Hydrodynamic Observations on Microplastic Abundances and Morphologies in the Danube Delta, Romania

Microplastics represent one of the most important concerns of the actual society. With a long environmental persistence, these plastic based particles are transported by the flow and deposited in sedimentary systems. This paper describes the distribution of microplastics in fluvial and lacustrine environments of the Danube Delta. Taking into account that the River Danube and its main distributaries (Kilia, Sulina and St. George) are the primary pathways along which MPs are transferred to the Black Sea, the superficial sedimentary material could testify the pollution degree. Microplastic concentrations identified previously by Pojar et al. (2021a) and the data of flow velocities and fluxes at different hydrological regimes were considered to characterise the MPs distribution, as their abundance and morphology change due to the discharge and currents speed. Our results show that moderate to higher concentrations have been found in the first and second rank locations, related closely with the main distributaries. Complementary, we discuss how hydrodynamics can elucidate the spatial distribution of MPs in the Danube Delta, as well as their path and behaviour in a regional-scale aquatic environment.