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The locations of the monitor boxes in the MOHID model simulation of the dispersal of plastic preproduction pellets in the NazaréNazar´Nazaré Canyon off the coast of Portugal. Boxes lie along the canyon axis and are 0.5 m 3 in volume, each initially containing ∼ 2000 pellets. Canyon topography and depth is depicted in the color scale; purple < 1000 m, blue < 2000 m, green < 3000 m, yellow < 4000 m, red < 5000 m.
Source publication
Given the complexity of quantitative collection, knowledge of the
distribution of microplastic pollution in many regions of the world
ocean is patchy, both spatially and temporally, especially for the
subsurface environment. However, with knowledge of typical hydrodynamic
behavior of waste plastic material, models predicting the dispersal of
pelagi...
Context in source publication
Context 1
... plotted for a 56 day period. Accurate atmospheric and oceanographic data for the time period be- tween 15 March and 20 May 2009 was available to drive the physical parameters of the model. The numerical model was adapted for the HD black pellet data from one used previously in the modelling of organo-mineral aggregate transport, as given in Pando (Fig. ...
Citations
... Such items are also more prone to wind influence (Jackson, 1998;Schwarz et al., (bags and foils) and Multilayer items (food wrapping) (van Emmerik et al., 2019) had lower net transport rates than average (between 11% and 17% vs 27% for all plastics). Because of their lower buoyancy, such items are more prone to vertical mixing and the influence of changes in turbulence and density fronts, such as salt concentrations (Acha et al., 2003;Ballent et al., 2012). This is particularly relevant for tidal rivers and estuaries, due to changes in the relative balance between fresh and salt water and higher turbulence resulting from the changes in density distribution, compared to the freshwater reaches of the river. ...
Plastic is an emerging pollutant, and the quantities in rivers and oceans are expected to increase. Rivers are assumed to transport land-based plastic into the ocean, and the fluvial and marine transport processes have been relatively well studied to date. However, the processes controlling the transport in tidal rivers and estuaries, the interface between fluvial and marine systems, remain largely unresolved. For this reason, current estimates of riverine plastic pollution and export into the ocean remain highly uncertain. Hydrodynamics in tidal rivers and estuaries are influenced by tides and freshwater discharge. As a consequence, flow velocity direction and magnitude can change diurnally. In turn, this impacts the transport dynamics of solutes and pollutants, including plastics. Plastic transport dynamics in tidal rivers and estuaries remain understudied, yet the available observations suggest that plastics can be retained here for long time periods, especially during periods of low net discharge. Additional factors such as riparian vegetation and riverbank characteristics, in combination with bidirectional flows and varying water levels, can lead to even higher likelihood of long-term retention. Here, we provide a first observation-based estimate of net plastic transport on a daily time scale in tidal rivers. For this purpose, we developed a simple Eulerian approach using sub-hourly observations of plastic transport and discharge during full tidal cycles. We applied our method to the highly polluted Saigon river, Vietnam, throughout six full tidal cycles in May 2022. We show that the net plastic transport is about 27–32 % of the total plastic transport. We found that plastic transport and river discharge are positively and significantly correlated (Pearson's r = 0.87, R2 = 0.75). The net transport of plastic is higher than the net discharge (27–32 % and 18 %, respectively), suggesting that plastic transport is governed by other factors than water flow. Such factors include wind, varying plastic concentrations in the water, and entrapment of plastics downstream of the measurement site. The plastic net transport rates alternate between positive (seaward) net transport and negative (landward) net transport, as a result of the diurnal inequality in the tidal cycles. We found that soft and neutrally buoyant items had considerably lower net transport rates than rigid and highly buoyant items (11–17 % vs 31–39 %), suggesting the retention time strongly depends on item characteristics. Our results demonstrate the crucial role of tidal dynamics and bidirectional flows in net plastic transport. With this paper we emphasize the importance of understanding fundamental transport dynamics in tidal rivers and estuaries to ultimately reduce the uncertainties of plastic emission estimates into the ocean.
