Modeling chronic oil pollution from ships.

Stochastic simulations of virtual oil spills from ships were performed for the Adriatic Sea over 2017-2020, applying the European Marine Observation and Data Network vessel densities as a proxy for starting locations of operational spillage. The MEDSLIK-II oil spill model was run using high-resolution currents provided by the Copernicus Marine Service and the European Centre for Medium-Range Weather Forecasts winds. Chronic exposure to operational oil spills was reported in terms of hazard indices for five vessel groups: pleasure and passenger ships, cargo and service vessels, the fishing fleet, tankers, and other ships. The northernmost Adriatic expectedly showed the highest hazard values, including the areas of Trieste and Venice, where cargo and service ships were the dominant polluters. The Croatian coastal waters were more chronically polluted than the Italian coastal waters; the predominant contribution was from coastwise pleasure and passenger ships.

Stochastic oil spill modeling for environmental protection at the Port of Taranto (southern Italy).

We performed stochastic simulations of hypothetical oil spills from a single-point buoy mooring and subsea pipeline for the Port of Taranto given that this port is an essential strategic hub in the European logistic chain. Our methodology integrates (1) the MEDSLIK-II oil spill model coupled to a high-resolution hydrodynamic model run on an unstructured grid in operational forecasting mode; (2) a hypothetical oil spill scenario based on a historical pipeline rupture at the Port of Genoa, 2016; and (3) randomly sampling the environmental conditions over 2018-2020. The main oil drift was found to be directed southwesterly towards the outlet to the open sea. When oil is transported by highly variable currents, waves and turbulent mixing, it is exposed to multiple strandings and washing-offs from concrete constructions in the port. Consequently, oil tends to be dispersed almost isotropically over the Mar Grande, indicating low to moderate pollution indices.

Model-based reconstruction of the Ulysse-Virginia oil spill, October-November 2018.

In response to the oil spill caused by the collision between the Ro-Ro ship Ulysse and CSL Virginia on 7th October 2018, the Lagrangian oil spill model MEDSLIK-II was utilized to predict spill transport and fate. Oil drift was forced by the high-resolution sea circulation provided by CMEMS and the ECMWF wind. Successive model runs were restarted 5 times with the distinct overflight- and satellite-derived observations provided by REMPEC and the Copernicus Sentinel-1 mission. The results were verified based on the ability to predict the first oil-beaching event that happened near Saint-Tropez (France) in the early afternoon of 16th October. Despite the general consistency among the runs, only the last initialization was able to forecast the oil beaching. Stochastic MEDSLIK-II simulations forced by the historical meteo-oceanographic datasets 2014-2018 revealed that the coastlines between Cap Lardier and the Gulf of Saint-Tropez were among the most impacted areas.

Are Mediterranean Marine Protected Areas sheltered from plastic pollution?

Comparisons of six selected Mediterranean MPAs were conducted to find similarities and site-specific differences in coastline fluxes and sources of plastic marine litter. Output from the recently developed 2D Lagrangian model for the Mediterranean was post-processed to study (1) the National Park of ses Salines d'Eivissa i Formentera, (2) Nature Reserve of Bouches de Bonifacio, (3) North-East Malta MPA, (4) Specially Protected Area of Porto Cesareo, (5) Community Importance Site of Torre Guaceto, and (6) Ethniko Thalassio Parko Alonnisou Voreion Sporadon. Model coastline fluxes of plastic ranged from 0.4 to3.6 kg (km day)-1, which is relatively low compared to the average flux of 6.2 ± 0.8 kg (km day)-1 calculated over the Mediterranean 2013-2017. Shipping was identified as a major source of plastic litter in all MPAs studied, contributing 55%-88% of total plastic. Site-specific rankings of the top 5 land-based plastic sources revealed that sea surface kinematics control plastic drift.

Tracking plastics in the Mediterranean: 2D Lagrangian model.

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

Regional approach to modeling the transport of floating plastic debris in the Adriatic Sea.

Sea surface concentrations of plastics and their fluxes onto coastlines are simulated over 2009-2015. Calculations incorporate combinations of terrestrial and maritime litter inputs, the Lagrangian model MEDSLIK-II forced by AFS ocean current simulations, and ECMWF wind analyses. With a relatively short particle half-life of 43.7 days, the Adriatic Sea is defined as a highly dissipative basin where the shoreline is, by construction, the main sink of floating debris. Our model results show that the coastline of the Po Delta receives a plastic flux of approximately 70 kg(km day)(-1). The most polluted sea surface area (>10 g km(-2) floating debris) is represented by an elongated band shifted to the Italian coastline and narrowed from northwest to southeast. Evident seasonality is found in the calculated plastic concentration fields and the coastline fluxes. Complex source-receptor relationships among the basin's subregions are quantified in impact matrices.