In this work we analyze how seasonal production and degradation of organic matter, and corresponding changes in the plankton ecosystem affect microplastics (MP) density and ability for transportation and burying in sediments. This is simulated with a coupled hydrodynamical-biogeochemical model that provides a baseline scenario of the seasonal changes in the planktonic ecosystem and changes in the availability of particulate and dissolved organic matter. We use a biogeochemical model OxyDep that simulates seasonal changes of phytoplankton (PHY), zooplankton (HET), dissolved organic matter (DOM) and detritus (POM). A specifically designed MP module BioPlast considers MP particles as free particles, particles with biofouling, particles consumed by zooplankton and particles in detritus, including fecal pellets. A 2D coupled benthic-pelagic vertical transport model 2DBP was applied to study the effect of seasonality on lateral transport of MP and its burying in the sediments. OxyDep and MP modules were coupled with 2DBP using Framework for Aquatic Biogeochemical Modelling (FABM). The model was applied to numerically predict the spatial distribution of MP in the water column and sediments after being discharged into the aquatic environment. We have used documented concentrations of MP (fibres) in the treated wastewater from a large wastewater treatment plant with discharge to the Bekkelaget basin in the Inner Oslofjord, Norway. Numerical experiments confirm, that biogeochemical cycling leads to seasonality in the vertical and horizontal transport of MP of neutral buoyancy from its source, with higher accumulation in the sediment during the summer-autumn period, while cleaning of the upper water layers resembles the winter period. That means that MP of neutral buoyancy could be transported to a smaller distance in summer, compared with winter. Transport of light density floating MP into the deep layers and the sediments can be explained by influence of biogeochemical processes. High density MPs are affected by the biogeochemical processes to a very small degree and tend to accumulate in the sediments close to the source point. Thus, we confirm that the “biological pump” can be one of the important drivers controlling the quantity and the distribution of MP in the water column. The biological pump can deplete MP from the surface water and accelerate MP burying in summer period compared to the winter.

The reported study was funded by RFBR according to the research project № 20-35-90056.

How to cite: Berezina, A. and Yakushev, E.: Modeling the influence of biogeochemical and ecosystem processes on microplastics transport, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-70, https://doi.org/10.5194/egusphere-egu22-70, 2022.

Among other marine environmental problems, the issue of marine litter accumulation in the World Oceans is of increased interest. It is relevant not only in areas with direct intense anthropogenic pressure, but also in remote and presumably pristine areas, such as the Arctic Sea. As the concentration of plastic waste in the marine environment increases, it can have impacts on various components of the marine ecosystem, at sea, on the seafloor, on the coasts and in particular in accumulation areas, while it also can negatively affect human social and economic activities. To reduce the release of plastic debris into the marine environment, litter occurrence and pathways need to be studied in order to identify litter sources, requiring monitoring studies that provide comparable results. Here we present the results of studies of the level of pollution by floating marine debris carried out using ship-based visual observations through a harmonised methodology, developed to obtain comparable data. The observations were carried out in the White Sea, Barents Sea and the Kara Seas during a research cruise of the Floating University project by the Shirshov Institute of Oceanology Russian Academy of Sciences in 2021. The studies included training and involvement of a large number of students as observers. Floating macro litter was observed in all study areas along the vessel’s route. In total 2500 km route and 19,8 km² were covered with observations. The concentration of litter varied on observed transects from 0 to 226 items/km², with a mean value of 10.1 items/km². 95% of registered items were made of plastic, the most common were unidentified, weathered plastic objects that could indicate the long presence of litter items in the environment. 

How to cite: Pogojeva, M., Novikov, M., Zhdanov, I., Berezina, A., Evenkova, T., Gettih, N., Likhacheva, G., Lepikhina, P., Osadchiev, A., Hanke, G., and Yakushev, E.: Floating marine macro litter distribution in White, Barents and Kara seas in 2021, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-469, https://doi.org/10.5194/egusphere-egu22-469, 2022.

In the frame of the MONGOOS-REMPEC agreement aiming to provide oil spill predictions in causes of major pollution incidents in the Mediterranean Sea, CMCC, ORION and Orbital EOS provided on a voluntary basis daily oil spill predictions based on satellite remote sensing data, following the large Syrian pollution crisis lasted from 23 August to 12 September 2021. As it was reported by REMPEC a total of 12,000 tons of crude oil was spilled in the NE Levantine Basin, at around 10:00 UTC on the 23 August from the fuel tanks of the Baniyas power station in Syria.The current pollution incident is of the same order of magnitude in terms of the amount of the oil spilled at sea from a similar source type, as the one caused during the Lebanon oil pollution crisis in July 2006.

The MEDESS4MS multi-oil spill modeling approach was applied, using the different resolution met-ocean forecasting data and two oil spill models. In the Syrian pollution crisis,met-ocean forecasting data from CMEMS Med MFC and ECMWF, CYCOFOS and SKIRON systems were used, as well as the well established MEDSLIK and MEDSLIK-II oil spill models. Moreover, the 27 satellite-derived SAR and optical images provided by the 7 surveillance satellites were processed in order to initiate the oil spill modeling predictions.

After the spillage, the oil was washed up on the Syrian coast at the higher concentration along the southern coast of Latakia. Part of the remained sea surface emulsified oil, which was identified as a thick oil (>0.1 mm) oil, was transferred offshore westward and it was widely spread in the NE Levantine between Syria and Cyprus, threatening the most eastern tip of Cyprus. The fast westward movement of the spill was due to the westward strong sea current generated along the southern and northern periphery of the anticyclone and cyclone eddies, respectively. Further on, the emulsified oil mostly was re-circulated by the anticyclone eddy, where part of the oil was re-landed at the Syrian coast and part of it was beached on the Turkish coast near Samandağ, under the increased southerly wind force. After the 6^th September the emulsified thin sheen oil was progressively dispersed under the increase of the wind-wave action.

The operational response of the MONGOOS members during the Syrian oil pollution crisis that threatened also the neighboring countries in the NE Levantine, demonstrate a best real practice within the broader context of the operational oceanography developments in the Mediterranean, the usefulness of the down streaming applications to the local and regional response agencies to support their decisions during major oil pollution incidents.

How to cite: Zodiatis, G., Coppini, G., Peña, J., Benjumeda, P., Sepp-Neves, A. A., Lardner, R., Liubartseva, S., Soloviev, D., Scuro, M., and Viola, F.: Operational response to the Syrian oil pollution crisis in 2021, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1098, https://doi.org/10.5194/egusphere-egu22-1098, 2022.

