Displays

Since 2016, an interdisciplinary consortium at the Carl von Ossietzky University in Oldenburg has been funded by the Lower Saxony Ministry for Science and Culture in order to provide solid, scientific knowledge of the sources, pathways and accumulation zones of plastic litter. This team consists of physical oceanographers, geoecologists, biologists and environmental planners.

Using simple wooden drifters, GPS-drifters and high resolution, numerical modelling, the consortium studied the dispersal of floating macroplastics (i.e. visible plastic fragments and objects) and accumulation areas within the German Bight and the Wadden Sea. Furthermore, coastal sensors and observation systems were employed to gather data of hydrodynamic parameters. In addition, the general public has actively participated in the collection of litter data via a web-based registration system for reporting the findings of wooden drifters.

In this presentation we will highlight some of the most important results of the project amongst them the surprising observation of a complete reversal of the circulation in the southern North Sea in March 2018, supported by drifter reports from citizen scientists from Britain. We will also shortly shed light on the heavy workload involved with presentations to the public (Radio, TV, print media, presentations to various stakeholder groups) which future projects should anticipate already at the planning stage.

How to cite: Wolff, J.-O., Hahner, F., Meyerjürgens, J., Ricker, M., Schöneich-Argent, R. I., Badewien, T., Lettmann, K. A., Schaal, P., Freund, H., Mose, I., Stanev, E., and Zielinski, O.: Macroplastics Pollution in the Southern North Sea – Sources, Pathways and Abatement Strategies, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10456, https://doi.org/10.5194/egusphere-egu2020-10456, 2020.

The presence of microplastics in the Arctic sea ice cover and water column, as well as on land, has raised the already high concerns about the dispersion of litter in the global environment. We present a 50-year simulation carried out with the NEMO ocean general circulation model of the dispersion of buoyant and neutrally buoyant microplastics in the global ocean that includes a simple formulation of microplastic accumulation in, and advection by, sea ice. Microplastics enter the Arctic predominantly through the Barents Sea, with a smaller input through the Bering Strait, although the simulation also takes into account small plastic sources along the Arctic coastline. Microplastics become trapped in newly formed sea ice chiefly on the Eurasian shelves and the Chukchi Sea, but a still significant amount is transferred from the mixed layer to the ice base through congelation in the central Arctic, where microplastics congregate nearer to the surface than elsewhere in the global ocean due to the strong stratification and the relatively small levels of vertical turbulence underneath multiyear sea ice. In the model, the maximum average residence time of sea ice in the Arctic is about six years, and this is also, therefore, the typical timescale for maximum microplastic accumulation in the ice cover. Plastics trapped in sea ice undergo a seasonal cycle of accumulation and release in consonance with the freeze and melt sea ice cycle but ultimately are release back into the ocean in the Greenland and Labrador seas, from where they will be subsequently transported into the North Atlantic.

How to cite: Morales Maqueda, M. A. and Mountford, A. S.: Modelling the accumulation and transport of microplastics by Arctic sea ice, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17048, https://doi.org/10.5194/egusphere-egu2020-17048, 2020.

Forty percent of the plastic produced annually ends up in the ocean. What happens to the plastic after that is poorly understood, though a growing body of data suggests it is rapidly spreading throughout the ocean. The mechanisms of this spread are not straightforward for small, weakly or neutrally buoyant plastic size fractions (the microplastics), in part because they aggregate in marine snow and are consumed by zooplankton. This biological transport pathway is suspected to be a primary surface microplastic removal mechanism, but exactly how it might work in the real ocean is unknown. We search the parameter space of a new microplastic model embedded in an earth system model to show biological uptake significantly shapes global microplastic inventory and distributions, despite its being an apparently inefficient removal pathway.

How to cite: Kvale, K., Prowe, A. F., Chien, C.-T., Landolfi, A., and Oschlies, A.: Modelling the global biological microplastic particle sink, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1892, https://doi.org/10.5194/egusphere-egu2020-1892, 2020.

The popularity of plastic as a cheap and easy to use, moldable material has been growing exponentially, leading to a likewise increase in plastic waste. As a result, plastic pollution has been surging in the marine realm, and the effects and fates of these modern, man-made compounds in our oceans are unresolved. Pathways of plastic degradation (physicochemical and biological) in the marine environment are not well constrained; yet, microbial plastic degradation is a potential plastic sink in the ocean. However, there is a lack of methods to determine this process, particular if the overall turnover is in the sub-percent range.  We developed a novel method based on incubations with isotopically labelled polymers for investigating microbial plastic degradation in marine environments. We tested our method with a Rhodococcus Ruber strain (C-208), a known plastic degrader, as a model organism. In our experiments we used granular polyethylene (PE) that was almost completely labelled with the stable isotope ¹³C (99%) as a sole carbon source. We monitored CO₂ concentration and stable carbon isotope ratios over time in the headspace during 35-day incubations at atmospheric oxygen concentrations and found an excess production of 13C-CO₂. This result provides direct evidence for the microbially mediated mineralization of carbon that was ultimately derived from the polymer. After terminating the incubation, we measured the dissolved inorganic carbon (DIC), and pH, allowing us to determine the total excess production of 13C-CO₂ and DIC, and thus the rate of plastic degradation. Of the 2000 μg PE added, ~0.1% was degraded over a time course of 35 days at a rate of ~1.5 μg month^-1, providing a first characterization of the mineralization kinetics of PE by R. Ruber. The results show that isotopically labelled polymers can be used to determine plastic degradation rates. The method shows promise for being more accurate than the classic gravimetrical methods.

How to cite: Goudriaan, M., Hernando Morales, V., van Bommel, R., van der Meer, M., Rachel Ndhlovu, R., van Heerwaarden, J., Hinrichs, K.-U., and Niemann, H.: A stable isotope assay for determining microbial degradation rates of plastics in the marine environment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15253, https://doi.org/10.5194/egusphere-egu2020-15253, 2020.

