沉水植物来源的DOM对湖泊沉积物中铁磷赋存和释放的影响机制研究

沉水植物能够抑制沉积物磷（P）的释放，从而降低浅水湖泊磷浓度；因此，修复沉水植物是浅水湖泊生态系统恢复的关键。基于溶解性有机质（DOM）和Fe的共沉淀作用方面的研究成果，我们提出假设：沉水植物来源的DOM可能参与到湖泊沉积物-水界面铁磷（Fe-P）的形成过程中，产生有机质和Fe-P结合的沉淀物质（OM-Fe-P），改变Fe-P的赋存形式和稳定性。本项目拟通过原位调查和室内受控实验，揭示沉水植物来源的DOM对Fe-P赋存形式和释放的影响机制。首先考察太湖典型草、藻型湖区沉积物中Fe-P、OM-Fe-P含量、有机质结构的差异；然后通过受控实验比较草源性、藻源性DOM在Fe-P沉降过程中的作用及其对Fe-P赋存形式的影响；最后比较不同来源DOM作用下形成的OM-Fe-P沉淀的稳定性的差异。结果有助于全面了解沉水植物抑制沉积物P释放的机制，为湖泊生态修复提供理论依据。

The restoration of submersed macrophyte communities is key for the ecosystem recovery of the shallow lakes because the release of the phosphorus (P) from the sediment could be inhibited by the submersed macrophyte. According to the previous researches on the coprecipitation of dissolved organic matter (DOM) with iron, we suppose that the macrophyte-derived DOM could easily take part in the precipitation of Fe-P at the sediment-water interface to form a very stable and insoluble mixture (OM-Fe-P), changing the forms and the stability of Fe-P. In this project, the role of macrophyte-derived DOM in the forms and release of Fe-P will be revealed by the in-situ investigation and the controlled experiments. Firstly, the difference in the fractions of Fe-P and OM-Fe-P, the composition of OM in the sediments between the macrophyte-dominated zone and the algae-dominated zone is investigated. Secondly, the role of macrophyte-derived and algae-derived DOM in the formation of Fe-P are compared by the microcosm experiments. Finally, the stabilities of OM-Fe-P and Fe-P by changing redox/pH condition or microbial degradation are evaluated. The results are helpful to understand systematically the role of the submersed macrophyte in the suppression of P release from the sediment, providing a scientific support for the ecosystem recovery of the shallow lakes.