Microplastics were defined as plastics that measure less than 5 mm and have strong hydrophobicity, small particle sizes, and large specific surface areas. Microplastics can serve as a carrier of heavy metals and a potential hazard in the ecosystem by biological accumulation. This study investigated the adsorption characteristics of chromium (Cr) and lead (Pb) onto microplastics based on various particle sizes. The high-density polyethylene (HDPE) was categorized into three particle size ranges (2.5 – 1 mm, 1 – 0.3 mm, and less than 0.3 mm), and batch adsorption tests were conducted with five different concentrations (0, 0.5, 1, 10, and 30 mg/L) of Cr and Pb solutions. In this study, the adsorption behaviors of Cr and Pb on all three particle sizes of HDPE were more suitable for the Langmuir model (R² > 0.99) than the Freundlich model (R² > 0.90). The maximum adsorption amount of Cr and Pb on HDPE (Q_m = 0.09 mg/g for Cr and 0.05 mg/g for Pb) was found in the size of less than 0.3 mm, indicating that the high specific surface area may affect adsorption capacities. For three different particle sizes, the adsorption of Pb on HDPE was higher than that of Cr. This result could be attributed to the higher adsorption binding strength of Pb (1.04) on the surface of HDPE than that of Cr (0.06) due to the larger ionic radius and higher electronegativity of Pb²⁺ than those of Cr⁶⁺.

How to cite: Ha, T., Park, S., and Yang, M.: The adsorption characteristics of Cr and Pb by various particle sizes of microplastics high-density polyethylene (HDPE), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1582, https://doi.org/10.5194/egusphere-egu22-1582, 2022.

In the framework of the Mediterranean Operational Network for the Global Ocean Observing System (MONGOOS), an oil spill modeling team supported the Regional Marine Pollution Emergency Response Centre for the Mediterranean Sea (REMPEC) to simulate the transport of hydrocarbons at sea and to assess the potential impact to neighbouring countries during an oil pollution incident reported in the second half of February 2021. The oil pollution incident constituted a large amount of tar balls, which were landed on the beaches of Israel, Lebanon and Gaza Strip following an offshore oil spill.

Two oil spill models were simultaneously run: MEDSLIK and MEDSLIK-II (Zodiatis et al., 2021). MEDSLIK was forced by the 6-hour Cyprus Coastal Ocean Forecasting and Observing System (CYCOFOS) currents and sea surface temperature with a horizontal resolution of 2 km, the hourly SKIRON’s winds and waves at a horizontal resolution of 5 km. MEDSLIK-II used the 6-hour wind datasets provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) at ~12.5 km horizontal resolution, and the oceanographic fields (currents and SST) produced by the Copernicus Marine Environment Monitoring Service (CMEMS) at a horizontal resolution of ~4 km. The Stokes drift was parameterized by JONSWAP.

Interestingly, the spill was not detected at early stages of its development. Therefore, the model results were compared with the coastline distribution of the accumulated oil represented by Israeli authority as a map of "Coastal Traffic Light". The map showed that the length of the affected coast was approximately 160 km with three distinct clusters located: (1) just south of Haifa; (2) near Nahariyya in the north of Israel; and (3) near Bat Yam in the south of Tel Aviv.

Preliminary MEDSLIK and MEDSLIK-II results showed reasonable level of consistency indicating the cluster between Haifa and Atlit. However, the other two clusters remained to be unpredicted by both models, despite the fact that the models predicted lower level of concentration on the coast of these two areas. Moreover, instead of the oil beaching onto the Lebanese coast, MEDSLIK-II predicted trapping the slick by the Shikmona gyre.

Although further usage of the updated satellite-derived polygons as the initial conditions allowed both models to improve their performances, the drift of tar balls in the coastal area and the map of "Coastal Traffic Light" could not to be represented with high precision.

Evidence from an investigation by the Israeli Environmental Protection Ministry has shown that the reason for observational and modeling problems could be related to the uncertainties in the early stage of the slick development. As the spilled oil aged, the formation of tar balls complicated both the satellite-derived detection and modeling the spill.

Reference

Zodiatis, G., Lardner, R., Spanoudaki, K., Sofianos, S., Radhakrishnan, H., Coppini, G., Liubartseva, S., Kampanis, N., Krokos, G., Hoteit, I., Tintore, J., Eremina, T., Drago, A., 2021. Operational oil spill modelling assessments. In “Marine hydrocarbon sill assessments. From baseline information through to decision support tools”. Edited by Makarynskyy O. pp. 145–194. ELSEVIER ISBN: 978-0-12-819354-9 https://doi.org/10.1016/B978-0-12-819354-9.00010-7 

How to cite: Liubartseva, S., Zodiatis, G., Coppini, G., Sepp Neves, A. A., Peña, J., Benjumeda, P., Lecci, R., and Soloviev, D.: Operational simulations of a Mediterranean oil spill in February 2021, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2276, https://doi.org/10.5194/egusphere-egu22-2276, 2022.

Massive plastic production has resulted in billions of tons of plastic material in landfills and the natural environment. A large portion of it ends up in the marine environment, with some of the most frequent and ubiquitous forms of plastics being cotton bud sticks, cigarette filters and plastic pellets. The enclosed character of Adriatic Sea results in substantial accumulation and plastic pollution, and plastic litter has been reported on beaches, seafloor and sea surface. Under certain physical and chemical conditions, marine (micro)plastics has the ability to adsorb different organic and inorganic matter, including potentially toxic trace metals. It becomes a vector for transport and contributes to the accumulation of trace metals, especially in the coastal areas. In order to evaluate the mass fractions of trace metals (Cd, Cu, Pb, Zn, Ni and Co) three types of the above mentioned plastic products were collected from the beached material in three geographically and antropogenically different areas of the eastern Adriatic sea coast, the Lastovo Islands Nature Park (southern Adriatic), and two enclosed and anthropogenically affected zones (middle Adriatic), Kaštela bay and the River Krka estuary (Port of Šibenik). Trace metal amounts on plastic particles and its concentrations in seawater samples were determined using differential pulse anodic stripping voltammetry (DPASV) by Metrohm Autolab modular potentiostat/galvanostat Autolab PGSTAT204, connected with a three-electrode system Metrohm 663 VA STAND. Working electrode used was static mercury drop electrode (SMDE).

