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Abstract

Drift of floating debris is studied with a 2D Lagrangian model with stochastic beaching and sedimentation of plastics. An ensemble of >1010 virtual particles is tracked from anthropogenic sources (coastal human populations, rivers, shipping lanes) to environmental destinations (sea surface, coastlines, seabed). Daily analyses of ocean currents and waves provided by CMEMS at a horizontal resolution of 1/16° are used to force the plastics. High spatio-temporal variability in sea-surface plastic concentrations without any stable long-term accumulations is found. Substantial accumulation of plastics is detected on coastlines and the sea bottom. The most contaminated areas are in the Cilician subbasin, Catalan Sea, and near the Po River Delta. Also, highly polluted local patches in the vicinity of sources with limited circulation are identified. An inverse problem solution, used to quantify the origins of plastics, shows that plastic pollution of every Mediterranean country is caused primarily by its own terrestrial sources.

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... The Mediterranean Sea, as an inland sea is containing a significant amount of marine debris and is globally considered to be one of the most affected seas by marine litter (Büyükdeveci and Gündoğdu, 2021;García-Rivera et al., 2017;González-Fernández et al., 2021;Liubartseva et al., 2018;Suaria and Aliani, 2014). The semi-enclosed characters of the Mediterranean Sea and the high spatio-temporal variability of the circulation prevent permanent accumulation areas of microplastics and support the cumulative interaction between floating and beach litter (Mansui et al., 2015;Simon-Sánchez et al., 2022). ...
... The semi-enclosed characters of the Mediterranean Sea and the high spatio-temporal variability of the circulation prevent permanent accumulation areas of microplastics and support the cumulative interaction between floating and beach litter (Mansui et al., 2015;Simon-Sánchez et al., 2022). Especially the Turkish coasts of the Mediterranean Sea are considered the most polluted coasts of the Mediterranean in terms of marine plastic litter (Çevik et al., 2021;Büyükdeveci and Gündoğdu, 2021;Gündoğdu and Çevik, 2017;Gündoğdu et al., 2018;Liubartseva et al., 2018). Previous studies have shown a high number of microplastic pollution for surface waters of Iskenderun Bay (Gündoğdu and Çevik, 2017;Gündoğdu, 2017) and the impact of a high run-off during a flood due to the excess rainfall (Gündoğdu et al., 2018). ...
... The Seyhan and Ceyhan Rivers and connected irrigation canals, and the Orontes (Asi) River are surrounded by urban settlements and different kinds of industrial activities. Thus, they carry a tremendous amount of plastics to the Mediterranean Sea (González-Fernández et al., 2021;Liubartseva et al., 2018). Especially plastic production and recycling facilities localized in Adana city, which is located around Seyhan and Ceyhan River, can be considered the source of microplastic pellets for Northeastern Mediterranean coasts of Turkey. ...
Article
Microplastic pellets were sampled in May and November 2018 during one-week surveys at 13 coastal beaches in Iskenderun Bay/Turkey. Pellet pollution index (PPI) was calculated for the beaches as a tool to assess beach pollution by microplastic pellets. Hydrometeorological conditions, including wind, current, wave, surface run-off, and precipitation, were examined during 2018 to reveal the effect on the transport of microplastic pellets within the study area. Sea-surface heights, including the astronomical tide and the storm surge and the wave runup heights, were also considered in the analysis to study the extent of hydrodynamic forcing on the beach. Hydrometeorological assessments indicated that the pellet concentrations in the coastal zone are mostly related to wind induced transport. Three major river discharges are considered as the main source of microplastic pellets effluents. A Lagrangian particle transport model was conducted to reveal the possible beaching hotspots of microplastic pellets released from these river mouths. Average microplastic pellets were calculated as 126.04 ± 54.08 items/m2 for May 2018 and 70.22 ± 18.25 items/m2 for November 2018. An overall mean PPI for May 2018 was calculated as 1.13, indicating a moderate degree of pellet pollution, and 0.56 for November 2018, indicating a low degree of pellet pollution. The simulations showed that Orontes River effluents affected the inner Iskenderun Bay coasts more than the Seyhan and Ceyhan River.
... Figure 5: Représentation des courants de surfaces régissant la méditerranée (Liubartseva et al.,2018) l'Italie contribuerait au 2/3 de la pollution plastique de la méditerranée (Jambeck et al. 2015;Geyer et al. 2017;Liubartseva et al. 2018). ...
... Figure 5: Représentation des courants de surfaces régissant la méditerranée (Liubartseva et al.,2018) l'Italie contribuerait au 2/3 de la pollution plastique de la méditerranée (Jambeck et al. 2015;Geyer et al. 2017;Liubartseva et al. 2018). ...
... Les plastiques tels que les bouteilles et les emballages sont quant à eux trouvés en majorité aux abords des côtes (zone littorale). On estime que plus de 75 % des plastiques flottants résident dans les 50 km des eaux côtières (Liubartseva et al. 2018) (Fig.5). Les plastiques benthiques sont aussi largement trouvés en mer Méditerranée (Liubartseva et al. 2018;Gerigny et al. 2019), concentrés eux aussi dans les zones côtières (30% des plastiques). ...
Thesis
De nos jours, les déchets plastiques ont envahi l’ensemble des écosystèmes marins du monde en n’épargnant aucune zone. La demande mondiale de plastique ne cesse de croitre d’année en année, malgré l’impact dramatique qu’il provoque sur l’environnement lorsqu’il est laissé dans la nature. On estime que chaque année entre 4.8 et 12.7 millions de tonnes de plastiques finissent dans les océans. Les travaux de cette thèse s’inscrivent dans le cadre de cette urgence environnementale, en permettant de mieux identifier les biofilms bactériens attachés aux différents plastiques (« plastisphère) et de mieux caractériser le phénomène de biodégradation de certains polymères en milieu marin. Dans un premier temps, l’analyse d’échantillons prélevés pendant deux expéditions (l’expédition Tara-Méditerranée et Tara-Pacifique) ont permis de caractériser la biogéographie des biofilms bactériens spécifiques des plastiques. Cette comparaison a permis de mettre en évidence une niche écologique à la surface des plastiques distincte de l’eau environnante, nettement influencé par la géographie, expliqué principalement par la température. L’étude taxonomique a permis de mettre en évidence un « core microbiome », dominé par un genre de cyanobactérie (Rivularia sp.) et des familles connues (Rhodobacteraceae et Flavobacteraceae) comme étant colonisateurs de plastique en milieu marin. Dans un second temps, la colonisation bactérienne sur différents polymères a été étudiée grâce à des aquariums en circuit ouvert sur la baie de Banyuls. Le processus de biodégradation a été étudié en milieu artificiel sans source de carbone que le polymère, imitant l’environnement marin et en suivant plusieurs paramètres expérimentaux. Dans notre étude aucune spécificité des communautés microbiennes liées à la nature des polymères a été observée pendant la phase de croissance du biofilm. Le processus de biodégradation à pu être mis en évidence sur certains polymères tels que le PHBV, Bioplast, Mater-Bi et la cellulose grâce notamment à une activité bactérienne maintenue tout au long de l’incubation. Dans un troisième temps, une souche provenant du biofilm mature du PHBV a pu être isolée pour étudier spécifiquement son processus de biodégradation. L’analyse du génome d’Alteromonas sp., a révélé la présence de 4 dépolymérases dont 3 externes et 1 interne, expliquant sa capacité à dégrader le PHBV. L’étude du génome a aussi permis de mettre en évidence deux voies de synthèse des PHA l’une permettant la synthèse de PHASCL et l’autre de PHAMCL. Enfin, l’étude de la biodégradation du PHBV par un consortium naturel a été approfondi grâce à un marquage isotopique du polymère. Cette nouvelle expérimentation couplée à une analyse métagénomique a permis d’étudier des communautés fonctionnelles pouvant assimiler le carbone du polymère. Les travaux menés durant cette thèse permettent de mieux identifier les biofilms bactériens se développant à la surface de polymères biodégradables et non dégradables, et également d'affiner la caractérisation du processus de biodégradation en milieu marin grâce à l'utilisation de différents paramètres tels que la production bactérienne, la respiration, la perte de poids, le suivi de l’assimilation du carbone marqué ou l’imagerie en microscopie. Ces études sont primordiales pour mieux comprendre le processus de biodégradation des plastiques en mer et ainsi proposer des adaptations aux normes de standardisations régissant l’environnement marin et actuellement peu représentative.
... In particular, the provisions of the MSFD Descriptor 10 and Ecological Indicator 10, respectively, aim to protect the marine ecosystems against harm caused by the emerging issue of plastic litter. As highlighted by several ocean circulation models (Fossi et al., 2017Liubartseva et al., 2018;Mansui et al., 2015;Politikos et al., 2020), the Mediterranean Sea has been considered a sensitive plastic litter accumulation zone with an average concentration comparable to the great oceanic gyres (Cózar et al., 2015;Suaria et al., 2016;UNEP/ MAP, 2015). Mainly due to the limited exchange of surface waters with the Atlantic Ocean, and intensive land-and marine-based sources of pollution significant amounts of marine litter enter and accumulate in this basin. ...
... Considering the other studies, the heterogeneity of the data could be attributed to different inputs from the coasts or to retention, vertical distribution, sedimentation and processes due to coastal currents (Zeri et al., 2018). As confirmed by several plastic distribution models, the Mediterranean Sea is not uniformly affected by human impacts, which, in combination with the seasonal formation of fronts, eddies and accumulation areas, can influence the presence and distribution of microplastics (Fossi et al., 2017;Liubartseva et al., 2018;Mansui et al., 2015;Ourmieres et al., 2018;Zambianchi et al., 2017). In this respect, the highest concentrations presented in Table 1 seem to correspond to the most critical and affected areas highlighted by these models. ...
... Characterized by local patterns of plastic distribution and limited sea circulation, this coastal stretch seems to be affected by the temporary formation of hot-spot accumulation areas (i.e. Gulf of Naples) and moderate fluxes of stranding beaching particles of 8.2 and 2.6 kg (km day − 1 ), respectively (Liubartseva et al., 2018). ...
Article
Full-text available
Plastic pollution in the Mediterranean Sea has been widely reported, but its impact on biodiversity has not been fully explored. Simultaneous sampling of microplastics (MP) with a manta net and surveys of large marine vertebrates were conducted along the coastal waters of Sicily (Western Ionian Sea). A total of 17 neustonic samples have been collected and 17 marine species (cetaceans, sea turtles, seabirds, and fish) have been sighted in the target area. Kernel density estimation was evaluated to highlight a possible overlap between the presence of large marine fauna and MP densities to provide a preliminary risk assessment. The highest biodiversity and MP concentration (0.197 ± 0.130 items/m²) were observed in the southernmost part of the studied area. The overlap between biodiversity hotspots and the occurrence of MP, potential contribute to the identification of sensitive areas of exposure in a poorly studied region.
... However, given the pros and cons of both Eulerian and Lagrangian approaches, they can be employed to complement each other. The particle-tracking model coupled with the hydrodynamic model can provide invaluable details about the potential trajectories of plastic litter from local [81][82][83] to global scales [70] that lead to the assessment of microplastics' transportation, distribution, residence time, and fate under various conditions [58,67,70,[84][85][86][87]. ...
... Moreover, some physical properties of microplastics, including shape, size, and density, which are dominant factors related to microplastics' buoyancy and mobility [59,[94][95][96], have not been parameterized in some numerical models. Furthermore, most of the aforementioned models use a 2D approach, neglect the dynamic behavior of microplastics, and only model marine debris neutral drifting within the surface layers [70,[84][85][86][87]93]. ...