The flocculation of combinations of microplastic particles (MP) and natural cohesive sediment has been investigated in a laboratory setup using unfiltered seawater. The experiments were conducted in order to test the hypothesis that MP may flocculate in estuarine and marine environments with natural organic and inorganic particles. MP particles in the size-range 63 – 125 µm were incubated with suspensions of local untreated seawater and untreated fine-grained sediment (< 20µm) collected from a tidal mudflat. Settling experiments were carried out with both a floc-camera video equipment (PCam) and conventional settling tubes.

Flocculation and sedimentation of MP-particles of PVC have been investigated as well as particles from high density polypropylene which is used in certain fishing gear. The studies have generally confirmed our hypothesis that microplastics are incorporated into aggregates along with other natural particles, thus settling faster than they would as single particles. The exact aggregation mechanisms still remains to be revealed but the general cohesiveness of fine-grained natural particles, organic particles as well as particulate and dissolved organic polymers are believed to be responsible for the flocculation. A strong effect of salt ions was also observed, confirming the classical concept of increased flocculation of fine-grained particles as they are transported from fresh-water to estuarine and marine waters.

The implication of the aggregation is that primary MP from land-based sources are likely to flocculate with other suspended particles, especially as they enter saline waters. The particles are therefore expected to deposit close to the sources, typically rivers. This applies to both micro-plastic particles that are denser than seawater but also to low-density plastic types which should otherwise float. However, secondary MP may be formed by disintegration of plastic anywhere and these MP particles could therefore settle wherever there is plastic present at the sea surface, for example under the ocean gyres where plastic is known to accumulate. Here, too, interaction with other particles in the water column is expected, but the concentration of natural particles is much lower than in coastal waters and it may be that the transport of natural organic and inorganic particles will start to be modified if the concentration of plastic in the marine environment continues to rise.

How to cite: Andersen, T. J., Rominikan, S., Laursen, I. S., Skinnebach, K. H., Grube, N. Z., Jedal, S. R., Laursen, S. N., and Fruergaard, M.: Flocculation of microplastic and cohesive sediment in natural seawater, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13617, https://doi.org/10.5194/egusphere-egu2020-13617, 2020.

Textile fibres are ubiquitous contaminants of emerging concern. Traditionally ascribed to the ’microplastics’ family, their widespread occurrence in the natural environment is commonly reported in plastic pollution studies, with the misleading belief that they largely derive from wear and tear of synthetic fabrics. Their synthetic nature has been largely used to motivate their persistence in the environment, thus explaining their presence in virtually all compartments of the planet, including sea-ice, deep-seas, soils, atmospheric fall-out, foods and drinks. As of today however, an extensive characterization of their polymeric composition has never been performed, even though the evidence that most of these fibres are not synthetic, is slowly emerging. By compiling a dataset of more than 916 seawater samples collected in six different ocean basins, we confirm that microfibres are ubiquitous in the world seas, but mainly composed of natural polymers. The chemical characterization of almost 2000 fibres through µFTIR techniques revealed that in striking contrast to global production patterns, only 8.2% of marine fibres are actually synthetic, with the rest being predominantly of animal (12.3%) or vegetal origin (79.5%). These results demonstrate the widespread occurrence of cellulosic fibres in the marine environment, emphasizing the need for full chemical identification of these particles, before classifying them as microplastics. On the basis of our findings it appears critical to assess origins, impacts and degradation times of cellulosic fibers in the marine environment, as well as to assess the wider implications of a global overestimation of microplastic loads in natural ecosystems.

How to cite: Suaria, G., Achtypi, A., Perold, V., Aliani, S., Pierucci, A., Lee, J., and Ryan, P.: All that glitters is not plastic: the case of open-ocean fibres , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3715, https://doi.org/10.5194/egusphere-egu2020-3715, 2020.

Increasing amounts of plastic debris in the ocean is a global environmental concern. Each year, several million tons of plastic waste enter the ocean from coastal environments. Transported by currents, wind and waves, positively buoyant plastic objects eventually accumulate at the sea surface of subtropical oceanic gyres, forming the so-called ocean garbage patches. To date, the fate of floating plastic debris ‘trapped’ in the oceanic gyres remains largely unknown. To more accurately assess the persistence of floating plastics accumulating in offshore areas, a better understanding of the plastic inputs and outputs into and from ocean garbage patches is crucial. An important component of this mass balance currently missing is the vertical plastic flux from the sea surface of subtropical waters towards the seabed. Numerical models have major difficulties in constraining the sinking flux of plastic to the ocean interior in these areas since validation against observational data is not possible yet.

Here, we provide the first water column profiles (0-2000m water depth) of plastic particles (>500µm) in the North Pacific subtropical gyre (Great Pacific Garbage Patch; GPGP). We show that plastic particles in the water column are mostly in the size range of particles that are apparently missing from the ocean surface and that their polymer composition is similar to that of floating debris circulating in the surface waters. Furthermore, water column plastic concentrations increase with higher concentrations at the sea surface and show a power law decline with water depth. These findings strongly suggest that plastics present in the deep sea below the GPGP are small fragments of initially buoyant plastic debris that accumulated at the sea surface. Although the amount of plastic in the GPGP water column is significant compared to the surface accumulation, our results further indicate that the ocean water column is unlikely to harbor a major fraction of the tens of millions of metric tons of missing ocean plastic.

How to cite: Egger, M., Sulu-Gambari, F., and Lebreton, L.: First evidence of plastic fallout from the Great Pacific Garbage Patch, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2387, https://doi.org/10.5194/egusphere-egu2020-2387, 2020.

