Fig 5 - uploaded by Laurenz Thomsen
Content may be subject to copyright.
The propagation of a modelled internal wave hourly from 17:00 to 20:00 UTC (a-d, respectively) on 1 October 2011 in the Nazaré Canyon where the vertical distribution of water density, σ T (kg m −3 ), at depths up to 200 m varies rapidly along the canyon axis, particularly at the canyon head. The contour interval for the isopycnal surfaces (black lines) is 0.3 kg m −3 except for the range (27.0-27.1) where the step is 0.5 kg m −3 .
Source publication
With knowledge of typical hydrodynamic behavior of waste plastic material, models predicting the dispersal of benthic plastics from land sources within the ocean are possible. Here we investigated the hydrodynamic behavior (density, settling velocity and resuspension characteristics) of non-buoyant preproduction plastic pellets in the laboratory. F...
Context in source publication
Context 1
... exceptionally strong transport event can be seen in Fig. 3b, where 10 % of pellets were transported out of box 2 on 1 October 2011 of the autumn/winter model run. To analyze the cause of this strong dispersion event, which was identified to occur between 18:00 and 19:00 UTC, we investigated the model input data for several days preceding the event. As wind shear stress could influence pellet trans- port at 262 m depth, wind patterns were analyzed but these did not show any significant change in direction or inten- sity. River discharges have been reported to influence current regimes on the western Iberian margin ( Oliveira et al., 2007;Martín et al., 2011); however, flow data provided by the hy- drometric stations (www.snirh.pt) from the Douro, Mondego and Tagus rivers near the canyon head showed that the con- tribution from those rivers' discharges was not significant during this period. Lastly, the modelled bottom currents in box 2 were analyzed and these showed a consistent pattern in the area during this period, with peak horizontal and verti- cal velocities in the bottom layer. The horizontal and vertical velocity modulus along the canyon axis for the time period between 17:00 and 20:00 UTC on 1 October 2011 is plotted in Fig. 4. Velocities up to 0.3 m s −1 were modelled to oc- cur in the bottom layer in box 2, which are sufficient to sus- pend and transport pellets. Bottom shear velocities near box 2 during this time period were a factor of 3 times higher than those used to suspend HD black pellets during laboratory experimentation (Tables 1 and 3). Considering water den- sity (ρ = 1026.69 kg m −3 ) used in laboratory simulations are similar to modelled water density at box 2 (σ T ∼ 27 kg m −3 ) the shear stresses experienced by the pellets in the model should be comparable to laboratory experimentation. To de- termine whether or not the increased current velocity was an artifact of an internal wave, we plotted the isopycnal surfaces, σ T (kg m −3 ), throughout the water column and along the axis of the canyon, arraying a series of plots for the same time pe- riod on 1 October 2011 (Fig. 5). The propagation of an inter- nal wave with amplitude up to 200 m is visible approaching and breaking within the upper canyon. To further verify that the pellet transport was caused by the passing of the internal wave, we compared the mean isopycnal surfaces and mean velocity modulus along the canyon axis between the 1 Oc- tober and a day during which pellet transport was modelled not to occur: 19 October 2011 (Fig. 6). The increased bottom shear stresses near box 2 at the shelf break coincide with the development of an internal wave at the head of the canyon ( Fig.s 4 and 5). Investigation of the bottom current velocity and isopycnal surfaces on the 1 and 19 October 2011 suggest that mean current velocities are insufficient to induce uni- directional transport of pellets, but amplified current veloci- ties due to large-scale hydrodynamic events, such as internal waves, are ...
Similar publications
Airsoft is a recreational combat sport that originated in Japan in the 1970s and is currently increasing in popularity in the UK. Participants use air or electrically powered weapons to fire small plastic pellets at a controlled pressure. UK law strictly regulates the maximum muzzle velocity and the type of ammunition used in these weapons. A searc...
Fulmars are effective biological indicators of the abundance of floating plastic marine debris. Long-term data reveal high plastic abundance in the southern North Sea, gradually decreasing to the north at increasing distance from population centres, with lowest levels in high-arctic waters. Since the 1980s, pre-production plastic pellets in North S...