... D-WAQ PART-TrackMPD [87] 17 ...
Article
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Microplastics pollution has led to irreversible environmental consequences and has triggered global concerns. It has been shown that water resources and marine food consumers are adversely affected by microplastics due to their physico-chemical characteristics. This study attempts to comprehensively review the structure of four well-known Lagrangian particle-tracking models, i.e., Delft3D—Water Quality Particle tracking module (D-WAQ PART), Ichthyoplankton (Ichthyop), Track Marine Plastic Debris (TrackMPD), and Canadian Microplastic Simulation (CaMPSim-3D) in simulating the fate and transport of microplastics. Accordingly, the structure of each model is investigated with respect to addressing the involved physical transport processes (including advection, diffusion, windage, beaching, and washing-off) and transformation processes (particularly biofouling and degradation) that play key roles in microplastics’ behavior in the marine environment. In addition, the effects of the physical properties (mainly size, diameter, and shape) of microplastics on their fate and trajectories are reviewed. The models’ capabilities and shortcomings in the simulation of microplastics are also discussed. The present review sheds light on some aspects of microplastics’ behavior in water that were not properly addressed in particle-tracking models, such as homo- and hetero-aggregation, agglomeration, photodegradation, and chemical and biological degradation as well as additional advection due to wave-induced drift. This study can be regarded as a reliable steppingstone for the future modification of the reviewed models.
... The Eastern Mediterranean basin is the most contaminated zone due to the trapping of plastic particles, the high coastal population density, and waste generation (Lots et al., 2017). According to Liubartseva et al. (2018), the excessive anthropogenic inputs with the weak offshore transport of plastics in the Levantine basin (from Alexandria of Egypt to Cilicia in Turkey) resulted in persistent plastic pollution. Approximate fluxes of 10-30 kg (km day) −1 were estimated in the coastal areas of Egypt, Israel, Lebanon, Syria, and Turkey (Liubartseva et al., 2018). ...
... According to Liubartseva et al. (2018), the excessive anthropogenic inputs with the weak offshore transport of plastics in the Levantine basin (from Alexandria of Egypt to Cilicia in Turkey) resulted in persistent plastic pollution. Approximate fluxes of 10-30 kg (km day) −1 were estimated in the coastal areas of Egypt, Israel, Lebanon, Syria, and Turkey (Liubartseva et al., 2018). Alexandria was estimated to be a significant contributor of plastic litter inputs into the Mediterranean Sea, with input intensity of 2209 tons per year representing 2.2%, followed by Barcelona (1.8%) and Izmir (1.6%) (Liubartseva et al., 2018). ...
... Approximate fluxes of 10-30 kg (km day) −1 were estimated in the coastal areas of Egypt, Israel, Lebanon, Syria, and Turkey (Liubartseva et al., 2018). Alexandria was estimated to be a significant contributor of plastic litter inputs into the Mediterranean Sea, with input intensity of 2209 tons per year representing 2.2%, followed by Barcelona (1.8%) and Izmir (1.6%) (Liubartseva et al., 2018). ...
Article
Microplastics (MPs) contamination has become a global concern with potential impacts on the marine environment. Alexandria is the second-largest city in Egypt and a significant contributor of plastic litter inputs into the Eastern Mediterranean Sea. The current study provides an in-depth analysis of the plastic particles accumulated along Alexandria beaches. Types, composition, and potential sources of MPs were investigated using microscopy and thermal analysis. A mean value of 389.1 ± 285.9 items kg−1 dry weight was detected in the shore sediments similar to other records from the Eastern Mediterranean region. An average of 457.4 ± 281.8 items m−3 was recorded in the surface water, which was the highest recorded MPs density in onshore waters of the Mediterranean region. Thermogravimetric analysis (TGA) showed that plastics made up 0.5% - 72% of the materials extracted from the sediment samples, and 0.58% - 20.6% from the water samples. Differential scanning calorimetry (DSC) identified ten semi-crystalline polymers. Low-density polyethylene (LDPE) and polyethylene vinyl acetate (PEVA) were the common polymers. The single-use plastic bags and detergents were the land-based sources of marine plastic litter. The sea-based sources included antifouling paints, maintenance of ships, and abandoned fishing gears. Proper management plans of domestic waste input, polluter-pay strategy, and education programs aiming at the fishermen and how plastic pollution would impact their livelihood are urgently needed.
... models of drift and transport of floating marine debris have proposed areas of seasonal plastic accumulation mainly related to proximity to sources such as large cities and rivers (Liubartseva et al., 2018;Mansui et al., 2015;Zambianchi et al., 2017), inconsistencies exist between these models and field data, in part due to poor sampling coverage of the basin (Cózar et al., 2015;Paper et al., 2016;Ruiz-Orejón et al., 2016). ...
... This combination allowed us to consider the geostrophic component, the Ekman effect, and the Stokes drift, which implicitly considers the windage effect. This choice is supported by recent Lagrangian models built specifically for the Mediterranean basin considering the importance of the effect of Stokes drift in plastic debris transport (Baudena et al., 2022;Liubartseva et al., 2018). Backward advection was computed with a 4 th order Runge-Kutta scheme, with a time step of 0.5 hours. ...
... Therefore, we consider them separately, in agreement with previous studies (Baudena et al., 2022;Liubartseva et al., 2018). Usually, city and river relative contribution to the total flux of plastic entering the oceans is estimated to be p c =40% and p r =40 % respectively (Lebreton et al., 2012;Li et al., 2016) while the rest (20%) is expected to originate from ships. ...
Article
The Mediterranean Sea is recognized as one of the most polluted areas by floating plastics. During the Tara Mediterranean expedition, an extensive sampling of plastic debris was conducted in seven ecoregions, from Gibraltar to Lebanon with the aim of providing reliable estimates of regional differences in floating plastic loads and plastic characteristics. The abundance, size, surface, circularity and mass of 75,030 pieces were analyzed and classified in a standardized multi-parameter database. Their average abundance was 2.60 × 10⁵ items km⁻² (2.25 × 10³ to 8.50 × 10⁶ km⁻²) resulting in an estimate of about 650 billion plastic particles floating on the surface of the Mediterranean. This corresponds to an average of 660 metric tons of plastic, at the lower end of literature estimates. High concentrations of plastic were observed in the northwestern coastal regions, north of the Tyrrhenian Sea, but also off the western and central Mediterranean basins. The Levantine basin south of Cyprus had the lowest concentrations. A Lagrangian Plastic Pollution Index (LPPI) predicting the concentration of plastic debris was validated using the spatial resolution of the data. The advanced state of plastic degradation detected in the analyses led to the conclusion that stranding/fragmentation/resuspension suggests it is a key process in the dynamics of floating plastic in Mediterranean surface waters. This is supported by the significant correlation between pollution sources and areas of high plastic concentration obtained by the LPPI.
... The Mediterranean Sea is very vulnerable to possible accumulations of floating plastics due to constant surface flow of water from the Atlantic by the Atlantic water current (Zambianchi et al., 2017). Surface plastic concentrations are high, variable in space and time, without stable long-term accumulations in Mediterranean Sea (Mansui et al., 2015;Zambianchi et al., 2017;Liubartseva et al., 2018) but with substantial accumulations on coastlines and sea bottom (Liubartseva et al., 2018). The most contaminated areas were identified in the Cilician subbasin and Levantine coast, Catalan Sea, and near the Po River Delta and Venice Lagoon (Liubartseva et al., 2018) and in the Tyrrhenian Sea, the north-western Mediterranean subbasin and the Gulf of Sirte (Mansui et al., 2015). ...
... The Mediterranean Sea is very vulnerable to possible accumulations of floating plastics due to constant surface flow of water from the Atlantic by the Atlantic water current (Zambianchi et al., 2017). Surface plastic concentrations are high, variable in space and time, without stable long-term accumulations in Mediterranean Sea (Mansui et al., 2015;Zambianchi et al., 2017;Liubartseva et al., 2018) but with substantial accumulations on coastlines and sea bottom (Liubartseva et al., 2018). The most contaminated areas were identified in the Cilician subbasin and Levantine coast, Catalan Sea, and near the Po River Delta and Venice Lagoon (Liubartseva et al., 2018) and in the Tyrrhenian Sea, the north-western Mediterranean subbasin and the Gulf of Sirte (Mansui et al., 2015). ...
... Surface plastic concentrations are high, variable in space and time, without stable long-term accumulations in Mediterranean Sea (Mansui et al., 2015;Zambianchi et al., 2017;Liubartseva et al., 2018) but with substantial accumulations on coastlines and sea bottom (Liubartseva et al., 2018). The most contaminated areas were identified in the Cilician subbasin and Levantine coast, Catalan Sea, and near the Po River Delta and Venice Lagoon (Liubartseva et al., 2018) and in the Tyrrhenian Sea, the north-western Mediterranean subbasin and the Gulf of Sirte (Mansui et al., 2015). The Northern current is responsible for the accumulations on the sea surface of the Catalan Sea and beaching of plastics in the area of Balearic Islands. ...
Chapter
An overview of the contamination of the Mediterranean marine environment with microplastics (MPs) is presented. At the sea surface various concentrations of MPs have been detected, which sometimes also coincide with modelling studies. The contamination of subtidal sediments ranges from few tens to few hundreds items per kilogram dry weight, with hotspots - few thousands items per kilogram in the deep Tyrrhenian Sea, in the lagoon of Venice and in Posidoinia oceanica meadow adjacent to agricultural hinterland in Spain. Polyethylene and polypropylene were most abundant material in both seawater and sediments, while fragments and filaments were the most frequently found shapes. Photodegradation is the main degradation driver, while biofouling has an important effect on microplastic sinking. Marine biota facilitate the sinking of MPs, the horizontal transport on the seafloor and burial in the sediments.
... Despite an important spatial and temporal variability, highest microplastic concentrations are found to be near the more densely populated coastlines (Pedrotti et al., 2016). Statistical calculations have estimated that more than 75% of floating plastics reside in the 50 km near-shore waters (Liubartseva et al., 2018). Moreover, a segregation of plastic types with increasing distance to shore has been observed (Pedrotti et al., 2016). ...
... <65% of PE). These MPs can come from four main sources: rivers, cities, maritime traffic and sea currents (Liubartseva et al., 2018;Soto-Navarro et al., 2020) (Fig. 8). There are currently no data for the Italian rivers flowing into the Tyrrhenian Sea. ...
... Furthermore, the relatively high average size and mass of the MPs collected in the north of the Tyrrhenian Sea can possibly be interpreted as an indication of a source of microplastic relatively close to the sampling areas. Cities such as Rome, Naples or Livorno are other potential important sources of MPs (Liubartseva et al., 2018;Soto-Navarro et al., 2020). However, data are very scarce in the case of Mediterranean cities and, more generally, in the case of this kind of proximal sources that therefore need to be better studied (de Haan et al., 2019). ...
Article
The Mediterranean Sea is one of the most studied regions in the world in terms of microplastic (MP) contamination. However, only a few studies have analysed the chemical composition of MPs at the Mediterranean Sea surface. In this context, this study aims to describe the chemical composition as a function of particle size, mass and number concentrations of MPs collected in the surface waters of the Mediterranean Sea. The chemical composition showed a certain homogeneity at the Mediterranean Sea scale. The main polymers identified by Fourier Transform Infra-Red (FTIR) spectroscopy were poly(ethylene) (67.3 ± 2.4%), poly(propylene) (20.8 ± 2.1%) and poly(styrene) (3.0 ± 0.9%). Nevertheless, discrepancies, confirmed by the literature, were observed at a mesoscale level. Thus, in the North Tyrrhenian Sea, the proportion of poly(ethylene) was significantly lower than the average value of the Mediterranean Sea (57.9 ± 10.5%). Anthropic sources, rivers, or polymer ageing are assumed to be responsible for the variations observed.