Plastic Litter (PL) has become more ubiquitous in the last decades posing socio-economic as well as health problems for the blue and green economy. However, to date PL monitoring strategies have been based on field sampling by citizens and scientists during recreational, sporting, scientific and clean-up campaigns. To this end, remote sensing technologies combined with artificial intelligence (AI) have gained rising interest as a potential source of complementary scientific evidence-based information with the capabilities to (i) detect, (ii) track, (iii) characterise and (iv) quantify PL. Within the smart algorithms, convoluted and recurrent neural networks ingest vast multi to hyperspectral images from smartphones, unmanned aerial systems, fixed observatories, high-altitude pseudo-satellites and space stations. Detection would involve the application of object recognition algorithms to true colour Red-Green-Blue (RGB) composite images. Typical essential descriptors that are derived from RGB images include apparent colour, shape, type and dimensions of PL. In addition to object recognition algorithms supported by visual inspection, AI is also used to classify and estimate counts of PL in captured imagery. Quantification assisted by smart systems have the advantage of uncertainties associated with predictions, a cruial aspect in determing budgets of PL in the natural environment. Hyperspectral data is then utilized to further characterise the polymer composition of PL based on spectral reference libraries of known polymers. Fixed observatories and repeated image capture at regions-of-interest have prospective applications in tracking of PL. Here we present plausible applications of remote detection, tracking and quantification of PL assisted by smart AI algorithms. Smart remote sensing of PL will be integrated in future operational smart observing system with near real-time capabilities to generate user (citizens, stakeholders, policymakers) defined end-products relevant to plastic litter. These tailor-made descriptors will thus contribute towards scientific evidence-based knowledge important in assisting legislature in policy making, awareness campaigns as well as evaluating the efficacy of mitigation strategies for plastic litter. Essential descriptors proposed need to include geolocations, quantities, size distributions, shape/form, apparent colour and polymer composition of PL.

How to cite: Garaba, S., Gnann, N., and Zielinski, O.: Smart algorithms for monitoring plastic litter, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-442, https://doi.org/10.5194/egusphere-egu2020-442, 2020.

Plastic pollution has a big impact on living organisms. At the same time, plastics are everywhere in our daily life. For example, plastic is used in packaging, construction of buildings, cars, electronics, agriculture and many other fields. In fact, plastic production has been increasing rapidly since the 1950s. However, plastic waste management strategies have not adapted accordingly to these rising amounts, which end up in the blue and green planet. Unfortunately, for developing nations it is even more complicated and strategies are still developing. Here we investigate the possibilities of plastic waste detection in Cambodia focusing on cities, rivers and coastal areas. Very fine geo-spatial resolution Red-Green-Blue (RGB) drone imagery was captured over regions of interest in Phnom Penh, Sihanoukville and Siem Reap. To this date, techniques of detecting plastic litter are based on RGB imagery analyses, generating descriptors such as colour, shape, size and form. However, we believe by adding infrared wavebands additional descriptors, such as polymer composition or type can be retrieved for improved classification of plastic litter. Furthermore, remote sensing technologies will be merged with object-based deep learning methodologies to enhance identification of plastic waste items, thus creating a robust learning system. Due to the size and complexity of this problem, automated detection, tracking, characterization and quantification of plastic pollution is a key aspect to improve waste management strategies. We therefore explore multispectral band combinations relevant to the detection of plastic waste and operational approaches in imagery processing. This work will contribute towards algorithm development for analysis of video datasets enhancing future near real-time detection of plastic litter. Eventually, this scientific evidence-based tool can be utilized by stakeholders, policymakers and citizens.

How to cite: Gnann, N., Garaba, S., and Zielinski, O.: Plastic waste detection assisted by artifical intelligence, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-975, https://doi.org/10.5194/egusphere-egu2020-975, 2020.

Satellite remote sensing is an invaluable tool for observing our earth systems. However, few studies have succeeded in applying this for detection of floating litter in the marine environment. We demonstrate that plastic debris aggregated on the ocean surface is detectable in optical data acquired by the European Space Agency (ESA) Sentinel-2 satellites. Furthermore, using an automated classification approach, we show that floating macroplastics are distinguishable from seawater, seaweed, sea foam, pumice, and driftwood.

Sentinel-2 was used to detect floating aggregations likely to include macroplastics across four study sites, namely: coastal waters of Accra (Ghana), Da Nang (Vietnam), the east coast of Scotland (UK), and the San Juan Islands (BC, Canada). Aggregations were detectable on sub-pixel scales using a Floating Debris Index (FDI), and were composed of a mix of materials including sea foam and seaweed. A probabilistic machine learning approach was then applied to assess if detected plastics could be discriminated from the natural sources of marine debris. Our automated Naïve Bayes classifier was trained using a library of pumice, seaweed, timber, sea foam and seawater detections, as well as validated macroplastics from Durban Harbour (South Africa). Across the four study sites, suspected marine plastics were classified as such with an accuracy approaching 90%. The ‘misclassified’ plastics were mostly identified as seawater, suggesting an insufficient amount of pixel was filled with materials.

Results from this study show that plastic debris aggregated on the ocean surface can be detected in optical data collected by Sentinel-2, and identified. With the aim of generating global ‘hotspot’ maps of floating plastics in coastal waters, automating this two-stage process across the Sentinel-2 archive is being progressed; however, the method would also be applicable to drones and other remote sensing platforms with similar band characteristics. To extend remote detection methods to river systems and optically complex and/or tidal coastal waters, in situ data collection across optical water types is the next key step.

How to cite: Biermann, L., Clewley, D., Martinez-Vicente, V., and Topouzelis, K.: Detecting and Identifying Floating Plastic Debris in Coastal Waters using Sentinel-2 Earth Observation Data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19145, https://doi.org/10.5194/egusphere-egu2020-19145, 2020.

Marine litter and microplastics are everywhere. Even the Arctic Ocean, Svalbard and Jan Mayen Island are contaminated as various publications confirm. Little, however, is reported about marine waters and shores of the Canadian Arctic Archipelago. This poster presents the results of a privately funded citizen science observation to scan remote beaches along the Northwest Passage for marine litter pollution.