As the consumption of coffee increases worldwide, the amount of spent coffee grounds (SCG) is gradually increasing every year. Some of these grounds are recycled for composting, but most are discarded, which causes widespread financial and social costs. We developed a bio-based plastic pellet by blending polypropylene (PP) with waste biomass SCG to...
Citations
... 19 Moreover, the settled MPs, especially the low-density ones, may be partly resuspended and released into wastewater under turbulent mixing. 19,58 Another explanation was that PET was usually in the shape of elongated fibers, which may make it easy to entangle and remove during wastewater treatment. 16,28 Size Distribution of MPs and NPs. Figure 5 shows 60 Pivokonsky et al. also found that MPs of 1−5 and 5−10 μm accounted for 40−60 and 30−40% of the total MPs, respectively. ...
... 61,62 Therefore, large MPs with low density may get resuspended under turbulent mixing while the hetero-aggregation between small particles and activated sludge contributed to their removal in the activated sludge tank. 19,58 Studies also suggested that the short residence time of smaller-sized MPs caused by the fast fragmentation and degradation was another reason for higher removal efficiency in secondary treatment. 19 The tertiary advanced treatment was necessary to reduce MP and NP pollution in the effluent but was not effective in removing small MPs and NPs, which was probably due to the fact that these small particles could pass the sand filter or membrane filtration more easily. ...
The level of microplastics (MPs) in wastewater treatment plants (WWTPs) has been well evaluated by the particle number, while the mass concentration of MPs and especially nanoplastics (NPs) remains unclear. In this study, pyrolysis gas chromatography-mass spectrometry was used to determine the mass concentrations of MPs and NPs with different size ranges (0.01-1, 1-50, and 50-1000 μm) across the whole treatment schemes in two WWTPs. The mass concentrations of total MPs and NPs decreased from 26.23 and 11.28 μg/L in the influent to 1.75 and 0.71 μg/L in the effluent, with removal rates of 93.3 and 93.7% in plants A and B, respectively. The proportions of NPs (0.01-1 μm) were 12.0-17.9 and 5.6-19.5% in plants A and B, respectively, and the removal efficiency of NPs was lower than that of MPs (>1 μm). Based on annual wastewater effluent discharge, it is estimated that about 0.321 and 0.052 tons of MPs and NPs were released into the river each year. Overall, this study investigated the mass concentration of MPs and NPs with a wide size range of 0.01-1000 μm in wastewater, which provided valuable information regarding the pollution level and distribution characteristics of MPs, especially NPs, in WWTPs.
... 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]. ...
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.
... While density separation was used as a means for microplastic extraction during our laboratory analysis, in the field, the density, or salinity, of the surrounding waters may not be the primary influencing factor affecting the sinking or settling rate, and thereby distribution, of microplastics. It has been found that the sinking velocity of microplastics is mostly related to and dependant on particle density, shape and size, as well as the location of the sampling site (Ballent et al., 2013;Kowalski et al., 2016;Lenaker et al., 2019). The same authors cite that sinking rates may also be altered by weathering and biofouling, especially in aged microplastics. ...
Microplastics are widespread in marine ecosystems, where they threaten biota and human wellbeing. Seagrasses may act as natural filters of microplastics due to their particle trapping abilities, yet little is known about the extent of microplastics in the sediment of seagrass beds. The aim of this study was to compare microplastic accumulation in the sediments of Zostera capensis meadows with adjacent bare sediments at a small spatial scale (~5 km) in the Knysna estuary in South Africa. No significant difference in total microplastic counts were found between seagrass and unvegetated sediments. However, fibre microplastic counts differed significantly between the two locations at which samples were collected. This may be due to pollution levels and proximity to larger human population densities. Importantly, our study reveals variability in microplastic abundance and type even at small spatial scales, an important consideration for the design of future studies aiming to monitor for microplastics.