... Here we link microplastic pollution on the seafloor to bottom currents by integrating high-resolution geophysical data, sediment sampling, microplastics analysis and numerical modeling. The Tyrrhenian Sea was selected for the study area because: (i) the dimensions and grain size of physiographic elements are broadly comparable to many global settings (29)(30)(31)(32), (ii) ocean circulation patterns and velocities are comparable to currents globally (31,33), (iii) plastic input volumes and locations are well-constrained (34), and (iv) high ...
... Previous Lagrangian modeling of microplastic transport in the Mediterranean [based on a model used to describe global microplastic distributions (3)] suggests that waves and sea surface currents ought to transport microplastics away from the Tyrrhenian Sea (34). Therefore, the bottom plastic flux (assuming vertical settling only) in this basin should be one of the lowest: 1.5 to 7 g km −2 day −1 , compared to a regional maximum of 70 g km −2 day −1 elsewhere in the Mediterranean (Fig. 1A). ...
... If that modeling is correct, microplastic abundances elsewhere in the Mediterranean may be even higher than the values we report here. We suggest however, that bottom currents, as well as surface currents are important for the concentration of microplastics, yet near-bed bottom current circulation is omitted from existing models (2,3,8,34). Ocean currents appear to be highly capable of diverting microplastics from shallow to deep water and may be responsible for entraining microplastics transported down-slope via submarine channels linked to terrestrial sources (Fig. 5). ...
... It has been previously suggested that microplastics might be trapped inside harbors due to their enclosed geometry and this hypothesis can be extended to large lagoon basins, such as those of the northern Adriatic Sea [51][52][53]. Moreover following the "boomerang effect" conceptual model proposed by Liubartseva et al. (2018) [54], the microplastic source may be local for about 50% of the polymers found. ...
... It has been previously suggested that microplastics might be trapped inside harbors due to their enclosed geometry and this hypothesis can be extended to large lagoon basins, such as those of the northern Adriatic Sea [51][52][53]. Moreover following the "boomerang effect" conceptual model proposed by Liubartseva et al. (2018) [54], the microplastic source may be local for about 50% of the polymers found. ...
Article
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Marine macrophytes are hypothesized to be a major temporary sink for microplastics. In this study, microplastic contamination was investigated in 15 macroalgal species and one seagrass from different sites in two lagoons of the northern Adriatic Sea: the Goro lagoon and the Venice lagoon. A high percentage (94%) of the macrophyte samples contained microplastics, ranging from 0.16 to 330 items g−1 fw, with the prevalent size in the range 30–90 µm and an average contamination per unit of fresh weight of 14 items g−1 fw. Microplastic contamination displayed a site-specific, rather than a species-specific, pattern of accumulation. In addition, exopolysaccharides (EPS) displayed a significant positive correlation with the microplastics ononcontamination on macrophytes acting as glue for the plastic particles available in the water column.
... Models for the global distribution of total plastic waste have been produced with focuses ranging from estimating accumulation zones for buoyant plastic waste in global oceans, such as in the model created by Lebreton et al. (Lebreton and Andrady, 2019), to the modelling done by Ryberg et al. which encompassed tracking the full life cycle of plastic products (Ryberg et al., 2019), to studies focused on plastic waste in terrestrial environments . Additional works have focused on the modelling of plastic waste within spatially limited marine systems such as the Mediterranean Sea (Liubartseva et al., 2018) and modelling the distribution of plastic particles specifically within the micro-size range, either within global oceans (Mountford and Morales Maqueda, 2019) or freshwater systems (Daily and Hoffman, 2020), has also been attempted. The fundamental basis for these models often includes considerations for environmental factors (e.g. ...
... General understanding is further enhanced through the creation of models focused on ranking the weathering of particles composed of various polymer types based on their physico-chemical properties such as density and transition temperatures . Approaches utilized to build the models range from computational fluid dynamic modelling such as Lagrangian (Liubartseva et al., 2018;Daily and Hoffman, 2020) (i.e. particles within the system are a discrete phase (Zhang and Chen, 2007)) or Eulerian (Mountford and Morales Maqueda, 2019) (i.e. ...
Article
Plastic particle pollution has been shown to be almost completely ubiquitous within our surrounding environment. This ubiquity in combination with a variety of unique properties (e.g. density, hydrophobicity, surface functionalization, particle shape and size, transition temperatures, and mechanical properties) and the ever-increasing levels of plastic production and use has begun to garner heightened levels of interest within the scientific community. However, as a result of these properties, plastic particles are often reported to be challenging to study in complex (i.e. real) environments. Therefore, this review aims to summarize research generated on multiple facets of the micro- and nanoplastics field; ranging from size and shape definitions to detection and characterization techniques to generating reference particles; in order to provide a more complete understanding of the current strategies for the analysis of plastic particles. This information is then used to provide generalized recommendations for researchers to consider as they attempt to study plastics in analytically complex environments; including method validation using reference particles obtained via the presented creation methods, encouraging efforts towards method standardization through the reporting of all technical details utilized in a study, and providing analytical pathway recommendations depending upon the exact knowledge desired and samples being studied.
... In this area, human activities, including industry, fishing, agriculture, and domestic waters, are likely to play a major role as MPs input (Fourati et al., 2018). In that regard, Liubasteva et al. (2018) have demonstrated by an exhaustive numerical modeling study that plastic emissions from Tunisia contribute more than 80% of their own coastline plastic pollution, defined as a "boomerang effect" (Liubasteva et al., 2018). The approach used in this study to investigate the influence of hydrodynamics in the spatial distribution of MPs has been already applied in several studies and has given satisfactory results in terms of identifying potential areas of floating particles accumulation and their dispersion in the Mediterranean Sea (Macias et al., 2019) and in the Black Sea (Miladinova et al., 2020). ...
... In this area, human activities, including industry, fishing, agriculture, and domestic waters, are likely to play a major role as MPs input (Fourati et al., 2018). In that regard, Liubasteva et al. (2018) have demonstrated by an exhaustive numerical modeling study that plastic emissions from Tunisia contribute more than 80% of their own coastline plastic pollution, defined as a "boomerang effect" (Liubasteva et al., 2018). The approach used in this study to investigate the influence of hydrodynamics in the spatial distribution of MPs has been already applied in several studies and has given satisfactory results in terms of identifying potential areas of floating particles accumulation and their dispersion in the Mediterranean Sea (Macias et al., 2019) and in the Black Sea (Miladinova et al., 2020). ...
Article
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Marine plastic pollution represents a major problem owing to its increasing presence in the environment, persistence and ability to spread in every compartment in the form of small plastic particles, namely microplastics (MPs). Studies concerning MPs abundance in the Mediterranean Sea are growing, but their occurrence in the Southern regions remains largely unexplored. In this study, distribution, abundance, size, and polymer type of microplastics were investigated in surface water samples collected with a Manta net (200 μm mesh size) and in 118 marine specimens of commercial interests, including fishes, crustaceans, and mollusks, during Spring and Autumn 2019 EU H2020 Claim Project sampling Campaigns in the Gulf of Gabes (Southern Mediterranean Sea). Laboratory characterization showed significant plastic pollution concentrations, with an average abundance of 312,887 and 77,110 items/km ² in surface water samples collected in Spring and Autumn, respectively. A 3D hydrodynamic and Tracking Model was used to identify dispersal and transport pathways of the floating plastics, reporting a seasonal variability observed in MPs distribution between I (Spring) and II Campaign (Autumn). Despite the high values of MPs abundance found in surface water samples, an overall low frequency of ingestion among studied species was observed, with a maximum value of 20% of individuals (in Scomber scombrus ) found with ingested MPs. The present study contributes to expand our state of knowledge regarding MPs pollution level in water and biota samples collected in the Gulf of Gabes, an area of particular interest for its biological resources, but still little investigated.
... Lobelle et al (2021) and/or aggregation in marine snow (Kvale et al 2020). It was parameterized by attributing to each particle a transport duration randomly extracted from an exponential distribution with an average of 50 days (Liubartseva et al 2018) and not exceeding 250 days. This resulted in a median particle sinking time of 34 days, a value coherent with the results by Fazey and Ryan (2016) and Lobelle et al (2021). ...
... New particles were released daily from significant sources of marine plastic pollution, of either landbased origin, as coastlines (Jambeck et al 2015) and rivers (Lebreton et al 2017, Boucher andBillard 2020), or offshore origin, namely fishing grounds (Ocean Conservancy 2011). We tracked around 100 million particles per year, assigned to each specific source by adopting the 50:30:20 coasts-to-rivers-to-ships ratio proposed by Liubartseva et al (2018). We further modulated in space and time the release of particles from each source point by adopting data-informed, source-specific proxies, as briefly detailed below (see also SM, section S1). ...
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The pervasiveness of microplastics in global oceans is raising concern about their impacts on organisms. While quantifying their toxicity is still an open issue, sampling evidence has shown that rarely are marine microplastics found clean; rather, they are often contaminated by other types of chemical pollutants, some known to be harmful to biota and humans. To provide a first tool for assessing the role of microplastics as vectors of plastic-related organic pollutants (PROPs), we developed a data-informed simulation model that accounts for the intertwined dynamics of Lagrangian microplastic particles transported by surface currents and the Eulerian advection-diffusion of pollutants that partition on them through seawater-particle interaction. Focusing on the Mediterranean Sea and using simple, yet realistic forcings for the input of PROPs, our simulations highlight that microplastics can mediate the export of PROPs across different marine regions. Particle origin, in terms of both source type (either coastal, riverine, or fishing-derived) and geographical location, plays a major role in determining the amount of PROPs conveyed by microplastics during their journey at sea. We argue that quantitative numerical modelling approaches can be focal to shed some light on the vast spatiotemporal scales of microplastics-PROPs interaction, complementary to much-needed field investigation.
... In this study, the majority of microplastics were found along the northern Levantine coast which is characterized by a large number of cities and rivers which potentially can generate important inputs of marine debris to the Mediterranean Sea (Liubartseva et al., 2018). Previous studies have already demonstrated that locations closer to large ...
Article
The abundance of microplastics items (debris particles of less than 5 mm) along the sea surface and in seafloor sediments have been extensively documented worldwide; however, little is known in terms of the vertical distribution of microplastics in the water column, especially in the epipelagic zone. Considering the biological importance of this area, the quantification of microplastics available here is essential to identify potential impacts for marine organisms. This study reports the vertical distribution of microplastic abundances throughout the water column in two Marine Strategy Framework Directive (MSFD) demarcations from the western Mediterranean Sea during July 2019. Three concatenated 5-L Niskin bottles were used for sampling at 5, 15 and 25 meters from the sea surface in stations with a total depth smaller than 50 meters and at 5, 25 and 50 meters from the sea surface in stations with a total depth greater than 50 meters. This study demonstrates the ubiquitous abundance of microfibers, 96% of the microplastic items identified, in the upper epipelagic layer of the western Mediterranean Sea. Microplastics exhibit a heterogeneous vertical and horizontal spatial distribution. Fragments had a very low representation (4% of the items) but showed a similar frequency of occurrence along all sampling depths. In terms of size, 68% of the microplastics were less than 2 millimeters in length. Microplastics quantified within the study area were mainly composed of low-density polyethylene (LDPE) and polypropylene (PP) (20% each) followed by cellulose acetate (CA) (16%) and polyestyrene (PS) (14%). Regarding the spatial distribution of microplastics, higher abundances were found at intermediate distances (5–10 km from the coast) with mean values of 2.41 ± 1.90 items L⁻¹ and further away (>20 km) from the coast, with mean values of 2.11 ± 1.80 items L⁻¹. A slight decreasing trend in the abundances of microplastics from the sub-surface to deeper waters was also observed. Stations within MPAs waters showed no significant differences in microplastic abundances when comparing to non-MPAs stations. Overall, the results of this study highlight the ubiquitous presence of microplastics, primarily microfibers, along the epipelagic layer of the Spanish Mediterranean continental shelf.