... As water becomes more saline (and water density increases), particles are more likely to stay suspended within the water column, although this also depends on physical influences such as flow velocity and turbidity. Settling velocity is thus a key parameter used to predict sediment transport pathways, yet no comprehensive study has yet experimentally quantified the combination of these effects (biofilm, salinity and sediment concentration) for microplastics (Supplementary Table 1) 4,22,[28][29][30][31][32][33] . ...
... Experimental set-up. The settling velocity of the microplastic particles was determined through a series of non-intrusive sinking experiments conducted in a Laboratory Spectral Flocculation Characteristics (LabSFLOC) plexiglass column with dimensions of 12 cm × 12 cm × 33 cm (Fig. 5, analogous to previous settling velocity experiments 22,[29][30][31]33,38,[54][55][56] combined with a LED light panel (9 × 7 cm) and high-resolution video camera with a field of view of approximately 13 mm (Fig. 5) that collects particle settling video data that is processed to understand size, shape and velocity of individual particles and flocs (detailed below). This is the first time a LabSFLOC water column has been used for microplastic settling experiments and allows individual particles to be easily analysed for their settling behaviour and aggregation. ...
Rivers are the major conveyor of plastics to the marine environment, but the mechanisms that impact microplastic (<5 mm) aquatic transport, and thus govern fate are largely unknown. This prevents progress in understanding microplastic dynamics and identifying zones of high accumulation, along with taking representative environmental samples and developing effective mitigation measures. Using a suite of settling experiments we show that non-buoyant microplastic settling is influenced by a combination of biofilm growth, water salinity and suspended clay concentrations typically seen across fluvial to marine environments. Results indicate that biofilms significantly increased settling velocity of three different polymer types of non-buoyant microplastics (fragments and fibres, size range 0.02–4.94 mm) by up to 130% and significant increases in settling velocity were observable within hours. Impacts were both polymer and shape specific and settling regimes differed according to both salinity and sediment concentrations. Our results further validate previous statements that existing transport formula are inadequate to capture microplastic settling and highlight the importance of considering the combination of these processes within the next generation of predictive frameworks. This will allow more robust predictions of transport, fate and impact of microplastic pollution within aquatic environments.
... However, i) transport processes in aquatic ecosystems are complex (e.g., coastal circulation patterns, sedimentation processes), and ii) MPs have different physical properties, such as size, shape, density, and buoyancy (Chubarenko et al., 2016;Zhang, 2017). The shape of MPs drives the vertical transport (Chubarenko et al., 2018;Shamskhany et al., 2021), as debris with an irregular shape can be submerged by surface turbulence, while spherical pellets are more resistant to sinking (Ballent et al., 2012). In addition, the large range of MPs densities (0.88-2.80 g cm −3 ; Shamskhany et al., 2021) seems to drive their buoyancy: particles with lower density than seawater float, while those with higher density sink (Andrady, 2011;Cole et al., 2011). ...
Microplastics (MPs) are recognized as a global emergent pollution impact, which can affect all food chains. Estimating MPs transport pathways in coastal ecosystems is needed to assess their likely effects. Here, we studied MPs accumulation and transport pathways in the Estero Urias lagoon system (low-inflow estuary) using field data and a 3D particle model. Field results showed that the MPs present similar abundances throughout the study area during the dry and rainy seasons. Model simulations indicated that i) morphology and tidal currents caused the MPs discharged in the lagoon to remain inside, and ii) wind-induced currents caused the MPs in the coastal area to be transported to the southwest. These transport processes may be responsible for homogenizing MPs concentrations through the studied area. In addition, model simulations suggested that EUL-dense waters can export MPs from the coastal area to the sea bottom.