... 미세플라스틱은 미국해양대기청에서 5 mm 이하의 크기 를 갖는 플라스틱 입자로 정의하고 있다 (Arthur et al., 2009 (Sadri and Thompson, 2014;Faure et al., 2015;Klein et al., 2015). (Ballent et al., 2013;Critchell and Lambrechts, 2016 (Dietrich, 1982;Cheng, 1997;Zhiyao et al., 2008) 이러한 연구들에서 입자의 최종침강속도 w s 는 입자의 가속도가 없는 등속운동에서의 최종속도로 정의된 다. 따라서 정지수체에서 가라앉는 작은 크기의 입자들은 연직방향으로 다른 힘이 작용하지 않는다는 가정하에 입자 에 작용하는 항력과 중력이 평형상태를 이룰 때의 하강하는 속도를 최종침강속도로 다음과 같이 정의한다( Fig. 1(a)). ...
Research on the effects of microplastics on water environments is being widely conducted because the discharge of microplastics into the ocean and freshwater systems is rapidly increasing. For the numerical simulation of the transport and diffusion of microplastics introduced into water systems and evaluation of the ecological impacts, the settling velocities of microplastics must be investigated first. The settling behavior of microplastics has been commonly assumed to be similar to that of sediment particles, but this has not been sufficiently verified for various types of microplastic. In this study, a laboratory experiment was performed to measure the settling velocities of spherical microplastic particles in freshwater using a particle tracking technique, and a new calibration coefficient of the settling velocity was proposed based on the experimental data. The experimental results showed a clear linear relationship between the settling velocity and dimensionless particle diameter in the laminar flow region, as suggested by Stokes' law. However, the settling velocities in the transition region had a nonlinear relationship, which was also clearly demonstrated in the relationship between the drag coefficient and the particle Reynolds number. The evaluation of the existing equations for settling velocity showed that previous empirical equations based on experiments on sediment particles produced relative errors of 20% or more. However, the proposed calibration coefficient provided a more accurate prediction of the settling velocities of microplastic particles than the existing empirical equations based on sediment studies.
... Macro and microplastics can eventually accumulate on the seafloor in those areas with low energy conditions (Chiarella and Hernández-Molina, 2021). It was observed that deep-sea currents play a relevant role in the dispersal and concentration of microplastics, in a similar manner to that of surface currents (Ballent et al., 2013;Chubarenko et al., 2018;Kane et al., 2020). It was estimated that the seafloor sediments constitute the major sink for plastic deposition (Thompson et al., 2004;Woodall et al., 2014). ...
... Furthermore, local cleaning operations should be carried out after events that magnify litter inputs, as in the case of storm surges, extreme rainfall, and river flood events (Castro-Jiménez et al., 2019;Chalhoub, 2022). Finally, web mobile app can be integrated with advanced monitoring procedures for plastic monitoring, such as machine learning techniques based on remote sensing data (Scardino et al., 2022;Wolf et al., 2020) or models for plastic distribution and accumulation (Ballent et al., 2013;de Haan et al., 2019;Liubartseva et al., 2018). ...
Plastic pollution is involving large coastal areas of the Mediterranean Sea. Innovative methods of plastic monitoring can be addressed through the citizen science approaches integrated with mobile phones. On the other hand, the availability of mobile phones is increasing among several users. Mobile phones can be integrated with a web mobile app, which allows to collect a lot of data for extended areas and in a short temporal range. In this study, the web service of iNaturalist was applied to implement a mobile phone-based tool to collect pictures of plastic items. At present, the web mobile app has been used to collect pictures of plastic debris in the Medi-terranean Sea. Results were compared with the Mediterranean hydrodynamic regime, to highlight the pathways and densities of the plastic items. The proposed mobile phone-based tool represented a citizen science approach useful for the acquisition of plastic observations in the marine and coastal environment.
... Microplastic transport is a difficult topic as transport includes physical, chemical, and biological processes [6]. Among the various difficulties, it should also be considered that the physical properties (e.g., size, shape, density, buoyancy) of microplastics can vary considerably, influencing their transport [10][11][12]. Their final destination seems to be mainly influenced by the density of the polymers: polymers with a density higher than that of water (>1.027 g/cm 3 ) will tend to settle on the bottom; while low density polymers will tend to float on the water column [6,13]. ...
