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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

富营养化水库在恶劣的厌氧条件下，从河床中释放出高浓度的营养物和离子物质。由于浸出过程在床上产生高盐度或重水团，因此在倾斜的床上重力作用产生倾斜的羽流，并将热量和质量输送到底层。这一过程可能带来严重的底层水体富营养化。为了预测由热溶质输运引起的热量和质量通量，并提出相应的对策，本文研究了以下几个方面。(1)针对厌氧底水热盐平衡问题，对某富营养化水库进行了水质测量。(2)在实验模型中，将从储层取样的床料安装在一个水箱中并充满厌氧水，研究了床层的盐度释放通量。(3)采用微泡曝气系统，进行了现场净水实验。(4)对倾斜羽流进行了模型实验和进一步的分析，以研究其浮力和流场。主要研究结果如下：热溶质对流是造成储层底水异常重盐的主要原因。由于其非常稳定的盐度分层，在过去的许多年里，被蓄水的水从未被推翻过。它使底层水的富营养化更加严重。从浅层到底层的暖水羽流对流是在底层产生逆温度分层的原因。热通量和质量通量可以用羽流理论计算出来，并得到了实验数据的验证。将通量定律成功地应用于野外观测的热、盐平衡计算。发现微泡曝气系统对促进垂直混合和底层曝气非常有用。曝气启动后，重质厌氧底水完全消失，池体完全倾覆。下一步应考虑热溶质对流过程，开发水质预报工具。我们还应该继续进行净水实验，以改进系统，方便用户使用。少