Erosion Behavior of Different Microplastic Particles in Comparison to Natural Sediments

Abstract

Microplastic (MP) has been detected in marine, limnic, terrestrial, and atmospheric environments. However, rivers are often only seen as transport paths for MPs from inland sources to the oceans, although transport rates in rivers can hardly be determined yet. MP in rivers can either be transported, or it settles to the bottom of the river and either remains there or is remobilized again at higher flow velocities. This remobilization, also known as erosion, depends on the critical shear stress of a particle and is influenced by the particle properties and the sediment bed. In this study, the critical shear stresses of 14 MP particles with different shapes, densities, and particle sizes on different sediment beds were experimentally determined and subsequently compared with the basic principles of erosion from sediment transport. Critical shear stresses of the MP particles were between 0.002 and 0.233 N/m 2 , depending on particle and sediment properties. Furthermore, the hiding-exposure effect was transferred to MPs and an equation was developed to determine the critical shear stress of different MP particles on natural sediment beds.

Transport and Behavior of Microplastics Emissions From Urban Sources in the Baltic Sea

“…and Waldschläger and Schüttrumpf (2019b) for the critical shear stress. The restriction of our approach to the 20-500 µm size class results from model limitations.…”

“…It is well known, that beside density, shape and size play an important role for the sinking velocity (e.g.,; Kowalski et al, 2016;Kooi and Koelmans, 2019). Waldschläger and Schüttrumpf (2019a;2019b) provide an overview of data and formulas, which were adapted by us. However, differences in shape and size did not play an important role for the temporal and spatial resolution we used in our model approach.…”

Baseline Study on Microplastics in Indian Rivers under Different Anthropogenic Influences

“…The results demonstrated a decrease in MP concentration downstream from 0.76 particles/L (P3) to 0.13 particles/L (P2), to the lowest concentration of 0.11 particles/L (P4). This decrease can be explained by the retention of MP by sediment as a common process of MP transport in fluvial systems [46]. Since there was a very low flow rate in the Adyar River during sampling, no remobilisation could have taken place with an increasing flow velocity [46][47][48].…”

Wave-Induced Distribution of Microplastic in the Surf Zone

“…The findings of the current study relate primarily to the transport behavior of spherical MP particles, with diameters larger than that of the surrounding sediment (except MP "B"). It is known that the ratio of the size between plastic particles and the surrounding sediment has an influence on the transport behavior (Waldschläger and Schüttrumpf, 2019b;Sebille et al, 2020) because if, for example, the particle size is smaller than the sediment grain size, the initiation of movement depends on the particle orientation to the flow.…”

“…It was proven that stormy winds, surface waves and sea level variations govern the occurrence and deposition of MP within the sandy body of beaches instead of anthropogenic loads (Chubarenko et al, 2018b). For the initiation of movement and entrainment of MP particles, the particle size and density in correlation with the sediment properties were more important than the particle shape (Ballent et al, 2013;Waldschläger and Schüttrumpf, 2019b). It was recently found that the infiltration depth increases with decreasing MP particle diameter and that spherical particles infiltrate deeper than fragments and fibers (Waldschläger and Schüttrumpf, 2020).…”