... With regard to biofouling, given the absence of experimental data, particularly on the size dependence of biofilm growth on microplastics, the adopted parameterization could not be directly validated. Still, the description of biofouling in Tsiaras et al. (2021) is among the most explicit, compared to other plastic dispersion models for the Mediterranean Sea (e.g., Liubartseva et al., 2018;Kaandorp et al., 2020;Soto-Navarro et al., 2020;Guerrini et al., 2021). ...
Article
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Micro- and macro-plastics pollution is a growing threat for marine biodiversity, ecosystem functioning, and consequently human wellbeing. Numerical models that consider main sources of plastics and simulate their dispersal characteristics are unique tools for exploring plastic pollution in marine protected areas (MPAs). Here, we used a Lagrangian plastic drift model, taking into account various sizes/types of plastic litter, originating from major land-based sources (coastal cities and rivers), to predict plastic accumulation zones in protected areas of the Mediterranean Sea (i.e., nationally designated MPAs, Natura 2000 sites, and Cetacean Critical Habitats). The model predicted that the size of plastic litters plays a key role in their dispersion and ultimate destination (i.e., larger litter travel longer distances). Most of the studied Mediterranean countries (13 out of 15) had at least one national MPA with over 55% of macroplastics originating from sources beyond their borders. Consequently, in many cases, local efforts to reduce plastic pollution in protected areas would be insufficient, especially for macroplastics management. Transboundary collaboration among Mediterranean countries is critical for implementing successful management plans against plastic pollution in their territorial waters and specifically in MPAs.
... This interaction is especially weak in the northern coast of Cyprus (Hetch et al. 1988;Alhammoud et al., 2005;Duncan et al., 2018). Lagrangian models further confirm this theory, suggesting that the Levantine Basin do tends to accumulate litter in the long-term (Lebreton et al., 2012;Sebille et al., 2015;Zambiachi et al., 2017;Liubarsteva et al., 2018;Mansui et al., 2020) and that western Mediterraenan coasts tend to be free of this phenomenon due to stronger currents that either tend to accumulate litter in specific areas or scatter it depending on the region (Mansui et al., 2015). Studying sea currents and winds could be the key to understand why there is differential deposition in different areas and to take measures accordingly. ...
Article
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We studied microdebris in three western Mediterranean beaches in East Spain. One of them is urban, while the other two are located in a protected environment. Moreover, one of them is used as hatchery for loggerhead turtles’ (Caretta caretta) sporadic nesting activity. Here, we discuss the amount and type of microdebris in the area in different seasons, as well as at the surface and at 40 cm depth, were loggerhead turtles lay their nests. Total mean ± SD in July was 5.66 ± 3.66 MPs/kg at surface and 12.15 ± 7.76 MPs/kg at depth; while in November values were 6.45 ± 4.42 MPs/kg at surface and 5.51 ± 3.14 MPs/kg at depth. There were no significant differences among beaches, months, depths nor protection regime. Polymers found were, by descent order, polyethylene, rubber, latex, polypropylene and ethylene vinyl alcohol; which are mainly used in consumer goods, tires and food packaging. Overall, microdebris in these beaches are not among the highest in the Mediterranean and do not seem to threaten turtles’ reproductive success, although more detailed studies are needed to determine potential effect on embryonic developmental processes.
... Plastic pollution is one of the serious threats for the endangered Mediterranean subpopulation of sperm whales , which also suffer from bycatch, ship strikes, noise pollution from oil and gas exploration (Notarbartolo di Sciara et al. 2012). And as the Cilician Sea that runs between Cyprus and the Mediterranean coast of Turkey has been identified as a regional marine plastic hotspot, where plastic threats to marine megavertebrates may be particularly acute (Liubartseva et al. 2018;Duncan et al. 2019), dietary studies on stranded marine animals are of great importance in monitoring environmental plastic levels and impacts on wildlife in this region. It was not possible to understand the effects of plastics on the individual's health due to decomposition in Case 3. To better understand the causes of death and interpret the effects of marine litter ingestion on the animals' health, it is important to access stranded animals on time and carry out post-mortem studies by all means. ...
... Such an approach is routinely used to model the dispersal of larvae, pollutants, sediments and many other tracers (e.g. Le Hénaff et al., 2012;Liubartseva et al., 2018;Figueiredo et al., 2013;Frys et al., 2020). Although some transport model might take wave-induced currents into account, most of them neglect wavecurrent interactions, which can lead to significant errors in storm conditions (Röhrs et al., 2012;Curcic et al., 2016). ...
Article
The intensity of major tropical cyclones has increased during the past decade. Their effect is particularly acute in coastal areas where they cause extensive damage leading to an influx of debris, sediments and waste to the sea. However, most operational coastal ocean models do not represent heavy-wind transport processes correctly if the hydrodynamics is not coupled with the wind-generated waves. This may lead to significant errors in ocean simulations under tropical cyclone conditions. Here, we investigate current-wave interactions during a major hurricane and assess their impact on transport processes. We do that by coupling the unstructured-mesh coastal ocean model SLIM with the spectral wave model SWAN, and applying it to the Florida Reef Tract during Hurricane Irma (September 2017). We show that the coupled model successfully reproduces the wave behavior, the storm surge and the ocean currents during the passage of the hurricane. We then use the coupled and uncoupled wave–current model to simulate the transport of passive drifters. We show that the wave radiation stress gradient alone can lead to changes of up to 1 m/s in the modeled currents, which in turn leads to differences of up to 5 km in the position of drifting material over the duration of the hurricane. The Stokes drift however appears to cause deflections up to 4 times larger and hence dominates wave-induced transport. Wave–current interactions therefore strongly impact the transport of drifting material such as sediments and debris in the aftermath of a hurricane. They should thus be taken into account in order to correctly assess its overall impact.
... Furthermore, it is estimated that about 20% of marine debris originates from offshore litter sources such as fishing and shipping, though this number can vary (Liubartseva et al., 2018). This difference between estimates of plastics entering the ocean from either terrestrial or offshore sources and plastics floating in the ocean has led to a search for possible sinks (Long et al., 2015). ...
Article
Anthropogenic debris has been reported in all studied marine environments, including the deepest parts of the sea. Finding areas of accumulation and methods of transport for debris are important to determine potential impacts on marine life. This study analyzed both sediment cores and Remotely Operated Vehicle video to determine the density and distribution of debris, including both micro- and macroplastics, in Norfolk and Baltimore canyons. The average microplastic density in Norfolk Canyon sediment was 37.30 plastic particles m⁻² within the canyon and 21.03 particles m⁻² on the adjacent slope, suggesting that microplastics could accumulate within submarine canyons. In video transects from both Norfolk and Baltimore canyons, the largest amounts of macroplastic were recorded near the canyon heads. Our findings contribute to a growing evidence base that canyons and their associated benthic invertebrate communities are important repositories and conduits for debris to the deep sea.
... Campanale et al., 2020), the importance of planning clean-up actions and program of measures (e.g., best waste management) is crucial to achieve a decreasing trend of MPs concentration.In offshore surface waters, MPs are widely dispersed and could be extremely conditioned by the hydrodynamic forcing (winds, tides, and currents)(Liubartseva et al., 2018;Zhang, 2017) or the speci c properties of plastic particles (Choy et al., 2019; Kooi et al., 2016). To date, the data acquired so far are not su cient to establish the primary causes of the accumulation of MPs on sea water surfaces. ...
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An increasing number of ecologists and researchers have addressed microplastics pollution in marine waters to explain the source, the transport, and the fate of these pollutants. Further data on the concentration of microplastics in the water column are crucial for understanding the impacts on ecosystems and to implement monitoring programs. This study provides information on the concentration and composition of sea water surface microplastics in three Italian subregions of the MSFD. We examined the flow of MPs from coastal to offshore areas, comparing their densities. We tested the efficiency of two sampling methodologies to evaluate the abundance and typology of MPs between marine layers. The results of this study confirm the high values of this pollutant in the Mediterranean Sea (0.029 ± 0.033 items · m⁻²), a MPs gradient from coastal to offshore areas, and a difference between the surface and subsurface marine layers.
... Final paper belongs to Liubartseva et al. (2018) was on modeling the drift of floating debris using a 2D Lagrangian particle-tracking algorithm (Markov chain model) considering both stochastic beaching and sedimentation of plastics. The authors applied the Monte Carlo technique for beaching and sedimentation processes of the particles for the first time. ...
Article
Microplastic pollution in marine and riverine environments is a threat not only for the aquatic ecosystem itself but also for human activity and life. Although there are reviews regarding microplastic debris in environments, most of them focus on the studies on their type, occurrence, and distribution. Only a limited number of these studies focus on the modeling methods, usually concentrating on particular aspects, such as settling or bioaccumulation. In this paper, physically-based existing microplastics modeling studies are classified and reviewed according to the environment, modeling methodology, and input-output relationships. Considering the strengths and weaknesses of all modeling methodologies, it is deduced that more reliable results are obtained using hybrid methods, especially the coupling of hydrodynamic and process-based models, and hydrodynamics and statistical models. The significance of having much more consideration and knowledge on the microplastics' physical properties and the environmental processes affecting their fate and transport in the aquatic environments is revealed for future research. It has also been recommended that a standardized method for data calibration, validation, and verification is necessary to be able to compare the modeling results with field investigations more efficiently than it is currently.
... Numerical models simulating the movement and fate of marine litter provide essential tools to gain a better understanding and predict accumulation areas of plastic debris (NOAA, 2016). Such models have been implemented on both global scale (e.g., Lebreton et al., 2012;Maximenko et al., 2012;van Sebille et al., 2015) and in the Mediterranean (e.g., Mansui et al., 2015;Zambianchi et al., 2017;Liubartseva et al., 2018;Kaandrop et al., 2020;Soto-Navarro et al., 2020;Macias et al., 2021) to simulate the pathways and accumulation patterns of floating plastics, originating from known sources (cities, rivers, and shipping lanes). However, except very few studies (e.g., van Sebille et al., 2015;Carlson et al., 2017;Kaandrop et al., 2020), simulated plastics concentrations were not validated against in situ data and model results provided mainly qualitative findings. ...
Article
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In this study, the abundance and properties (size, shape, and polymer type) of microplastics (MPs) in sea surface water samples, collected during two sampling campaigns over 2018–2019, in four coastal areas of the Mediterranean Sea (Saronikos Gulf, LIgurian Sea, Gulf of Lion, and Gabes Gulf) were investigated. Coupled hydrodynamic/particle drift model simulations with basin-scale Mediterranean and high resolution nested models were used to provide a better understanding on the variability of the abundance/size of MPs, originating from wastewater and river runoff, in the four areas. Different size classes of MPs were considered in the model, taking into account biofouling induced sinking, as a possible mechanism of MPs removal from the surface. The Gabes Gulf showed the highest mean MPs abundance (0.073–0.310 items/m ² ), followed by Ligurian Sea (0.061–0.134 items/m ² ), Saronikos Gulf (0.047–0.080 items/m ² ), and Gulf of Lion (0.029–0.032 items/m ² ). Overall, the observed MPs abundance and size distribution was reasonably well reproduced by the model in the four different areas, except an overestimation of small size contribution in Saronikos Gulf. The basin-scale simulation revealed a strong decrease of smaller size MPs in offshore areas, due to biofouling induced sinking, with larger (floating) MPs being able to travel longer distances in the open sea. A significant impact of waves drift and advection of MPs from non-local sources was identified from model simulations, particularly in the Gulfs of Lion and Gabes, having a stronger effect on larger microplastics. In Gabes Gulf, most MPs originated from offshore areas, being mainly (floating) larger size classes, as suggested by the observed quite small contribution of <1 mm particles. The MPs observed abundance distribution in each area could be partly explained by the adopted sources distribution. The modeling tools proposed in this study provide useful insight to gain a better understanding on MPs dynamics in the marine environment and assess the current status of plastic pollution on basin and regional scale to further develop environmental management action for the mitigation of plastic pollution in the Mediterranean Sea.
