State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, Sichuan, 610065, China.
State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, Sichuan, 610065, China.
Water Res. 2020 Sep 15;183:116087. doi: 10.1016/j.watres.2020.116087. Epub 2020 Jun 28.
Hydropower, which utilizes energy from fast-moving water, can help alleviate the energy crisis and promote economic development. For safety and ecological purposes, dams must discharge periodically. This discharge process, which occurs with the supersaturation of total dissolved gas (TDG), affects the fish and other aquatic organisms living in downstream river areas. Previous studies have shown that the supersaturated TDG dissipation process is closely related to hydraulic properties such as the flow rate, water depth and turbulent kinetic energy. Additionally, the presence of solid walls such as vegetation leaves in water can adsorb dissolved gases in water, thereby promoting the supersaturated TDG dissipation process, and the adsorption effect is closely related to the solid wall material. However, systematic studies on how solid walls in water can quickly absorb dissolved gases from water and rapidly reduce the TDG saturation of water are lacking. Herein, a series of experiments was conducted to study the dissipation process of supersaturated TDG under the action of solid walls in water and to reveal the adsorption effect of solid wall surface properties on dissolved gas. The results showed that the surface roughness and hydrophobicity (contact angle) are the key factors related to the adsorption effect of solid walls on the TDG in water. Generally, the dissipation rate of supersaturated TDG first increased and then decreased with increasing surface roughness. The supersaturated TDG dissipation rate increased monotonically with increasing contact angle. Based on the experimental data, the adsorption coefficient, which represents the adsorption effect of the solid wall for dissolved gas in water, was proposed, and a prediction formula between the adsorption coefficient and the contact angle of the solid wall was established. These results can provide theoretical support for the utilization of the solid wall adsorption effect to mitigate the adverse effects of supersaturated TDG and protect fish.
水力发电利用高速水流的能量，可以帮助缓解能源危机并促进经济发展。出于安全和生态目的，大坝必须定期放水。这种放水过程会导致总溶解气体（TDG）过饱和，从而影响生活在下游河流区域的鱼类和其他水生生物。先前的研究表明，过饱和 TDG 消散过程与水流速度、水深和湍流动能等水力特性密切相关。此外，水中的固体壁（如植物叶片）的存在会吸附水中的溶解气体，从而促进过饱和 TDG 消散过程，并且吸附效果与固体壁材料密切相关。然而，关于水中的固体壁如何能够快速吸收水中的溶解气体并迅速降低水的 TDG 饱和度的系统研究还很缺乏。在此，进行了一系列实验来研究水中固体壁作用下过饱和 TDG 的消散过程，并揭示固体壁表面性质对溶解气体的吸附效果。结果表明，表面粗糙度和疏水性（接触角）是固体壁对水中 TDG 吸附效果的关键因素。通常，过饱和 TDG 的消散速率随表面粗糙度的增加先增加后减小。过饱和 TDG 的消散速率随接触角的增加而单调增加。基于实验数据，提出了代表固体壁对水中溶解气体吸附效果的吸附系数，并建立了吸附系数与固体壁接触角之间的预测公式。这些结果可为利用固体壁吸附效应减轻过饱和 TDG 的不利影响和保护鱼类提供理论支持。