... Microplastic particles are extremely variable in both their composition and physical form, due to their variable sources and the weathering actions to which they are exposed during all of their existence [41]. They present high heterogeneity in composition and resulting buoyancy behavior, depending on their physical properties, such as particle density, shape, and size [20][21][22]42], directly influencing their transport through any environmental path. Initially, density represents one of the priority factors to be considered when dealing with fluctuation and diffusion through the aqueous medium [41]. ...
... Laboratory simulations performed by some researchers evaluated and tried to correlate plastic microparticles' physical and chemical aspects and their impacts on deposition processes [22,43]. Ballent et al. (2012) [21] experimentally compared the settling speeds of pellets with three different densities, under seawater values. The authors proved that settling velocity increased with higher density most of the time. ...
Microplastic pollution in aquatic ecosystems has drawn attention not only because microplastics are likely to accumulate anywhere but also because they cause negative impacts both to aquatic biota and, indirectly, to public health, as a result of their presence. The understanding of the distribution and accumulation patterns of this “new contaminant” is fundamental for the calibration of environmental risk studies. However, research on its migration pattern and consequent distribution is still limited. The present study has focused on the peculiar physical characteristics of plastic microparticles and the response to environmental factors such as hydrodynamics and physical chemistry of water on the diffusion dynamics of these pollutant agents. Therefore, we examined information about the vertical abundance distribution, the composition, and the sizes of microplastics, along with the varied aquatic environments existing on Earth. This study provides valuable evidence for the accumulation trend of microplastics across the environment and the peculiar particle characteristics that dictate their distribution patterns. The present study concluded that detailed studies should be carried out in order to add information about the behavior of plastic microparticles in aquatic environments and thus subsidize the calibration of existing information, thus increasing its accuracy in understanding the diffusion patterns of these polluting agents.
... Rivers, ocean currents, turbulence (Ballent et al., 2012;Turra et al., 2014;Wagner et al., 2018), surface flows from agricultural areas (Nizzetto et al., 2016), waste water treatment plants (Murphy et al., 2016), wind and erosion (Zalasiewicz et al., 2016) are responsible in the transport of microplastics to different ecosystems. Wind is considered to play a key role in the transportation of microplastics to many different regions of the world. ...
Plastic wastes released into the environment break down into fine particles due to exposure to meteorological events such as wind, precipitation, UV radiation, and abrasion. These smaller plastic particles, ranging between 1 µm and 5 mm, are called microplastics and they can be transported over longer distances with the aid of erosion, waste water discharges, winds, and currents. Aquatic habitats are the final sink for many pollutants including heavy metals, pesticides, nanoparticles, and microplastics released into environment. Thus, these pollutants are considered a major threat to aquatic life. In this study, we reviewed studies i: focusing on the type, size and the quantity of mi-croplastics observed in freshwater and marine ecosystems, and ii: studies on the effects of micro-plastics on aquatic organisms. The data gathered clearly indicates that microplastics are quite abundant in freshwater and marine ecosystems. Furthermore, nearly in all studies reviewed, micro-plastic uptake and alterations in several biochemical parameters depending on microplastic exposure are recorded. The studies also point out that microplastics will become a global serious health concern both for human beings and aquatic organisms in the near future.
... Due to the vastly different shapes and dimensions available and their lightweight and low density, MPs are easily transported and dispersed over long distances on land and within aquatic systems by storm sewers, wind, and other natural currents (Horton and Dixon, 2018). Ballent and colleagues (Ballent et al., 2012) discovered that oddly shaped MPs with uneven geometries and sharp ends are more likely to remain underwater rather than return to the surface, whereas spherical particles are more likely to stay at the surface (Lagarde et al., 2016). The paths through which MPs move through the air are not completely known (Horton and Dixon, 2018). ...
