沉水植物分解对湖泊沉积物磷释放的影响及机制研究

沉水植物群落是维持浅水湖泊清水态的关键；然而沉水植物衰亡分解对沉积物磷释放的影响却存在分歧。我们通过分析沉水植物分解的不同阶段、产物与沉积物中铁/铝/钙化合物（结合磷的物质）的反应，提出以下假设：沉水植物经过较长时间分解，能产生的稳定产物如腐殖质，这些物质通过增强沉积物中的（氢）氧化铁/铝或碳酸钙对磷的结合，从而抑制沉积物磷的释放。围绕上述研究思路，本项目拟开展以下几个方面的研究。选择湖泊常见沉水植物——苦草作为研究对象，首先分析苦草分解过程及产物的组成；其次研究稳定产物特别是含酚羟基和羧基的腐殖质等对（氢）氧化铁/铝和碳酸钙结合磷的能力的影响；最后开展模拟实验，阐明不同时间尺度苦草分解对沉积物中金属（铁/铝/钙）和磷赋存形态以及沉积物结合磷能力的影响；从而揭示沉水植物分解对沉积物磷释放的影响机制。研究结果有助于进一步了解沉水植物在湖泊生态系统中的功能，也为沉水植物管理提供科学依据。

The submerged macrophyte communities is key for maintaining the clear water states of shallow lakes. However, the effects of the decomposition of submerged macrophytes on phosphorus release from the sediments of lakes are not clear. Based on the analysis of the decomposition process of submerged macrophytes and the reaction of decomposition products with the iron/aluminum/calcium compounds in the sediments, it is proposed that humic substances produced from the decomposition of submerged macrophytes could enhance the binding ability of ferric/aluminum (hydro)oxides or calcium carbonate with phosphorus. In this project, the role of the decomposition products of the submerged macrophyte on phosphorus release from the sediments of lakes will be revealed through the following experiments. Firstly, the decomposition process of Vallisneria natans, one common submerged macrophyte in Chinese lakes, will be investigated and the composition of the products will be characterized. Secondly, the effect of the decomposition products which contain carboxyl and phenolic hydroxyl groups on the binding capacity of ferric/aluminum (hydro)oxides or calcium carbonate with phosphorus will be examined. Finally, the effect of the decomposition of Vallisneria natans on the fractions of phosphorus and the metals (iron/aluminum/calcium), thus the capacity of the sediments to bind phosphorus will be studied by means of microcosm experiments. The results will be helpful to understand further the role of submerged macrophytes in lake ecosystems and provide scientific information to achieve better management of the submerged macrophytes of shallow lakes.