Abstract

The present study investigated the influence of geotechnical properties of bed sediments on the resuspension potential in the Ashtamudi estuary, India. Bed sediment samples collected from different locations were analyzed for grain size distribution, atterberg limits, consolidation coefficient and shear strength. The suspended sediment concentrations (SSC) and flow velocity at three different depths such as near-bed, mid-depth, and near-surface were also measured. The locations having lower shear strength and coefficient of consolidation and with higher sand content exhibited higher SSC in the water column. The sediment with weak particle–particle bonding demonstrated higher resuspension leading to a higher concentration of SSC in the water column. The higher current in the near-bed region also contributed to the resuspension of bed sediments. The laboratory experiments conducted using consolidated soil specimens in a jar test apparatus at different turbulence rates ascertained that the bed sediments, from those locations of the estuary with higher SSC in the water column, exhibited a higher rate of erosion. It was further observed that the resuspension of bed sediments has an impact on the heavy metal partitioning in the Ashtamudi estuary, whereby the resuspension leads to the uptake of Fe and possible release of Cr in the water column.

摘要

本研究调查了床层沉积物的岩土特性对印度 Ashtamudi 河口再悬浮潜力的影响。分析从不同地点采集的床底沉积物样品的粒度分布、阿特伯格极限、固结系数和抗剪强度。还测量了近床、中深度和近地表三个不同深度的悬浮泥沙浓度（SSC）和流速。具有较低剪切强度和固结系数以及较高含砂量的位置在水体中表现出较高的SSC。颗粒-颗粒结合较弱的沉积物表现出更高的再悬浮，导致水柱中 SSC 的浓度更高。近床区域较高的水流也有助于床沉积物的再悬浮。在不同湍流速率的罐子测试装置中使用固结土壤样品进行的实验室实验确定，来自河口的水柱中具有较高 SSC 的那些位置的河床沉积物表现出较高的侵蚀速率。进一步观察到，床层沉积物的再悬浮对 Ashtamudi 河口中的重金属分配有影响，因此再悬浮导致水体中铁的吸收和铬的可能释放。