Mass transfer at the sediment/water interface for permeable sediments in an inland aquatic system

沉积物/水界面上的物质交换，如溶解氧的吸收、磷酸盐的释放等，对河流、湖泊和水库的水质和生态系统起着重要的作用。沉积物需氧量（SOD）是从沉积物上方的水柱到沉积物表面的氧通量，主要针对不可渗透的有机沉积物进行了研究。桑迪渗透性沉积物的SOD还没有研究。本研究考虑一个桑迪渗透性沉积物。在不渗透的沉积物中，分子扩散是质量传递的主要机制。另一方面，近床湍流穿透引起的间隙水运动对桑迪渗透性沉积物的传质有显著影响。本文建立了一个由近床湍流相干运动引起的沉积物/水界面压力波动引起的孔隙水流动模型。该模型结合了沉积物中微生物的摄氧量。所提出的模型不仅可以量化非渗透性有机沉积物的SOD，也可以量化桑迪渗透性沉积物的SOD。

Mass transfer at the sediment/water interface, e.g. dissolved oxygen uptake, phosphate release and so on, plays an important role for water quality and ecosystem in rivers, lakes, and reservoirs. Sedimentary oxygen demand (SOD) is the oxygen flux from water column over a sediment to the sediment surface, and has been studied for mainly impermeable organic sediments. SOD for sandy permeable sediment has not been investigated. This study considers a sandy permeable sediment. In impermeable sediments, molecular diffusion is a major mechanism for mass transfer. On the other hand, interstitial water motions caused by near-bed turbulence penetration has a significant effect on mass transfer for sandy permeable sediments. A model for pore water flow induced by pressure fluctuations at the sediment/water interface due to near-bed turbulent coherent motions has been developed. The model incorporates microbial oxygen uptake in the sediments. The proposed model quantifies SOD for not only impermeable organic sediments, but also sandy permeable sediments.