Deep Sea environments represent the final collector of anthropogenic debris mainly represented by both plastic and non-plastic materials with different size. This led to potential contamination of deep marine fauna due to direct and indirect ingestion, representing a potential hazard for the species itself and for the final consumer. In this framework, the present study explored the occurrence of anthropogenic debris in the gastrointestinal tract of three Decapoda species of high commercial and ecological value (Parapenaeus longirostris, Aristeus antennatus, and Aristaeomorpha foliacea) from south-western Ionian Sea. After morphometrical measurements and sex determination, the gastrointestinal tract of 136 specimens were extracted and then chemically digested. A total of 230 low density microparticles were isolated, with a high frequency of occurrence in all the analyzed species (76% in P. longirostris, 70% in A. antennatus, and 83% in A. foliacea) mainly represented by fibers (92.6%) with a size between 0.10 and 0.49 mm, and with a dominance of the blue color. The results of the present study report for the first time the anthropogenic debris presence in the studied Decapoda from south-western Ionian Sea, highlighting the necessity to broaden the knowledge about anthropogenic debris pollution status in Mediterranean deep-sea species.
... However, density is not the only criteria for polymer distribution within the water column since even low density polymers may be deposited in the sediments. The vertical distribution of microplastics is also dependent on other factors such as temperature, wind, storms, internal waves and the surface to volume ratio (Ballent et al., 2012(Ballent et al., , 2013Sadri and Thompson, 2014;Zhao et al., 2015). Over a period of time the polymer density may change due to particle binding or accumulation of biomass (Lobelle and Cunliffe, 2011;Morét-Ferguson et al., 2010). ...
The authors of the present research aimed to assess microplastics (MPs) contamination in the gills and gut of selected fishes from various aquatic zones and also to bring out the risks of the identified polymers. Accordingly, about 200 fish specimens of 10 different species were collected from the landing center at Parangipettai, southeast coast of India. The fishes were dissected to investigate MPs contamination in their gills and gut. The dissected tissues were acid digested and filtered to observe its microplastic contamination using a stereozoom microscope. In gills, Cynoglossus arel had the least contamination (0.4 ± 0.01 particles/ind) and Mugil cephalus had highest microplastic contamination (1.7 ± 0.01 particles/ind). In gut, C. arel had the minimum contamination (0.7 ± 0.09 particles/ind) and Rastrelliger kanagurta had maximum contamination (2.3 ± 0.26 particles/ind). The size of microplastics isolated from the present study ranged from 100 to 1000 μm. Among microplastic shapes, fibers (97%) and pellets (3%) were observed. About eight colours of microplastics were observed in the fishes among which black was dominant. Three polymers such as LDPE, PP and PS were identified by μFTIR, among which LDPE (57%) was dominant. Polymer Hazard Index denotes that LDPE (6.27), PP (3.4) and PS (2.7) have a PHI score of 1–10 classifying them in the hazard category II which has a medium risk. These polymers may directly enter the human body when consumed and cause health implications which require further investigation.
... To tackle this problem, precisely controllable laboratory environments have to be developed, measuring the impact on the fragmentation rate while only one influence at a time variates without the exclusion of others. The demand for this basic data roots in extrapolations and numerical simulations which model the lifecycle of a plastic object entering an ocean, eventually allowing to balance the amount of hardly detectable nanoplastics (d < 100 nm) in oceans (Ballent et al., 2013;Cózar et al., 2014;Eriksen et al., 2014;Hinata et al., 2017;Hinata et al., 2020;Iwasaki et al., 2017;Kaandorp et al., 2021;Mattsson et al., 2021;Zhang et al., 2020). However, since numerical models improve their accuracy with increasing data points, it is crucial to implement as much data as possible (Chen et al., 2020). ...
