Fig. 3. Conceptual model of plastic burial in mangrove sediments.

Mangrove forests, through the mesh created by their pneumatophores, enhance the deposition of plastic particles on their sediments. Since sinking of plastics is size dependent (17), mostly small plastic particles reach the bottom, while larger items may remain suspended in surface waters longer. Once deposited, plastics are sequestered for decades undisturbed. Therefore, sediments are an archive of the chronology of plastic consumption, as demonstrated by the absence of plastic particles in sediments dated older than 1907 (year of the invention of the first fully synthetic polymer) and by the exponential increase of plastic particles toward the most recent sediment layer, as a consequence of the mass production that began in the 1950s.