The mass fraction of metals from plastic pellets and cigarette filters is similar to those found in literature, as for the cotton bud sticks, to our knowledge, it has not been reported so far. The highest amount of most metals (Zn, Cd, Pb, Cu)  was found on cigarette filters, possible due to its high porosity. Kaštela Bay, as a home of former chloralkali plant, was a source of the highest amount of adsorbed metals (Pb, Cu, Ni, Co). Zn, as the most abundant in seawater of all measured metals, was also present in the highest amounts on all plastic surfaces. The concentration factors for all metals except Ni were highest for filters compared to other materials, for most metals in the River Krka estuary, and for Cu in the Kaštela bay. The cotton bud sticks from Kaštela Bay showed highest concentration factor for Ni. There are numerous factors and processes influencing interaction between metal ions and microplastics, from seawater chemistry to characteristics of plastic materials including biofouling and degradation rate. Further research is required for better understanding of this interaction in different aquatic environments.

This research has been fully supported by Croatian Science Foundation under the project lP-2019-04-5832. Work of doctoral student, Ana Rapljenović, has been co-funded by Croatian Science Foundation under the “Young Researchers’ Career Development Project - Training New Doctoral Students”.

How to cite: Rapljenović, A. and Cuculić, V.: Comparison of the trace metals mass fractions adsorbed on the beached plastic litter: different ubiquitous items of every day use, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4329, https://doi.org/10.5194/egusphere-egu22-4329, 2022.

The “missing plastic” phenomenon remains, whereby the transport and ultimate fate of microplastics in aquatic environments is mostly unknown. Marine plastic pollution mainly originates from terrestrial sources and upon reaching coastal zones interacts with nearshore ecosystems. Coral reefs in coastal areas are likely exposed to microplastics, especially shallow reefs at low tides, yet the interactions between microplastics and corals are largely unexplored. Reefs can form extremely complex canopies that can trap sediment, and likely act as a sink for microplastic pollution through serval ways: acting as a physical barrier, modifying turbulence and depositional processes, or through incorporation within coral tissue and skeletons. Given reefs form the foundation of highly biodiverse ecosystems, the entrapment of microplastics by coral would possibly increase ingestion by, and physiological damage to, corals and other reef organisms. The broader ecological impact may be considerable, as well as the repercussions for associated ecosystems services for hundreds of millions of people. Furthermore, the impacts of climate change and rising sea temperatures may be accentuated. Despite the growing concern of these consequences and field measurements revealing accumulation in a variety of aquatic canopies, the transport and dispositional processes that drive microplastic trapping in coral canopies is barely understood.

Here, we investigated for the first time the prevalence of microplastic retention by branching coral canopies in a hydraulic flume under several unidirectional flow conditions. Coral colonies were created using 3D-printed models of staghorn coral, Acropora genus, an important reef building species found globally. A set weight of microplastics (biofilmed ground melamine, density 1.6 g/cm³) was released into canopies that represented recovering and healthy reefs to determine entrapment efficiency. Overhead and side cameras tracked microplastic distribution and trapping mechanisms. Furthermore, complimentary flow velocity profiles were acquired to understand the relationships between the canopy hydrodynamics and microplastic distribution. Our results provide an insight into microplastic transport dynamics and entrapment mechanisms within coral canopies. Results show that even sparse reefs may be vulnerable to notable microplastic trapping. The results provide insight that support the conjecture that canopies may act as a global sink for microplastic pollution. Further investigation is required in the exposure of these ecosystems to microplastics and impacts on the wider ecological system health, function, and potential subsequent transfer through food webs.

How to cite: Mendrik, F., Houseago, R., Waller, C., Hackney, C., and Parsons, D.: Transport and trapping in complex aquatic canopies: how do coral reefs act as sinks for microplastics?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4646, https://doi.org/10.5194/egusphere-egu22-4646, 2022.

Estimates of plastic quantities entering our oceans are not yet consistent with observed concentrations in the marine environment. This has led to the often-quoted statement that 99% of the marine plastics are missing. Here, we present a framework where the global transport of marine plastics is modelled over long time scales, in which the effects of different sources and sinks is investigated. Data assimilation techniques are used to inform unknown parameters regarding these sources and sinks, enabling us to quantify their role on the global plastic mass budget.

State-of-the-art numerical models are included in the framework to capture for the first time the combined effect of marine plastic beaching, resuspension, biofouling, turbulent mixing, and fragmentation. The relative importance of different marine plastic sources is investigated, such as mismanaged coastal plastic waste, riverine outflow, and fishing activity. Unknown parameters are found by means of calibration to a large set of observational data of plastic concentrations in the ocean surface water, water column, ocean floor, and on coastlines.

We show that with this framework, the global marine plastic mass budget can be closed. An overview is given of which environmental reservoirs are likely to contain most of the plastic mass, which sources are contributing to most of the pollution, and what the residence times of litter in the marine environment is. With the model calibration approach, we additionally get a better insight in the physics governing the transport of marine litter. 

How to cite: Kaandorp, M., Lobelle, D., Kehl, C., and van Sebille, E.: A global 3D map of marine plastic litter: a data assimilated modelling framework  , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5680, https://doi.org/10.5194/egusphere-egu22-5680, 2022.

One of the major knowledge gaps in the study of plastic pollution is the understanding of residence times of these anthropogenic particles once they reach our oceans. Observations report a mismatch between estimates of plastic loads from worldwide plastic production and mismanaged plastic waste and actual plastic concentration seen floating at the sea-surface. Surveys of the water column -from the surface to the deep sea- are rare. Most of the recent efforts have thus addressed this question with modeling approaches or laboratory experiments that individuate in biofouling an important factor for the removal efficiency of plastics at sea and a likely explanation for the “missing plastic”. For the first time, we provide in-situ measured fluxes and removal rates of microplastics using deployments of drifting sediment traps in the North Atlantic Gyre from 50 m down to 600 m depth. We identified and quantified plastic contents with two different analytical approaches, FTIR and Py-GC/MS to determine polymer mass and particle distribution over depth.  From derived data, interaction with biogenic polymers and thus particles transfer from the surface to the deep ocean are reconstructed. These findings shed a light on important pathways that regulate microplastics fate in marine ecosystems, from possible harmful repercussions on marine biota to impacts on fundamentals elements cycles.

How to cite: Galgani, L., Schulz-Böttcher, B., Gossman, I., Liu, Z., Jiang, X., Scheidemann, L., Schlundt, C., and Engel, A.: Biogenic polymers aggregation drives the export and vertical dynamics of small microplastics in the North Atlantic Gyre , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6220, https://doi.org/10.5194/egusphere-egu22-6220, 2022.