The observations were conducted while enjoying the 2019 Northwest Passage sailing expedition of the Tecla, a 1915 gaff-ketch herring drifter. The expedition started in Ilulissat, Greenland, on 1 August and ended in Nome, Alaska, on 18 September. After crossing Baffin Bay, the ship continued along Pond Inlet, Navy Board Inlet, Lancaster Sound, Barrow Strait, Peel Sound, Franklin Strait, Rea Strait, Simpson Strait, Queen Maud Gulf, Coronation Gulf, Amundsen Gulf, Beaufort Sea, Chukchi Sea and Bering Strait. The vessel anchored in the settlement harbours of Pond Inlet, Taloyoak, Gjoa Haven, Cambridge Bay and Herschel Island. In addition, Tecla’s crew made landings at remote beaches on Disko Island (Fortune Bay, Disko Fjord), Beechey Island (Union Bay), Somerset Island (Four Rivers Bay), Boothia Peninsula (Weld Harbour), King William Island (M’Clintock Bay), Jenny Lind Island, and at Kugluktuk and Tuktoyaktuk Peninsula.

Following the categorization of the OSPAR Guideline for Monitoring Marine Litter on Beaches, litter observations were conducted without penetrating the beach surfaces. Beach stretches scanned varied in length from 100-400 m. No observations were conducted at inhabited settlements or at the abandoned settlements visited on Disko Island (Nipisat) and Beechey Island (Northumberland House).

Observations on the most remote beaches found 2-5 strongly bleached or decayed items in places such as Union Bay, Four Rivers Bay, Weld Harbour, Jenny Lind Island (Queen Maud Gulf side). Landings within 15 km of local settlements (Fortune Bay, Disko Fjord, Kugluktuk, Tuktoyaktuk) or near military activity (Jenny Lind Island, bay side) showed traces of local camping, hunting or fishing activities, resulting in item counts between 7 and 29. At the lee shore spit of M’Clintock Bay, significant pollution (> 100 items: including outboard engine parts, broken ceramic, glass, clothing, decayed batteries, a crampon and a vinyl record) was found, in contrast to a near-pristine beach on the Simpson Strait side. The litter type and concentration, as well as the remains of a building and shipwrecked fishing vessel indicate that this is an abandoned settlement, possibly related to the construction of the nearby Distant Early Warning Line radar site CAM-2 of Gladman Point. DEW Line sites have long been associated with environmental disturbances.

Given the 197 beach items recorded, it can be concluded that the beaches of the Canadian Arctic Archipelago, which are blocked by sea ice during most of the year, are not pristine. Truly remote places have received marine pollution for decades to centuries. Where (abandoned) settlements are at close range pollution from local activities can be discovered, while ocean currents, wind patterns, ice rafting, distance to river mouths, and flotsam, jetsam and derelict also determine the type and amount of marine litter along the Northwest Passage.

How to cite: Gijsbers, P. and Jiskoot, H.: Beach observations of plastic and marine litter along the Northwest Passage, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7312, https://doi.org/10.5194/egusphere-egu2020-7312, 2020.

Plastic pollution has become one of today’s biggest environmental problems. Yearly worldwide production of plastic was 360 million tonnes in 2018, of which approximately 10 million reached the oceans. But there is very little data from remote regions of the world^.

Several studies have pointed to the tourism and fishing industries as the main sources of plastic marine litter. Hurtigruten as an operator of expedition cruise vessels, believes that it is our responsibility to invest in the understanding and conservation of the areas we visit, this is reflected on our sustainability efforts: Single Use Plastics were banned from all our ships and Hotels in 2018, we have built the first electric/fuel hybrid ships and are transforming other ships in the fleet to the same technology or to run on Liquid biogas.

Scientific data collection in the polar regions is challenging due to remoteness, the harsh environment and high operational costs. For the last couple of years, we have supported the scientific community by transporting researchers and their equipment to and from their study areas in polar regions, we have established collaborations with numerous scientific institutions, such as University Centre in Svalbard, Norwegian Polar Institute, Institute for Marine Research, and Norwegian Institute for Water Research (NIVA) and we have been actively participating in clean-up projects, and are contributing to the SALT and MALINOR projects.

Plastic pollution is having a significant impact on wildlife, and recent studies show that the concentration of microplastics is also greater than estimated. The understanding of the status and impacts of marine litter has many gaps, further studies are needed to improve our knowledge of its distribution and interaction with the marine biota. In partnership with NIVA we have installed a FerryBox on MS Roald Amundsen. Amongst other sensors it has a microplastic collector and preliminary data from the first collection between Tromsø and Longyearbyen agree with published results from the same area. MS Roald Amundsen will sail to both polar areas, where data on microplastic litter is required, making it the perfect ship of opportunity and platform for data collection. Lastly, the large advantage of using cruise ships as sampling and research platforms is the long-term presence in the polar regions, allowing for continued measurements over longer time periods.

How to cite: Meraldi, V., Morgan, T., and Van Bavel, B.: Norwegian Institute for Water Research (NIVA) and Hurtigruten partnership to bring light to the gaps in plastic marine litter knowledge. , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22246, https://doi.org/10.5194/egusphere-egu2020-22246, 2020.

