基于微生物群落水动力空间差异响应的太湖河网交汇区氮转化机制研究

河流交汇区是河网的重要组成部分，交汇区复杂的水动力条件会影响氮的迁移转化，并通过河网水系联通，进一步影响流域氮污染分布。本课题针对平原河网河流交汇过程对氮迁移转化影响的问题，拟以太湖河网为研究区域，以氮转化过程为研究对象，借助高通量测序、分子生物学分析、动态可调节水工物模和水动力水质数模等方法，首先研究不同水量、水位、交汇角度、河床宽深比等交汇条件下河网水动力空间差异及其对微生物群落分布特征的影响，识别交汇水动力条件下氮循环微生物群落演变的主导驱动因子；再基于水工物模，研究动水条件下氮循环微生物群落结构和功能的环境响应机制，以及该机制作用下氮污染物的降解过程；最后结合基因中心模型，解析扩散-掺混-吸附-降解多机制耦合作用下平原河网交汇区中氮转化规律，建立多机制耦合下的交汇区氮污染物的自净方程，并将其嵌入EFDC开源代码，为流域河网污染防控、环境治理和综合管理提供科学支撑。

The confluence of rivers is an important part of the river network. The complex hydrodynamic conditions in the confluence area will affect the migration and transformation of nitrogen, and will be connected through the river network and water system, further affecting the distribution of nitrogen pollution in the basin. In this study, the problem is the influence of the river network of plains and rivers on the migration and transformation of nitrogen. It is planned to take the Taihu river network as the research area and the nitrogen conversion process as the research object, through methods such as high-throughput sequencing, molecular biological analysis, dynamically adjustable hydraulic model and hydrodynamic water quality model. First, study the spatial differences of river network hydrodynamics and their effects on the distribution characteristics of microbial communities under different conditions of water volume, water level, intersection angle, river bed width and depth ratio. Identify the dominant driving factors for the evolution of the nitrogen cycle microbial community under confluence hydrodynamic conditions. Based on the physical model test, the environmental response mechanism of the structure and function of the nitrogen cycle microbial community under dynamic water conditions and the degradation process of nitrogen pollutants under the action of this mechanism are studied. Finally, combined with the gene center model, the law of nitrogen transformation in the plain river network confluence area under the coupling effect of diffusion-mixing-adsorption-degradation is analyzed. Establish the self-purification equation of nitrogen pollutants in the junction area under multi-mechanism coupling, and embed it in the EFDC open source code. This research provides scientific support for pollution prevention and control, environmental governance and comprehensive management of river networks in the basin.