As microplastics are being discovered on every corner of the earth, it is imperative to understand how they get there. Modeling capabilities of both the hydrodynamic processes and particle behavior are improving, but it remains expensive to collect and identify microplastics in coastal settings. This highlights the need for and potential of accurate marine debris models. This project compares microplastic deposition field measurements and model predictions on the New Jersey, USA coastline. The objective is to better understand the primary hydrodynamic forcing mechanisms of marine debris. Here, we test the hypothesis that the ability of the model to capture the longshore distribution of microplastic deposition is sensitive to hydrodynamic conditions, particle density, source location(s), and beaching and resuspension rates.

We created a regional hydrodynamic model in Delft3D of the New Jersey coastline from back bay river mouths to 50km offshore, using tidal, wind, wave, and river discharge conditions from 2016. We ran the model from January 1st, 2016 until December 31st 2016 to capture the seasonality of the flow and wind conditions. We used the Delft3D particle tracking module to insert particles with properties (e.g. particle density, horizontal diffusivity, and beaching probability) defined to best represent the behavior of microplastic particles and monitor their transport and fate. To assess the ability of a regional hydrodynamic model paired with a particle tracking module, 28 beaches were selected from the New Jersey coastline and sampled for microplastics (1-5mm) using methods similar to the US Environmental Protection Agency’s Microplastic Beach Protocol that detail consistent and characteristic microplastic measurement techniques of sandy beaches. The same sites were measured once in the winter of 2020/2021 and again in summer 2021 in an effort to capture the different seasonal flow regimes of the Mid-Atlantic coast. 

Here, we show the comparison between the predicted microplastic deposition on the New Jersey coastline to the measured microplastic distribution for both the summer and winter. We assess the ability of the model to predict transport and deposition of various types and densities of microplastic debris. We illustrate the power that particle tracking models have to capture the transport and fate of microplastic debris and highlight the limitations of such models that need to be addressed. Further, we discuss the importance of predictive microplastic models for targeting specific geographical regions for cleanup and mitigation efforts. 

How to cite: McCormack, T., Sherman, A., Watkins, L., Obando, F., and Hopkins, J.: Evaluation of Delft3d Microplastic Model of the Mid-Atlantic New Jersey Coast Using Summer and Winter Field Measurements, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6655, https://doi.org/10.5194/egusphere-egu22-6655, 2022.

The pollution of the seas and oceans due to plastic waste has become one of the environmental problems that generate the most concern, both for the scientific community and for society as a whole. In that framework, marine litter (ML) forecasting systems are potentially a powerful tool for an efficient management of ML, to optimize the removal strategies  and/or to better characterize the ML distribution. ML forecasting systems are typically based on explicit numerical models which simulate ocean currents and, afterwards, the advection and diffusion of passive particles in the ocean that mimic the evolution of ML. This approach is considered to be the most accurate one, at least as accurate as the quality of the forcing and the initial conditions are. However the downside is that this approach involves a high technical complexity and computational cost. In order to overcome those limitations we propose to explore a new approach implementing a fast and light forecasting system based on the analogue downscaling method. The main idea is to use statistical properties of the ML concentration fields, and the relationship between those fields and the state of the atmosphere to produce ML forecasts from atmospheric forecasts, which are readily available by several meteorological services. As this is a new approach never tested before for ML concentration forecasts, the first step will be to run several tests to fine-tune the methodology and to characterize its limits of validity.

Our results show that the analog-based forecast method presented here has potential to become a suitable cost effective forecasting method for ML concentration. The quality of the forecasts depends on the region of application: the larger the region of application the better, as we get better results for the whole Mediterranean or for the East/West basins than in smaller local areas. The method struggles to capture the extreme values as it produces smooth spatio-temporal patterns of ML concentration. Therefore, in locations or regions where short intense events or small scale features dominate the variability, the method performs worse. On the other hand, if instead of the time variability, what are aimed at are the spatial structures, the method shows high skills.

How to cite: Jordà, G. and Soto-Navarro, J.: An analogue based forecasting system for Mediterranean marine litter concentration, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7267, https://doi.org/10.5194/egusphere-egu22-7267, 2022.

Although most oil spill accidents occur at the sea surface, the growing offshore oil exploration activities increase the likelihood of subsurface releases. In this context, it is necessary to develop a subsurface oil spill model to forecast the oil transport in the water column and to prepare the response once the oil reaches the coasts and the surface. The novelty is to combine this buoyant plume model with realistic subsurface currents and ocean density fields and compare the results with idealized conditions.  The model will be combined later with a community oil spill model Medslik-II (http://www.medslik-ii.org).

Following the literature (1,2), a 3D model of a buoyant jet/plume is developed, which simulates the key processes in the nearfield approximation. Turbulent entrainment of ambient water (both through forced and shear fluxes), dissolution and turbulent diffusion of oil droplets and gas bubbles are realistically represented. The used ambient oceanographic fields are provided by the Monitoring and Forecasting Centre (MED-MFC) of the Copernicus Marine Service. These fields, in particular water density and current velocity, directly control the evolution of the plume in time. In the model, there are options to simulate both oil and oil/gas mixture discharges. Additionally, it is possible to compute instantaneous and continuous subsurface releases.

The model is validated with a unique DeepSpill field experiment conducted in the North Sea with the release of oil and gas (3,4,5).

References

[1] J. H. W. Lee and V. Cheung, Generalized Lagrangian model for buoyant jets in current, Journal of Environmental Engineering, ASCE, 116, (6), 1085-1105, 1990.

[2] P. D. Yapa and L. Zheng, Simulation of oil spills from underwater accidents I: Model development, Journal of Hydraulic Research, 35 (5), 673-688, 1997.

[3] P. D. Yapa, L. Zheng, K. Nakata, Modeling Underwater Oil/Gas Jets and Plumes, Journal of Hydraulic Engineering, 125, (5), 1999.

[4] P. D. Yapa, H. Xie, Modeling Underwater Oil/Gas Jets and Plumes: Comparison with Field Data, Journal of Hydraulic Engineering, 128, (9), 2002.

[5] H. Rye, P. J. Brandvik, T. Strøm, Subsurface blowouts: Results from field experiments, SpillScience and Technology Bulletin, 4, (4), 1997.

How to cite: Gronchi, G., Pinardi, N., Coppini, G., Liubartseva, S., and Sepp Neves, A.: Preliminary model results for subsurface oil and gas release, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7607, https://doi.org/10.5194/egusphere-egu22-7607, 2022.

