## 3 Results
### Mineralogical Analysis of Soil Samples
#### 3.3.3 Fourier-Transform Infrared (FT-IR) Spectra Analyses  
Figure 4 shows the infrared absorption spectrum of each particle size fraction. The band at 3697 cm\({}^{-1}\) was assigned to the stretching vibration of a hydroxyl group (-OH) on the octahedral sheet in kaolinite [41,42]. It could be obviously seen in the spectra of clay, silt, and fine sand, but not in that of coarse sand. The band at 3620 cm\({}^{-1}\) was assigned to the stretching vibrations of inner hydroxyl groups, found between the tetrahedral and octahedral sheets [42,43]. The intensity of this band decreased and broadened in coarse sand compared to other particle fractions. The Si-O in-plane stretching vibration band of kaolinite also appeared near 1032 cm\({}^{-1}\)[41,44]. The Al\({}_{2}\)OH bending bands of silicate mineral near 913 cm\({}^{-1}\) were a function of inner OH group vibrations [41,45]. The absorption bands near 3430 and 1631 cm\({}^{-1}\) were due to the H-O-H stretching and bending vibrations of absorbed water, respectively [41], appearing in all particle-size fractions.  
The band at 1430 cm\({}^{-1}\) was assigned to the asymmetric stretching vibration of C-O groups, representing the characteristic absorption peak of carbonate minerals [46,47]. The band at 875 cm\({}^{-1}\) was attributed to the out-of-plane bending vibration of CO\({}_{3}\)\({}^{2-}\)[48]. On the other hand, the in-plane bending vibration at 712 cm\({}^{-1}\) and 729 cm\({}^{-1}\) allowed for the distinguishing of calcite and dolomite, respectively [48,49]. Bands at 2520 cm\({}^{-1}\) (combined CO\({}_{3}\)\({}^{2-}\) out-of-plane and in-plane bending vibration) and 1799 cm\({}^{-1}\) (combined CO\({}_{3}\)\({}^{2-}\) symmetrical stretching and in-plane bending vibration) [47] could also be observed in silt and sand. The sharp double bands at 799 and 779 cm\({}^{-1}\) appeared in all particle size fractions, representing characteristic peaks of quartz attributed to the symmetrical stretching vibrations of the Si-O bonds [48]. On the other hand, the bands at 1164 and 1082 cm\({}^{-1}\) were attributed to the nonsymmetrical stretching vibrations of the Si-O bonds [49]. The  
Figure 3: XRD patterns of different particle-size fractions (a—Clay, b—Silt, c—Fine Sand, d—Coarse Sand, e—Bulk Soil).  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Sample** & **Fractions** & **Quartz** & **Muscovite** & **Dolomite** & **Kaolinite** & **Calcite** & **Albite** & **Orthoclase** \\ \hline \multirow{4}{*}{A} & Bulk Soil & 31.01 & 25.53 & 16.52 & 14.04 & 10.38 & 1.42 & 1.21 \\  & Clay & 11.82 & 21.11 & 1.65 & 62.52 & 2.08 & 0 & 0 \\  & Silt & 24.93 & 33.28 & 6.34 & 25.97 & 6.02 & 1.65 & 1.18 \\  & Fine Sand & 35.07 & 24.77 & 25.43 & 1.65 & 9.65 & 1.19 & 1.27 \\  & Coarse Sand & 35.23 & 12.74 & 24.01 & 0 & 24.21 & 2.24 & 1.97 \\ \hline \multirow{4}{*}{B} & Bulk Soil & 30.26 & 25.61 & 16.88 & 13.43 & 11.12 & 1.26 & 1.09 \\  & Clay & 11.56 & 21.64 & 1.43 & 63.68 & 1.44 & 0 & 0 \\ \cline{1-1}  & Silt & 23.67 & 33.93 & 6.02 & 25.75 & 6.62 & 1.82 & 1.43 \\ \cline{1-1}  & Fine Sand & 35.33 & 24.63 & 25.02 & 1.82 & 9.86 & 1.08 & 1.32 \\ \cline{1-1}  & Coarse Sand & 35.82 & 13.12 & 24.64 & 0 & 23.82 & 2.11 & 1.75 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Mineral concentration of different particle-size fractions (%).  
band near 646 cm\({}^{-1}\), characteristic of feldspars [49; 50], was present in silt and sand, but not in clay. The bands near 753 and 695 cm\({}^{-1}\) were attributed to the vertical vibrations of the hydroxyl groups on the surface of kaolinite [49]. The band near 530 cm\({}^{-1}\) was due to the stretching vibration of the Si-O-Al group [42]. The bands near 470 and 430 cm\({}^{-1}\) were assigned to Si-O-Si bending vibrations [42].