# Methods for Obtaining Humus Substances: Advantages and Disadvantages
## 3 Results and Discussion  
### Qualitative Analysis of the Tested Substances  
Analysis of the elemental composition (Table 1) shows that HS(A) contains 55.33% of C, less than HS(B), and more than HS(C). The oxygen content of 38.15% suggests it is aliphatic. HS(B) acids (a product from brown coal) contain a lot of carbon (71.01%), which characterizes substances with a high degree of humification, 20.89% of oxygen, 7.1% of hydrogen, and small amounts of nitrogen < 1%. The high content of hydrogen (7.10%) and carbon (71.01%) and low content of oxygen (20.89%) indicate high hydrophobicity.  
HS(C) is characterized by a small amount of carbon (49.12%), a high amount of nitrogen (9.42%), and oxygen (33.85%). Using NH\({}_{3(\mathrm{aq})}\) in extraction contributes to high nitrogen content. HS(C) composition indicates a low degree of carbonization and aliphatic character. The atomic ratios confirm the findings. High O/C and O/H values indicate the presence of functional groups containing oxygen, a low degree of humification, and good solubility. The O/H ratio values are 0.46 for HS(A), 0.18 for HS(B) and 0.28 for HS(C) and the O/C ratio for HS(A) = 0.52, for HS(B) = 0.22 and HS(C) = 0.52. These values indicate that HS(A) contains considerable amounts of FA, and HS(B) contains high amounts of HA. HS(C) is aliphatic-aromatic. The O/C ratio of 0.52 is typical for FA. The O/C ratio = 0.22, according to the van Krevelen diagram, is typical for HA.  
Table 2 shows the content of inorganic microppollutants in HS samples in mg/kg of dry matter.  
The content of inorganic microppollutants in HS(A) is significant due to the ash content of 38.13% m/m. The ash content of HS(B) is lower and amounts to 29.59%. The lowest content of inorganic substances is in HS(C). The inorganic microppollutant (ash) content indicates a higher sorption capacity of HS(A), confirming its aliphatic character, resulting from the high content of functional groups containing oxygen, mainly carboxyl and hydroxyl.  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Elementals Ash-Free Content (\%)**} & \multicolumn{4}{c}{**Atomic Ratios (-)**} \\ \cline{2-10} \multirow{2}{*}{**HS**} & **C** & **H** & **N** & **O** & **Ash** & **O/C** & **H/C** & **C/N** & **O/H** \\ \hline HS(A) & 55.33 & 5.18 & 1.34 & 38.15 & 38.13 & 0.52 & 1.12 & 4.80 & 0.46 \\ HS(B) & 71.01 & 7.10 & \textless{}1 & 20.89 & 29.59 & 0.22 & 1.20 & \textgreater{}83.3 & 0.18 \\ HS(C) & 49.12 & 7.60 & 9.42 & 33.85 & 27.31 & 0.52 & 1.86 & 6.09 & 0.28 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Elemental composition of extracted HS.  
The composition of inorganic micropollutants of HS(A) includes such elements as K (76,405 mg/kg), Na (1635 mg/kg), Ca (992 mg/kg), Cu (776 mg/kg), Co (101 mg/kg). In addition, some amounts of Al, B, Fe, Mg, Mn, and Zn were determined. The high amount of K results from the HS extraction technology. The lowest values are Ba, 2 mg/kg, and Sr, 6 mg/kg. Inorganic micropollutants in HS(B) include K (68,300 mg/kg), Ca (23,800 mg/kg), Fe (15,100 mg/kg), Al (6443 mg/kg), Mg (1372 mg/kg), and Si (2142 mg/kg). Also, a significant K content in HS(B) results from using KOH to extract it from brown coal. Some amounts of Ba, La, Cr, Mn, Ni, P, Sr, V, and Zn were also found. HS(C) contains mainly K (36,559 mg/kg), P (29,222 mg/kg), Ca (5133 mg/kg), Fe (3991 mg/kg), and Al (2186 mg/kg).