Extraction and identification of plastic debris in Sargassum spp. from the beaches of Cancun and Cozumel, Mexico

Abstract

The beaches of the Mexican Caribbean have been affected by the arrival of pelagic sargassum since 2011, which has caused economic losses in the area. This research consisted on the evaluation and identification of recovered plastic particles (Rpp) from pelagic sargassum collected at eleven beaches in Cancun and Cozumel. The Rpp were extracted manually before and after washing the sargassum, as well as by filtering the water used to wash it. The Rpp were classified by their size and color using optical microscopy; obtaining that these corresponded to secondary shape plastics and are mostly white in color (35.56 %). They were classified as microplastics (90 %), mesoplastics (9 %) and macroplastics (1 %). Also, Rpp were analyzed by Fourier transform infrared spectroscopy (FTIR) and compared with FTIR spectra of standard plastics, namely, polyethylene (PE), polypropylene (PP) and polystyrene (PS); It was found that the Rpp corresponded to PE (47 %) and PP (41 %). Finally, to corroborate wear or changes in the morphology of the Rpp, they were evaluated by environmental scanning electron microscopy; and wear, fractures and holes were observed on the surface of the particles; this result could be attributed to mechanical wear by ocean waves, as well as exposure to solar radiation for long periods.