Embedding marine macro litter observations into the Lagrangian particle tracking model

In the last decade, there has been a significant rise in interest in anthropogenic litter and plastic pollution in the marine environment. The recently proposed Integrated Marine Debris Observing System is expected to encompass three main components: in situ observations, remote sensing, and numerical modeling (Maximenko et al. 2019).

In this work, we show the model-based outcome from systematic observations of floating marine macro litter in the Western Mediterranean and Adriatic seas. Regular ship-based observations of marine litter in the Mediterranean provide unique field data generated by complex hydrodynamic conditions and uncertain pollution sources. The observed floating macro litter distributions 2023–2024 were tracked for 150 days (Liubartseva et al., 2018) using the Parcels Lagrangian model (Delandmeter and van Sebille, 2019). Simulations were implemented using the plasticparcels python package, which is specifically designed for plastic transport and dispersion (Denes and van Sebille, 2024). The drift of virtual particles was forced by the sea surface currents provided by the Copernicus Marine Service reanalysis (Escudier et al., 2021) and by 10-m wind fields from the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5 reanalysis (Hersbach et al., 2023). Turbulent diffusion was represented as a 2D random walk process.

Monthly maps of litter occurrence frequency showed the areas where the litter was most/least likely to be transported. These maps can be superposed with the distributions of the Mediterranean megafauna, such as cetaceans and sea turtles, to conduct the associated risk assessment.

A dedicated web-based application was developed to track the fate of beached litter under the absorbing boundary conditions. This analytical tool allows interactive analysis of the histograms and spatial distributions of beached virtual particles. The results can be compared with vulnerable coastlines as turtle nesting sites to evaluate the risk of contact.

This work was carried out within the framework of the Life CONCEPTU MARIS Project (LIFE20 NAT/IT/001371).

 

References

 

Delandmeter, P., van Sebille, E., 2019. The Parcels v2.0 Lagrangian framework: new field interpolation schemes. Geosci. Model Dev. 12, 3571–3584.

Denes, M.C., Van Sebille, E., 2024. Plasticparcels: A python package for marine plastic dispersal simulations and parameterisation development using parcels. J. Open Source Softw. 9, 7094.

Escudier, R., Clementi, E., Cipollone, A., et al., 2021. A high resolution reanalysis for the Mediterranean Sea. Front. Earth Sci. 9, 1060.

Hersbach, H., Comyn-Platt, E., Bell, B., et al., 2023. ERA5 post-processed daily statistics on pressure levels from 1940 to present. Copernicus Climate Change Service (C3S) Climate Data Store.

Liubartseva, S., Coppini, G., Lecci, R., Clementi, E., 2018. Tracking plastics in the Mediterranean: 2D Lagrangian model. Mar. Pollut. Bull. 129, 151–162.

Maximenko, N., Corradi, P., Law, K.L., et al., 2019. Toward the Integrated Marine Debris Observing System. Front. Mar. Sci. 6, 447.