Effects of solute release position on transient solute dispersion across the sediment-water interface: A modeling study

<p>Understanding the fundamental mechanisms of solute transfer across the sediment-water interface (SWI) is essential for comprehending river functioning. Considering the stochastic and complex pollutant emissions across the SWI, we investigate the effects of release position on the solute transport in this work. Linking turbulent momentum and solute transport in the hyporheic zone through numerical modeling. Simulation results reveal that the location of the point source release determines the initial convection and dispersion intensity, which in turn affects the process of solute dispersion across the SWI. The location of solute release can affect hyporheic mixing processes more significantly than changes in streambed permeability. The penetration of turbulence into the streambed directly controls both interfacial exchange and mixing within a transition layer below the SWI, which is consistent with previous findings. In addition, the finite-time Lyapunov exponents are used to describe the lagrangian coherent structures of the flow field in the whole process, which provides a new perspective to reveal the mixing process of solutes across the SWI.</p> <p><strong>Acknowledgments</strong></p> <p>This research was funded by the National Key R&D Program of China (2022YFC3202605), the Fundamental Research Funds for the Central Universities (B200204044), the Research funding of China Three Gorges Corporation (202003251).</p>