# Determination of Arsenic Species Distribution
## 4 Results of Geochemical and Geophysical Studies
### Forms of Metals  
During the experiment, the concentration of main cations and metals in the leaching fractions were also determined (Tables 7 and 8). The table does not show alkali metals due to the use of buffer solutions with sodium salts during sequential extraction. Based on general considerations, the following forms of metals are extracted during leaching:  
F1--water-soluble;  
F2 and F3--exchangeable;  
F4--sorbed on the surface of oxides/hydroxides of iron and manganese;  
F5--associated with easily oxidized minerals, as well as being associated with organic material;  
F6--associated with sparingly soluble minerals. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Component** & **Water Extract** & **F1 Fraction** & **F2 Fraction** \\ \hline Solutions, mg/L & 26 \(\pm\) 3 & 8.1 \(\pm\) 0.8 & 33 \(\pm\) 5 \\ Solid sample, mg/kg & 260 \(\pm\) 30 & 400 \(\pm\) 40 & 1300 \(\pm\) 150 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Comparison of the content of water-soluble forms. We observe a different result from that of arsenic. The mobile forms of metals have been determined in small quantities. The largest proportion of water-soluble and exchangeable species (F1-F3) is formed by Mg, Ca, and Sr: 11, 9.4, and 20%, respectively (residual and redeposited carbonates) (Table 8). The proportion of water-soluble forms of other metals is \(<1\%\) or 0. Note that antimony, like arsenic, exhibits a significantly higher mobility than \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Elements** & **Fraction** & **F1** & **F2** & **F3** & **F4** & **F5** & **F6** \\ \hline Mg & \(6\pm 1.5\) & \(35\pm 7\) & \(20\pm 7\) & \(125\pm 25\) & \(330\pm 50\) & \(280\pm 20\) \\ Ca & \(30\pm 15\) & \(60\pm 30\) & \(100\pm 50\) & \(1500\pm 130\) & \(290\pm 80\) & \(280\pm 60\) \\ Sr & \(50\pm 3\) & \(220\pm 10\) & \(220\pm 90\) & \(1500\pm 130\) & \(620\pm 60\) & \(280\pm 10\) \\ Cd & \(<\)10 & \(<\)10 & \(<\)10 & \(90\pm 15\) & \(60\pm 10\) & \(140\pm 20\) \\ Co & \(20\pm 6\) & \(390\pm 80\) & \(1000\pm 400\) & \(7600\pm 740\) & \(5400\pm 680\) & \(1700\pm 300\) \\ Cu & \(10\pm 6\) & \(160\pm 30\) & \(300\pm 140\) & \(10,000\pm 1000\) & \(11,000\pm 800\) & \(10,000\pm 1600\) \\ Ni & \(8\pm 2\) & \(180\pm 50\) & \(370\pm 110\) & \(5000\pm 670\) & \(10,000\pm 1600\) & \(10,000\pm 1500\) \\ Zn & \(<\)10 & \(440\pm 110\) & \(320\pm 100\) & \(5300\pm 660\) & \(6000\pm 1000\) & \(4200\pm 700\) \\ Ba & \(<\)15 & \(20\pm 6\) & \(25\pm 15\) & \(1300\pm 400\) & \(1600\pm 200\) & \(960\pm 200\) \\ Cr & \(<\)25 & \(<\)75 & \(<\)75 & \(250\pm 90\) & \(900\pm 130\) & \(1200\pm 100\) \\ Mn & \(<\)15 & \(85\pm 20\) & \(490\pm 360\) & \(23,000\pm 300\) & \(19,000\pm 4000\) & \(14,000\pm 1500\) \\ Fe & \(<\)300 & \(<\)300 & \(<\)300 & \(1400\pm 500\) & \(590,000\pm 70,000\) & \(760,000\pm 70,000\) \\ Sb & \(30\pm 3\) & \(70\pm 8\) & \(40\pm 4\) & \(170\pm 20\) & \(25\pm 5\) & \(290\pm 30\) \\ Pb & \(<\)10 & \(<\)20 & \(<\)20 & \(400\pm 200\) & \(620\pm 180\) & \(250\pm 150\) \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Content of cations and metals in leach fraction solutions: Mg and Ca in mg/L and Sr–Pb in ug/L. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Elements** & **Fraction** & **F1** & **F2** & **F3** & **F4** & **F5** & **F6** & **Total Content** \\ \hline Mg & \(0.30\pm 0.075\) & \(1.4\pm 0.28\) & \(0.79\pm 0.28\) & \(5.0\pm 1.0\) & \(8.1\pm 1.2\) & \(7.7\pm 0.55\) & \(23\pm 1.7\) \\  & \(1.3\) & \(6.1\) & \(3.4\) & \(22\) & \(35\) & \(33\) & \\ \hline Ca & \(1.5\pm 0.74\) & \metals, the percentage of its water-soluble forms is 7.1%, and that of the exchangeable forms is 22%. The main part of the metals is concentrated in fractions F4-F6, which contains forms sorbed on the surface of Fe and Mn hydroxides, enclosed in easily oxidized minerals, associated with organic material, and in the composition of hardly oxidized minerals.