2 - Microplastics in seawater and sediments—distribution and transport

Abstract

An overview of the contamination of the Mediterranean marine environment with microplastics (MPs) is presented. At the sea surface, various concentrations of MPs have been detected, which sometimes also coincide with modeling studies. The contamination of subtidal sediments ranges from few tens to few hundreds items per kilogram dry weight, with hotspots—few thousands items per kilogram in the deep Tyrrhenian Sea, in the lagoon of Venice (Adriatic Sea) and in Posidonia oceanica meadows adjacent to agricultural hinterland in Spain. Polyethylene and polypropylene were the most abundant materials in both seawater and sediments, while fragments and filaments were the most frequently found shapes. Photodegradation is the main degradation driver, while biofouling has an important effect on microplastic sinking. Marine biota facilitate the sinking of MPs, the horizontal transport on the seafloor and burial in the sediments.