## 3 Results and Discussion
### Major and Trace Elements
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & **Unit** & **Average** & **SD** & **VC** & **Min** & **Max** & \
\begin{tabular}{c} **Ref. values** \\ **Spanish soils** [17] \\ \end{tabular} &
\begin{tabular}{c} **Ref. values** \\ **Castilla–La** \\ **Mancha soils** [18] \\ \end{tabular} \\ \hline Al & \% & 1.0 & 0.6 & 59.2 & 0.3 & 3.7 & 6.2 & — \\ \hline Ca & \% & 0.2 & 0.2 & 100.9 & 0.1 & 1.1 & 5.3 & — \\ \hline Fe & \% & 3.5 & 1.7 & 49.4 & 0.6 & 8.0 & 3.0 & — \\ \hline K & \% & 0.1 & 0.1 & 48.6 & 0.1 & 0.3 & 1.9 & — \\ \hline Mg & \% & 0.2 & 0.3 & 144.2 & 0.1 & 2.3 & 0.9 & — \\ \hline Si & \% & 24.0 & 2.8 & 11.6 & 16.1 & 30.2 & — & — \\ \hline Na & mg kg\({}^{-1}\) & 100.0 & 100.0 & 53.6 & 100.0 & 200.0 & 7600.0 & — \\ \hline As & mg kg\({}^{-1}\) & 15.3 & 19.4 & 126.5 & 3.0 & 190.0 & 21.7 & 16.1 \\ \hline Ag & mg kg\({}^{-1}\) & 0.15 & 0.2 & 143.1 & 0.1 & 1.9 & 0.11 & — \\ \hline Ba & mg kg\({}^{-1}\) & 114.3 & 87.4 & 76.4 & 30.0 & 740.0 & 400.3 & 1049.3 \\ \hline Be & mg kg\({}^{-1}\) & 1.0 & 0.4 & 42.0 & 0.3 & 2.0 & 2.7 & — \\ \hline Co & mg kg\({}^{-1}\) & 14.3 & 10.3 & 72.3 & 1.0 & 65.0 & 11.7 & 20.8 \\ \hline Cr & mg kg\({}^{-1}\) & 34.2 & 37.9 & 110.9 & 2.0 & 292.0 & 70.2 & 113.4 \\ \hline Cu & mg kg\({}^{-1}\) & 18.3 & 13.8 & 75.4 & 3.0 & 93.0 & 25.9 & 27.1 \\ \hline Hg & mg kg\({}^{-1}\) & 2.9 & 7.5 & 258.3 & 0.1 & 51.5 & 0.1 & — \\ \hline Mn & mg kg\({}^{-1}\) & 619.0 & 397.6 & 64.2 & 29.0 & 2300.0 & 608.7 & — \\ \hline Ni & mg kg\({}^{-1}\) & 26.8 & 30.3 & 113.3 & 2.0 & 216.0 & 32.7 & 42.6 \\ \hline P & mg kg\({}^{-1}\) & 430.9 & 313.1 & 72.7 & 120.0 & 2000.0 & 590.0 & — \\ \hline Pb & mg kg\({}^{-1}\) & 56.5 & 130.6 & 231.0 & 15.0 & 1190.0 & 37.8 & 44.2 \\ \hline Sb & mg kg\({}^{-1}\) & 4.1 & 6.2 & 151.7 & 1.0 & 45.0 & 2.1 & — \\ \hline Sr & mg kg\({}^{-1}\) & 13.9 & 9.8 & 70.4 & 5.0 & 81.0 & 159.4 & 1868.4 \\ \hline V & mg kg\({}^{-1}\) & 35.0 & 31.7 & 90.7 & 8.0 & 226.0 & 60.0 & 123.2 \\ \hline Zn & mg kg\({}^{-1}\) & 51.9 & 28.6 & 55.0 & 9.0 & 146.0 & 74.2 & 86.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Statistical summary of major (in %) and trace elements (in mg kg\({}^{-1}\)). Abbreviations: standard deviation (SD); variation coefficient (VC). Complete data available in Table S1. from Roman times to the present, and ancient mining techniques were very ineffective and likely caused the wide dispersion of these elements. This anthropogenic distortion can be more complicated for Sb, a low-mobility metalloid with a very low possibility of creating a dispersion halo around an ore deposit or even a derelict mine. For Hg, however, anthropogenic and geogenic dispersion are processes that are certainly almost equal in importance since the mining district comprises a huge mine and several much smaller mines in the Almaden syncline [26]. Elements such as Fe, Mn, Ag, and Co were found to have a slightly higher average than Spanish soils, showing a great variation for both synclines; these elements are likely related to the presence of granitic rocks, mafic volcanic rock outcrops and clayey rocks rich in these elements [17]. An opposite trend could be observed for Al, Ca, K, Ba, and Sr, with values well below the reference levels for Spanish soils. This may be due to the predominant lithology of the area, generally deficient in these elements, and their higher mobility rates from parent materials. Other elements, including Mg, As, Be, Cr, Cu, Ni, V, and Zn, showed concentrations slightly below or similar to the reference values for Spanish soils. The average concentration of P was lower than the reference values for Spanish soils, likely suggesting an agronomic factor, possibly the use of manure instead of P-based fertilizers in the area.