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Numerical modelling is an effective tool complementing in-situ or remote sensing observations of plastic litter from rivers to the ocean. It allows exhaustive simulation of particle dispersal dynamics and fate after their disposal in aquatic environments. Several modeling methods have been proposed. The most commonly used in the literature is based on the Lagrangian framework. It allows to follow individual particle trajectories by time-integration of the flow velocity. The tracking of a large amount of particles is at the cost of a high complexity. Nevertheless, it remains helpful when identifying (macro-) plastics spatial distribution patterns. On the other hand, the Eulerian framework is more efficient to follow the evolution of the number or mass concentrations. Compared to the Lagrangian framework, it is suitable for modelling transport and fate of micro-plastics in large-scale estuarine and marine systems. However, plastic debris are known to exhibit high polydispersity in their sizes, shapes, and densities. Hence, an in-depth study of microplastics distribution patterns in a large domain would require a numerous number of discrete classes, leading to higher model complexity . However, the polydispersity of plastics could be addressed in an effective way by using population balance equations (PBE) to track the evolution of the size distribution. In PBE, the moments of the number density function (NDF) are advected and diffused within the Eulerian framework. Subsequently, the plastic NDF can be recovered from the resulting moments of the distribution. With the three discussed modelling frameworks, we propose to investigate the effects of tidal pumping on the exportation or importation of plastics. These methods will be tested in a schematized estuary including deposition terms. Their performance in terms of computational resources and spatio-temporal dispersal of plastic litter will also be analyzed. Also see: https://micro2022.sciencesconf.org/427122/document, In MICRO 2022, Online Atlas Edition: Plastic Pollution from MACRO to nano

Hydrodynamics

Hydrodynamics

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ispartof: pages:26-34 ispartof: Online proceedings of the papers submitted to the 2020 TELEMAC-MASCARET User Conference pages:26-34 ispartof: 2020 TELEMAC-MASCARET User Conference location:Antwerp (Belgium) / online status: Published online

ispartof: Final Report status: Published online

Hydrodynamics

Title : Volume : Issue : Pagination : 12

The new Coastal and Ocean Basin (COB) located at the Greenbridge Science Park in Ostend, Belgium is under construction since February 2017. The laboratory will provide a versatile facility that will make a wide range of physical modelling studies possible, including the ability to generate waves in combination with currents and wind at a wide range of model scales. The facility is serving the needs in Flanders, Belgium, in the fields of mainly offshore renewable energy and coastal engineering. The COB will allow users to conduct tests for coastal and offshore engineering research and commercial projects. The basin will have state-of-the-art generating and absorbing wavemakers, a current generation system, and a wind generator. It will be possible to generate waves and currents in the same, opposite and oblique directions. The basin is expected to be operational in 2019. This paper presents an overview of the basin’s capabilities, the ongoing work, and selected results from the design of the COB.

ispartof: pages:1483-1494 ispartof: Proc. Coastal Dynamics 2017 pages:1483-1494 ispartof: Coastal Dynamics location:Helsingør (Denmark) date:12 Jun - 16 Jun 2017 status: published

Organic matter in the water environment can enhance either flocculation or stabilization and thus controls the fate and transportation of cohesive sediments and causes seasonal variation in the turbidity of river water, determining floc morphology and settling velocity. The aim of this study was to elucidate the way that biological factors change the organic matter composition and enhances either flocculation and stabilization in different seasons. Jar test experiments were performed using a mixture of standard kaolinite and the filtered river water samples collected (bi-)weekly or monthly from April to December 2015 upstream a constructed weir in Nakdong River, to estimate the flocculation potential of the seasonal river water samples. Chlorophyll-a concentration, algae number concentration, and the fluorescence characteristics of organic matter were used to represent the biological factors. Our results revealed that flocculation potential depended on not only the algal population dynamics but also the origins (or chemical composition) of organic matter in the river water. Extracellular polymeric substances (EPS), as algal organic matter, enhanced flocculation, while humic substances (HS), as terrestrial organic matter, enhanced stabilization, rather than flocculation. Since flocculation potential reached its maximum around the peaks of algal population, algae-produced EPS likely enhanced flocculation by binding sediment particles in the flocs. This observation supports previous findings of seasonal variation in EPS production and EPS-mediated flocculation. However, when HS was transported from the surrounding basin by a heavy rainfall event, cohesive sediments tended to be rather stabilized. Supplementary flocculation potential tests, which were performed with artificial water containing refined EPS and HS, also showed the opposing effects of EPS and HS. ispartof: Water - Basel vol:9 issue:5 pages:335-348 status: published

© 2017 American Chemical Society. Plastic in the global oceans fulfills two of the three conditions for pollution to pose a planetary boundary threat because it is causing planetary-scale exposure that is not readily reversible. Plastic is a planetary boundary threat if it is having a currently unrecognized disruptive effect on a vital Earth system process. Discovering possible unknown effects is likely to be aided by achieving a fuller understanding of the environmental fate of plastic. Weathering of plastic generates microplastic, releases chemical additives, and likely also produces nanoplastic and chemical fragments cleaved from the polymer backbone. However, weathering of plastic in the marine environment is not well understood in terms of time scales for fragmentation and degradation, the evolution of particle morphology and properties, and hazards of the chemical mixture liberated by weathering. Biofilms that form and grow on plastic affect weathering, vertical transport, toxicity, and uptake of plastic by marine organisms and have been underinvestigated. Laboratory studies, field monitoring, and models of the impact of weathering on plastic debris are needed to reduce uncertainty in hazard and risk assessments for known and suspected adverse effects. However, scientists and decision makers must also recognize that plastic in the oceans may have unanticipated effects about which we are currently ignorant. Possible impacts that are currently unknown can be confronted by vigilant monitoring of plastic in the oceans and discovery-oriented research related to the possible effects of weathering plastic. ispartof: Environmental Science & Technology Letters vol:4 issue:3 pages:85-90 status: published

ispartof: De Boomklever vol:44 issue:4 pages:102-108 ispartof: De Boomklever status: published