Density effects on solute release from streambeds |
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| Authors: | Guangqiu Jin Wenhai Yang Huiyu Xu Zhongtian Zhang Saiyu Yuan Hongwu Tang Ling Li David Andrew Barry |
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| Institution: | 1. State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing, China;2. Department of Construction and Management, Pearl River Water Resources Commission of the Ministry of Water Resources, Guangzhou, China;3. School of Engineering, Westlake University, Hangzhou, China;4. Laboratoire de technologie écologique (ECOL), Institut d'ingénierie de l'environnement (IIE), Faculté de l'environnement naturel, architectural et construit (ENAC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland |
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| Abstract: | Contaminants that entered the streambed during previous surface water pollution events can be released to the stream, causing secondary pollution of the stream and impacting its eco-environmental condition. By means of laboratory experiments and numerical simulations, we investigated density effects on the release of solute from periodic bedforms. The results show that solute release from the upper streambed is driven by bedform-induced convection, and that density effects generally inhibit the solute release from the lower streambed. Density gradients modify the pore water flow patterns and form circulating flows in the area of lower streambed. The formation of circulating flows is affected by density gradients associated with the solute concentration and horizontal pressure gradients induced by stream slope. The circulating flows near the bottom of the streambed enhance mixing of the hyporheic zone and the ambient flow zone. |
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| Keywords: | circulating flow mixing release solute transport variable density |
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