Polyurethane (PUR) ether sponges represent a widely-used cleaning tool with a short service lifetime resulting in
the production of high quantities of waste. However, the fate of PUR in natural environments is poorly understood. In this study, sponges were exposed to the natural environments of Danish weather and seawater for two
years. Physiochemical changes were monitored using visual, microscopic, spectroscopic and chromatographic
techniques. Results from Attenuated Total Reflection-Fourier Transform Infrared spectroscopy and change in
mass indicated that photo-oxidation was the primary degradation pathway of polyurethane ether- based sponges
with a specific surface degradation rate of 12,500 μm year− 1 in Danish weather. Significantly, analysis by gas
chromatography-mass spectrometry showed the release to the environment of toxic substance TDI as a product
of photo-oxidation. Although PUR degraded more slowly in seawater than in weather, flame retardant TMCP
leached from sponges to water, indicating potential health risks of PUR waste to aquatic life.
... To tackle this problem, precisely controllable laboratory environments have to be developed, measuring the impact on the fragmentation rate while only one influence at a time variates without the exclusion of others. The demand for this basic data roots in extrapolations and numerical simulations which model the lifecycle of a plastic object entering an ocean, eventually allowing to balance the amount of hardly detectable nanoplastics (d < 100 nm) in oceans (Ballent et al., 2013;Cózar et al., 2014;Eriksen et al., 2014;Hinata et al., 2017;Hinata et al., 2020;Iwasaki et al., 2017;Kaandorp et al., 2021;Mattsson et al., 2021;Zhang et al., 2020). However, since numerical models improve their accuracy with increasing data points, it is crucial to implement as much data as possible (Chen et al., 2020). ...
Polyurethane (PUR) ether sponges represent a widely-used cleaning tool with a short service lifetime resulting in the production of high quantities of waste. However, the fate of PUR in natural environments is poorly understood. In this study, sponges were exposed to the natural environments of Danish weather and seawater for two years. Physiochemical changes were monitored using visual, microscopic, spectroscopic and chromatographic techniques. Results from Attenuated Total Reflection-Fourier Transform Infrared spectroscopy and change in mass indicated that photo-oxidation was the primary degradation pathway of polyurethane ether- based sponges with a specific surface degradation rate of 12,500 μm year−1 in Danish weather. Significantly, analysis by gas chromatography–mass spectrometry showed the release to the environment of toxic substance TDI as a product of photo-oxidation. Although PUR degraded more slowly in seawater than in weather, flame retardant TMCP leached from sponges to water, indicating potential health risks of PUR waste to aquatic life.
... The transport of MP has been studied in aquatic environments using various numerical models such as Lagrangian, two-way particle tracking, PELETS-2D, ARIANE, Lagrangian-Markov chain, MEDSLIK-II oil spill code, Track MPD etc (Yoon et al., 2010;Ballent et al., 2013;Kako et al., 2014;Neumann et al., 2014;Mansui et al., 2015;Liubartseva et al., 2016;Jalón-Rojas et al., 2019). The transport of MP has been studied in the Seine River, Paris (Dris et al., 2015(Dris et al., , 2018, Yangtze River, China (Zhao et al., 2014;Wang et al., 2017;Di and Wang, 2018), Lawrence River, Canada (Crew et al., 2020), Danube River, Austria (Lechner et al., 2014;Pojar et al., 2021). ...
Microplastics, an emerging contaminant, is ubiquitous in almost every compartment of the environment. They are of great environmental concern not only due to their pervasive, persistent, and toxic nature but also due to their ability to act as carriers of toxic metals, microbes, pesticides, etc. Comprehensive knowledge of the transport and degradation pathways of microplastics through water bodies is a prerequisite for identifying critical issues and their effective management. In this review, the basic characteristics and various methods of analysis of microplastics in the aquatic environment is summarized. A detailed discussion of the various physical, chemical and biological mechanisms causing degradation of microplastics is presented. The influencing factors affecting the fate, transport and degradation are summarized. Emphasis has been given to include the influential factors that occur in estuarine systems on the degradation of microplastics. The review is expected to give insight into the current understanding of the fate of microplastics in the aquatic environment and directions for future research in the remediation of microplastics in the aquatic realm.