... Some researchers have stated that the eastern Mediterranean coasts present the highest concentrations of plastic debris (Gündogdu and Çevik, 2019;Liubartseva et al., 2018). At the same time, as cited in the introduction, Mansui et al. (2015) and Macias et al. (2019) predicted that a high concentration of stranded plastics could be found on the southern Mediterranean coasts. ...
Article
This study is the first attempt to provide original data on plastics debris occurrence in beach sediments of the Gulf of Skikda in Algeria (southwestern Mediterranean). Sediment samples from seven beaches were collected to extract, quantify and characterize mesoplastics and microplastics. Particles were classified by size into mesoplastics (5–25 mm) and large microplastics (1–5 mm). Overall, microplastics were the most abundant size fraction in terms of number of items. The average mass of mesoplastics was twice that of microplastics, revealing a notable reservoir of plastics that is scarcely ever reported in the literature. The predominant types were fragments and pellets, white/transparent in color. The average concentrations of total plastic were 1067.19 ± 625.62 items/m2, 106.98 ± 62.39 items/kg, and 50.65 ± 9.82 g/m2, showing variability between beaches and within sampling sites. Thus, the Skikda coast has high levels of pollution compared to other areas of the Mediterranean Sea.
... According to Liubartseva et al. (2018), plastics found in Italy and France are mostly derived from their own terrestrial sources, with low contribution from shipping or other countries. In fact, food was found to be an important sector producing litter in the area, and no relationship with naval traffic was observed, conversely to other studies (Vauk and Schrey 1987;Galgani et al. 2013;Caric and Machelworh 2014). ...
Article
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The conservation of the highly mobile marine mammals species is challenging. One of the primary tools for conservation of marine species and the maintenance of ecosystem processes is the establishment of marine protected areas which is based on the identification of areas of high ecological value, or the identification of effective mitigation measures for the main threats. Bonifacio Bouches is mainly a coastal area which encompasses several Natura 2000 sites and is included in the Pelagos Sanctuary for the protection of marine mammals. Numerous regulations are applied here targeting shipping and related activities for environmental protection and navigation safety. Integrated data on cetacean species, maritime traffic and marine litter were collected from systematic surveys performed on board ferries crossing the Bonifacio Strait (2013–2019). Data were seasonally investigated considering spring/summer and autumn/winter as potentially different for ecological and anthropogenic conditions. Seasonal models of preferred habitat for fin whale, striped dolphin and bottlenose dolphin were compared with the existing protected areas, evidencing gaps of spatial protection measures for the species. A species sensitivity score was integrated with threats analyses highlighting the priority areas/seasons requiring enhanced conservation efforts. Despite the existing regulations, results showed that the intense anthropogenic pressure represents a risk for the ecological richness in many areas lacking of protection. Outcomes provide us indication on candidate areas where an extension of spatial protection measures could favour the priority bottlenose dolphin species, and the areas/seasons that need improved mitigation of the main threats. The application of similar approach in wider areas can be useful to verify protection measures for highly mobile species.
... Since the AIS, the main sea current governing the large-scale velocity field of our model, is most intense in the depth range 13-30 m and weakens with depth (Sorgente et al., 2011), forcing the vertical movement of the particles in the lower layers could promote retention and reduce dispersion (Calò et al., 2018). This is just what we have observed by comparing the results presented here with preliminary numerical simulations bility of particles may be meaningful, especially in conjunction with the particle resuspension probability (see Hinata et al., 2020;Liubartseva et al., 2018;Onink et al., 2021 for applications to marine plastic debris), and the vertical migration (see Berline et al., 2013). ...
Article
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Backward‐in‐time Lagrangian dispersion models can efficiently reconstruct drifters trajectories by linking known arrival positions to potential sources. This approach was applied to the deep water rose shrimp (Parapenaeus longirostris) in the Strait of Sicily (central Mediterranean Sea). The objective was to identify the potential spawning areas of the larvae that settle in the known nursery grounds of the northern sector of the Strait of Sicily, thus quantifying the extent of the potential contribution to recruitment from the surrounding regions. Numerical simulations were performed over 11 years (2005–2015) and for two different periods (spring/summer and autumn/winter) corresponding to the species' spawning peaks in the region. The persistence over time of potential spawning areas was identified through a Hotspot analysis of the backward trajectories end‐points, filtered to meet a suitable depth range for spawners. The results confirmed the expected downstream connectivity between spawning and nursery grounds along the Sicilian–Maltese shelf and, notably, indicated that these spawning grounds contribute to the high productivity and resilience of deep water rose shrimp fisheries in the northern Strait of Sicily more than the spawning grounds in surrounding regions. A minor and time‐varying contribution is due to potential spawning areas identified on the African shelf. These results are important to adequately define the geographical scale for the assessment and management of this important fishery resource in the Strait of Sicily. In particular, the assumption of a single stock that does not consider the spatial structure of the population should be revised for the purpose of fisheries management.
... In order to track the floating marine plastic debris' trajectories in the ocean, studies apply existing Lagrangian models (used for tracking oil spills, larvae, sediment transport, etc.), that include currents and diffusion processes Potemra, 2012;Eriksen et al., 2013;Law et al., 2010). Langragian particle-tracking models coupled to circulation models have been widely used for investigating microplastic sources, fate and trajectories in the marine environment (Liubartseva et al., 2016;Liubartseva et al., 2018;Isobe et al., 2009;Martinez et al., 2009;Yoon et al., 2010;Lebreton et al., 2012;Neumann et al., 2014;Mansui et al., 2015;Carlson et al., 2017;Kubota, 1994). Also, transport models assist in understanding the spatial and temporal variability of MP accumulation in the marine environment and inform policies (Braunschweig et al., 2003;Mateus et al., 2012). ...
Article
The Mediterranean Sea is among the most affected areas of our planet by microplastic (MP) pollution. However, some regions are still underrepresented in the current literature. This work studied the fate of microplastics (MPs) released from major populated areas within the NE Ionian Sea, an area that contains highly significant biodiversity. This was accomplished by incorporating oceanographic data into a Lagrangian particle-tracking numerical model that simulated the transport of MP particles for the interval of 27 months. The findings report a high possibility of beaching within the first weeks of the simulation for most locations, where 63% of MPs were beached and 37% were still floating at the end of the simulation. Seaward transport and eddy diffusivity are the controlling mechanisms of the MP transport, with diffusion being the primary force controlling the movement of MP particles in 1/3 of the simulated regions. This is highly significant, because in areas where diffusion is the main mechanism controlling MP transport, accumulation of floating MP particles is occurring, as reported in previous studies. The MPs’ transport and beaching behavior, as well as the observed residence times, were used to determine the threat level that MPs pose to the biodiversity of specific areas.
... The Particle Tracking Model (PTM), a model based on the Lagrangian Principle was used to simulate the fate and transport of spilled MP pellets from discharge source (sunken X-Press Pearl ship) and to understand the landfall along coastlines (Politikos et al., 2017;Liubartseva et al., 2018), and their transport is mainly driven by the regional hydrodynamic forgings (Rangel-Buitrago et al., 2019;Mugilarasan et al., 2021). The amount of plastic pellets spilled (the total amount of plastic pellets was estimated to be about 1600 tonnes; Hassan et al. (2021) has been accounted as the source of particles and transferred to the model input. ...
Article
Microplastics (MPs) are a global environmental concern and pose a serious threat to marine ecosystems. This study aimed to determine the abundance and distribution of MPs in beach sediments (12 beaches), marine biota (6 beaches) and the influence of microbes on MPs degradation in eco-sensitive Palk Bay and Gulf of Mannar coast. The mean MP abundance 65.4 ± 39.8 particles/m2 in beach sediments; 0.19 ± 1.3 particles/individual fish and 0.22 ± 0.11 particles g−1 wet weight in barnacles. Polyethylene fragments (33.4%) and fibres (48%) were the most abundant MPs identified in sediments and finfish, respectively. Histopathological examination of fish has revealed health consequences such as respiratory system damage, epithelial degradation and enterocyte vacuolization. In addition, eight bacterial and seventeen fungal strains were isolated from the beached MPs. The results also indicated weathering of MPs due to microbial interactions. Model simulations helped in tracking the fate and transboundary landfall of spilled MPs across the Indian Ocean coastline after the X-Press Pearl disaster. Due to regional circulations induced by the monsoonal wind fields, a potential dispersal of pellets has occurred along the coast of Sri Lanka, but no landfall and ecological damage are predicted along the coast of India.
... The most important vector carrying non-native litter to Mediterranean coasts is the cyclonic Central Mediterranean current system which flows from Libya, Egypt, Israel, Lebanon, and Syria to the southern Turkish Mediterranean coastline. The Levantine Sea is estimated as one of the most important plastic waste accumulation areas of the Mediterranean in modeling studies (Liubartseva et al. 2018 ). Although it is assumed that the transportation of litter from the countries mentioned above further accelerates pollution in the Levantine Sea, there is no data to support this assumption yet. ...
Article
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Turkey is one of the major plastic pollution sources in the Mediterranean and the Black Sea. This review summarizes present information, data, and legislation on plastic pollution in Turkish aquatic ecosystems. According to results derived from reviewed studies, both macro and microplastic pollution were documented in Turkish aquatic ecosystems. Most of the studies on plastic pollution in Turkish waters were performed in the marine environment while only four were conducted in freshwater environments. Spatially, the majority of these studies, which were on levels in the marine environment, were conducted on the northeastern Mediterranean coasts of Turkey, especially Iskenderun and Mersin Bays. Additional studies were carried out on either the ingestion/presence/impact of microplastics by/to aquatic organisms or the entanglement of marine organisms in plastics. There were also studies assessing the microplastic content of commercial salt, and another has reported microplastic presence in traditional stuffed mussels sold in Turkish streets. Some studies were conducted on microplastic presence and/or their removal in wastewater treatment plants in Mersin, Adana, Mugla, and Istanbul cities. Macro- and microliter loading from a few Turkish rivers to the sea was also estimated. All these investigations indicate that Turkish aquatic environments have significant plastic pollution problems, which were also underlined by the legislative studies. The need for further studies in this field still exists, especially in freshwater environments.
... -1 ) in the region (UNEP MAP, 2015). Additionally, a model study covering all Mediterranean Region reports highest percentage of plastic litter generation from Turkish terrestrial region that contributes to floating debris compare to other countries in the region (Liubartseva et al., 2018). Present study was designed to reveal the abundance and spatio-temporal distribution of MPs pollution in the three main freshwater systems (Aksu and Köprü Streams, Manavgat River), located through the costal line of the Antalya Bay. ...