There is extensive documentation of plastic debris in the marine environment [1]. Citizen science programs and tracking apps have been used more recently in the collection of data on plastics in marine settings [1]. These programs, however, are focussed on debris collected from beach cleanups and coastal environments. Large debris currently afloat in ocean garbage patches, which contribute significantly to marine plastic pollution, are less well-characterised. Buoyant plastics accumulate offshore in the five ocean gyres, the largest of which is the Great Pacific Garbage Patch (GPGP) in the North Pacific Ocean. There, they are seen floating in a loosely concentrated ‘soup’. Over time they degrade in saltwater, under UV radiation, with the help of wind and wave action. They also serve as substrates for trace metal and organic pollutant adsorption, as well as the growth of microbial consortia and larger potentially invasive organisms. There is currently limited data collection on sources of large floating plastics in ocean gyres. Majority of data collected on plastics in the garbage patches is based on trawled sampling techniques that exclude objects larger than 0.5m [2]. Large debris are important for elucidation of the overall mass of plastic in the patches. We know that 8% of the GPGP is comprised of microplastics and thus larger objects constitute the greater fraction of the total plastic mass [2], which we know little about. It is important to understand what types of debris accumulate in the patches, their land-/marine-based origins and the locations from which they enter the ocean. Where the debris is produced and what practices (commercial, cultural, industrial) contribute to their accumulation in the garbage patches is also pivotal data that needs to be collected. This information, coupled to data on how long the plastics persist and how well they persevere in the marine environment, is necessary for creating effective and efficient mitigation strategies.

References

[1] Jambeck, J. R. & Johnsen, K. Citizen-Based Litter and Marine Debris Data Collection and Mapping. Computing in Science & Engineering, 17, 20-26 (2015).

[2] Lebreton, L. et al. 2018. Evidence that the Great Pacific Garbage Patch is rapidly accumulating plastic. Scientific Reports, 8, 4666 (2018).

How to cite: Sulu-Gambari, F., Egger, M., and Lebreton, L.: What’s that Floating in my Soup? Characterisation and Handling of Floating Debris in the Great Pacific Garbage Patch, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16315, https://doi.org/10.5194/egusphere-egu2020-16315, 2020.

Predicted global figures for plastic debris accumulation in the ocean surface layer range on the order of hundreds of thousands of metric tons, representing only a few percent of estimated annual emissions into the marine environment. A commonly accepted explanation for this difference is that positively buoyant macroplastic objects do not persist on the ocean surface. Subject to degradation into microplastics, the major part of the mass is predicted to have settled below the surface. However, we argue that such emission-degradation model cannot explain the occurrence of decades-old objects collected by oceanic expeditions. We show that debris circulation dynamics in coastal environments may be a better explanation for this difference. The results presented here suggest that there is a significant time interval, on the order of several years to decades, between terrestrial emissions and representative accumulation in offshore waters. Importantly, our results also indicate that the current generation of secondary microplastics in the global ocean is mostly a result of the degradation of objects produced in the 1990s and earlier. 

How to cite: Lebreton, L. and Egger, M.: Searching for the missing plastic: a global surface mass budget for floating ocean plastics., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20962, https://doi.org/10.5194/egusphere-egu2020-20962, 2020.

It is now widely recognized that marine plastics, which are strongly resistant to chemical and biological degradation, have become a widespread and massive pollutant in the world’s oceans. Despite this resistance, in the environment, larger plastic items fragment and degrade into secondary microplastics which are ingestible by some marine organisms and are therefore a potential threat to aquatic foodwebs. The present study aims to better understand factors that contribute to the weathering of plastics in a coastal marine environment, where most microplastics appear to be generated. 

Here we performed a field experiment to test the influence of different coastal conditions on macro-plastic weathering. Strips of commercial grade high-density polyethylene (HDPE) and polystyrene (PS) were mounted in replicate on racks (similar in appearance to keys on a glockenspiel, though all of the same length) and deployed at different treatment depths (subtidal versus intertidal) and different treatment hydrodynamic intensity zones (erosional versus depositional) in a sub-estuary of Chesapeake Bay (Maryland, USA). Strips were collected after environmental exposure of 4, 8 and 43 weeks and were analyzed for mass loss, surface chlorophyll accumulation, and surface appearance via SEM imaging.

We observed the PS strips degraded more quickly than the HDPE strips. The results show minor mass variation, in some samples even a slight mass increase, contrary to expectation. This was probably due to the deposition of clay and the presence of microorganisms into the microstructure of the strips, as observed by SEM. Moreover, the SEM images show different kind of fragmentation, with holes or with desquamations. The fragmentation was most marked for the PS strips located at intertidal depths caused by a more intense hydrodynamic energy. Finally, an increase over time was observed in the concentration of chlorophyll in both subtidal depositional PS strips and in subtidal erosional HDPE strips, associated with a lower hydrodynamic energy compared to the intertidal zones. This appears to confer a greater protection of the plastic which therefore undergoes less weathering.

How to cite: Rizzo, M., Lane, B., Malkin, S., Vaccaro, C., Simeoni, U., Nardin, W., and Corbau, C.: Macro-plastic weathering in a coastal environment: field experiment in Chesapeake Bay, Maryland, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7442, https://doi.org/10.5194/egusphere-egu2020-7442, 2020.

Plastic contamination of marine beaches, sediments, water is widely reported. It is known that lot of plastic debris appears on marine shores after storms together with natural marine litter, like ragged vegetation, pieces of wood, etc. The goal of our field campaign in the southeastern part of the Baltic Sea was to check whether growing macrophytes also concentrate and retain plastics, particularly that of microplastic (MP, 0.2-5 mm here) size range. Three summer expeditions were conducted (July 30, August 5 and 7, 2019) in sea coastal zone (depth down to 10 m), where communities of attached macroalgae (Furcellaria lumbricalis, Coccotylus truncatus, Polysiphonia fucoides, Cladophora rupestris) are developed on underwater boulders off the Cape Taran. Samples were collected at 8 stations, covering areas with filamentous algae (at depths of 3.2 and 4 m) and with perennial algae furcellaria (depths of 5.6 and 8.2 m). Along with sampling of growing algae (from area 25x25 cm2 in triplicate), a hand pump was used to sample 20-100 liters of sea water from both algae thicket and algae-free water in surrounding area.

