Sea Waves Transport of Inertial Micro-Plastics: Mathematical Model and Applications

Abstract

Plastic pollution in seas and oceans has recently been recognized as one of the most impacting threats for the environment, and the increasing number of scientific studies proves that this is an issue of primary concern. Being able to predict plastic paths and concentrations within the sea is therefore fundamental to properly face this challenge. In the present work, we evaluated the effects of sea waves on inertial micro-plastics dynamics. We hypothesized a stationary input number of particles in a given control volume below the sea surface, solving their trajectories and distributions under a second-order regular wave. We developed an exhaustive group of datasets, spanning the most plausible values for particles densities and diameters and wave characteristics, with a specific focus on the Mediterranean Sea. Results show how the particles inertia significantly affects the total transport of such debris by waves.

Settling Velocity of Microplastics Exposed to Wave Action

“…The behavior described above for the experiments reported in Figure 3 can be considered typical of all experiments performed during the present study. Similar behaviors have been presented in recent theoretical and numerical studies [28][29][30]. The inertial character of the particles is the main reason to this difference with respect to the Stokes drift trajectories for a fluid particle.…”

“…The set of waves generated in the present experimental campaign was such that the wave parameter H/gT 2 was monotonically increasing moving from the first wave condition (W1) to the last one (W4). Overall, the experimental values of H/gT 2 were in a realistic range, and they can well represent typical sea state conditions of several sea basins [29]. All wave conditions fell in the intermediate depth regime except for W1, which corresponded to shallow water conditions.…”

“…Recent contributions have been devoted to filling in this gap in understanding the role of the inertial character of heavy particles, using more refined models to describe the particle trajectories. More specifically, the particle model of Maxey and Riley (1983) [27] has been employed in theoretical and numerical models to study the interactions among negatively buoyant spherical [28,29] and non-spherical [30] particles and the sea wave Stokes drift. Additional insight into the inertial effects has been provided by recent experimental laboratory studies of MP dispersion in the nearshore [31].…”

Unraveling the Role of Plastic Waste Pollution in the Amvrakikos Wetlands National Park, Greece: The Stakeholders’ Views

“…The existence of plastics and microplastics in marine environments is an important indicator of their environmental degradation. Therefore, the introduction of monitoring and prediction models on their pathways would provide fundamental information on their location and distribution in marine ecosystems [48]. The main sources of the aquatic ecosystem are proven to be uncontrolled waste disposal at sea, fishing aquaculture, shipping transport tourism, and coastal mining activities.…”

Occurrence, Composition, and Relationships in Marine Plastic Debris on the First Long Beach Adjacent to the Land-Based Source, South China Sea

“…Recently, the worldwide production of plastic reached 300 million tons [8]. Land-based sources are the key sources of plastic debris, and mismanaged plastic debris can eventually enter the ocean via inland waterways, wastewater outflows, and transport by wind, wave and tides [3,7,[9][10][11][12][13]. When plastic debris enters marine environments, it can influence water quality and become a threat to marine biology [14][15][16].…”