Article
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Microplastic pollution is one of the pressing environmental issues over the world that pose risks to aquatic ecosystems and humans. Significant amount of anthropogenic plastic litter known to be transported with freshwater systems to marine environment. The aim of the present study is to reveal the abundance and spatio-temporal distribution of MPs pollution in the three main freshwater systems (Aksu and Köprü Streams, Manavgat River), located through the costal line of the Antalya Bay. 106 water samples obtained from these three freshwater systems and fishing grounds located in the vicinities of these systems were evaluated. A total of 2444 MPs with a mean size of 1777.16±1168.81 µm detected within these samples. A homogeneous MPs pollution was observed in the area. Four colours (Black-27.3%, White-19.4%, Red-18.7% and Blue-16.2%) found to composed more than 80% of the detected MPs. Majority of MPs detected within the framework of the study were fiber (57.1%) and fragment (32.6%). Most common polymer type was Polyproplene-(PP) with 50%. Results obtained from this study have the potential to form the basis for future studies that take into account the terrestrial use and the prevailing physical factors in the region in the study area.
... Therefore, the high MP ingestion in European anchovy samples collected from Station 8 might be due to the MP abundance found in this region (Gedik and Eryaşar, 2020;Eryaşar et al., 2021;Terzi et al., 2022). The results show that the MP abundance in the fish may be mainly related to the seawater MP pollution (Liubartseva et al., 2018;Sun et al., 2019). For red mullet, the mean number of MPs was found to be lower than the findings of previous studies for the Adriatic Sea and Mediterranean coasts (Avio et al., 2015;Bellas et al., 2016;Anastasopoulou et al., 2018;Digka et al., 2018;Giani et al., 2019;Gündogdu et al., 2020). ...
Article
Microplastic (MP) contamination is a serious threat to today's marine life. Therefore, this study investigates MP ingestion in three commercial fish species (European anchovy Engraulis encrasicolus, whiting Merlangius merlangus, and red mullet Mullus barbatus) from the Turkish coast of the Black Sea. Ninety-five MPs were detected in all examined fish (371). Fiber forms were detected in the majority of cases based on the MP morphology. Polyethylene and polypropylene were the most dominant polymer type. The mean of ingested MPs was found as 0.15±0.04, 0.28±0.06, 0.40±0.07 in anchovy, whitting and red mullet, respectively. The size of the MPs ranged from 118 μm and 4854 μm. The MP waste was detected in each species, and the highest MP amount was determined in the red mullet, which was significantly higher than European anchovy. The present study's data might be a baseline on the ecological risk assessment of MPs in the fish and future experimental studies on the fish species living in the Black Sea.
Chapter
Microplastic pollution in the marine environment is a growing concern. Microplastic particles floating or settled in the sea affect both biotic and abiotic components of the marine environment through absorption by biota, entanglement, and colonization. There is also strong evidence that microplastics support microbial growth (also known as plasticizers) and adsorb primary hydrophobic contaminants on their surfaces. The first addresses of floating microplastic particles are the coastal environment. According to (Liubartseva et al. 2018), the relative contributions of floating plastic that arrive at the coastlines can be divided into three groups according to the origins of plastics. It appears that the majority of the plastics come from the closest terrestrial inputs (Gündoğdu et al. 2018; Liubartseva et al. 2018). For instance, in the model implemented by (Liubartseva et al. 2018), the flux onto the coastlines is bigger than the flux to the bottom in the Mediterranean.
Article
Plastic litter pollution is one of the major concerns for the health of marine ecosystems worldwide. This pervasive form of pollution affects all oceans and seas and it's interacting with multiple levels of the marine food webs. In the European context, several pieces of legislation try to fight against this pervasive and ubiquitous form of pollution. Recently, EU Member States have agreed to a maximum threshold of litter items per coast length (20 items/100 m coastline). One major concern among stakeholders to reach this consensus was the transboundary litter, as measures need to be implemented in the country of origin. Henceforth, a solid method to estimate the amounts of the transboundary litter to a given Member State's coasts is needed. In this contribution, we use a combination of hydrodynamic and Lagrangian models for the Mediterranean Sea in order to understand the origin of coastal litter. Simulations show that the amount of transboundary litter in Mediterranean countries could be as large as 30% although both regional and seasonal differences could be significant.
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Although the ingestion of plastics has been reported in a wide variety of organisms, there remains a lack of knowledge regarding the extent of spatial and temporal gradients and no consensus concerning the definition of monitor species for benthic marine environments. The present study aims at demonstrating the correlation between the presence of tangled balls of fibres and high levels of total plastic fibre ingestion in Nephrops norvegicus to assess the potential use of the prevalence of tangled balls as indicators of fibre pollution. To do so, the presence of plastics in stomach contents from several European populations of N. norvegicus is characterized in detail, including size distribution and polymer composition, and then its correlation with the prevalence of balls tested. Our results demonstrate that the prevalence of balls (>20%) is significantly correlated to higher levels of plastic ingestion, regardless of polymer composition and size distribution of ingested fibres. Plastic fibre ingestion levels across wide temporal and geographical scales are assessed using only the prevalence of balls, highlighting areas of increased fibre ingestion (e.g., the Gulf of Cadiz, N Barcelona) and areas of potentially lower fibre pollution (e.g., the Ebro Delta, the NW Iberian margin). Moreover, the relationship between the prevalence of balls and diet composition is analysed to discard a potential relationship with geographical differences in diet habits. Finally, we discuss the benefits and drawbacks of the use of the prevalence of tangled balls of fibres as an affordable, cost-effective and easy to implement indicator of fibre pollution for monitoring purposes in this species.
Conference Paper
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Plastic litter had become world major concerned since 2015 and Indonesia had been placed as the second contributor after China. Around 200,000 metric tons of plastic wastes discharged from Indonesia rivers mainly from Java and Sumatra Islands every year. This surge of waste then become a serious threat to ocean and coastal ecosystem, as well as marine biota conservation in Indonesia. Therefore, it is very important to study the seasonal pattern of marine debris and monitor the dispersion within Indonesian water in near real time. By year 2020, an initiative action has been taken by The Ministry of Marine Affairs and Fisheries of Indonesia. More than 20 drifters were released on 3 selected rivers' mouth in Indonesia namely Cisadane, Bengawan Solo and Musi. Results indicated that marine debris are drifted away, influenced by wind and current from time to time. The simulation will forecast the time and location where the marine debris expected to traverse and stranded in each season. This information will be ve ry important to provide the baseline information of marine debris movement, locally and even beyond of Indonesian. Also, it will improve the mitigation, better coordinative action plan and encouraging further marine debris research in Indonesia.
Article
Worldwide, plastic debris is becoming a great environmental problem, with potentially negative effects also on human health, although currently the topic is highly debated in the scientific community. In the basin, microplastics come mainly from three coastal regions, namely Egypt, Turkey and Italy, in decreasing order. Today, the knowledge about the possible interactions of microplastics in the biotic system is unclear and huge efforts are required to discover their effects on human health. Therefore, it is necessary to reduce the production and use of plastics by investing money in research planning and strengthening any kind of human efforts to solve this new kind of marine pollution.
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Every year, vast quantities of plastic debris arrive at the ocean surface. Nevertheless, our understanding of plastic movements is largely incomplete and many of the processes involved with the horizontal and vertical displacement of plastics in the ocean are still basically unknown. In this chapter we review the dynamics associated with the transport of plastics and other pollutants at oceanic fronts. Fronts had been historically defined as simple barriers to exchange, but here we show that the role of these structures in influencing the transport of plastics is more complex. The tools used to investigate the occurrence of frontal structures at various spatial scales are reviewed in detail, with a particular focus on their potential applications to the study of plastic pollution. Three selected case studies are presented to better describe the role of fronts in favoring or preventing plastic exchanges: the large-scale Antarctic Circumpolar Current, a Mediterranean mesoscale front, and the submesoscale fronts in the Gulf of Mexico. Lastly, some aspects related to the vertical subduction of plastic particles at oceanic fronts are discussed as one of the most promising frontiers for future research. The accumulation of floating debris at the sea surface is mainly affected by the horizontal components of frontal dynamics. At the same time, vertical components can be relevant for the export of neutrally buoyant particles from the surface into the deep sea. Based on these evidences, we propose that submesoscale processes can provide a fast and efficient route of plastic transport within the mixed layer, while mesoscale instabilities and associated vertical velocities might be the dominant mechanism to penetrate the deeper ocean on slower but broader scales. We conclude that given the ubiquitous presence of fronts in the world’s ocean, their contribution to the global plastic cycle is probably not negligible and the role of these processes in vertically displacing neutrally buoyant microplastics should be investigated in more detail.
Chapter
Lagrangian methods are a common tool in physical oceanography. Due to the quasi-Lagrangian characteristics of floating marine litter (FML) and the chemical substances released from it, Lagrangian methods can be used to study this environmental threat. Most of the existing investigations of this topic have been carried out in the deep ocean, where baroclinic dynamics dominate. In contrast, studies of tidally dominated, shallow regions are much fewer in number. Compared to the deep ocean, shallow shelves are more strongly influenced by freshwater inputs, bottom stress, complex coastlines, and wind, which imply higher diffusion rates, especially in the presence of tides. Furthermore, they steer the transport of FML from rivers to the deep ocean with fronts as an important driver. The present chapter reviews Lagrangian methods for visualizing and assessing frontal dynamics in tidal basins with data obtained from numerical modeling and satellite-tracked drifters. The specific requirements for the two data sources are described and discussed. Some of these methods are applied in the North Sea, located on the European northwest shelf, where tidal mixing fronts and fronts due to freshwater runoff exist. It is demonstrated how surface convergence and gradients in temperature, salinity, and density are connected with the accumulation of virtual and satellite-tracked drifters. The effect of tides on the propagation of Lagrangian particles is shown to be significant and demonstrates the importance of tidal forces and vertical dynamics in Lagrangian simulations in tidal basins. The chapter ends with the future outlook, illuminating the numerous knowledge gaps remaining and proposing areas for future research.
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The ingestion of anthropogenic plastic debris by marine wildlife is widespread in the Mediterranean Sea. The endangered status (in the IUCN Red List) of Loggerhead turtle (Caretta caretta, Linnaeus, 1758) is a consequence of its vulnerability. In this study, macro-/meso-plastics (5–170 mm) collected from faeces of twelve loggerhead turtles rescued (live) in the Aeolian Archipelago (Southern Tyrrhenian Sea, Italy) were analyzed by size, weight, shape, color and polymer type through Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR). The defecation rate during hospitalization (7–14 days) varied among turtles (from 0.08-0.58). The mean number of plastic expulsions (2.7 ± 1.8 items for turtle) was higher during the 5th day of hospitalization (Kruskal-Wallis test, P = 0.01). However, the mean number of plastic-like items defecated during the common days of hospitalization did not vary among turtles (Kruskal-Wallis test, P > 0.05). All turtles were found to have ingested plastic. A total of 114 debris items were recovered from their faeces, 113 of which were identified as plastic. Their color was mostly white-transparent (64.9%) and light (19.3%). Shape was mainly fragments (52.6%), sheets (38.6%), followed by nylon, net-fragments, elastic plastic, foamed plastic and industrial granules (8.8%). Meso-plastics (5–25 mm) represented 72% of the total number of debris and were found more frequently in turtle with Curved Carapace Length (CCL) ≤ 60 cm (CCL = 30–60 cm, n = 5) than those with CCL >60 cm (CCL = 60–71 cm, n = 7). Plastic items were composed mainly of polyethylene (48.2%) and polypropylene (34.2%). Polypropylene (R² = 0.95, P < 0.001) and polyisoprene (R² = 0.45, P = 0.017) were more common in meso-plastics while polyethylene (R² = 0.44, P < 0.01) in macro-plastics. Finally, high-density polyethylene, polyvinyl chloride, polyamide and polyurethane were also found in some turtles. This study reveals high spreads of plastic contamination in faeces of both turtles with CCL ≤60 cm and CCL >60 cm, particularly vulnerable to the increasing quantity of floating plastic into their foraging sites highlighting the need of further research to associate debris ingestion with turtle diet and their size.
