## 3 Results  
The Chemical Composition of the Sterile before Planting (1988) and of the Soil from Forest Plantations (2019)  
The sterile ore contains high quantities of sulfates (150 mg/dm\({}^{3}\)), chloride (67.4 mg/dm\({}^{3}\)), calcium (135 mg/dm\({}^{3}\)), sodium (43 mc/dm\({}^{3}\)), and potassium (10.5 mg/dm\({}^{3}\)), completed by small quantities (0.04-0.16 mg/dm\({}^{3}\)) of magnesium, lead, copper, iron, manganese, and very rarely, phenols.  
Figure 2: The design of the realized methods and the work flux (using mentalmodeller.org) (the tasks in the figure are colored according to work flows from the right side).  
As for the soil's chemical composition (sand), we can see the predominance of SiO\({}_{2}\) (31.82%) and CaO (15%). Fe (5.33%) and S (1.48%) are present in average quantities, while heavy metals, rare metals, and Al\({}_{2}\)O\({}_{3}\) are in small quantities (under 1%). All the other compounds are weakly represented or appear only as marks (Table 1). In the sampling points where some compounds appear only as marks, the compounds are below the limit of quantification. For calculation, their percentage participation is mathematically expressed numerically through 10\({}^{-99}\).  
The analysis conducted in 2019 (Table 2) with the purpose of evaluating the current chemical composition of the waste heap's soil and comparing the results with the ones realized 31 years ago, shows a composition decrease in some potentially toxic elements such as Cd and Pb. A data comparison was conducted for common elements from both sets (1988 and 2019) of chemical analyses (Fe, Pb, Zn, Cd, and CaO).  
After the analysis, we observed an increase in the concentration of some micro elements, such as Fe, as well as some macro elements, such as Ca. All other micro and potentially toxic elements are in a very low percentage (<1%), with the exception of Mg (1.16%).  
Potentially toxic elements such as V and Ra identified in some samples analyzed in 1988 were not identified in the analyses conducted in 2019. These recent analyses intended to determine some macro elements, such as P, K, and Mg, as well as some heavy metals, such as Cu, which was not determined in the 1988 analyses but whose presence was evident, taking into account the exploited Cu deposit.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Sampling Point**} & \multicolumn{8}{c}{**Chemical Elements, wt.\% of Total**} \\ \cline{2-13}  & **Fe** & **S** & **V** & **Pb** & **Zn** & **Cd** & **Ra** & **CaO** & **SiO\({}_{2}\)** & **Al\({}_{2}\)O\({}_{3}\)** & **TiO\({}_{2}\)** \\ \hline V1 & 7.230 & 2.260 & 0.0170 & 0.100 & 0.090 & 0.001 & 0.104 & 20 & 31.310 & 0.0 & 0.150 \\ \hline V2 & 5.470 & 1.790 & 0.030 & 0.100 & 0.050 & 0.010 & 0.0 & 24 & 31.560 & 0.0 & 0.230 \\ \hline V3 & 5.560 & 3.800 & 0.0 & 0.0 & 0.120 & 0.010 & 0.100 & 18 & 33.750 & 0.0 & 0.770 \\ \hline V4 & 6.400 & 0.450 & 0.020 & marks & 0.010 & 0.001 & 0.002 & 15 & 32.650 & 0.0 & 0.370 \\ \hline V5 & 3.830 & 0.610 & 0.020 & 0.010 & 0.060 & marks & 0.003 & 24 & 32.700 & 0.0 & 0.310 \\ \hline V6 & 4.400 & 0.710 & 0.0 & 0.001 & 0.060 & 0.010 & 0.0 & 4 & 30.390 & 0.0 & 0.240 \\ \hline V7 & 4.400 & 0.710 & 0.0 & 0.0 & 0.0 & 0.0 & 0.0 & 0 & 30.390 & 4.320 & 0.240 \\ \hline Average & 5.327 & 1.478 & 0.012 & 0.030 & 0.056 & 0.005 & 0.029 & 15 & 31.821 & 0.617 & 0.330 \\ \hline \hline \end{tabular}
\end{table}
Table 1: The chemical composition of sand from waste heaps (1988).  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Sampling Point**} & \multicolumn{8}{c}{**Chemical Elements, as wt.\% of Total**} \\ \cline{2-13}  & **Pa\({}_{\text{AL}}\) *** & **K\({}_{\text{AL}}\) *** & **Cu** & **Cd** & **Cr** & **Ni** & **Pb** & **Zn** & **Fe** & **Mn** & **CaO** & **Mg** \\ \hline V8 & 0.00101 & 0.015 & 0.063 & 0.00021 & 0.0013 & 0.0016 & 0.0057 & 0.015 & 8.594 & 0.048 & 2.019 & 1.037 \\ \hline V9 & 0.00004 & 0.026 & 0.056 & 0.00020 & 0.0025 & 0.0028 & 0.0025 & 0.017 & 8.217 & 0.060 & 29.557