## 3 Results and Discussion
### Periphyton Sorption Abilities  
The dominant periphyton species, _Klebsormidium acidophilum_, was collected from S1 and S2 to analyze its metal sorption characteristics using ICP-OES. The results are detailed in Table 5. Student's \(t\)-test was applied to compare the mean metal sorption abilities of _K. acidophilum_ between S1 and S2. The analysis showed no statistically significant difference in the adsorption of Al and Fe between the two sites (\(p>0.05\)). However, there was a significant difference in Mn adsorption, with higher Mn adsorption at S1 compared to S2 (\(p<0.05\)). Regarding metal absorption, a significant difference was observed between the sites (\(p<0.05\)), with Al, Fe, and Mn predominantly absorbed at S1. These findings highlight the varying sorption capacities of _K. acidophilum_ at different locations within the wetland. Research on the biosorption of microelements has demonstrated that green macroalgae can effectively accumulate minerals, facilitating the bioaccumulation of specific elements [78]. Certain benthic filamentous algae species have shown the ability to absorb metals across various pH levels, making them suitable for passive treatment of AMD-contaminated water [80]. Ref. [80] also highlighted that the pH of surface water significantly influences algal metal absorption, with Fe absorption being most efficient at pH 3, and Mn and Al absorption improving at a neutral pH (pH 7.0). The most substantial shifts in periphyton species composition and nutrient cycling typically occur within a pH range of 4.7 to 5.6 [53; 81]. However, in the current study, surface water pH values were lower at S1 (pH = 3.9) and S2 (pH = 3.84) compared to S3 (pH = 7.10), where _K. acidophilum_ was absent. In this study, the metal adsorption sequence for S1 and S2 was Mn \(>\) Fe \(>\) Al, while metal absorption followed Fe \(>\) Al \(>\) Mn at both sites. Ref. [82] emphasized that the algal metal accumulation can vary widely depending on the species and types of metals involved. This variability was also observed by [80], where different filamentous algae species exhibited distinct patterns of metal bioaccumulation at various sites. For example, _Oedogonium crissum_, _Klebsormidium krebsii_, and _Microspora tumidula_ showed different metal bioconcentration patterns at four different sites: _O. crissum_ at S1 (Al \(>\) Fe \(>\) Mn), _K. krebsii_ at S2 (Al \(>\) Fe \(>\) Mn), _M. tumidula_ at S3 (Fe \(>\) Al \(>\) Mn), and _M. tumidula_ at S4 (Fe \(>\) Mn \(>\) Al). In this study, _K. acidophilum_ displayed trends similar to _M. tumidula_, although the latter showed higher bioconcentrations, reaching up to 401,739 mg/kg dry weight for Fe. Ref. [80] also found that Fe bioaccumulation increased as the pH decreased, attributed to the precipitation of Fe at pH \(\geq\) 4, making it more available to algal species. Their results suggested that Mn bioaccumulation was favored near neutral pH conditions. However, in this study, Mn adsorption was higher than that of Al and Fe at S1. An experimental study by [83] showed that Fe removal occurred rapidly within the first hour, with up to 94.4% of Fe removed after four hours of exposure to metal-enriched water, whereas \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Element**} & \multirow{2}{*}{**Unit**} & \multicolumn{3}{c}{**Average Concentration**} & \multicolumn{3}{c}{**Student’s \(t\)-Test (S1; S2)**} \\ \cline{3-7}  & & **S1** & **S2** & **Mean Difference** & \(T\) & \(p\)**Value** \\ \hline \hline \multicolumn{7}{c}{**Adsorption**} \\ \hline Aluminum (Al) & (mg/kg) & 0.48 & 0.44 & 0.04 & 0.38 & 0.73 \\ \hline Iron (Fe) & (mg/kg) & 0.79 & 0.78 & 0.01 & 0.22 & 0.84 \\ \hline Manganese (Mn) & (mg/kg) & 1.13 & 0.37 & 0.76 & 56.24 & 0.00 \\ \hline \multicolumn{7}{c}{**Absorption**} \\ \hline Aluminum (Al) & (mg/kg) & 170.3 & 38.61 & 131.68 & 572.71 & 0.00 \\ \hline Iron (Fe) & (mg/kg) & 284.78 & 241.43 & 43.34 & 45.63 & 0.00 \\ \hline Manganese (Mn) & (mg/kg) & 8.91 & 4.41 & 4.50 & 199.84 & 0.00 \\ \hline \hline \end{tabular}
\end{table}