富营养湖泊磷胁迫下水生植物根际分子/离子流变化及其对微环境的影响

Phosphorus is one of the important limiting nutrients for primary productivity in the freshwater lakes. Molecular/ions such as H+/O2 are important intermediate and/or metabolic products which involve in life activities on ingestion and metabolism of phosphorus, and have important effect on biogeochemical cycle of phosphorus in freshwater ecosystem. This program will employ noninvasive measurement of micro technology (NMT) and microelectrode measurement technology to research microenvironment system around typical aquatic plant root organization and rhizosphere sediment under different phosphorus stress in the aquatic ecosystem. Using in-situ monitoring analysis, combined with indoor simulation analysis method, the coupling relationship among different phosphorus stress, physiological and biochemical parameters including concentration, flow and the velocity of important molecular/ ions, H+/O2, in rhizosphere microsystem of aquatic plants, and the influence of dynamic change of molecular/ions flow in rhizosphere microenvironment as well as the response of phosphorus species to change of molecular/ion flow will be studied effectively. These objects will be helpful to promote the research of physiological and ecological response of aquatic plants in micro-scale under high phosphorus level, assess the influence of phosphorus stress on aquatic plant community and ecosystem structure from the microscopic view, and provide theoretical and practical basis for ecological restoration to polluted lakes based on the use of aquatic plants.

磷是淡水湖泊初级生产力的重要限制性营养盐，H+、O2等分子/离子是水生植物根际参与磷摄取和代谢等生命活动的重要中间或代谢物，对富营养湖泊生态系统中磷的生物地球化学循环过程有着重要影响。本项申请拟采用先进的非损伤微测（NMT）技术及微电极技术，以典型淡水湖泊水生植物根系组织-根际沉积物微环境系统为研究对象，采用野外原位监测分析结合室内模拟培养分析的方法，通过不同磷压力下水生植物根际微系统H+、O2等分子/离子浓度、流向及流速等指标的动态变化，阐明磷负荷与H+、O2等分子/离子流响应关系、进而研究H+、O2等分子/离子流的动态变化对根际微环境的影响以及根际沉积物中磷的形态与分子/离子流变化的互馈关系，促进高磷负荷压力下水生植物的生理生态学微尺度响应及反馈过程机理研究，从微观角度评估磷胁迫对水生植物群落及生态系统结构的影响，为高效利用水生植物开展富营养湖泊生态修复提供理论基础和现实依据。

磷是湖泊富营养化的限制性营养因子。通过对典型湖泊沉积物中磷的形态的连续提取分析，有机磷（Po）的组分含量按残渣磷有机磷（Res-P）、腐殖酸结合态有机磷（HU-P）、富里酸结合态有机磷（FA-P）、生物活性有机磷（biomass-P）的顺序依次减少。在Po的组成中，残渣磷所占的比例是最高的。FA-P和HU-P对Po的生成过程起了很重要的作用，并且它们也可以重新矿化生成无机磷（Pi）。沉积物中的其他有机磷种类的比例在按正磷酸盐、磷酸单酯、磷酸二酯、焦磷酸盐的顺序依次下降。磷酸单酯在沉积物中的含量较高。PCA和相关的分析表明相比于HU-P和FA-P，磷酸二酯产生于残渣磷的可能性更大，同时正磷酸二酯可以转化为磷酸单酯，并进一步转化为焦磷酸盐等Pi。