沉水植物根系泌氧驱动根际微界面磷迁移机制

The migration of phosphorus (P) across the sedimentary interface is one of important pathways controlling the eutrophication, which can be strongly affected by the radial oxygen loss (ROL) from the submerged macrophytes. However, our understanding of the relevant mechanisms has not been fully explored so far because of the unsatisfactory in the traditional methods with low-resolution (cm level) and 1D measurement. In this project, three 2D, high-resolution planar imaging technologies, i.e. planar optode (PO), diffusive gradient in thin films (DGT) and diffusive equilibrium in thin films (DET) will be firstly optimized and combined in a new in-situ instrument. The instrument described will be applied to in-situ investigate the effects of ROL from three dominate species, i.e. Potamogeton malaianus, Vallisneria natans, Potamogeton crispus in eutrophic lake Taihu on the P migration in the rhizosphere. The 2D spatiotemporal variations of ROL from the investigated plant at a submillimeter resolution and its major determinant will be studied. Meanwhile, the simultaneous variations of micro-environmental conditions and P migration in the rhizosphere at a 2D, high-resolution scale, which were affected by the ROL under different simulated conditions will be quantitatively characterized for exploring the major driving mechanisms responsible for the ROL effects on P migration in the rhizosphere. It is expected that this work could support the technical operations in P pollution control and ecological restoration of eutrophic lakes.

沉积物磷界面迁移是造成水体富营养化主要途径之一，沉水植物根系泌氧被证实是界面磷迁移的重要驱动因子，但长期以来，受限制于现有的一维、低分辨率的研究手段，相关驱动机制并未明确。本项目以富营养化太湖优势沉水植物马来眼子菜、苦草、菹草为研究对象，在对平面光电极、薄膜扩散梯度与薄膜扩散平衡等二维高分辨成像技术进行优化集成和装置化的基础上，原位高分辨获取沉水植物根系泌氧时空分布特征并明确关键控制因子；通过室内模拟实验，同步、高分辨获取根系泌氧、界面微环境与界面磷迁移的二维空间分布信息，深入分析三者之间响应驱动关系，结合湖区原位现场试验，阐明沉水植物根系泌氧驱动根际微界面磷迁移的主要机制，为富营养化湖泊磷污染治理与生态修复提供理论依据。