Thermosolutal transport in reservoirs generated by release and leaching of salinity and nutrients from anaerobic bed

厌氧床释放和淋滤盐度和营养物而产生的水库热溶质输送

基本信息

批准号：
10650505
负责人：
MICHIOKU Kohji
金额：
$ 2.56万
依托单位：
Kobe University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10650505/
关键词：
Reservoir Dynamics Algae Bloom Thermal Siphon Buoyancy Flows Eutrophication Thermosolutal Convection Internal Circulation Double Diffusion 閉鎖水域水質環境

项目摘要

In eutrophic reservoirs, high concentration of nutrients and ionic matters are released from the bed under badly anaerobic condition. Since the leaching process produces high salinity or heavy water mass on the bed, it gravitationally generates an inclined plume on the sloping bed and transport heat and mass to the bottom layer. This process may bring serious eutrophication of bottom water.In order to predict heat and mass flux due to the thermosolutal transport and device a countermeasure against this, the following were examined. (1)Focusing on heat and salinity balance in the anaerobic bottom water, a water quality measurement was performed in a eutrophic reservoir. (2)Release flux of salinity from the bed was examined in an experimental model in which the bed materials sampled from the reservoir were installed in a tank and filled with anaerobic water. (3)Using a micro-bubble aerator system, an in-situ experiment of water purification was carried out. (4)A model experiment and an a … More nalysis on the inclined plume were performed in order to investigate buoyancy and flow fields.The main findings are as follows. The thermosolutal convection is the main reason of making the reservoir bottom water to be extraordinary heavy and salty. Because of its very stable salinity stratification, the impounded water has never been overturned in the last many years. It makes the bottom water to be more seriously eutrophicated. It is the plume convection of warm water from the shallow layer to the bottom layer that is responsible for producing an inverse temperature stratification in the bottom layer. The heat and mass flux can be computed by the plume theory which was verified with the experimental data. The flux law was successfully applied for computing heat and salinity balance observed in the field survey. The micro-bubble aeration system was found to be very useful for promoting vertical mixing and aerating the bottom layer. After starting the aeration, the heavy and anaerobic bottom water mass was completely disappeared and the reservoir was fully overturned.The next step we should take is to develop a prediction tool of water quality by considering the thermosolutal convection process. We should also continue the water purification experiment for improving the system to be of user-convenience. Less

在富营养化水库中，在严重缺氧的条件下，高浓度的营养物和离子物质从床层中释放出来，由于淋滤过程在床层上产生高盐度或重水团，它在重力作用下在倾斜床层上产生倾斜羽流并输送热量和热量。这个过程可能会带来严重的底层水体富营养化。为了预测由于热溶质输送而产生的热量和质量通量并采取对策，如下： (1)以厌氧底水的热量和盐度平衡为中心，对富营养化水库进行了水质测量。(2)在床层材料的实验模型中检查了床层的盐度释放通量。 (3)利用微气泡曝气系统进行水体净化原位实验。 (4)对倾斜羽流进行了模型实验和分析，研究了浮力场和流场。主要研究结果如下：热溶质对流是造成水库底水异常的主要原因。由于其盐度层结非常稳定，多年来从未发生过翻转，使底层水体富营养化更加严重。水从浅层到底层负责在底层产生逆温度分层，可以通过羽流理论计算热量和质量通量，并成功地应用了通量定律。计算现场调查中观察到的热量和盐度平衡，发现微气泡曝气系统对于促进垂直混合和底层曝气非常有用。曝气开始后，重的、厌氧的底层水团完全消失了。水库下一步我们应该采取的措施是开发一种考虑热溶质对流过程的水质预测工具，我们还应该继续进行水净化实验，以改进系统以方便用户。