were obtained between the pH and TDS, EC, PO4\({}^{3-}\), and Sa, showing the influence of these parameters brought by marine waters on the pH, which was higher in the downstream (Lagoon of Aneho). Positive correlations were also obtained between these parameters (TDS, EC, PO4\({}^{3-}\), and Sa) and some trace elements (Zn, Cr, Pb, Cu, and Cd). This relationship between variables could indicate the same source for them. This is confirmed by a significantly positive correlation obtained between these trace elements, such as Cd and (Pb, Cu, or Cr), Pb and (Cu or Cr), Cr and (Zn or Cu), as well as between Zn and Cu. Figure 3: Prediction maps of the spatial distribution of Cd, Pb, Cr, Ni, Cu, As, Zn, and Mn. The Eigenvalues and variances expressed by the PCA show that in the dry season, the first three factors explain 72.62% of the total variance with F1: 47%; F2: 15.35%; and F3:9.42% (Table 6). The factorial plan (F1 \(\times\) F2) explains the total information. The projection of variables in the plan F1 \(\times\) F2 (Figure 4A) shows that the axis F1 (47.84%) is negatively defined by TDS, PO4, pH, EC, Sa, Cr, Pb, Cu, and Zn, probably \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Parameters**} & \multicolumn{3}{c}{**Factorial Axes**} \\ \cline{2-4}  & **F1** & **F2** & **F3** \\ \hline TDS & \(-\)0.95 & \(-\)0.20 & \(-\)0.10 \\ \hline PO4 & \(-\)0.89 & \(-\)0.16 & 0.09 \\ \hline Cr & \(-\)0.88 & 0.26 & 0.14 \\ \hline EC & \(-\)0.86 & \(-\)0.35 & \(-\)0.19 \\ \hline Sa & \(-\)0.86 & \(-\)0.34 & \(-\)0.21 \\ \hline pH & \(-\)0.79 & 0.27 & \(-\)0.13 \\ \hline Cu & \(-\)0.70 & 0.28 & 0.07 \\ \hline Pb & \(-\)0.62 & 0.32 & 0.18 \\ \hline Zn & \(-\)0.57 & \(-\)0.51 & 0.18 \\ \hline Cd & \(-\)0.63 & 0.66 & \(-\)0.08 \\ \hline Ni & \(-\)0.11 & \(-\)0.61 & \(-\)0.10 \\ \hline Mn & 0.01 & 0.49 & \(-\)0.66 \\ \hline As & \(-\)0.17 & 0.25 & 0.76 \\ \hline Eigenvalues & 6.22 & 2.00 & 1.23 \\ \hline \% Total variance & 47.84 & 15.35 & 9.42 \\ \hline \% Cumulative variance & 47.84 & 63.19 & 72.62 \\ \hline \end{tabular}
\end{table} 
Table 6: Eigenvalues, percentage of variance explained, and coefficient of correlation between factorial axes and variables. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline  & **Cd** & **Pb** & **Cr** & **Ni** & **Cu** & **As** & **Zn** & **Mn** & **pH** & **EC** & **Sa** & **TDS** & **PO4** \\ \hline Cd & \(1\) & - & - & - & - & - & - & - & - & - & - & - \\ \hline Pb & 0.61 & 1 & - & - & - & - & - & - & - & - & - & - \\ \hline Cr & 0.71 & 0.57 & 1 & - & - & - & - & - & - & - & - & - \\ \hline Ni & \(-\)0.27 & 0.01 & \(-\)0.12 & 1 & - & - & - & - & - & - & - & - \\ \hline Cu & 0.56 & 0.47 & 0.73 & 0.11 & 1 & - & - & - & - & - & - & - \\ \hline As & 0.16 & 0.23 & 0.23 & \(-\)0.07 & 0.20 & 1 & - & - & - & - & - & - \\ \hline Zn & 0.05 & 0.23 & 0.42 & 0.40 & 0.40 & 0.03 & 1 & - & - & - & - & - \\ \hline Mn & 0.30 & 0.04 & \(-\)0.05 & \(-\)0.04 & 0.17 & \(-\)0.11 & \(-\)0.29 & 1 & - & - & - & - \\ \hline pH & 0.65 & 0.44 & 0.76 & \(-\)0.03 & 0.60 & 0.09 & 0.32 & 0.14 & 1 & - & - & - \\ \hline EC & 0.32 & 0.37 & 0.62 & 0.20 & 0.37 & \(-\)0.01 & 0.52 & \(-\)0.06 & 0.56 & 1 & - & - \\ \hline Sa & 0.33 & 0.37 & 0.61 & 0.18 & 0.36 & \(-\)0.03 & 0.50 & \(-\)0.05 & 0.55 & 1.00 & 1 & - & - \\ \hline TDS & 0.44 & 0.48 & 0.76 & 0.17 & 0.56 & 0.09 & 0.53 & \(-\)0.05 & 0.69 & 0.97 & 0.96 & 1 & - \\ \hline PO4 & 0.43 & 0.48 & 0.71 & 0.08 & 0.53 & 0.22 & 0.53 & \(-\)0.12 & 0.58 & 0.83 & 0.83 & 0.88 & 1 \\ \hline \end{tabular}
\end{table}