The world has witnessed massive and preeminent microplastics (MPs) pollution in water bodies due to the inevitable continuous production of plastics for various advantageous chemical and mechanical features. Plastic pollution, particularly contamination by MPs (plastic particles having a diameter lesser than 5 mm), has been a rising environmental concern in recent years due to the inappropriate disposal of plastic trash. This study presents the recent advancements in different technologies for MPs removal in order to gain proper insight into their strengths and weaknesses, thereby orchestrating the preparation for innovation in the field. The production, origin, and global complexity of MPs were discussed. This study also reveals MPs' mode of transportation, its feedstock polymers, toxicities, detection techniques, and the conventional removal strategies of MPs from contaminated systems. Modification of conventional methods vis-à-vis new materials/techniques and other emerging technologies, such as magnetic extraction and sol-gel technique with detailed mechanistic information for the removal of MPs are presented in this study. Conclusively, some future research outlooks for advancing the MPs removal technologies/materials for practical realization are highlighted.
... Besides, vertical mixing could also be a significant factor determining the probability of particles hitting each other (McNair et al., 1997). Under turbulent flows where more mixing occurs at higher shear velocities, rapid vertical transport would occur, resulting in a more uniform vertical distribution of particles (Ballent et al., 2012). In this regard, increased mixing and cross-sectional particle exchange would probably delay the downstream transport or detain microparticles (Frei et al., 2019;Haberstroh et al., 2021). ...
Particle tracers are sometimes used to track sources and sinks of riverine particulate and contaminant transport. A potentially new particle tracer is ~200 nm sized superparamagnetic silica encapsulated DNA (SiDNAFe). The main objective of this research was to understand and quantify the settling and aggregation behaviour of SiDNAFe in river waters based on laboratory settling experiments. Our results indicated, that in quiescent conditions, more than 60% of SiDNAFe settled within 30 hours, starting with a rapid settling phase followed by an exponential‐like slow settling phase in the three river waters we used (Meuse, Merkske, and Strijbeek) plus MilliQ water. In suspensions of 1000x higher particle concentrations, the hydrodynamic diameter (Dh‐DLS) of SiDNAFe increased over time, with its polydispersity index (PDI) positively correlated with particle size. From these observations, we inferred that the rapid SiDNAFe settling was mainly due to homo‐aggregation and not due to hetero‐aggregation (e.g., with particulate matter present in river water). Incorporating a first‐order mass loss term which mimics the exponential phase of the settling in quiescent conditions seems to be an adequate step forward when modelling the transport of SiDNAFe in river injection experiments. Furthermore, we validated the applicability of magnetic separation and up‐concentration of SiDNAFe in real river waters, which is an important advantage for carrying out field‐scale SiDNAFe tracing experiments. This article is protected by copyright. All rights reserved.
... This is explained by the settling velocity difference between fragments and fibers. In general, the settling velocity of dense and regular fragments is relatively fast, while that of light and irregular fibers is slow (Ballent et al., 2012;Kowalski et al., 2016;Khatmullina and Isachenko, 2017). ...
Marine microplastics are widely distributed in deep-sea sedimentary environments and are altering sediment compositions and ecological conditions on the seafloor. However, the relation between the distribution of microplastics in deep-sea sediments and the sedimentary dynamic conditions is poorly understood. In this study, we collected surface sediments from some typical geomorphological units (sand dune, sediment drift, and submarine canyon channel/levee) in the northern South China Sea to study composition and distribution of the deep-sea microplastics and their controlling factors. The results show that the microplastic abundance in surface sediments ranges from 19 to 347 p·kg–1, and the identified microplastics consist of 10 types, including dominant polycarbonate (29%), polyethylene (27%), polyester fiber (16%), polyvinyl chloride (13%), and polypropylene (7%), and minor polyethylene terephthalate resin, acrylonitrile-butadiene-styrene, epoxy resin, hydrocarbon resin, and acrylic. The source analysis shows that the deep-sea microplastics may be influenced by riverine inputs from Taiwan and South China. In addition, the microplastic spatial distribution shows that the sand dune and canyon channel contain the highest abundances (136–347 p·kg–1) and more types (4–6 types) of microplastics, which are dominated by relatively high-density polycarbonate or polyvinyl chloride. The canyon levee contains the lowest abundances (19–132 p·kg–1) and less types (1–3 types) of microplastics, which are dominated by relatively low-density polyester fiber or polyethylene. Nevertheless, the microplastic composition of the sediment drift is between those of the canyon channel and the canyon levee. The abundance and polymer type (density) of microplastics all increase with the increased mean grain size of detrital sediments, which represents the progressively enhanced intensity of sedimentary dynamic conditions. We therefore infer that the sedimentary dynamic conditions control the composition and distribution of microplastics in the deep-sea sediments. This study highlights that some deep-sea environments with stronger sedimentary dynamic conditions may accumulate more microplastics, which is of great significance for evaluating the storage and ecological damage of deep-sea microplastics.