The samples were processed and examined in laboratory. Microplastic particles were found in all the collected samples. Preliminary analysis shows 1.3-5.3 times higher microplastic contamination in water samples taken from algae thicket than in samples taken in free water nearby. The majority of microparticles are fibers, mainly colorless and blue, but also red, black, golden, and yellow.

Investigations are supported by the Russian Science Foundation, grant No. 19-17-00041.

How to cite: Chubarenko, I., Esiukova, E., Lobchuk, O., Volodina, A., Kupriyanova, A., and Bukanova, T.: Marine macrophytes retain microplastics, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9473, https://doi.org/10.5194/egusphere-egu2020-9473, 2020.

Plastic pollution of the world’s oceans represents a threat to marine eco-systems and human health and has come under increasing scrutiny from the general public. Today the global input of plastic waste into the oceans is in the order of 10 million tons per year and predicted to rise by an order of magnitude by 2025; much of this plastic ends up on the seafloor. Plastics, and microplastics, are known to be concentrated in submarine canyons due to their proximity to terrestrial plastic sources, i.e. rivers. Plastics are transported in canyons by turbidity currents, mixtures of sediment and water which flow down-canyon due to their density; these flows can also ‘flush’ canyons, eroding and entraining the sediment lining the canyon walls and bottom. A single turbidity current can last for weeks and transport more sediment than the annual flux of all terrestrial rivers combined. Although it is known that these flows play a critical role in delivering terrestrial sediment and organic carbon to the seafloor, their ability to transport and bury plastics is poorly-understood. Using flume experiments we investigate turbidity currents as agents for the transport and burial of microplastic fragments and fibers. Microplastic fragments are focused at the flow base, whereas fibers are more homogeneously distributed throughout the flow. Surprisingly though, the resultant deposits show the opposite trend with fibers having a higher concentration that fragments. We explain this observation with a depositional mechanism whereby fibers are dragged out of suspension by settling sand grains, are trapped in the aggrading sediment bed and are buried in the deposits. Conversely, fragments may remain suspended in the flow and are less likely to be trapped on the bed. Our results suggest that turbidity currents can transport microplastics over long distances across the ocean floor, and that turbidity currents potentially distribute and bury large quantities of microplastics in seafloor sediments.

How to cite: Pohl, F., Eggenhuisen, J., Kane, I., and Clare, M.: Microplastic transport, deposition and burial in seafloor sediments by turbidity currents, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2303, https://doi.org/10.5194/egusphere-egu2020-2303, 2020.

Plastic pollution is a global concern and potential marker of the Anthropocene, yet controls on the environmental fate of this contaminant remain underexplored. Synthetic polymers emitted to aquatic systems undergo chemical, physical and biological forces that affect their weathering, aggregation, degradation, leaching, transport and burial. In the aquatic environment, plastic surfaces attract both biological and mineralogical loading. The presence of biofilm on marine plastics suggests a significant microbial role in the fate of plastic in this new ecological niche, called the Plastisphere. Microorganisms may influence degradation, transport and burial of plastic in the sediment, but also plastic´s incorporation into biogeochemical cycles. Likewise, mineral crystallization on plastic surfaces (i.e., phosphate, iron – rich) induced by microbial processes or formed abiotically may play an important role in plastic aggregation, transport, degradation and burial of meso- to nanoscale size plastics. 

Here, we present our current field and laboratory investigations of biological and mineralogical loading of plastics in various geochemical settings. We combine bioimaging (He-ion microscopy (HIM), Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDS), microbial community and eco-physiology studies, as well as elemental analysis to test mechanisms of loading on plastics, aggregation, transport, and potential impact on element cycling. Results of an on-going in situ study of polystyrene (PS), polyethylene (PE), marine paint, and wood exposed in Svanemøllen Harbor, Copenhagen and laboratory experiments are described. We explore whether surface characteristics and biogeochemical setting are important drivers for the development of mineral-rich biofilm and the role of these mineral-microbe associations in the fate of plastics.

How to cite: Posth, N. R., Carreres Calabuig, J. A., Mueller, S., Rogers, K., and Keulen, N.: The influence of biofilms and mineral loading on marine plastic fate , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21376, https://doi.org/10.5194/egusphere-egu2020-21376, 2020.

A coupled wave and ocean model within the COAWST Modelling System is used in a one-way nesting scenario to investigate the importance of wind, surface currents and Stokes drift for the distribution of surface drifting objects in the nearshore region of the East Frisian barrier island Spiekeroog in the North Sea. Stokes drift and surface currents are computed on a high resolution grid. Combination with meteorological data, Lagrangian floats and in situ data of surface drifters and wave radar measurements allows for a realistic estimation of wind drag coefficients and Stokes Drift. Therefore GPS-Box Drifters have been developed which resemble surface floating macroplastics. Complex topographic features with shallow areas and deep channels within this coastal region lead to strongly heterogeneous wave and current fields. Due to the high resolution of our numerical model these features can be described with the needed accuracy. At the same time computational costs are minimized by using a two-step nesting approach. We show that Stokes Drift becomes a major role in shallow coastal regions, even exceeding the influence of the wind drag, hence playing a key role for realistic descriptions of beaching and the recognition of litter accumulation.

How to cite: Hahner, F., Meyerjürgens, J., Wüllner, T., Lettmann, K. A., Badewien, T., Zielinski, O., and Wolff, J.-O.: Investigating the impact of wind, waves and currents on the distribution of surface drifting particles with drifter data and a high resolution numerical model in the nearshore region, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21417, https://doi.org/10.5194/egusphere-egu2020-21417, 2020.

