Author(s): Xuyang Qiao; Shangtuo Qian; Hui Xu; David Z. Zhu
Linked Author(s):
Keywords: Microplastic release Plume characteristics Plume width Entrainment coefficient
Abstract: Understanding the behavior of microplastics after they have been released in water is a prerequisite for assessing the extent of their contamination to the aquatic environment. Over recent years, an increasing number of physical experiments and numerical simulations of microplastics, providing support for revealing the dynamics of microplastic transport in water. But there are few studies on the continuous release of a mass of microplastics into the water, which happens to be common in real environments. Unlike the settling of individual microplastic particles in water, microplastics have plume characteristics when they are continuous released into the water, where they continuously entrain the surrounding water and expand the plume width. In order to study the dynamics of microplastics that are continuously released into water, we mixed microplastics of different sizes and densities with water to form solutions of different concentrations, and released them into stagnant water at different rates using hoses of different inner diameters. The concentration and velocity of the microplastic plume at the same depth showed a Gaussian distribution, and the Gaussian spreading rate is about 0.08-0.18 in our experiments. The Particle Image Velocimetry method is utilized to obtain the entrainment velocity, and an entrainment velocity expression for the microplastic plume is developed using buoyancy flux B and Stokes number St.
Year: 2025