Every aspects of a hydrocarbon release in deep waters are accompanied by uncertainties. Theses releases can occur from leaking wrecks, pipeline ruptures, or even blowouts. As the most catastrophic event, the blowout (subsequent to the total loss of control of the well head) lead to a massive release of hydrocarbons in the water column which can drastically impact the ecosystem for a long time frame. When this event happens in deep sea, such as in DeepWater Horizon in 2010, subsea application of dispersant can be employed to reduce the surfacing amount of oil. This technics have several benefits as it limits the risks incurred by workers above the well by reducing the volatile organic component concentrations. In addition, dispersant volumes can be lessen by a factor 5 and the application of dispersant can be carried out 24/7 even under harsh conditions. With the addition of dispersant, the oil behavior in the water column is notably modified and many questions remain concerning the fate of the dispersed oil.

Acquiring data in deep waters is very challenging. In order to better understand the action of dispersant on oil we used the CEC (Cedre Experimental Column), an original tool developed at Cedre to study the behavior of substances in the water column. In this study, pilot-scale experiments were carried on using different ratios of oil/dispersant. Thanks to shadowgraph imaging method, set up with the use of two high speed cameras at different heights in the water column, processing the data acquired on the shape and sizes of oil droplets allow to assess how the droplets evolve after their formation.  

The results obtained show substantial differences in term of behavior between the different ratios of oil/dispersant tested. The tip-streaming phenomenon, known to take place in fluids with a low interfacial tension and a sufficiently high viscosity, was clearly identified. In addition, for each oil/dispersant ratio we were able to assess some characteristics of the plume and its evolution in the water column. Data collected from these experiments can be compared to field data and then, could be integrated to the validation process of modeling softwares.

How to cite: Le Bihan, T., Giraud, W., and Le Floch, S.: Subsea Dispersant Injection: How to Assess Oil Droplets Behavior in the Water Column from Pilot-Scale Experiments, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7911, https://doi.org/10.5194/egusphere-egu22-7911, 2022.

Release of volatile Hazard Noxious Substances (HNS) at sea can lead to the formation of toxic, flammable or even explosive gas plumes that can travel large distances and pose risks over a wide area in relatively short timescales.

Yet, when an emergency is declared, key information is not always available for all the needs of responders. A case in point is the lack of knowledge and data to assess the risks that responders or rescue teams could take when intervening, or those that could impact coastal communities when allowing a shipping casualty to dock at a place of refuge. Evidence-based decisions are thus needed to inform maritime authorities in terms of detection and monitoring in order to protect crews, responders, coastal populations as well as the environment.

When maritime accidents occur, knowledge about any chemical released in open sea (e.g. physical and chemical properties and behaviour in the environment) is essential to predict potential environmental consequences and to adapt first-response. For light chemicals, one critical parameter that should be systematically predicted and/or assessed is the evaporation kinetics: this would warn first-responders against toxic or explosive gas clouds that might originate from the surface slick. The MANIFESTS project aims to address these knowledge gaps by developing modelling tools and providing new experimental data on evaporation and dissolution kinetics of volatile HNS as well as gas cloud fate^[1].

Here we present new experimental data obtained at lab-scale on the evaporation kinetics of 6 pure chemicals along with 7 liquid mixtures. The final objective is to assess mass fluxes at the sea-air interface due to evaporation process and to compare it to analytical models. The chemicals studied included acrylonitrile, aqueous ammonia, cyclohexane, petroleum benzine and vinyl acetate. They were chosen to reflect key groups of HNS routinely carried at sea or reportedly involved in spills. Liquid samples of 2-5 component systems were prepared by mixing each chemical in equal volume ratio. Evaporation rates of pure chemicals and mixtures were then assessed by following the weight loss fraction (Okamoto et al. 2010). All pure chemicals except ammonia showed a linear mass loss over time with a full evaporation observed between 2,5 and 30h after the beginning of the experiment. However, the same chemicals spilled at the surface of seawater generally presented a non-linear mass loss over time, i.e. different and longer evaporation rates. An intermediate behaviour was also observed for mixtures. Given that, these new data could be used to adapt the equations routinely used to model evaporation, particularly on addressing the variations observed for the evaporation rates. This will offer crisis management stakeholders more precise information regarding the formation of toxic, flammable or explosive gas clouds (Go/No Go decision).

How to cite: Cotte, L., Giraud, W., Lepers, L., Legrand, S., Aprin, L., Harold, P., Kibble, A., and Le Floch, S.: On the evaporation kinetics of volatile HNS: A key challenge for Marine Pollution response, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7934, https://doi.org/10.5194/egusphere-egu22-7934, 2022.

Over the last century, anthropogenic emissions led to increasing pollution levels in the environment, including coastal areas. Along with hundreds of other persistent organic pollutants (POPs), polychlorinated biphenyls (PCBs) have been introduced into the environment. Due to their long residence time, these pollutants can not only affect the local ecosystem, but they are also able to go on a steady journey to remote areas, such as the polar regions.

In the presented study, we investigate the role of the North Sea for long range transport of PCBs. For northern Europe, the North Sea is the major transit area between land-based emissions and the open ocean (North Atlantic). Here, local hydrodynamic and biogeochemical features determine whether PCBs are deposited or transported into the open ocean. The interplay and seasonality of sedimentation and resuspension processes determine the overall fate of PCBs in the coastal seas. On the one hand, the biological pump transports PCBs to the sediments. On the other hand, turbulence and mixing can lead to the resuspension of previously deposited PCBs. In the North Sea tidal activity strongly impacts not only the local turbulence regime, but consequently also biological production through the resuspension of nutrients.

Here, we investigate the influence of tides on regions with seasonal stratification and permanently mixed areas. For that we used our newly developed PCB model based on the hydrodynamic biogeochemical modelling system GOTM-ECOSMO. The model has been run for 2 different regimes including model runs with and without tidal activity. Simulations are presented exemplarily for one PCB congener – PCB₁₅₃.

Model results indicate that the seasonality of sedimentation and resuspension has a profound impact on the speciation of PCB in the water column. Removal of PCB from surface waters in summer leads to increased air-sea exchange. Meanwhile, the timing of seasonal resuspension from sediments can lead to peaks of bioavailable PCB species coinciding with primary production peaks leading to increased bio-accumulation.

How to cite: Mikheeva, E., Bieser, J., and Schrum, C.: Impact of tidal activity on the fate of PCB153 in the North Sea, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8333, https://doi.org/10.5194/egusphere-egu22-8333, 2022.

