平原河网典型全氟化合物输移分异机制及多尺度耦合模拟研究

Presently, environmental issues caused by emerging contaminants have become a global research hotspot for their enormous load, high toxicity and wide harm in plain river network area. According to the hydrodynamic characteristics of plain river network area, the mixing and transportation process of Perfluorinated Compounds (PFCs) as a representative of emerging contaminants will be studied. The response mechanism of different topological confluent structures on the distribution of PFCs will be revealed. The influence of the characteristic factors such as the shape of confluence, confluent angle, confluence flowrate ratio, branching ratio and bending rate on the transport difference of PFCs will be analyzed. Simultaneously the interaction between water and sediments in the case of the operation of the gate water pump, the propeller disturbance and the emergency water diversion will be revealed. Moreover, the transport and fate mechanism of PFCs under specific conditions will be analyzed in the end points of river network including small lake and estuary. The method of nesting coupling and scale conversion between different scale models will be proposed. Based on the uncertainty and sensitivity analysis of model parameters, a new automatic method for parameters estimation on inverse problems will also be proposed. Finally, a multi-scale coupling model of PFCs transportation in river network will be established. The result of this project will supply a cornerstone of the transport mechanism, prevention and control of emerging contaminants in plain river network area.

我国经济发达、人口众多的平原河网地区新兴污染物产生量大、毒性强、危害广，引发的环境问题已成为当前的研究热点。本项目针对平原河网地区的水动力特性，以新兴污染物全氟化合物作为代表，研究全氟化合物在平原河网水系中掺混、输移与交互的过程，揭示河网不同拓扑交汇结构对全氟化合物输运分配的响应机制，解析河网中交汇结点形态、交汇角度、汇流比、分枝比、曲折系数等特征因子对全氟化合物输移分异的胁迫影响；同时考虑闸泵水利设施运行、船舶螺旋桨扰动和应急调水情形下水与沉积物的全氟化合物交互过程；剖析河网端点小型湖荡及入湖河口区等特定条件下全氟化合物迁移归趋机制；提出不同尺度模型间的嵌套耦合与尺度转换衔接方法，同时针对模型参数的不确定性和敏感性，基于反问题方法提出模型关键参数自动率定新方法，构建河网全氟化合物多尺度耦合模型，为平原河网地区新兴污染物迁移机制与防控铺垫理论基石。

针对平原河网地区以全氟化合物（Perfluorinated compounds, PFCs）为代表的新污染物污染问题，本项目聚焦平原河网地区河道纵横交错、湖荡星罗棋布的区域特征和闸门开启、船舶航行与应急调水等人工干预的复杂水动力特征，对PFCs的时空分布特征、多介质迁移归趋行为和多尺度模拟方面进行了系统研究，取得创新性成果如下：(1)探明了太湖流域和里下河流域等平原河网地区不同类型河道和典型湖泊中14种典型PFCs的时空分异特征，明确了PFCs在水、悬浮颗粒物、沉积物和间隙水等介质中的分配行为，揭示了不同类型河道和湖泊中PFCs的生态风险水平；(2)自主研发了河网不同交汇方式下河道沉积物释放物理模型实验系统，解析了不同汇流形态下河道交汇区的三维水流结构和水动力参数特征，明确了不同交汇方式下受污底泥中典型PFCs的释放过程和水流特征参数的响应机制；(3)构建了闸门突然开启下泄水流冲击作用下底泥污染释放试验模拟系统、船舶螺旋桨射流扰动下底泥污染释放可控水槽模型试验系统和应急调水情形下不同强度水动力作用下沉积物中PFCs污染物释放试验系统，揭示了河网特定水动力作用下沉积物-孔隙水-悬浮物-上覆水系统中的多介质分异特征和迁移规律，厘清了水动力特征和环境因子与PFCs释放通量间的响应关系；(4)明确了河网调蓄节点湖荡沉水植物对多种PFCs的生态毒理学响应和抗氧化机制，探明了水生植物全生命周期下多种PFCs在“水-沉积物-植物组织-不同生态位微生物”中的迁移分配机制，解析了PFCs分子特征对其迁移分配过程的调控机制；(5)构建了河网特定动力条件下PFCs水土界面交互运动微观模型、基于水-沉积物-水生生物交互作用的PFCs中微观尺度的湖泊逸度模型和河网典型区域PFCs输移的多尺度耦合模型；最终阐明了平原河网地区全氟化合物的分配行为、界面输运过程和多介质迁移归趋行为。