## 3 Results and Discussion
### Macrophyte Sorption Abilities  
_Typha capensis_, a macrophyte species, was collected from each site to analyze its ability to adsorb and absorb Al, Fe and Mn. The results of the inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis are summarized in Table 4, highlighting distinct patterns of metal sorption. For adsorption, the concentration order was Al (S1 \(>\) S2 \(>\) S3), Fe (S2 \(>\) S3 \(>\) S1), and Mn (S2 \(>\) S3 \(>\) S1). In terms of absorption, the concentration order was Al (S1 \(>\) S3 \(>\) S2), Fe (S2 \(>\) S3 \(>\) S1), and Mn (S3 \(>\) S2 \(>\) S1). These findings demonstrate the varying capabilities of _T. capensis_ to uptake different metals across the sampling sites. Student's _t_-test was utilized to compare the metal adsorption and absorption capabilities of _T. capensis_ between the inflow (S1) and the far middle (S3) of the wetland. The results revealed a significant difference (_p_\(<\) 0.05) in the adsorption of Al and Mn between S1 and S3. Specifically, Al was adsorbed in higher quantities at S1, whereas Mn showed greater adsorption at S3. However, the adsorption of Fe remained relatively consistent between S1 and S3 (_p_\(>\) 0.05). In terms of absorption, significant differences were observed for all the metals analyzed. Al was absorbed more at S1, while Fe and Mn were predominantly absorbed at S3. This indicates that the adsorption and absorption of Al by _T. capensis_ primarily occurred at S1, whereas Fe and Mn were mainly adsorbed and absorbed at S3. Wetland bottom sediment provides an optimal growth environment for _T. capensis_, with its roots playing a crucial role in rhizosphere processes that alter metals and sulfur  
Figure 5: Percentage of clay, silt, and sand in the bottom sediment of each site in the dry season (May 2022). compounds in AMD-impacted wetlands [1]. The rhizosphere, the soil-root interface, involves complex physical, chemical, and biological interactions [77]. Sorption, which includes both adsorption and absorption, is vital for metal removal in wetlands [7; 78]. Adsorption involves the physical adhesion of substances to a solid surface, while absorption entails the incorporation of substances from one state to another [78]. In macrophye roots, adsorption involves ions and molecules binding to the root epidermis surface, precipitating metals [6; 78]. Metal precipitation appears as coatings in various colors, such as orange to brown for Fe oxides or dark brown for Mn oxides, indicating adsorption on the root surface [1]. This process, known as metal plaque formation, depends on the solubility of Fe and Mn and the oxidizing conditions facilitated by oxygen translocation from roots to the rhizosphere. Oxidized environments promote Mn\({}^{2+}\) and Fe\({}^{3+}\) oxyhydroxides' precipitation on the root surface [6; 7]. Mn adsorption was most pronounced at S2, where the ORP measurements and OM% were the highest, suggesting oxygen release from emerging roots promoted Mn precipitation. This highlights the relationship between OM, ORP, and Mn oxidation. Mn adsorption exceeded that of Fe and Al, indicating a higher oxidizing capacity for Mn. In an experimental study, Ref. [79] found Mn plaque concentrations of 983.4 ug/g and internal Mn concentrations of 421.9 ug/g at pH 6, with the plaque concentrations surpassing the internal concentrations at higher pH levels. Sediments utilize electron acceptors in order of the decreasing free energy [73], with dissolved O\({}_{2}\) consumed in the following order: O\({}_{2}\) > Mn-oxides > Fe-oxides > SO\({}_{4}\). Although Mn adsorption exceeded Fe adsorption, the typical orange to brown coloration associated with iron plaque formation was observed on _T. capensis_ roots both visually and microscopically (Figure 6).