Per- and polyfluoroalkyl substances (PFASs) present themselves as a large self-imposed risk to human health and the environment as a whole. This risk is amplified by the high persistence and long-range transport in oceans. Therefore, this study considers the marine transport of the most widely used PFAS: Perfluorooctanoic acid (PFOA) in the North- and Baltic-Sea, to determine and quantify the relationship between the physico-chemical properties and the potential for long range transport, temporary storage and permanent degradation respectively.

For this purpose, an extensive model chain was established. It contains a newly developed emission model for PFOA approximating global emissions centred around the year 2001 by combining specific point sources (e.g., PTFE production sites) and diffuse emissions by population, from which total PFOA- oads of European rivers are obtained by a hydrological-discharge-model (HDM). This discharge as well as approximations of the air sea exchange based on observed atmospheric concentrations form the input for the Hamburg Shelf Ocean Model (HAMSOM) which is combined with the ecosystem-model ECOSMO. These models are complemented by several newly implemented, locally resolved mechanisms, including photolytic and bio-chemical degradation, adhesion to dissolved and particulate organic matter as well as sedimentation.

To relate the properties of PFOA to its environmental fate, this novel system has been used to consider the PFOA budgets of the major input and output pathways and the exchange between the North and Baltic Sea. In multiple simulations these uncertain physico-chemical properties, as well as boundary conditions for input and output were varied and the simulation was run over multiple years until a quasi-equilibria state was reached.

The simulated budgets show that degradation plays in general a minor role for the North- and Baltic-Sea while the ratio of PFOA stored in sediments compared to the amount lost to the Arctic- and Atlantic Ocean strongly depends on the chosen partitioning coefficients. Furthermore, the comparison of simulated concentrations to actual marine measurements allowed to narrow the plausible range of these uncertain physico-chemical properties, based on marine conditions in contrast to lab measurements.

Understanding the sensitivity of the transport and long-term fate of PFOA depending on its properties may point to simpler approaches to assess the fate of other PFASs where, due to their limited use, less data is available.

How to cite: Simon, P., Bieser, J., and Schrum, C.: Modelling the fate of per- and polyfluoroalkyl substances in the North- and Baltic Sea, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8400, https://doi.org/10.5194/egusphere-egu22-8400, 2022.

The dependence on petroleum-based polymers such as polypropylene (PP) has led to a series of environmental issues, including the persistence of microplastic (MP), i.e. plastic particles smaller than 5 mm in diameter, in the global ocean. Polymers made from a natural-sourced feedstock, like polylactic acid (PLA), known as bio-based polymers, are seen as more sustainable alternatives to petroleum-based polymers. However, our knowledge remains limited about their degradation rates and fate in the marine environment. Studies have provided evidence of the release of MP from larger debris under ultraviolet (UV) radiation in laboratory conditions. However, quantitative evidence of MP formation, i.e. observation, identification and enumeration of MPs formed after UV radiation, is limited. Indeed, only a few studies have assessed the disintegration of bio-based polymers and their capacity to form MPs. As part of the Interreg 2 Seas Mers Zeeën project SeaBioComp (seabiocomp.eu), we aim to compare, quantify and characterise the MP formation of a newly developed bio-based composite (i.e. bio-based polymers integrated with synthetic or natural fibres) and a reference petroleum-based polymer during their degradation under UV radiation. To do so, we exposed 3D printed cylinders (1 x 1 x 1 cm) of self-reinforced PLA (SR-PLA) and PP respectively, immersed in natural seawater, to accelerated UV radiation for 1,368 h, simulating about 18 months of natural solar exposure in central Europe. Dark controls (i.e. in sealed vials from the UV) were incubated in the same conditions also for 1,368 h. To identify, characterise and quantify the formed MPs, we used a combination of fluorescent microscopy, infrared technology (μFT-IR) and image analysis. We observed 263 ± 285 PP MPs (> 50 µm) and 14 ± 9 SR-PLA MPs in UV-weathered samples, while 3 ± 4 PP MPs and 7 ± 3 SR-PLA MPs in dark control samples. 1,368 h UV exposure accelerated the MP formation of PP (P < 0.05, Kruskal-Wallis) but not SR-PLA (P = 0.29, Kruskal-Wallis), suggesting that the bio-based composite SR-PLA is more resistant to releasing MPs than the reference petroleum-based polymer. We anticipate that our results will contribute to assessing the sustainability of future bio-based polymers and composites applications and to supporting a transition process to more sustainable plastic materials.

How to cite: Niu, Z., Catarino, A. I., Le Gall, M., Curto, M., Demeyer, E., Hom, D., Davies, P., and Everaert, G.: Release of microplastics from a bio-based composite after ultraviolet irradiation  , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8508, https://doi.org/10.5194/egusphere-egu22-8508, 2022.

The polar plastics research community have recommended the spatial coverage of microplastic investigations in Antarctica and the Southern Ocean be increased, and that focus is given to areas with likely microplastic and zooplankton presence and overlap, such as South Georgia. Presented here is a baseline estimate of microplastics in the nearshore, marine waters of South Georgia, the first systematic study of the north-east coast of the island. We estimate the mean concentration of microplastics in seawater to be 2.39 ± 3.58/L (± SD), approximately one order of magnitude higher than the majority of other studies of sea surface waters south of the Polar Front. The maximum concentration of microplastics in wastewater from King Edward Point research station was 1.44 ± 4.93/L (mean ± SD). Following FT-IR polymer analysis and categorisation of microplastics solely by material, multivariate analysis revealed a 22% similarity in the microplastic profiles of wastewater and the seawater it enters. We hypothesise that microplastic pollution from the research base constitutes a fraction of the input into the local marine environment. To explain the observed discrepancy, we hypothesise alternative sources of contamination to be microplastic transported from afar, microplastic from ships (estimated to be up to 36.8 million synthetic fibres per year) and precipitation based on the concentration of microplastic in a single snow sample (15.89 ± 23.72/L, mean ± SD). There was no significant difference in the microplastic concentration between seawater sites, and no significant bilateral relationship between concentration and distance from the research station outlet, however we recommend further finescale mapping of the nearshore hydrological regime to develop a holistic picture of microplastic dispersal and retention at the coast. 

South Georgia is a biodiversity hotspot to which the potential hazard of microplastic pollution is relatively unknown. This research is part of a wider project examining the ecological fate of microplastics in the marine nearshore waters of South Georgia using a source to sink approach. Additional research currently producing preliminary results includes determining the level of microplastic ingestion by keystone plankton and economically important fish species, as well as assessing the potential for trophic transfer of microplastics to higher predators in the region.

