## 3 Results
### The Variation of the Soil's Chemical Compositions in Forest Plantations from Waste Heaps  
The variation of the soil's chemical composition in forest plantations from Moldova Noua waste heaps between 1988 and 2019 was analyzed for the Pb and Cd potentially toxic elements, for the Fe and Zn micro elements, and for the CaO macro elements (Table 3). The values of the variation coefficient calculated for the concentration of elements from the analyzed samples show a homogeneity in the time of concentrations for different elements. We can observe a leveling of potentially toxic element concentrations, given especially by the decrease in their concentration in different areas of the waste heap. By testing differences in the concentration of elements between 1988 and 2019, we can observe distinct significant differences in Fe concentration (\(p<1\%\)) and significant differences in Zn and Cd concentrations (\(p<5\%\)). No significant differences are observed for Pb and CaO between the analyzed samples. By testing Fe concentration differences, we can see significantly distinct and very significant growths in most pairs of analyzed samplings (Table 4). Fe growths with statistical significance (*--significant; **--distinct significant; ***--very significant) were recorded in most sampling pairs, with the exception of V2-V12, V3-V12, and V4-V11. As can be seen in Figure 3, the average Fe content among all 21 analyzed sub-samples (each sample was tripled in the laboratory for analyses) from the waste heaps' soil (tested above with an ANOVA--Table 3) grows during the studied period. Significant decreases in the Zn content were recorded by comparing their content from sampling points V1, V3, and V5 with the content from sampling points from 2019 (V8-V14) and between V7 and V8 (Two-Sample Assuming Unequal Variances t-test with Two-tail). After adjusting the \"False Discovery Rate\" using the Benjamini-Hochberg method, it was proven that there is no statistical significance regarding the differences in Zn concentration in the soil between 2019 and 1988 for any of the significance thresholds, with the adjusted values of \(p\) in all cases being greater than 0.05. As for Cd, if we compare the samplings analyzed in 1988 with the ones analyzed in 2019, we can see important and significant decreases from a statistical perspective, as well as increases, but in a quantum significantly lower than the decreases (Table 5). Significant statistical decreases were emphasized between V2, V3, V4, and V6 sampling points (1988) and most samplings that were analyzed in 2019. Statistically significant reduced growths were determined by comparing the Cd concentration from V5 and V7 with most of the samplings from 2019. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Macro elements,** & \multicolumn{3}{c}{**1998**} & \multicolumn{3}{c}{**2019**} & \multicolumn{3}{c}{**\(p\) Values (ANOVA**} \\
**Micro elements, and Potentially** & & & & & & **Disferences in** \\
**and Potentially** & & & & & & & **Concentrations of** \\
**Toxic Elements** & **Average (\%** & **Conditional** & **Deviation** & **Coefficient** & **Heaps Tota)** & **Deviation** & **Coefficient** & **1988 and 2019** \\ \hline Fe & 5.328 & 1.212 & 0.227 & 7.970 & 1.633 & 0.205 & 0.005 ** \\ \hline Pb & 0.030 & 0.048 & 1.588 & 0.005 & 0.002 & 0.385 & 0.184 \\ \hline Zn & 0.056 & 0.002 & 0.133 & 0.016 & 0.042 & 0.753 & 0.028 * \\ \hline Cd & 0.005 & 0.005 & 1.114 & 0.0002 & 0.0001 & 0.519 & 0.043 * \\ \hline CaO & 15.000 & 9.504 & 0.634 & 19.640 & 12.369 & 0.630 & 0.447 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Average values of some of the macro, micro, and potentially toxic elements from the waste heaps’ soil in 1988 and 2019, and \(p\) values (ANOVA test) for testing differences in concentrations of elements between 1988 and 2019 (significant (\(p<0.05\)) = *; distinct significant (\(p<0.01\)) = **).