Effectiveness of a bubble-plume mixing system for managing phytoplankton in lakes and reservoirs
Effectiveness of a bubble-plume mixing system for managing phytoplankton in lakes and reservoirs
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DOI：
10.1016/j.ecoleng.2018.01.002
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发表时间：
2018-04
影响因子：
3.8
通讯作者：
Shengyang Chen;C. Carey;John C. Little;M. Lofton;R. McClure;C. Lei
中科院分区：
文献类型：
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作者：
Shengyang Chen;C. Carey;John C. Little;M. Lofton;R. McClure;C. Lei
气泡羽流混合系统通常部署在富营养化湖泊和水库中以管理浮游植物类群。不幸的是，文献中经常报道气泡羽流（诱导）混合的不一致结果。本研究通过水生生物地球化学建模 (FABM) 框架，利用全储层现场实验和三维水动力模型 (Si3D) 与水生生态动力学 (AED) 模型相结合，研究浮游植物对诱导混合的响应。耦合的 Si3D-AED 模型经过 24 小时现场混合实验的验证，随后用于数值参数研究，以研究浮游植物对各种诱导混合场景的响应，其中浮游植物沉降速率、浮游植物生长速率、水库深度和混合系统扩散器深度依次变化。混合实验期间的现场观察表明，在24小时混合期间，整个水库的浮游植物总浓度（以μg/L为单位）减少了近10%。数值模拟结果表明，浮游植物浓度可能很大程度上受到浮游植物功能特性和混合扩散器部署深度的影响。有趣的是，数值结果表明，在深层水库（> 20 m）中，浮游植物浓度受到光照限制导致的生长速率降低的控制，而在浅层水库混合期间，沉降损失是更重要的因素。此外，耦合的 Si3D-AED 模型结果表明，将混合扩散器部署在水柱深处以增加混合深度通常可以提高使用气泡羽流混合系统对蓝藻的成功管理。因此，本研究中引入的耦合 Si3D-AED 模型可以帮助气泡羽流混合系统的设计和操作。
Bubble-plume mixing systems are often deployed in eutrophic lakes and reservoirs to manage phytoplankton taxa. Unfortunately, inconsistent outcomes from bubble-plume (induced) mixing are often reported in the literature. The present study investigates the response of phytoplankton to induced mixing using a whole-reservoir field experiment and a three-dimensional hydrodynamic model (Si3D) coupled with the Aquatic EcoDynamics (AED) model through the framework for aquatic biogeochemical modelling (FABM). The coupled Si3D-AED model is validated against a 24-h field mixing experiment and subsequently used for a numerical parametric study to investigate phytoplankton responses to various induced mixing scenarios in which the phytoplankton settling rate, phytoplankton growth rate, reservoir depth, and mixing system diffuser depth were sequentially varied. Field observations during the mixing experiment suggest that the total phytoplankton concentration (measured in μ g/L) across the reservoir was reduced by nearly 10% during the 24-h mixing period. The numerical modeling results show that phytoplankton concentration may be substantially affected by the functional traits of the phytoplankton and the deployment depth of the mixing diffuser. Interestingly, the numerical results indicate that the phytoplankton concentration is controlled by reduced growth rates due to light limitation in deep reservoirs (> 20 m), whereas settling loss is a more important factor in shallow reservoirs during the mixing period. In addition, the coupled Si3D-AED model results suggest that deploying the mixing diffuser deeper in the water column to increase mixing depth may generally improve the successful management of cyanobacteria using bubble-plume mixing systems. Thus, the coupled Si3D-AED model introduced in the present study can assist with the design and operation of bubble-plume mixing systems.