Research
| Title： | Enhanced effects of LMA combined with Vallisneria spiralis in controlling sediment organic phosphorus: The pivotal role of submerged macrophytes roots |
|---|---|
| First author： | Han, Tianlun; Wang, Yan; Bao, Meijun; Wang, Wanzhong; Yin, Hongbin; Li, Jian; Zhang, Yi; Kong, Ming |
| Journal： | JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING |
| Years： | 2025 |
| DOI： | 10.1016/j.jece.2025.117287 |
| Abstract： | Lanthanum (La)-modified clay combined with submerged macrophytes has been widely applied to control internal phosphorus (P) loading. However, most studies focused on controlling inorganic P, with limited attention paid to the effectiveness and mechanisms of organic P (OP), especially from the perspective of rhizosphere effects. In this study, a root box simulation system was constructed, integrating microelectrode, planar-optode, 16S rRNA sequencing, and sequential OP extraction to investigate the effectiveness of La-modified attapulgite (LMA) combined with Vallisneria spiralis in controlling sediment OP and the root-mediated mechanisms involved. The results indicated that LMA combined with Vallisneria spiralis achieved significantly greater OP reductions in both overlying water (10.10 %-25.87 %) and all sediment fractions (1.94 %-25.49 %) compared to LMA capping alone. The Mantel test and Partial Least Squares Path Modeling further revealed that oxygen and organic acids secreted by Vallisneria spiralis roots played key roles in controlling sediment OP mobilization. Root oxygen release significantly boosted dissolved oxygen levels and penetration depth at the sediment-water interface by 1.16 and 3.41 times, respectively. This created favorable conditions for the growth of P-solubilizing bacteria, particularly the BD1-7 clade, subsequently accelerating the mineralization of Fulvic-OP to Labile-OP in sediments. Root-secreted organic acids lowered pH by 4.18 % in rhizosphere sediment, promoting the dissolution of Res-OP to Labile-OP. The transformed Labile-OP was absorbed by roots and LMA simultaneously, leading to a substantial decrease in sediment OP mobilization. These findings revealed the synergistic mechanisms of LMA and submerged macrophytes in efficiently remediating internal OP pollution, offering a promising solution for eutrophic waters. |