... However, not all plastics remain floating at the ocean surface. Under the influence of weathering processes and interactions with organic particles and biota, the physical properties of plastics constantly change which alter their behaviour and transport pathways (Ballent et al., 2012;Coppock et al., 2019;Kaiser et al., 2017;Khatmullina and Chubarenko, 2019;Kvale et al., 2020). Additionally, vertical mixing from wind and turbulence can distribute plastics through the upper ocean (Enders et al., 2015). ...
Plastic pollution has been reported in the North Atlantic Ocean since the 1970s, yet limited data over subsequent decades pose challenges when assessing spatio-temporal trends in relation to global leakages and intervention strategies. This study quantified microplastics within the upper ocean along a longitudinal transect of the North Atlantic and its subtropical gyre. Microplastics were sampled from surface and subsurface (−25 m) water using a manta trawl and NIKSIN bottle respectively. The surface water polymer community varied significantly between geographic positions (‘inshore’, ‘gyre’, ‘open ocean’), and was significantly influenced by fragment quantity. Compared to other positions, the North Atlantic gyre was associated with high concentrations of polyethylene, polypropylene, acrylic and polyamide fragments. Subsurface water was dominated by polyamide and polyester fibres. Backtracked 2-year Lagrangian simulations illustrated connectivity patterns. Continued monitoring of microplastics throughout the water column of the North Atlantic Ocean is required to address knowledge gaps and assess spatio-temporal trends.
... This high concentration of fibers could be related to the higher density of Mediterranean waters (generally >1.026 g cm -3 ), which allows fibers such as polyamides, commonly used in the textile industry and fishing (density between 1.02 and 1.15 g cm -3 ), to remain in the upper layers in higher proportions [15], when compared to other seas [73,74]. Another explanation is related to their shape, as vertical advection velocities are lower for fibrous microplastics than for sheets and other shapes [75], which may contribute to a longer residence time for these fibrous materials, favoring their transport as potential vectors for organisms, including putative pathogens. ...
Microfibers, whether synthetic or natural, have increased dramatically in the environment, becoming the most common type of particles in the ocean, and exposing aquatic organisms to multiple negative impacts. Using an approach combining morphology (scanning electron microscopy-SEM) and molecular taxonomy (High-Throughput DNA Sequencing- HTS), we investigated the bacterial composition from floating microfibers (MFs) collected in the northwestern Mediterranean Sea. The average number of bacteria in 100 μm2 on the surface of a fiber is 8 ± 5.9 cells; by extrapolating it to a whole fiber, this represents 2663 ± 1981 bacteria/fiber. Attached bacterial communities were dominated by Alteromonadales, Rhodobacterales, and Vibrionales, including the potentially human/animal pathogen Vibrio parahaemolyticus. This study reveals a high rate of bacterial colonization on MFs, and shows that these particles can host numerous bacterial species, including putative pathogens. Even if we cannot confirm its pathogenicity based only on the taxonomy, this is the first description of such pathogenic Vibrio living attached to MFs in the Mediterranean Sea. The identification of MFs colonizers is valuable in assessing health risks, as their presence can be a threat to bathing and seafood consumption. Considering that MFs can serve as vector for potentially pathogenic microorganisms and other pollutants throughout the ocean, this type of pollution can have both ecological and economic consequences.