Ocean surface drift forecasts are essential for numerous applications. It is a central asset in search and rescue and oil spill response operations, but it is also used for predicting the transport of pelagic eggs, larvae and detritus or other organisms and solutes, for evaluating ecological isolation of marine species, for tracking plastic debris, and for environmental planning and management. The accuracy of surface drift forecasts depends to a large extent on the quality of ocean current, wind and waves forecasts, but also on the drift model used. The standard Eulerian leeway drift model used in most operational systems considers near-surface currents provided by the top grid cell of the ocean circulation model and a correction term proportional to the near-surface wind. Such formulation assumes that the 'wind correction term' accounts for many processes including windage, unresolved ocean current vertical shear, and wave-induced drift. However, the latter two processes are not necessarily linearly related to the local wind velocity. We propose three other drift models that attempt to account for the unresolved near-surface current shear by extrapolating the near-surface currents to the surface assuming Ekman dynamics. Among them two models consider explicitly the Stokes drift, one without and the other with a wind correction term. We assess the performance of the drift models using observations from drifting buoys deployed in the Estuary and Gulf of St. Lawrence, Canada. Drift model inputs are obtained from regional atmospheric, ocean circulation, and spectral wave models. The performance of these drift models is evaluated based on a number of error metrics (e.g. speed, direction, separation distance between the observed and simulated positions) and skill scores determined at different lead times ranging from 3h to 72h. Results show that extrapolating the top-layer ocean model currents to the surface assuming Ekman dynamics for the ageostrophic currents, and adding the Stokes drift predicted by a spectral wave model, leads to the best drift forecast skills without the need to include a wind correction term.

How to cite: Tamtare, M. T., Dumont, D., and Chavanne, C.: The Stokes drift in ocean surface drift prediction, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9752, https://doi.org/10.5194/egusphere-egu2020-9752, 2020.

The CleanAtlantic project (http://www.cleanatlantic.eu/) aims to protect biodiversity and ecosystem services in the Atlantic Area by improving knowledge and capabilities to monitor, prevent and remove (macro) marine litter. The project will also contribute to raise awareness and change attitudes among stakeholders. Marine litter originates from diverse sources (land and sea-based origins) and has no frontiers as the coastal and ocean circulation turns it into a transnational issue that demands collaborative work and coordination. The need for transnational consistent approaches is at the heart of the Marine Strategy Framework Directive (MSFD) implementation, which requires consistency in terms of marine litter assessment, monitoring and development of programme of measures. This modeling objective, within the CleanAtlantic project, is fully aligned with the collective action nº55 of the OSPAR Regional Plan, which aims to develop sub-regional or regional maps of hotspots of floating litter. These maps will be based on mapping of circulation of floating masses of marine litter, identification of hotspots of accumulation on coastal areas and the role of prevailing currents and winds. The biggest challenge to marine litter modeling is the heterogeneity of the actual litter particles spanning a wide range of different physical properties such as size, density or shape, among others. This, together with a strong interaction with the medium, through processes such as degradation, sinking, beaching, etc and an inherent sensitiveness to initial conditions due to chaotic advection by ocean currents, the effect of wind and waves and the necessary time and space scales to resolve ocean transport, shows how intricate marine litter modeling can be. The number of free parameters, absence of well-known initial conditions and precise equations set to describe all the processes involved require the use large ensembles of simulations to explore a range of possible scenarios, in order to derive useful information about the motion of marine litter.  As part of the project, the MARETEC modeling group at the Instituto Superior Técnico – Universidade de Lisboa in collaboration with the University of Santiago de Compostela, developed a Lagrangian transport model, MOHID Lagrangian. This tool can be applied to forecast the formation of retention areas (hotspots) with the highest probability for litter accumulation in any particular region. The abilities of this open-source lagrangian tool include its easy implementation, robustness, computing efficiency being able to simulate millions of particles in short times, the capacity to use any Eulerian circulation fields from other models, as well as the ability to simulate different types of lagrangian particles. The capabilities of the models to predict the origin of marine litter accumulated on the seafloor and coastal areas were assessed and the connection of major rivers with sinks of marine litter during heavy raining conditions was studied. When appropriate, models were calibrated by matching real and predicted marine litter accumulations locations on the shoreline. The area of influence of land and sea-based marine litter sources was assessed and different scenarios of mitigation measures will be evaluated.

How to cite: de Pablo, H., Garaboa-Paz, D., Canelas, R., Campuzano, F., and Neves, R.: MOHID-Lagrangian: A lagrangian transport model from local to globals scales. Applications to the marine litter problem., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21895, https://doi.org/10.5194/egusphere-egu2020-21895, 2020.

The 3D dispersion of marine litter (ML) over the Mediterranean basin has been simulated using the current fields from a very high resolution regional circulation model (RCM) as a base to run a 3D lagrangian model. Three simulations have been carried out to mimic the evolution of ML with density lower, in the range of, or higher than seawater. In all cases a realistic distribution of ML sources has been used. Our results show that the accumulation/dispersion areas of the floating and buoyancy neutral particles are practically the same, although in the latter the particles are distributed in the water column with 90% of the particles inside the photic layer. Regarding to the denser particles, they rapidly sink and reach the seafloor close to their origin. The analysis of the temporal variability of the ML concentration shows that the regions of higher variability mostly coincide with the accumulation regions. Seasonal variability occurs at a sub-basin scale as a result of the particles redistribution induced by the seasonal variability of the current field. The comparison with previous studies suggests that the accuracy of numerical studies is strongly dependent on the quality of the information about ML sources, and to the modelling strategy adopted. Finally, our results can be used to guide the design of effective observational sampling strategies to estimate the actual ML concentrations in the Mediterranean.

How to cite: Soto-Navarro, J., Jordá, G., Deudero, S., Compa, M., Alomar, C., and Amores, Á.: 3D hotspots of marine litter in the Mediterranean: a modeling study, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4795, https://doi.org/10.5194/egusphere-egu2020-4795, 2020.