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Plain Language Summary A large part of plastic in the ocean is located at or near beaches. This plastic can break down into micro‐plastics or be ingested by animals. Therefore, it is important to clean up these beaches. The easiest way to do so is to prevent the plastic from entering the oceans initially by interfering at the source. In this study, we develop a framework to find these sources for a given beach. We first simulate the path that plastic has taken to reach this beach. We do this by releasing virtual plastic particles at the beach where they end up. Next, we calculate their paths back in time, computing their trajectories until they reach this beach. We then combine these simulations with data on the sources of plastic: where and when did plastic enter the ocean? We apply this framework to a beach in southwest Netherlands, near the town of Domburg. We quantify seasonal effects, where time‐varying currents cause the plastic to come from different sources. Lastly, we study how plastic sources vary with plastic age (the time between the plastic entering the ocean and beaching at its final location).
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Beach litter can affect public health and economic activities worldwide forcing local authorities to expensive beach cleaning. Understanding the key mechanisms affecting the accumulation of this waste on beaches, such as sea state and proximity to entry points, is critical to plan effective management strategies. In this one-year study, we estimated the impact of storm events and waterways runoff on litter abundance and local economy using as a model a managed, peri-urban beach facing a north-western sector of the Mediterranean Sea. We also investigated the relationship between litter composition/density and beach proximity to major/closest harbors/rivers at regional scale by combining our data with those on litter density available in literature. Autumn/winter storms caused larger litter depositions than spring/summer ones in the peri-urban beach. No preferential accumulation occurred near to waterway mouths. Litter mainly consisted of plastic, and its composition in terms of micro-categories varied over seasons. In total, 367,070 items were deposited along 4.7 km of beach over one year, and the cost for the removal of this waste amounted to approximately 27,600 euros per km/year. At regional scale, beach litter density was positively correlated to the proximity of major harbors while its composition was related to the proximity to both major harbors and rivers. Results indicate that autumn/winter storms are important drivers of marine litter deposition. They also suggest that beaches in front of the convergence zone of littoral currents and close to major harbors can be particularly subjected to this kind of pollutant. To increase their effectiveness, litter mitigation/cleaning activities should be planned based on predictions of major storm events and performed at spatial scales encompassing at least coastal regional sectors.
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Cesium-137, as the main fission product, is of special interest in the marine environment because of its solubility, which results to very low sinking time. Nevertheless, the conservative form of the main percentage of ¹³⁷Cs introduced in the marine environment (70%) makes ¹³⁷Cs to be included in the salinity of sea water. Based on this property, in this study, we examine potential relations between ¹³⁷Cs activity concentrations and marine parameters issued from Earth Observation (EO) data products in the Southern Aegean Sea, in order to investigate the possibility of ¹³⁷Cs to be recorded by satellite data. In particular, measurements of physical and biological marine parameters issued from the Copernicus Marine Environment Monitoring Service (CMEMS) database and MODIS ocean products are retrieved for the dates of ¹³⁷Cs field measurements. Single and multiple regression analyses are performed between the marine parameters and ¹³⁷Cs activity concentration measurements for three distinctive time periods (total, cold, and warm period). The best results are obtained from multiple regressions, one for each time period (r² > 0.70). The models show that during cold period, ¹³⁷Cs activity concentrations are highly correlated to both chlorophyll and nutrients (phosphates) while during warm and the total period, they seem to be mainly correlated to the photosynthetic available incident solar radiation on the sea surface. For each period, we propose a multiparameter model linear in its parameters. Although the results of this study must be considered preliminary due to the limited size of the datasets, for the first time, we show that estimations of ¹³⁷Cs activity concentrations from EO measurements and CMEMS environmental models are feasible, and they can be used as a marine radiological assessment tool for a closed Mediterranean bay such as Souda Bay in Greece.
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Turbulent mixing is a vital component of vertical particulate transport, but ocean global circulation models (OGCMs) generally have low-resolution representations of near-surface mixing. Furthermore, turbulence data are often not provided in OGCM model output. We present 1D parametrizations of wind-driven turbulent mixing in the ocean surface mixed layer that are designed to be easily included in 3D Lagrangian model experiments. Stochastic transport is computed by Markov-0 or Markov-1 models, and we discuss the advantages and disadvantages of two vertical profiles for the vertical diffusion coefficient K z. All vertical diffusion profiles and stochastic transport models lead to stable concentration profiles for buoyant particles, which for particles with rise velocities of 0.03 and 0.003 m s −1 agree relatively well with concentration profiles from field measurements of microplastics when Langmuir-circulation-driven turbulence is accounted for. Markov-0 models provide good model performance for integration time steps of t ≈ 30 s and can be readily applied when studying the behavior of buoyant particulates in the ocean. Markov-1 models do not consistently improve model performance relative to Markov-0 models and require an additional parameter that is poorly constrained.
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Plastic debris is a ubiquitous pollutant on the sea surface. To date, substantial research efforts focused on the detection of plastic accumulation zones. Here, a different paradigm is proposed: looking for crossroad regions through which large amounts of plastic debris flow. This approach is applied to the Mediterranean Sea, massively polluted but lacking in zones of high plastic concentration. The most extensive dataset of plastic measurements in this region to date is combined with an advanced numerical plastic-tracking model. Around 20% of Mediterranean plastic debris released every year passed through about 1% of the basin surface. The most important crossroads intercepted plastic debris from multiple sources, which had often traveled long distances. The detection of these spots could foster understanding of plastic transport and help mitigation strategies. Moreover, the general applicability and the soundness of the crossroad approach can promote its application to the study of other pollutants. Plastic pollution in seas is widespread, but some areas lack the high concentrations of plastic debris. Here the authors identified places where large amounts of plastic debris pass in the Mediterranean Sea thus helping to study plastic dispersion in regions where plastic debris does not accumulate, and a tool for mitigation strategies.
Chapter
Given that approximately half of the plastics produced is heavier than seawater, the seafloor, from intertidal to abyssal and hadal depths, is an important long‐term sink for marine macro and microplastics. Some seafloor areas can be difficult to monitor due to differences in the seabed, such as, structures and types, which can be sandy, muddy, or rocky. A range of different approaches may be used to cost effectively monitor seafloor areas, such as, using simple litter quantification protocols based on existing fish stock surveys. Abandoned, lost or otherwise discarded fishing gear, also called as, ALDFG is one of the major components of sea‐based marine litter and seafloor litter. One of the main impacts of marine litter on the seafloor is entanglement by marine fauna. Because litter on the seafloor is usually not retrieved, monitoring it will tend to reflect accumulation processes.
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Considering everything between macroplastics and nanoplastics, this chapter aims to provide a comprehensive and detailed assessment of the available methods to monitor and model plastics in freshwater bodies and to visualize the geographical distribution of studies reporting plastics in rivers and lakes. Both in marine or freshwater ecosystems, five steps can be distinguished for monitoring, namely, sampling, extraction, analysis, identification, and extrapolation. Despite the rapidly increasing number of publications on plastic occurrences in freshwater bodies, several aspects still carry high levels of uncertainty. The chapter highlights four key aspects that deserve more attention when designing and performing monitoring campaigns and when developing and interpreting numerical models. These four aspects are: temporal variation, transfer between environmental compartments, harmonization of monitoring and modeling investigations regarding plastic size ranges, and, finally, data quality control and validation of results.
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Pollution of plastics to the environment is uninhibitedly increasing, from densely populated city centers to remote oceans. This chapter discusses different methodologies and approaches for scientific studies on ocean plastic pollution. It presents three general methodologies with a focus on the scientific background and the contributions to plastic pollution research. The first method is the assessment of plastic pollution to the environment directly from the emission source. The second method identifies plastic pollution ‘behavior’ in the environment and the transport pathways through the environment. The final method assesses plastic pollution through pollution identification. The chapter presents three strategies to stimulate synergies between the three determined methodologies. These are: the ferry method—input–output data sharing; the bridge method—feedback between methodologies; and the polder method—a universal plastic pollution model.
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Offline particle tracking (OPT) is a widely used tool for the analysis of data in oceanographic research. Given the output of a hydrodynamic model, OPT can provide answers to a wide variety of research questions involving fluid kinematics, zooplankton transport, the dispersion of pollutants, and the fate of chemical tracers, among others. In this paper, we introduce ROMSPath, an OPT model designed to complement the Regional Ocean Modeling System (ROMS). Based on the Lagrangian TRANSport (LTRANS) model (North et al., 2008), ROMSPath is written in Fortran 90 and provides advancements in functionality and efficiency compared to LTRANS. First, ROMSPath calculates particle trajectories using the ROMS native grid, which provides advantages in interpolation, masking, and boundary interaction while improving accuracy. Second, ROMSPath enables simulated particles to pass between nested ROMS grids, which is an increasingly popular scheme to simulate the ocean over multiple scales. Third, the ROMSPath vertical turbulence module enables the turbulent (diffusion) time step and advection time step to be specified separately, adding flexibility and improving computational efficiency. Lastly, ROMSPath includes new infrastructure which enables inputting of auxiliary parameters for added functionality. In particular, Stokes drift can be input and added to particle advection. Here we describe the details of these updates and performance improvements.
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The needs of society and the emerging blue economy require access and integration of data and information for the construction of dedicated products. A “transparent and accessible ocean” is one of the key objectives of the Ocean Decade 2021–30. In this context, marine infrastructures become significant components of a global knowledge environment, enabling environmental assessment and providing the necessary data for scientifically valid actions to protect and restore ocean health, to use marine resources in a sustainable way. The data is collected, analyzed, organized, and used by people and their good use/reuse can be obtained with social practices, technological and physical agreements aimed at facilitating collaborative knowledge, decision-making, inference. The vision is a digital ocean data ecosystem made up of multiple, interoperable, and scalable components. The huge amount of data and the resulting products can drive the development of new knowledge as well as new applications and services. Predictive capabilities that derive from the digital ecosystem enable the implementation of services for real-time decision-making, multihazard warning systems, and advance marine space planning. The chapter develops following the progressive complexity and information content of products deriving from oceanic data: data cycle and data collections, data products, oceanic reanalysis. The chapter discusses the new challenges of data products and the complexity of deriving them.
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Although plastic is ubiquitous in marine systems, our current knowledge of transport mechanisms is limited. Much of the plastic entering the ocean sinks; this is intuitively obvious for polymers such as polystyrene (PS), which have a greater density than seawater, but lower density polymers like polyethylene (PE) also occur in sediments. Biofouling can cause large plastic objects to sink, but this phenomenon has not been described for microplastics < 5 mm. We incubated PS and PE microplastic particles in estuarine and coastal waters to determine how biofouling changes their sinking behavior. Sinking velocities of PS increased 16% in estuarine water (salinity 9.8) and 81% in marine water (salinity 36) after 6 weeks of incubation. Thereafter sinking velocities decreased due to lower water temperatures and reduced light availability. Biofouling did not cause PE to sink during the 14 weeks of incubation in estuarine water, but PE started to sink after six weeks in coastal water when sufficiently colonized by blue mussels Mytilus edulis, and its velocity continued to increase until the end of the incubation period. Sinking velocities of these PE pellets were similar irrespective of salinity (10 vs. 36). Biofilm composition differed between estuarine and coastal stations, presumably accounting for differences in sinking behavior. We demonstrate that biofouling enhances microplastic deposition to marine sediments, and our findings should improve microplastic transport models.
