Microplastic pollutions in the Anzali Wetland sediments, Southwest Caspian Sea (Guilan Province, Iran)

Occurrence and abundance of Microplastics (MPs) were studied in sediments of the Anzali wetland for the first time in spring 2018. Sediment samplings were carried out using Van Ween Grab. After density separation in saline solution, MPs were counted by a stereomicroscope. The number of MPs was at the range of 14-282 items/100g dry sediment (140-2820 items/kg dry sediment). Stations 10 and 9 with 282 ± 171.14 and 14 ± 3 items/100g dry sediment exhibited the highest and lowest contaminations, respectively. The MPs gathered during the survey varied in size from 0.3 to 5 mm, and those with 1–2 mm in size had the highest frequency (37.3%). The dominant shape of MPs was fiber; Followed by fragments and films. Red, black, and blue were the most abundant colors by 34.1%, 30.8% and 26.4%, respectively. In total, 5 microplastic polymers including polystyrene (PS), polypropylene (PP), polyester (PEST), polyethylene (PE) and poly acrylonitrile (PAN) were identified. This first work provides original data on the presence of MPs, determining their bioavailability to organisms as seafood, and then possible transfer to human. The results provide useful information for further studies.