How to cite: Buckingham, J., Waller, C., Manno, C., Waluda, C., and Parsons, D.: Microplastic in the marine nearshore waters of South Georgia: a source to sink approach , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9416, https://doi.org/10.5194/egusphere-egu22-9416, 2022.

Microplastic (MP) in the ocean is a major environmental problem. Better understanding of how MP, released from anthropogenic sources, is transported is crucial to quantify and close the global inventory of marine MP. At the same time, neutrally buoyant MP can be considered as a passive tracer that provides the opportunity to learn more about the turbulent dynamics of the ocean across multiple scales.

This work explores the turbulent dispersion of MP with a 3D Lagrangian stochastic model, developed by the authors, with particular attention on the Ocean Surface Boundary Layer (OSBL).

The inputs of the model are operational oceanographic data, downloaded from the Copernicus Marine Monitoring Environment Service, such as current velocities, mixed layer depth and friction velocity. The simulated trajectories are described by a Wiener process in which the vertical turbulent diffusivity is parameterized with a novel method developed by the authors. The advantage of the Lagrangian approach is to reproduce turbulent dispersion processes at sub-grid scales.

A 10-year 3D simulation of the MP dispersion in the Mediterranean basin has been performed.  MP pathways and accumulation zones in different periods of the year have been identified.

The distribution of MP in the water column has been obtained. The behavior of different polymers has been investigated showing that particle settling prevails with respect to vertical turbulent dispersion. Despite the concentration of particles is maximum at the sea surface, the quantity spread into the water column is not negligible.

How to cite: Zazzini, S., Pini, A., Bello, P., Monti, P., and Leuzzi, G.: 3D pathways and distribution of microplastics in the Ocean Surface Boundary Layer, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9935, https://doi.org/10.5194/egusphere-egu22-9935, 2022.

Deep-sea oil releases from accidents during offshore exploratory drilling or production are of particular concern, as the potential for such accidents increases with the expansion of the offshore industry to more extreme environments. During the 2010 Deepwater Horizon, huge amounts of oil were released into the Gulf of Mexico, adversely affecting marine wildlife. What prevented a worse outcome was the ability of nature to biodegrade oil.  

To this end, the community oi spill model MEDSKIL-II has been modified to incorporate biodegradation kinetics of dissolved oil and oil droplets dispersed in the water column. Biodegradation of oil can be modelled by Monod kinetics or as a first order decay process. The kinetics of oil particles size reduction due to the microbe-mediated degradation at water-oil particle interface is represented by the shrinking core model. Furthermore, a Lagrangian plume module has been developed and coupled to MEDSLIK-II, for predicting the fate of the spill until reaching the sea surface. The Lagrangian plume model is represented by elements that trace the plume’s trajectory. Each Lagrangian element represents a mixture of water, oil and gas. Changes in the mass and composition of the element are accounted for by the turbulent entrainment of ambient water, leakage of gas bubbles and oil droplets from the plume, dissolution of gas in seawater, and formation or disintegration of gas hydrates. The motion of the element is computed from the conservation equations for mass, momentum, and buoyancy. Biodegradation kinetics are also represented in the model, to enhance prediction of fate and transport of deep-sea spills.

A novel sampling apparatus was designed for the collection of indigenous microbial populations from the deep Eastern Mediterranean Sea, maintaining in situ pressure throughout the entire process of retrieval and experimentation to determine microbial oil degradation. Seawater samples were collected on board the R/V Aegaeo (Hellenic Centre for Marine Research) on 2-29-2020, off Southeast Crete, Greece. The High Pressure (HP) Sampler collected seawater between 600 to 1000 m depth. A known volume of the collected sample was transferred via a piston pump, without pressure disruption, into a HP-Reactor, at 10 MPa pressure and was incubated with crude oil at plume concentration for 77 days at in situ temperature (14^οC). Iranian light crude oil bioremediation was monitored for 35 days, and then the effect of dispersant addition (1:25 v/v COREXIT 9500) was observed until day 77. Kinetic analysis was used to estimate the degradation rates of hydrocarbon compounds, which were incorporated into the integrated modified MEDLSLIK-II model to simulate the effect of biodegradation on the fate and transport of subsurface spills for the Sea of Crete. Several scenarios have been considered to include the different laboratory data and oceanographic fields (water density, currents) for the area. To our knowledge, this is the first modelling effort incorporating area-specific data for biodegradation capacity of hydrocarbon degrading consortia to predict the fate of deep-water oil releases in the Eastern Mediterranean Sea.

Acknowledgement:

This research was funded by the GSRT and HFRI projects DEEPSEA, GA No 1510 and HEALMED, GA No 1874.

How to cite: Spanoudaki, K., Antoniou, E., Fragkou, E., Charalambous, G., Gontikaki, E., and Kalogerakis, N.: Modelling of deep-sea oil spill releases incorporating hydrocarbon biodegradation kinetic rates of the Eastern Mediterranean deep-sea consortia , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10236, https://doi.org/10.5194/egusphere-egu22-10236, 2022.

It is well known, that after World War II, during the Potsdam Conference, the decision was made to demilitarize Germany, resulting in ammunition containing Chemical Warfare Agents (CWA) being dumped into the selected dumpsites area of the Baltic Sea. In some other region, such as Skagerrak, ammunition was loaded on ships that were sunk. Some ships have been damaged in sinking at sea, causing munitions to be scattered on the seabed, while others are still relatively intact (Tørnes et al., 2020).  Some of the bulk ammunition has been observed to be opened by corrosion (Hansen RE, et al. 2019)

A few decades later, scientists wondered what consequences a leak from such dumped munitions could have on the marine ecosystem. Although, more than 70 years have passed since World War II, the impact of a potential leak of the CWA has not been properly assessed yet.

The main goal of this work is to assess pollution from a CWA release from a collapse of the entire shipwreck’s hull in the Skagerrak area. As a main tool High Resolution Dispersion Model (HRDM, Jakacki et al. 2020) has been used for estimating the leakage from the wreck. The horizontal resolution of this model has been increased to about 10 meters for properly holding the release processes and currently, the domain of the model covers an area about 525 km². In our work we will take into account three chemical agents: sulfur mustard, Clark I and tabun. It is planned to make different scenarios that will represent different hydrodynamic conditions in shipwreck area. The calculations will also include the degradation processes of sulfur mustard and tabun, which are not stable in sea water.

