Effects of Sediment Concentration on Removal Rate and Settling Velocity of Particles in the Minas Basin, Bay of Fundy, Canada

Many researchers confuse particle settling velocity with the rate at which the water column clears, especially in areas dominated by fine-grained cohesive sediment. The removal rate of sediment from suspension through settling varies approximately linearly with concentration This concentration dependence of removal rate leads to the assumption that particles settle at higher velocities at higher concentrations yet multiple studies have shown that flocculated sediment over a wide range of sediment concentration has a settling velocity on the order of 1 mm s^-1 . A laboratory study of the still water settling of mud suggests that clearance rate is the result of the concentration dependence of the time required for the particles in suspension to flocculate and not a concentration dependence of settling velocity. To examine this further, sediment concentration, particle size, particle settling velocity and estimates of apparent particle bulk density were collected during two deployments of a tripod in the Minas Basin, Upper Bay of Fundy, in June 2013 and March 2014. Using these data we examine the concentration dependence of the settling velocity and removal rate of particles after tidal resuspension.