冰封期水库氮磷多介质迁移过程及其影响机制研究

In middle and high latitudes of China, the ice-covered period lasts for several months. During that period, the multimedia pattern of ice, water and sediment is formed, which affects the transfer process of nitrogen (N) and phosphorus (P) and finally brings about environmental effects different from the non ice-covered period. In addition, water quality during the ice-covered period is seldom monitored limited by the ice-covered condition, which leads to water quality issues during icebound period becoming an inevitable short slab in water environment management. This study takes the example of Biliuhe Reservoir, the most important source water reservoir of Dalian city as an example. First, a special sampling scheme was designed based on the analysis of formation and deglaciation process of ice, which contributes to a better understanding of the characters of environmental factors and elemental status of reservoir water quality in the ice-covered period. Then, the time-spatial distribution of N, P, environmental factors and their relationship was studied, to figure out the transfer processes and chemical speciations of N and P in multimedia of ice-water-sediments. Afterwards, by simulating the transfer processes of N and P between the interface of ice and water, the interface of water and sediment, and in the system of ice-water-sediment, the influence of factors such as ice thickness, water depth, pH, temperature and dissolved oxygen (DO) on the transfer process was analyzed. Subsequently, a N and P transfer model in multimedia environment was built. The work hopes to promote the fundamental research of ecological water conservancy from both phenomenon and mechanism, and provide important technical support for water environment protection during the ice-covered period.

在我国中高纬度地区，具有长达数月的冰封期，使得水库形成了冰-水-沉积物的多介质格局，改变了氮磷的迁移过程，带来与非冰封期不同的环境效应。由于冰封条件的限制，很少有水库对冰封环境下的水质进行监测，使得冰封环境下的水质问题成为环境管理中无法规避的薄弱点。本项目以大连市最大的水源水库-碧流河水库为例进行研究。首先，在分析冰生消过程的基础上设计水质监测方案，明确冰封期水库环境因子特征与基础水质状态。进而，对氮、磷、环境因子在分层冰、分层水、间隙水、沉积物中的时空特性及相互关系进行系统研究，揭示氮、磷在冰-水-沉积物多介质间的赋存形态与迁移过程。最后，设计实验模拟冰-水界面、沉积物-水界面、冰-水-沉积物体系下的氮、磷迁移过程，从机理层面探索冰厚、水深、pH、温度、溶解氧对氮、磷迁移过程的影响，并建立氮、磷多介质迁移模型。通过上述工作，促进生态水利基础研究，为水库冰封期的水环境保护提供技术支撑。

在我国中高纬度地区，具有长达数月的冰封期，使得水库形成了冰-水-沉积物的多介质格局，改变了氮磷的迁移过程，带来与非冰封期不同的环境效应。由于冰封条件的限制，很少有水库对冰封环境下的水质进行监测，使得冰封环境下的水质问题成为环境管理中无法规避的薄弱点。本项目以大连市最大的水源水库-碧流河水库为例进行研究，重点探索冰生消过程下水库氮磷在冰-水-沉积物中的迁移过程和冰封环境下各环境因子对水库氮磷多介质迁移的影响机制。本项目利用小波分析、秩次相关检验法和M-K检验法等方法分析了碧流河水库的冰生消特征，在此基础上设计了冰封期水库水质监测方案，明确了冰封期水库环境因子特征与基础水质状态。进而，探索了氮、磷在分层冰、分层水、间隙水、沉积物中的时空特性及相互关系，利用模拟实验分析了冰、沉积物对水库水质的影响，并将其应用到综合水质评价中。最后，结合锥形瓶、柱状模拟实验分析了冰-水界面、沉积物-水界面的迁移特征与环境因素的影响，量化了水库冰水界面的排盐系数与沉积物释放通量，在模拟实验和现场调查的基础上，构建了冰封期水库污染物蓄积模型。本项目成果为碧流河水库冬季水质管理提供了支撑，促使碧流河水库加强了冬季水质监测，相关技术方法可为东北地区水库冬季水质管理提供借鉴，促进了生态水利基础研究，具有较好的社会效益和应用价值。