Ocean plastic debris poses a large threat to the marine environment. Millions of tons of plastic end up in the ocean each year and the Mediterranean Sea is one of the most plastic polluted sea. Ocean plastic particles are typically covered with microbial biofilms, but it remains unclear if different polymer types are colonized by different communities. Knowledge in this aspect strengthens our understanding if microbes purely use plastic debris as attachment surface or if they may even contribute to the degradation of plastic. To gain a better understanding of the composition and structure of biofilms on micro plastic particles (MP) in the Mediterranean Sea, we analyzed microbial community covering floating MP in a bay/marina (Marina di Campo) on the island of Elba. MPs were collected with a plankton net (mesh size 50µm), fixed for fluorescence microscopy and stored for subsequent DNA extraction, and identification of the polymer with Raman spectroscopy. The particles were mainly comprised of polyethylene (PE), polypropylene (PP) and polystyrene (PS) and were often brittle and with cracks (PE, PP) and showed visual signs of biofouling (PE, PP, PS). Fluorescence in situ hybridization and imaging by high resolution confocal laser scanning microscopy of single MPs revealed high densities of colonization by microbes. 16S rRNA gene amplicon sequencing (Illumina Miseq) revealed higher abundance of archaeal sequences on PS (up to 29% of the reads) in comparison to PE or PP (up to 3% of the reads).  The bacterial community in the biofilms on each of the three plastic types consisted mainly of the orders Flavobacteriales, Rickettsiales, Alteromonadales, Cytophagales, Rhodobacterales and Oceanospirillales. Furthermore, we found significant difference in the community composition of biofilms on PE compared to PP and PS but not between PP and PS. The indicator species on PE were Calditrichales, detected at 10 times higher sequence abundance on PE than on PP and PS, as well as several uncultured orders. This study sheds light on preferential microbial attachment and biofilm formation on microplastic particles, yet it remains to be revealed, whether and which of these may contribute to plastic degradation.

How to cite: Vaksmaa, A., Knittel, K., Abdala Asbun, A., Goudriaan, M., Ellrott, A., Witte, H., and Niemann, H.: Differential microbial colonization on microplastic in the Mediterranean Sea coastal zone, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7975, https://doi.org/10.5194/egusphere-egu2020-7975, 2020.

The initial conditions of marine litter transport models continue to be one of the big handicaps to produce accurate results to obtain useful information for stakeholders. The amount and the type of marine debris emitted by the different sources introduces a huge uncertainty.

In marine local environments under industrial activity, the sources are confined in space and time and some industrial activities introduce particular debris objects. This allows us to reduce the uncertainties mentioned above in the marine litter modelling problem. 

One of these activities is the mussel aquiculture. In Galicia (NW Spain), the mussel farms (Fig.(1)) are based in floating rafts inside the rias(estuaries), with vertical ropes submerged where the mussels are attached to grow up. To avoid the mussel detachment, plastic sticks called mussel pegs or stoppers with a length of 22 cm and a width of 2 cm on average are used (Fig. (2)). These mussel pegs can be lost when the mussel extracting activity takes place. There are estimations of lost around 3 million units per year due to this activity.

The CleanAtlantic project (http://www.cleanatlantic.eu/) aims to protect biodiversity and ecosystem services in the Atlantic Area by improving knowledge and capabilities to monitor, prevent and remove (macro) marine litter. In the scope of this project, we will focus on the modelling of floating mussel pegs lost by mussel farm activity in Ría de Arousa, in the region of Galicia (northwest of Spain).

To that end, we use the met-ocean operational model data from Meteogalicia to perform Lagrangian simulations with MOHID-Lagrangian transport model to obtain concentrations of mussel pegs and the probability maps on surrounding areas inside the Ría de Arousa for the years 2018-2019. Also, we analyze the impact of the different met-ocean conditions in the beaching and coastal accumulation.

Finally, we validate the results with real data obtained from clean beaches surveys from beaches inside the ría during 2018 and 2019.

How to cite: Garaboa-Paz, D., Cloux-González, S., Montero-Vilar, P., and Pérez-Muñuzuri, V.: Marine litter in local environments from mussel aquiculture activities: modelling and validation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19500, https://doi.org/10.5194/egusphere-egu2020-19500, 2020.

Marine plastic pollution has been recognized as a serious issue of global concern with substantial risks for marine ecosystems, fisheries, and food supply to people. Yet, the amount of plastic entering the ocean from land and rivers is barely understood. Currently, estimates exist for the coastal plastic input in the year 2010 on country-level resolution and for riverine plastic input for the year 2017. Key limitations are the restricted data availability on plastic waste production, waste collection and waste management. In addition, the transport of mismanaged plastic via wind and rivers is currently not well understood.

We present a model to estimate the global plastic input to the ocean for the years 1990-2015 on a 0.1x0.1° raster. To this end, we first train a machine learning model (random forests) and a linear mixed model to predict plastic waste production on country level, using data of municipal waste collection and several socio-economic predictor variables. We then estimate the amount of plastic waste that enters the environment, using high resolution population data and waste management data of each country. This is combined with distance-based probabilities of land and river transport to obtain the annual amount of plastic entering the ocean on a 0.1x0.1° spatial resolution. Our results indicate that global plastic waste production increased roughly linearly between 1990 to 2015. However, estimating the amount of mismanaged waste and the subsequent transport towards the ocean is afflicted with high uncertainties.

We then use the estimated plastic input into the ocean to force several Lagrangian model runs. These Lagrangian simulations include different parameterizations of plastic beaching, in particular they vary in terms of the beaching probabilities and the assumed residence time of plastic on beaches. We present the global distribution of beached plastic and the size of the reservoir of beached plastic in these model scenarios.

How to cite: Laufkoetter, C., Lang, K., Benedetti, F., Onink, V., and Vogt, M.: Marine plastic waste input between 1990-2015 and potential beaching scenarios, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18476, https://doi.org/10.5194/egusphere-egu2020-18476, 2020.