Hansen, R. E., Geilhufe, M., Bakken, E. M., Sæbø, T. O., Comparison of synthetic aperture sonar images and optical images of UXOs from the Skagerrak chemical munitions dumpsite. Underwater Acoustics Conference & Exhibition (UACE) 2019 s. 429-436,

Jakacki J., Andrzejewski J., Przyborska A., Muzyka M., Gordon D., Nawala J., Popiel S., Golenko M., Zhurbas V., Paka V., High resolution model for assessment of contamination by chemical warfare agents dumped in the Baltic Sea , Marine Environmental Research, doi: 10.1016/j.marenvres.2020.105079

Tørnes J. Aa., Vik T., Kjellstrøm T.T., Leakage rate of the nerve agent tabun from sea-dumped munition, Marine Environmental Research, doi: 10.1016/j.marenvres.2020.105052

Calculations were carried out at the Academic Computer Centre in Gdańsk

How to cite: Jakacki, J., Tørnes, J. A., Johnsen, A., Muzyka, M., and Przyborska, A.: Modelling study of potential contamination of chemical warfare agents (CWA) from collapsing shipwreck hull in Skagerrak region, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10414, https://doi.org/10.5194/egusphere-egu22-10414, 2022.

The program “PlastEcoTrack”, or “PETrack”, aims at providing an operational support to reduce Floating Marine Litter (FML). More precisely, PET aims at supporting FML reduction strategies both downstream (interception at sea with collect vessels and on beaches with cleaning facilities) and upstream (source identification and reduction), by tracking the dispersion of FML in estuaries and in the coastal ocean. PETrack is currently supported by the European Spatial Agency through the “Plastic-less society” Feasibility Study, as well as by SUEZ group subsidiaries SERAMM and LYDEC.

Using a combination of innovative detection technologies and operational metocean modelling, the service targeted by PETrack will produce tailored decision-aid indicators to monitor and guide FML collect operations, including day-to-day operation support in near real time. Guidance offered by these indicators helps maximizing the amount of FML removed from the natural environment, while at the same time contributing to reduce the cost and impacts of operations (i.e. cost per kilogram of collected FML, fuel consumption, carbon footprint). Moreover, tracking technologies contribute to the reduction of FML emission at the source, by helping to identify most probable emission sectors depending on metocean conditions.

To achieve these purposes, PETrack combines innovative detection solutions based on satellite imagery and video monitoring in the coastal area, together with metocean-based FML transport modelling at local scale. In the operational mode of the service, it provides a decision-aid dashboard supporting day-to-day FML collect operations. The dashboard offers indicators aiming at guiding FML collect operations, to monitor and optimize their efficiency. It especially provides a tracking of FML in the coastal area and a prediction of concentration hotspots to guide collect vessel at sea; and anticipate massive onshore arrivals to help beach cleaning at land.

The service demonstration is under construction in the coastal Atlantic coast of Morocco, in the Casablanca area, and along the French Mediterranean littoral Marseille bay, North Western Mediterranean Sea. It took benefit of pre-existing components developed during the former LIFE LEMA (European Union LIFE program) and FML-TRACK (Copernicus Marine Service User Uptake) projects, which were further improved and complemented to bring the tool and service to a new stage of development and on new application sites with other configurations.

How to cite: Declerck, A., Delpey, M., Voirand, T., Liria, P., Epelde, I., and Mader, J.: Innovative combination of ocean modeling and remote observations to track floating marine litter in the coastal area., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11115, https://doi.org/10.5194/egusphere-egu22-11115, 2022.

Marine plastic litter is one of the most significant signal of the impact of human activities on the marine environment. Therefore, improved methods and models are needed to better understand the distribution pattern of plastics (mainly microplastics) on the sea surface, along the water column, and on the seabed. So far, most plastics sampling campaigns have collected sea surface data, but these data were very scattered and mostly unrepresentative of the seasonal variability of their distribution. A comprehensive overview of the presence of plastic litter in marine enviroment must rely on models having the skill to better represent spatial patterns, interactions with marine ecosystems, and even predict the possible presence of plastic clusters at a specific time and position. Numerous studies adopted models of plastic transport which consider some sources of pollution (rivers, ports, ship routes) to determine plastic distribution in the open sea due to meteo-marine forcing. However, most of these models have not been validated against field data.

In this presentation we show the results of a validation procedure of the modelled marine debris distributions expected in the North-Western Mediterranean between May and September 2019, through the comparison with field observations on the sea surface from campaigns carried out within the Interreg Med project Plastic Busters MPA. Marine debris observations show a significant variability, especially along the coasts, highlighting the need to employ a hydrodynamic model with a resolution much higher than that of basin-scale models. In the comparison between the observed and modelled surface plastic concentrations, the effect of model resolution will be specifically addressed.

How to cite: Brandini, C., Doronzo, B., Bendoni, M., Stefano, T., Maria, F., Massimo, P., Chiara, L., Panti, C., Baini, M., Galli, A., and Fossi, M. C.: Validation of marine plastic litter distribution models on the North-Western Mediterranean, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12815, https://doi.org/10.5194/egusphere-egu22-12815, 2022.

Although microplastic pollution is ubiquitous, accurate quantification is still required and plastic associated chemicals from environmental samples remain largely unexplored. Given the difficulties associated with deep water data acquisition (e.g. costly and opportunistic sampling, weather dependency and engineering restrictions), much of the research carried out on marine plastics to date are either restricted by low spatial or temporal resolution, are isolated studies or are subject-specific in nature due to a lack a multidisciplinary approach. Preliminary video data collected by a Remotely Operated Vehicle (ROV) from an earlier project led by the team previously showed that large plastic items are abundant, especially fishing items, in deep water Irish coral reefs from the Porcupine Bank Canyon and Moira Mounds, both currently listed as Special Areas of Conservation (SACs). This study expands on such previous knowledge of the area and focusses on microplastics by integrating a large spatial range, temporal resolution and novel methodologies. Microplastics and their associated chemicals are being analysed from samples collected by eight Benthic Lander systems and sediment traps deployed between 2019 to 2021. QA/QC techniques are given special importance to ensure the reliability of the analytical results produced. The main outcomes of this study are to (1) accurately quantify the abundance and fate of microplastics and their associated chemicals in deep sea Irish canyons, (2) the interactions and impacts to the health of cold-water corals present in Special Areas of Conservation (SACs) and (3) the potential cause for observed coral health variability throughout time.

How to cite: Mateos Cardenas, D. A., Wheeler, A., and Lim, A.: Monitoring microplastics and their associated chemicals in an Irish deep water Special Area of Conservation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13208, https://doi.org/10.5194/egusphere-egu22-13208, 2022.