Alsina José M, Jongedijk Cleo E, van Sebille Erik
Laboratory of Maritime Engineering Department of Civil and Environmental Engineering Universitat Politècnica de Catalunya Barcelona Spain.
Department of Civil and Environmental Engineering Imperial College London London UK.
J Geophys Res Oceans. 2020 Dec;125(12):e2020JC016294. doi: 10.1029/2020JC016294. Epub 2020 Dec 16.
The transport of plastic particles from inland sources to the oceans garbage patches occurs trough coastal regions where the transport processes depend highly on wave-induced motions. In this study, experimental measurements of the plastic particles wave-induced Lagrangian drift in intermediate water depth are presented investigating the influence of the wave conditions, particle size and density on the motion of relatively large plastic particles. A large influence of the particle density is observed causing particles to float or sink for relative densities lower and larger than water respectively. The measured net drift of the floating particles correlates well with theoretical solutions for particle Stokes drift, where the net drift is proportional to the square of the wave steepness. Floating particles remain at the free water surface because of buoyancy and no evidence of any other influence of particle inertia on the net drift is observed. Nonfloating particles move close to the bed with lower velocity magnitudes than the floating particles' motion at the free surface. The drift of nonfloating particles reduces with decreasing wave number, and therefore wave steepness.
塑料颗粒从内陆源输送到海洋垃圾带是通过沿海地区进行的，在这些地区，输送过程高度依赖于波浪引起的运动。在本研究中，给出了中等水深条件下塑料颗粒波浪诱导拉格朗日漂移的实验测量结果，研究了波浪条件、颗粒大小和密度对相对较大塑料颗粒运动的影响。观察到颗粒密度有很大影响，导致相对密度分别低于和高于水的颗粒上浮或下沉。所测量的漂浮颗粒的净漂移与颗粒斯托克斯漂移的理论解相关性良好，其中净漂移与波陡的平方成正比。由于浮力，漂浮颗粒停留在自由水面，未观察到颗粒惯性对净漂移有任何其他影响的证据。非漂浮颗粒靠近床面移动，其速度大小低于自由表面漂浮颗粒的运动速度。非漂浮颗粒的漂移随着波数的减小而减小，因此也随着波陡的减小而减小。