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This work describes the first step towards a fully coupled modelling system composed of an ocean circulation and a wind wave model. Sensitivity experiments are presented for the Mediterranean Sea where the hydrodynamic model NEMO is coupled with the third-generation wave model WaveWatchIII (WW3). Both models are implemented at 1/16° horizontal resolution and are forced by ECMWF 1/4° horizontal resolution atmospheric fields. The models are two-way coupled at hourly intervals exchanging the following fields: sea surface currents and temperature are transferred from NEMO to WW3 by modifying the mean momentum transfer of waves and the wind speed stability parameter, respectively. The neutral drag coefficient computed by WW3 is then passed to NEMO, which computes the surface stress. Five-year (2009–2013) numerical experiments were carried out in both uncoupled and coupled mode. In order to validate the modelling system, numerical results were compared with coastal and drifting buoys and remote sensing data. The results show that the coupling of currents with waves improves the representation of the wave spectrum. However, the wave-induced drag coefficient shows only minor improvements in NEMO circulation fields, such as temperature, salinity, and currents.
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The role of riverine freshwater inflow on the Central Mediterranean Overturning Circulation (CMOC) was studied using a high-resolution ocean model with a complete distribution of rivers in the Adriatic and Ionian catchment areas. The impact of river runoff on the Adriatic and Ionian Sea basins was assessed by a twin experiment, with and without runoff, from 1999 to 2012. This study tries to show the connection between the Adriatic as a marginal sea containing the downwelling branch of the anti-estuarine CMOC and the large runoff occurring there. It is found that the multiannual CMOC is a persistent anti-estuarine structure with secondary estuarine cells that strengthen in years of large realistic river runoff. The CMOC is demonstrated to be controlled by wind forcing at least as much as by buoyancy fluxes. It is found that river runoff affects the CMOC strength, enhancing the amplitude of the secondary estuarine cells and reducing the intensity of the dominant anti-estuarine cell. A large river runoff can produce a positive buoyancy flux without switching off the antiestuarine CMOC cell, but a particularly low heat flux and wind work with normal river runoff can reverse it. Overall by comparing experiments with, without and with unrealistically augmented runoff we demonstrate that rivers affect the CMOC strength but they can never represent its dominant forcing mechanism and the potential role of river runoff has to be considered jointly with wind work and heat flux, as they largely contribute to the energy budget of the basin. Looking at the downwelling branch of the CMOC in the Adriatic basin, rivers are demonstrated to locally reduce the volume of Adriatic dense water formed in the Southern Adriatic Sea as a result of increased water stratification. The spreading of the Adriatic dense water into the Ionian abyss is affected as well: dense waters overflowing the Otranto Strait are less dense in a realistic runoff regime, with respect to no runoff experiment, and confined to a narrower band against the Italian shelf with less lateral spreading toward the Ionian Sea center.
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A circulation model is coupled to a Lagrangian particle-tracking model to simulate the transport floating litter particles in the Aegean Sea, Greece (Eastern Mediterranean). Considering different source regions and release dates, simulations were carried out to explore the fate and distribution of floating litter over 1990–2009, taking into account the seasonal and interannual variability of surface circulation. Model results depicted recurrently high concentrations of floating litter particles in the North Aegean plateau, the Saronikos Gulf, and along Evia and Crete islands. Modeled transport pathways of floating litter demonstrated that source regions are interconnected, with Saronikos Gulf being a main receptor of litter from other sources. Notably higher percent of litter exit (∼35%) than enter the model domain (∼7%) signified that Aegean Sea seems to act as a source rather than receptor of floating litter pollution in the Eastern Mediterranean Sea. Beached litter was found around 10%, mostly located in the western part of the Aegean Sea. This is the first modeling study to explore the transport of floating marine litter in Greek waters.
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The Mediterranean Sea is greatly affected by marine litter. In this area, research on the impact of plastic debris (including microplastics) on biota, particularly large filter-feeding species such as the fin whale (Balaenoptera physalus), is still in its infancy. We investigated the possible overlap between microplastic, mesoplastic and macrolitter accumulation areas and the fin whale feeding grounds in in a pelagic Specially Protected Area of Mediterranean Importance (SPAMI): the Pelagos Sanctuary. Models of ocean circulation and fin whale potential habitat were merged to compare marine litter accumulation with the presence of whales. Additionally, field data on microplastics, mesoplastics, and macrolitter abundance and cetacean presence were simultaneously collected. The resulting data were compared, as a multi-layer, with the simulated distribution of plastic concentration and the whale habitat model. These data showed a high occurrence of microplastics (mean: 0.082 items/m 2 , STD ± 0.079 items/m 2) spatial distribution agreed with our modeling results. Areas with high microplastic density significantly overlapped with areas of high macroplastic density. The most abundant polymer detected in all the sampling sites was polyethylene (PE), suggesting fragmentation of larger packaging items as the primary source. To our knowledge, this is the first study in the Pelagos Sanctuary in which the simulated microplastic distribution has been confirmed by field observations. The overlap between the fin whale feeding habitat and the microplastic hot spots is an important contribution for risk assessment of fin whale exposure to microplastics.
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Concern about marine litter has been rising in the last decades, triggered by the discovery of the great mid-ocean garbage patches. The Mediterranean Sea is strongly affected by the presence of floating litter, as it has a very high amount of waste generated annually per person that eventually ends up in its waters, with plastic objects accounting for a large percentage of all manmade debris. In principle, the basin looks very vulnerable to possible accumulation of floating debris, since its dynamics is characterized by an inward surface flow of water from the Atlantic hampering surface floating items from being flushed out. Yet, no evidence of permanent litter accumulation areas has been reported so far in the Mediterranean. In this paper we utilized the largest available set of historical Lagrangian data gathered in the Mediterranean Sea to estimate the probability of debris particles to reach different subareas of the basin, with the main objective of singling out possible retention areas. Climatological reconstructions of the time evolution of litter distribution in the basin carried out on the basis of observed Lagrangian displacements suggest a general tendency of floating matter to collect in the southern portion of the basin, and in particular a long term accumulation in the southern and southeastern Levantine basin, areas not yet sampled by marine litter observation campaigns, whose targeted organization we strongly recommend at the end of this paper.
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The Cilician Basin located in the Northeastern Mediterranean is a region that is affected by a diversity of anthropogenic pressures and is further expected to suffer from negative economic, environmental and social impacts of coastal litter. To provide a baseline for litter management plans, the standing crop of coastal macro-litter was sampled on 13 beaches following MSFD guidelines. Environmental predictors characterizing beach use and potential land based litter point sources in the vicinity of the beaches were related to litter densities to identify litter sources. The average litter density was 0.92 ± 0.36 items/m2. Litter items resulting from convenience food consumption and smoking made up more than half of the total litter collected, while agricultural, industrial, fishing activities together contributed only 6% of the total number of items. Plastic items on average constituted more than 80% of the dominant material type. Percentages of the litter transported with currents from neighbouring countries (transboundary litter) varied from 0 – 4.23% between beaches. Direct deposition on the beaches was identified as the main method for transport of items to the coastal environment. Our results show poor local awareness and underline the need for educational programs that can help reduce coastal litter. © Published by Central Fisheries Research Institute (CFRI) Trabzon, Turkey.
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Microplastic debris floating at the ocean surface can harm marine life. Understanding the severity of this harm requires knowledge of plastic abundance and distributions. Dozens of expeditions measuring microplastics have been carried out since the 1970s, but they have primarily focused on the North Atlantic and North Pacific accumulation zones, with much sparser coverage elsewhere. Here, we use the largest dataset of microplastic measurements assembled to date to assess the confidence we can have in global estimates of microplastic abundance and mass. We use a rigorous statistical framework to standardize a global dataset of plastic marine debris measured using surface-trawling plankton nets and coupled this with three different ocean circulation models to spatially interpolate the observations. Our estimates show that the accumulated number of microplastic particles in 2014 ranges from 15 to 51 trillion particles, weighing between 93 and 236 thousand metric tons, which is only approximately 1% of global plastic waste estimated to enter the ocean in the year 2010. These estimates are larger than previous global estimates, but vary widely because the scarcity of data in most of the world ocean, differences in model formulations, and fundamental knowledge gaps in the sources, transformations and fates of microplastics in the ocean.
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Contamination levels by plastic debris, trace elements and persistent organic pollutants were assessed and related to macrobenthic diversity within soft bottoms of Grand Harbour (Malta, Central Mediterranean). Sediment toxicity was evaluated by ecotoxicological method, deploying Bacteria (Vibrio fischeri), Echinodermata (Paracentrotus lividus) and Crustacea (Corophium orientale). Univariate analysis (Pearson's test) was used to test relationships between biodiversity indices, pollutants and grain size. A multivariate approach (PERMANOVA) was applied to investigate for any significant differences among sampling stations concerning plastic abundances and to test the relationship between infaunal abundances and pollutant concentrations (the BIOENV test). Significant differences in the plastic abundances were found between sampling stations. The lowest value for Shannon-Wiener biodiversity index was associated to the highest sediment pollution level. Multivariate analyses suggest that MBT and TBT were factors that most influenced macrozoobenthic abundance and biodiversity. The bivalve Corbula gibba and the introduced polychaete Monticellina dorsobranchialis were the most abundant found species.
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The dynamic behavior of coastal litter is followed on Israeli beaches. Subsequently, the impact of the coastal geomorphology on litter dynamics is examined. Six prototype sampling beaches of different morphology were selected. The position, number, composition and nature of all the litter pieces, within a 50 m beach front, were recorded on each beach. Strips of litter concentration were demarcated and their movement was mapped along shore-normal transects. All items were tagged in situ, each beach strip by a different color. These sampling procedures enabled to define inflow, outflow, transfer, storage and reemergence of buried litter. We also calculated the litter budget at each site, traced litter movement through the beach and calculated the residence time and the turnover period. The littered area in all beaches, over the entire study period, was less than one percent. The widest beaches were the most littered. Specific beach morphology, as ridge and runnel, made the backshore an efficient trap for the litter. The results show that the narrower the beach the higher its litter flux. The narrowest sandy beach showed the highest range of dynamics. The litter is spread and organized in distinct strips. Their pattern reflects the specific beach depositional dynamics. The Israeli Mediterranean coast is homogeneous in its high mobility of litter, shown by a similar input and output of litter items and by the almost balanced budget of litter on each studied site. Turnover time, i.e., the time needed to replace the total litter on each beach, is only a few months long and less than half a year. This high mobility of the litter means poor persistence and a good self-cleaning capacity. The data suggests that the Israeli beaches are essentially a transfer route for the litter, which migrates along and finally seems to bypass them.
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The processes of transport, diffusion and transformation of surface oil in seawater can be simulated using a Lagrangian model formalism coupled with Eulerian circulation models. This paper describes the formalism and the conceptual assumptions of a Lagrangian marine surface oil slick numerical model and rewrites the constitutive equations in a modern mathematical framework. The Lagrangian numerical representation of the oil slick requires three different state variables: the slick, the particle and the structural state variables. Transformation processes (evaporation, spreading, dispersion and coastal adhesion) act on the slick state variables, while particle variables are used to model the transport and diffusion processes. The slick and particle variables are recombined together to compute the oil concentration in water, a structural state variable. The mathematical and numerical formulation of oil transport, diffusion and transformation processes described in this paper, together with the many simplifying hypothesis and parameterizations, form the basis of a new, open source Lagrangian surface oil spill model, the so-called MEDSLIK-II, based on its precursor MEDSLIK (Lardner et al., 1998, 2006; Zodiatis et al., 2008a). Part 2 of this paper describes the applications of the model to oil spill simulations that allow the validation of the model results and the study of the sensitivity of the simulated oil slick to different model numerical parameterizations.
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