大型浅水湖泊沉积物营养盐时空变化模型研究

The endogenous pollution which was caused by polluted sediment has great influence on algal blooming and water quality in eutrophic lakes. The research on temporal and spatial variation of nutrients in sediment is of great significance in controlling endogenous pollution of large shallow lake. There are spatial and vertical difference in physical-chemical elements in the sediment of Lake Taihu. Thus, based on previous research achievements of nutrients exchange in water-sediment interface, field observations of different types of bottom conditions and different lake zones will be carry out to study physical-chemical elements of sediment. In view of research results, the express of Source and sink terms and boundary conditions will be found and 3-D sediment nutrients simulation model in Lake Taihu can be built and then tested on measured data from different regimen. In addition, we shall reveal the mechanism of sediment nutrients spatial difference in Taihu Lake with numerical simulation experiments under different scenarios.

沉积物引起的内源污染释放对富营养化湖泊藻类水华暴发和水质具有重要影响，开展沉积物污染物含量时空变化研究对加强湖泊内源污染控制具有重要意义。本申请针对大型浅水湖泊太湖，沉积物物理化学要素存在显著的水平和垂直方向差异特征，拟在国内外水-土界面营养盐交换等方面的研究成果基础上，重点进行不同类型湖区和底质条件下的水-沉积物物理、化学成分的观测，研究水-沉积物交换量、沉积物营养盐变化过程的参数化表达，构建太湖三维沉积物营养盐时空变化模型；通过数值模拟和现场实测对比，进行模型校验和验证；开展不同情景的数值试验，通过结果对比分析，揭示太湖沉积物营养盐空间差异的驱动机制。

本研究以太湖为例，通过原位观测和室内水槽实验，对水动力过程和沉积物再悬浮释放进行了综合观测，根据实验结果建立了太湖三维悬浮物模型和太湖底泥床面模型，进而建立了太湖三维沉积物营养盐动态释放模型，通过实验得出了太湖底泥在不同起动标准下的起动切应力，进而利用泥沙起动的理论模型给予了验证。对悬浮物疏运，底床变化等进行了模拟。同时根据实验还建立了底泥中TN、TP的释放通量与悬浮物的关系，综合考虑外源污染，取得了较好的效果。